Mendelianists generally concentrated on "unit characters" that, often as not, involved a mutant defect that is transmitted in opposition to a presumed "normal" trait. Such alternative characters depend entirely on chromosomes. Any alteration in expression that might be influenced by the position of the anther or seed in the flower, or by the position of the flower on the plant, would be dismissed as random environmental variation. In fact, the methods adopted by Mendelianists—sowing seeds together without regards to the source of pollen or ovum within the flower—would conceal any other influence.
Nevertheless, evidence exists that in flowers with two or more distinct types of stamens, pollen from different anthers may produce regular differences in the offspring. Similarly, position of the ovum in the ovary, or seed in the developing fruit, may also influence the expressions of some traits. These differences are probably, in many cases, due to differences in nutrient partitioning.
As Kidd & West (1918) explained:
IT may not always be fully realised to what a degree the developmental capacity of plants is pre-determined by the action of environmental conditions during the earliest stages of their life-histories. During the course of germination and in the seedling stage, or even earlier during the sojourn of the seed upon the parent and in the dormant period, the "potentialities" of plants may be affected by actions which only subsequently produce visible results. These results appear during the later stages of development, without reference to the conditions then existing. In this way adverse conditions in the later stages of development may not suppress a vigour of growth which has been pre-determined under favourable conditions during the ripening of the seed in the previous year; or favourable conditions during summer may fail to increase the yield owing to adverse conditions which have previously operated during the period of germination. It is such effects, namely those which are to be traced to the environmental conditions which have operated in the past stage of the plant's life, that we may term effects of physiological pre-determination in order to mark their distinction from those which are due to hereditary causes.
The same influence may sometimes be traced to the condition of the pollen or ova even before the embryo has formed, and may be found in animals as well as plants.
I think that many instances commonly attributed to the "Inheritance of Acquired Characters" are more properly described as physiological predetermination.
Tull: Of change of Individuals (1751)
So Silkworms, hatch'd and bred in France, of Eggs or Seed brought from Italy, will make as fine Silk as the Italian; but the Eggs of these laid in France, and their Issue, will make no better Silk than the French; though their Food be from Leaves of the same Mulberry-trees, when they make fine Silk and coarse: Therefore 'tis from the Climate, where the Eggs are impregnated, not where they have their Incubation or Food when hatch'd, and fed to their Lives End, that this Difference happens.
Differences in Pollen or Pollination
Vines: A Student's Text-book of Botany, Volume 2
p. 453 (1895)
In the great majority of Phanerogams, however, cross-pollination is the rule. In the case of monosporangiate flowers (e.g. Gymnosperms) it is clear that pollen must be conveyed from a staminate to a carpellary flower. It is also known that in a great number of ambisporangiate flowers, pollination is effected by the transfer of pollen from one flower to another: in some of these cases it has been demonstrated that it is only the pollen of another flower which can effect fertilisation; in other cases, that the pollen of the same flower, though not absolutely useless, has less fertilising power than that of another flower; and in yet other cases, that though the pollen of the flower itself has sufficient fertilising effect, yet the progeny is less vigorous than when pollen is supplied from another flower.
Reychler: Traumatic Pollination (1926)
By experimenting on buds, by fertilising thus direct in the imperfectly developed ovary, conditions are established which nature does not realize: the pollen not passing through the pistil comes directly on the ovules, which are in a state of comparatively imperfect maturity. Thus there are necessarily other physiological influences which, theoretically, seem to be able to manifest themselves by the appearance of new phenomena or by morphological results different from those in normal fertilisation.
In fact, I saw the seeds of the Impatiens sultani germinate by growing two adjacent leaves instead of opposite ones. (Fig. 1). Certain seedlings showed among the normal flowers, here and there, flowers with united ovaries (two and even three), thus showing corollas of strange formation (Fig. 2 and 3). Other seedlings had leaves more or less abnormal; one of them even had all its leaves different in shape (Fig. 4).
Science 248(4963): 1631-1633 (29 June 1990)
Influence of Environmental Quality on Pollen Competitive Ability in Wild Radish
Helen J. Young and Maureen L. Stanton
Pollen of Raphanus raphanistrum produced under low nutrient conditions sired fewer seeds than pollen produced under better conditions when the two types were applied on a stigma together. No difference was seen in single-donor crosses. Male mating success can be strongly influenced by the environmental conditions of pollen-bearing plants, a factor overlooked in studies of plant reproductive biology and in standard quantitative genetic crossing designs, where effects of male parent are equated with heritable genetic variation.
(CybeRose note: If the almost-abortive anthers on the short stamens of rhododendrons, pelargoniums, etc., are nutrient-deficient, we might expect the pollen tubes to grow more slowly than those from the better nourished anthers on the long stamens. This would, as Anderson-Henry suggested, make such pollen grains roughly equivalent to those from parents with short stamens. But if the pollen from long and short stamens is mixed, pollen tubes from the short stamens would have much less chance of reaching the ovary.)
Sexual Plant Reproduction, 3(1): 7-17 (February, 1990)
Relationships of pollen size, pistil length and pollen tube growth rates in Rhododendron and their influence on hybridization.
E. G. Williams and J. L. Rouse:
Pollen size and pistil length data have been collected for 93 species of Rhododendron (Ericaceae) belonging to a number of different subgeneric taxa. For a sample of eight species in section Vireya, pollen tube growth in the style after self- or interspecific pollination has been quantified. Pollen volume and the time taken for pollen tubes to reach the ovary were both related to pistil length. Pollen-tube growth rates were generally greater for species with longer pistils and larger pollen. Increasing temperature increased the rate of pollen-tube growth. There was no detectable effect of pollen tube density on tube growth rate in the style. After interspecific pollinations tube growth rates in foreign styles could be faster or slower than in self styles. A semisterile individual with two viable pollen grains per tetrad and a plant grafted as scion to a longer-styled stock both showed more rapid pollen-tube growth than expected on the basis of pistil size. Data collected for 26 species in section Vireya showed that where extreme disparity of pollen/pistil size causes failure of interspecific crosses, one or more bridging species with intermediate pollen/pistil size can generally be selected.
Darwin: Sexual Relations of the Three forms of Lythrum salicaria (1865)
Disparity of pollen/pistil size in Lythrum salicaria distinguishes breeding groups, rather than species as in the Vireya section of Rhododendron.
Darwin: Self- and Cross-Fertilisation
It is, however, possible that the stamens which differ in length or construction in the same flower may produce pollen differing in nature, and in this manner a cross might be made effective between the several flowers on the same plant. Mr. Macnab states in a communication to M. Verlot 'La Production des Varietes' 1865 page 42, that seedlings raised from the shorter and longer stamens of rhododendron differ in character; but the shorter stamens apparently are becoming rudimentary, and the seedlings are dwarfs, so that the result may be simply due to a want of fertilising power in the pollen, as in the case of the dwarfed plants of Mirabilis raised by Naudin by the use of too few pollen-grains. Analogous statements have been made with respect to the stamens of Pelargonium. With some of the Melastomaceae, seedlings raised by me from flowers fertilised by pollen from the shorter stamens, certainly differed in appearance from those raised from the longer stamens, with differently coloured anthers; but here, again, there is some reason for believing that the shorter stamens are tending towards abortion.
In the great bulk of the Scarlet or Horseshoe Geraniums there are but seven stamens, four long ones, one of medium length, but which is often wanting, and two almost sessile like the anthers of Wheat—that is, very short indeed, and opening at the bottom face to face. These two are they which reduce a whole family to beggary; first to dwarfs or Tom Thumbs, or better still, to minimums, or the smallest of that kind consistent with vigour sufficient to become a useful plant in cultivation, and, lastly, to the brink of ruin, and drive that race out of existence altogether, if there were not other means provided to arrest the decline, or keep it from manifesting itself at all in a state of Nature.
Mr. Beaton as the first, perhaps, to find out, and certainly the first so far as I know, to announce this strange discovery, is entitled to its full merit. Its full value has not yet been sufficiently tested. For although I have produced the tiny things in the Rhododendron family which he has done with Pelargonium, inquiry should not stop here. And for my part I did not limit my aim merely to produce by them more dwarfish plants than the parents. Regarding as I did, the pollen of these small anthers as of finer particles than the pollen of the longer and larger ones, I used it as a provision of Nature's own suggesting, in preference to the latter in crossing the smaller species whose pollen-tubes I feared might not admit the grosser globules of these larger anthers. And when the two dwarf stamens failed, I used the smallest and shortest of the remaining stamens.
Journal of Horticulture and Practical Gardening, 16: 341 (May 20, 1869)
Among the Rhododendrons from Mr. Lloyd Wynne, of Coed Coch, was a specimen of R. Falconeri, grown in the open air. Rhododendrons were stated to flourish there on the slate formation; but three miles off, on the mountain limestone, it was hardly possible to get them to grow. Mr. Standish informed him he had tried to hybridise other Rhododendrons with R. Falconeri, but without success, and the reason appeared to be that the pollen tubes are too large to penetrate to the ovules of the kinds used as female parents. He might also mention that totally different results had been obtained by using pollen from short stamens, as compared with that from long stamens, and he believed the same thing had been observed with Pelargoniums.
Country Gentleman's Magazine, 3: 554-555 (December 1869)
How the Tricolor Pelargoniums are Raised.
If, for instance, the pollen of a weak growing variety be placed on four of the five divisions of the style, and pollen from a stronger-growing variety be placed on the fifth division, the seedlings will all have foliage like the stronger. Does not this shew that, to ensure a given result, something more is required than simply placing pollen upon the style? May not the disease (or affection) called 'variegation' be able so far to overcome the power of the pollen from the coarser-growing zonal, as to transmit itself to the seedlings in certain cases, as, when the pollen-bearing plant is a weaker grower; or not in prime health, if a stronger grower; when the pollen itself is immature, or produced by the anthers of the short stamens—anything, in fact, which should just sufficiently restrain the power of the pollen? Whatever may be the cause, the fact remains: that the best plan is to let the green zonal be the seed bearer, and this is the plan adopted by cross breeders generally. Nor is this all: the pollen borne upon the two shortest stamens seems to have special power in increasing the tendency to variegation, but with one drawback, that it also dwarfs the seedlings.
It will be recollected that the stamens of the Zonal Pelargonium are seven in number, five generally being long, and two always on very short filaments, or sessile. These have sometimes been considered as sterile, or imperfect; but I have proved to my own satisfaction that the pollen produced by them is at least not always sterile; and it might perhaps be used with advantage if a dwarfing influence was considered desirable; but this is never the case with regard to Variegated Pelargoniums, as there is very little danger to be apprehended from producing them of an over robust constitution, and, consequently, the pollen produced by the short stamens may safely be dispensed with altogether.
The Floral World and Garden Guide (July 1869)
Raising New Varieties of Zonal Pelargoniums
To breed for large flowers use pollen from the long stamens; both parents should be of the best form possible. If any difference, follow the old rule—take pollen from the best-coloured flower, make the best-formed flower the seed parent. Whites and scarlets bred together produce several shades of cerise and pink.
To breed for bedding plants.—The orthodox method is to take pollen from the short stamens only; and in selecting the parents to consider habit and colour without respect to form. The orthodox method will secure you plenty of ugly flowers, very few good ones. Better follow my plan of breeding from long stamens always, and take your chance of dwarf plants adapted for bedding. My Thomas Moore is a long-stamened plant; it is none too vigorous for a bedder, and the flowers are so grand, that no one who has enjoyed its beauty for a season would dream of going back to Tom Thumb again.
To breed for Tricolors.—Select for seed parent a vigorous dark-leaved zonal, such as Monsieur Barre, or Madame Vaucher, for example. A flat or slightly convex, thick textured, perfectly round leaf, without lobes, is to be desired. In a batch of seedlings you will always have plenty of good breeders for tricolors. Cross the flowers with pollen taken from tricolors of the finest kinds you can get. Variegates and bicolors may be bred the same way. Never breed tricolors or variegates together, for the progeny will be worthless. Green zonals crossed with gold-edged or self varieties will produce a good proportion of bicolors; such as Cloth of Gold and Golden Chain make good pollen parents.
Darlington and Mather: Elements of Genetics, p. 195. (1949) 1969
The differentiation of the embryo-sacs and pollen grains of flowering plants exactly parallels that of the blood precursors. In the pollen of Angiosperms one of the daughter nuclei is pressed by the first mitotic spindle against the wall, while the other is left in the middle of the cell. The peripheral, or generative, nucleus forms a small cell and is rich in nucleic acid: it divides again to give the two condensed sperm nuclei, often before the germination of the grain. The central, or vegetative, one forms a large cell and is poor in nucleic acid: it becomes large and diffuse and loses first its staining power, and then its coherence. It vanishes without further mitosis. (The nucleus of the ripe red blood corpuscle, similarly drained of nucleic acid, similarly dissolves.) This differentiation must depend on the fact that the distribution of materials in the pollen grain before mitosis is not uniform. There is a gradient and the position of the mitotic spindle is adjusted to lie along this gradient. If the axis of the spindle lies crosswise to the normal (following heat shock) cells and nuclei with similar properties are produced: differentiation fails.
American Journal of Botany. 1999; 86:261-268.
The effects of pollen load size and donor diversity on pollen performance, selective abortion, and progeny vigor in Mirabilis jalapa (Nyctaginaceae).
Richard A. Niesenbaum
The influence of pollen competitive environment on pollen performance (pollen germination, stigmatic penetration, and pollen tube growth rate), the maturation or abortion of initiated fruit, seed size, and seedling vigor was explored by manipulating the size and diversity of stigmatic pollen loads on Mirabilis jalapa. All aspects of pollen performance significantly increased with the number of pollen grains on a stigma or pollen tubes in a style, but was not influenced by the diversity of pollen donors. Plants tended to mature single-ovulate fruits that came from flowers where pollen load size and diversity were greatest and aborted those where these were lowest. No plants from seeds resulting from pollinations with a single pollen grain survived, but other fitness measures were mostly determined by maternal plant.
Morse: Pollen Selection (1902)
Pollen grains vary in size and vitality, though they may have been grown in the same stamen. In fact, I am selecting my pollen grains. Method used: A piece of unglazed paper is used, shaking the ripe pollen onto it and curving the paper, and at the same time elevating one end so that the pollen runs down onto a plate. On looking at the pollen with a lens we find that a certain amount of inferior grains are left on the paper, and by repeating the operation only the heaviest grains reach the plate. From experience I have found that these selected grains carry with them the general make-up of the plant bearing them, unless the energy of the stigma overpowers the pollen life. If such is the case the progeny is intermediate between the two in all points. But if the vigor of the pollen predominates it carries with it all the characteristic traits of its parent except color, which invariably leans to the seed-bearing parent. Mixed pollens from differently colored flowers produced all flaked flowers in Gladiolus.
Bradley: Hippeastrums (1906)
Seeing that the top division of the perianth is always the largest and best coloured, I generally use the anther, the filament of which is adnate to this division; whether this be the reason or not I do not know, but the progeny generally have more equal divisions to the perianth, and the bottom division is greatly improved.
On the other hand, with a view to getting as white a bloom as possible, I use the bottom division (generally all white) from the white red-striped varieties; and in the seedlings the flowers have much less colour; but the shape of the bloom is spoilt, the divisions being narrow.
Journal of Evolutionary Biology, 18(1):1-18 (2005)
Pollen and sperm heteromorphism: convergence across kingdoms?
I. Till-Bottraud, D. Joly, D. Lachaise & R. R. Snook
In angiosperms, the different morphs are fertile and produced in similar proportions by all anthers of all flowers of a plant (Till-Bottraud et al., 1994) but they have different physiological characteristics that influence germination and survival rates (Table 3; Dajoz et al., 1991, 1993; Till-Bottraud et al., 1999). The different morphs are sometimes produced within the same tetrad (i.e. from the same germinal cell or the plant equivalent of a sperm cyst; Mignot et al., 1995; Ressayre et al., 1998, 2002), and are determined by variations of the meiosis parameters, such as cytokinesis, tetrad conformation and cell wall deposition (Ressayre et al., 2002). This definition is restrictive compared with that of invertebrates and eliminates the production of different pollen morphs by different anthers of a flower (anther heteromorphism). Given the parallel of anther heteromorphism with double spermatogenesis in animals (i.e. the stamens differentiate early in development), anther heteromorphisms will also be considered. One type of anther heteromorphism occurs in heterostylous species where all plants have two (or three in some species) anther or style heights (Barrett, 2002; Table 3). Each anther height produces a specific pollen morphology that can only germinate and grow in same-height stigmas. Thus, pollen with different morphologies very rarely compete on a stigma. Anther heteromorphism may also occur when two, or rarely three, different anther types are localized in different areas of the flower (heterandry; Faegri & Van der Pijl, 1966). The anthers from which pollen is systematically transported to the stigma are called pollinating anthers and produce fertile pollen. The anthers from which pollen is never or only rarely transported to the stigma are called feeding anthers and act as an attractant to insect visitors. Pollen from feeding anthers can be absent, sterile or fertile (Bowers, 1975). This type of anther heteromorphism is the equivalent of double spermatogenesis in invertebrates.
Position of Seed
The position of a seed upon a plant seems to exert a marked influence. Thus in peas a marked earliness, as much as five days, was found in favor of the lowest, or earliest maturing pods of the Tom Thumb variety, as compared with the higher or later formed pods. In the Sunflower, plants from seeds taken from auxiliary flowers had narrower leaves, and were of a lighter green than other plants from seed taken from terminal flowers. In the Red-top Strap-leaf Turnips the seeds from the terminal blooms were distinctly larger than those from the lower branches. In Sorghum the seed ripens from the summit of the plume downward, and from germination trials we may infer that through selecting terminal seed for successive plantings, increase of earliness would be obtained. In maize the tip kernels showed greater vigor and prolificacy and a finer ear in the crop than did the butt or central kernels of the cob. Experiments in this direction are well worth the attention of the originator's of new varieties.
New Phytol. (1998) 140:655-665
Persistent, non-seed-size maternal effects on life-history traits in the progeny generation in squash, Cucurbita pepo.
Ali El-Keblawy and Jon Lovett-Doust
In control plants, progeny arising from seeds in the large, fully mature 'early' fruits produced significantly more, and larger leaves by day 30 than did those from late fruits (suggesting differential provisioning in seeds during development).
The Floricultural Cabinet. 10: 62 (1842)
On Raising Double Stocks
A South Briton, in Hampshire
Not having heard, or seen elsewhere, the following plan of raising double stocks, I presume to forward the particulars thereof for insertion in the CABINET, assured the readers who attend to the method will find it an excellent one. By practising it I have succeeded in obtaining so many double ones as scarcely to raise a sufficiency of single ones for seed.
In the autumn of 1839 I thought I would try an experiment on the German stock, for which purpose I took out the centre spike of seed and saved it by itself; the others I also saved separately. When the plants raised from the seeds bloomed, I found that those saved from the centre shoots were nearly all double, while the others were nearly all single. I have also tried several other plans, but never succeeded so well with any as with this. Perhaps to some of your readers it is not new, but to others I trust it may not be altogether useless.
Double Stocks (1904)
Prof. de Vries
The first point, is the question, which seeds become double-flowered and which single-flowered plants? Beyond all doubt, the determination has taken place before the ripening of the seed. But though the color of the seed is often indicative of the color of the flowers, as in some red or purple varieties, and though in balsams and some other instances the most “highly doubled” flowers are to be obtained from the biggest and plumpest seeds, no such rule seems to exist respecting the double stocks. Now if one half of the seeds gives doubles, and the other half singles, the question arises, where are the singles and the doubles to be found on the parent-plant?
The answer is partly given by the following experiment. Starting from the general rule of the great influence of nutrition on variability, it may be assumed that those seeds will give most doubles, that are best fed. Now it is manifest that the stem and larger branches are, in a better condition than the smaller twigs, and that likewise the first fruits have better chances than the ones formed later. Even in the same pod the uppermost seeds will be in a comparatively disadvantageous position. This conception leads to an experiment which is the basis of a practical method much used in France in order to get a higher percentage of seeds of double-flowering plants.
This method consists in cutting off, in the first place the upper parts of all the larger spikes, in the second place, the upper third part of each pod, and lastly all the small and weak twigs. In doing so the percentage is claimed to go up to 67-70%, and in some instances even higher. This operation is to be performed as soon as the required number of flowers have ceased blossoming. All the nutrient materials, destined for the seeds, are now forced to flow into these relatively few embryos, and it is clear that they will be far better nourished than if no operation were made.
In order to control this experiment some breeders have made the operation on the fruits when ripe, instead of on the young pods, and have saved the seeds from the upper parts separately. This seed, produced in abundance, was found to be very poor in double flowers, containing only some 20-30%. On the contrary the percentage of doubles in the seed of the lower parts was somewhat augmented, and the average of both would have given the normal proportion of 50%.
Opposed to the French method is the German practice of cultivating stocks, as I have seen it used on a very large scale at Erfurt and at other places. The stocks are grown in pots on small scaffolds, and not put on or into the earth. The obvious aim of this practice is to keep the earth in the pots dry, and accordingly they are only scantily watered. In consequence they cannot develop as fully as they would have done when planted directly in the beds, and they produce only small racemes and no weak twigs, eliminating thereby without further operation the weaker seeds as by the French method. The effect is increased by planting from 6-10 separate plants in each pot.
It would be very interesting to make comparative trials of both methods, in order to discover the true relation between the practice and the results reached. Both should also be compared with cultures on open plots, which are said to give only 50% of doubles. This last method of culture is practiced wherever it is desired to produce great quantities of seeds at a low cost. Such trials would no doubt give an insight into the relations of hereditary characters to the distribution of the food within the plant.
A second point is the proportional increase of the double-flowering seeds with age. If seed is kept for two or three years, the greater part of the grains will gradually die, and among the remainder there is found on sowing, a higher percentage of double ones. Hence we may infer that the single-flowered seeds are shorter lived than the doubles, and this obviously points to a greater weakness of the first. It is quite evident that there is some common cause for these facts and for the above cited experience, that the first and best pods give more doubles. Much, however, remains to be investigated before a satisfactory answer can be made to these questions.
The Canada Farmer, 1: 269 (Sept. 15, 1869)
The following directions for growing these beautiful flowers, so that they will be constantly improving with every year's cultivation, we find in substance in the Genesee Farmer:—
The plants should be started so early in the season that they will give a second bloom, for the reason that the first and best blooms of very double balsams seldom bear seed. The seed should be saved from the centre shoots only, and as low down on the stalk as possible. It is recommended to cut off all the branches or side shoots, so as to throw all the strength into the centre shoot. Seed should never be taken from side shoots, nor from the top of the centre stalk. By planting the best double-rose balsams in close proximity to the others, they will be hybridized by the bees, thereby rendering the others more double next year, and imparting to them a double colour.
The soil can not be too rich, but the manure should be well rotted and thoroughly mixed with the soil. If the seed is sown thinly in the hotbed, and the plants allowed to stand until they show for bloom, they can then be removed with a ball of earth and receive less check than if transplanting when quite small.
The Floricultural Cabinet. 10: 10-11 (1842)
On Selecting Flower Seeds
R. F. of Roxburghshire
Much has been both said and written on the growing of flowers, and what soil they should be grown in, &c; but there has been little about collecting the seed. A few observations upon it I think are required; and as no other writer in the CABINET has touched upon it, I venture to forward the following, and commence with the Dahlia.
When one considers the vast quantity of seedlings raised every year, and comparatively so few good double flowers are produced, if there could be means used by which to curtail the quantity raised in the whole, and yet get as many good flowers, there would be a great saving of trouble as well as expense. I have always been partial to flowers, and am much interested in experiments. One that I tried on the English Marigold exceeded my most sanguine expectations. I took a head and planted each row of seed separate from the others, and I found that the plants from seed nearest the centre of the head was the most double.
I mentioned the circumstance to a nurseryman, and advised him to try the same with the Dahlia seed, which he did the last two years, and the seedlings raised from the seed as collected turned out far better than any he had raised before; so much so, that when one of the Edinburgh nurserymen saw them, he said, "Bless me, Mr. —, how comes it to pass for you to have so many double flowers; for we have only a double one here and there, but you have only a single one here and there?"
If you, or any other readers of the CABINET should think it worthy of a trial, I am confident they will succeed, and I shall feel happy in promoting the interests of floriculture.
Theor Appl Genet (1993) 85: 506-512.
Nuclear DNA changes within Helianthus annus L.: changes within single progenies and their relationships with plant development
L. Natali, A. Cavallini, G. Cionini, O. Sassoli, P. G. Cionini and M. Durante
The variations in the basic nuclear DNA content, which previous results indicated to occur within one and the same progeny of Helianthus annuus, were studied in detail and correlated with certain developmental features of the plants. The size and organization of the genome of seedlings obtained from seeds (achenes) collected at the periphery (P-seedlings) or in the middle (M-seedlings) of the flowering heads of plants belonging to a line selfed for 10 years were compared. Cytophotometric determinations indicated that the nuclear DNA content of P-seedlings is 14.7% higher than that of M-seedlings. Thermal denaturation and reassociation kinetics of extracted DNAs showed that variations in the redundancy of repetitive DNA, in particular of a family of medium repeated sequences with a Cot range of 2–100, account for the differences in genome size. These findings were confirmed by the results of molecular hybridizations (slot blots), which also indicated a higher amount of ribosomal DNA in the P-seedlings than in the M-seedlings. Cell proliferation is affected by DNA content, and mitotic cycle time is 1h30' longer in the P-seedlings.
By studying mature plants, positive correlations were also found between genome size and both the surface area of leaf epidermal cells (P≤0.01) and flowering time (P≤0.001). It is suggested that the variations of nuclear DNA content and organization observed play a role in determining developmental variability in plant populations, which may be of importance in buffering the effects of changing environmental conditions.
Theor Appl Genet (1996) 92: 285-291.
Nuclear DNA changes within Helianthus annuus L.: variations in the amount and methylation of repetitive DNA within homozygous progenies
A. Cavallini, L. Natali, T. Giordani, M. Durante, P. G. Cionini
Complex alterations in the redundancy and methylation of repeated DNA sequences were shown to differentiate the nuclear genome of individuals belonging to single progenies of homozygous plants of the sunflower. DNA was extracted from seedlings obtained from seeds collected at the periphery of flowering heads (P DNA) or from seedlings obtained from seeds collected in their middle (M DNA). Three fractions of repeated sequences were isolated from genomic DNA: a highly repetitive fraction (HR), which reassociates within an equivalent Cot of about 2 x 10-1, and two medium repetitive fractions (MR1 and MR2) having Cot ranges of about 2 x 10-1-2 and 2-102, respectively. Denaturation kinetics allowed different sequence families to be recognized within each fraction of repetitive DNA, and showed significant differences in sequence redundancy to occur between P and M DNA, particularly as far as the MR2 fraction is concerned. Most DNA sequence families are more represented in P DNA than in M DNA. However, the redundancy of certain sequences is greater in the latter than in the former. Each repetitive DNA fraction was hybridized to Southern blots of genomic P or M DNA which was digested to completion by three pairs of isoschizomeric restriction endonucleases which are either insensitive or sensitive to the methylation of a cytosine in the recognition site. The results obtained showed that the repetitive DNA of H. annuus is highly methylated. Clear-cut differences in the degree of methylation of P and M DNA were found, and these differences were particularly apparent in the MR2 fraction. It is suggested that alterations in the redundancy of given DNA sequences and changes in their methylation patterns are complementary ways to produce continuous genotypic variability within the species which can be exploited in environmental adaptation.
Experiment Station Record, 42: 138 (1921)
Possible correlations concerning position of seeds in the pod, B. D. Halsted (Bot. Gaz., 67 (1919), No. 3 pp. 243-250).—In continuation of a similar study of soy beans (E. S. R., 41, p. 42), the author conducted a study with the Henderson Lima bean to determine the possible relationship existing between the position of the seed in the pod and its weight, size, and value for cropping. The results are presented in a series of tables and summarized.
The greatest viability in the variety tested was associated with seeds borne in the middle of the pod. Three-seeded pods constituted over four-fifths of the crop, these and 4-seeded pods being more numerous in the second of the two field harvests of ripe pods. Seeds from the middle of the pods produced a much larger number of pods than did seeds from the base or tip. The heaviest seeds are produced in the 3-seeded pods, and seeds increased in weight from base to tip in all types of pods. Each pod position gave heavier seeds in the second than in the first crop. Seeds associated with aborts excelled those in more normal pods as regards individual weight, this being true for each type of pod and for each pod position. Abortiveness was less in the first harvest, and was least in plants grown from seeds taken from the middle of the pods. Abortiveness was associated chiefly with basal position, decreasing regularly toward the tip of the pod. Pod position giving the greatest seed weight gave also the lowest percentage of abortlveness.
Experiment Station Record, 41: 42 (1920)
Studies on heredity and environment, B. D. Halsted (New Jersey Stas. Rpt. 1917, pp. 372-394).—Studies on heredity and environment (E. S. R., 39, p. 746) were continued with corn, beans, soy beans, peas, and tomatoes.
Some results are given of a preliminary test conducted with soy beans to determine whether a somewhat constant relationship exists between the position of the seed in the pod and its weight, size, and value for cropping. The largest crop of pods came from the seeds borne at the tip of 3-seeded pods and the lowest yield from seeds at the base of the same pods. Seed from 2-seeded pods averaged the highest yield of pods, and seed from 1-seeded pods the lowest A high percentage of l-ovuled 1-seeded pods was associated with the crops from 1-seeded pods and the basal ends of 3-seeded pods. The highest percentage of 2-ovuled 2-seeded pods was associated with the crops from 2- seeded pods with both the basal and tip seeds. The highest percentage of
3-ovuled 3-seeded pods was associated with the crops from tipped seeds of 3-seeded pods. The test indicates that, if possible, it might be well before planting to eliminate the basal seeds from the 3-seeded pods and all 1-seeded pods.
The yield of seeds was best in the 3-seeded tip crop and poorest from the 3-seeded basal crop. For pods as a whole the best average yield of seed was from the 2-seeded pods and the poorest from the 1-seeded pods. Among the full pods the heaviest seed was in the 1-seeded pods, the weight diminishing as the pods increased in number of seeds. In pods containing more than 1 seed the tip seeds were heavier than those at the base. In 3-seeded pods the middle seed was somewhat heavier than the tip seed. Abortiveness was much more frequent in the basal ovules than in the tip ovules, and was in positive correlation with weight of seed.
Kansas Agricultural Experiment Station, Bulletin 30 (Dec. 1891) p. 187-188
Experiments with Corn
C. C. Georgeson
All of these plats were husked and weighed the same day, October 29, when both stalks and ears were thoroughly air dry. Careful examination failed to reveal any difference in the shape of the ears, or in the extent that they were filled out at the tips, all plats being alike in this respect. There is, however, a marked difference in yield in the three grades, the butt kernels not only producing the highest total yield, but also the highest per cent. of good merchantable corn, the middle kernels being intermediate and the tips the lowest, both in total yield and good corn, and highest in poor corn. This is contrary to results obtained at Geneva, N. Y., some years ago, when it was found the tips yielded best. They used, however, a flint corn, whereas this is dent.
...from the observations of de Buzareingues, [*Footnote: 'Ann. Sci. Nat .,' vols. 16 , 24, and 30; 1829, etc.] it appeared that there is a more or less definite distribution of the sexes among the seeds of dioecious plants, the females being more commonly derived from seeds of one region, and the males from those of another. This of course is no proof of original differentiation of sex among the female cells, but it is readily consistent with that hypothesis.
Jones: Selective Pollination (1928)
The sex in Melandrium is determined by the pollen, and Correns considers the difference in the two classes to be due to a faster rate of growth of the pistillate-determining pollen tubes, as indicated in the foregoing results and also in the following experiment. The seeds of this plant are borne on a common placenta in which the pollen tubes grow. The first tubes to reach the ovary fertilize the ovules in the upper part of the seed capsule; while the later tubes have to pass on down and fertilize those in the lower part. This was proved to be the case by pollinating a white-flowered plant with pollen from a red-flowering sort. Later, pollen from a white plant was applied. The upper third of the capsule yielded 45 percent, while the lower two-thirds gave 7 percent, red-flowered plants. The greater proportion of white flowers in both lots indicates a selective action in favor of the plants' own kind of pollen, although this is not the question at issue. The difference in position of the seeds shows that the first pollen tubes to enter the ovary tend to fertilize the ovules in the upper part. For that reason the difference which Correns obtains of 67 percent pistillate plants from the upper part and 55 percent from the lower part indicates also that the female-determining pollen grains produce faster-growing pollen tubes. More pistillate plants were also obtained by pollinating at the tip than at the base of the pistils. Apparently the rate of growth of the pollen tubes is not the only factor involved, since an excess of pistillate plants is obtained even when every pollen grain has a chance to function. A selective elimination, sufficient to account for this difference, may occur after fertilization.
The age of the pollen profoundly affects the proportion of pistillate plants. Starting with approximately equal numbers of the two types obtained from fresh pollen, the percentage of pistillate plants regularly decreased to zero as the pollen was aged up to 100 days before being applied, the staminate-determining grains being more viable.
Condition of Parents
Science 248(4963): 1631-1633 (29 June 1990)
Influence of Environmental Quality on Pollen Competitive Ability in Wild Radish
Helen J. Young and Maureen L. Stanton
Pollen of Raphanus raphanistrum produced under low nutrient conditions sired fewer seeds than pollen produced under better conditions when the two types were applied on a stigma together. No difference was seen in single-donor crosses. Male mating success can be strongly influenced by the environmental conditions of pollen-bearing plants, a factor overlooked in studies of plant reproductive biology and in standard quantitative genetic crossing designs, where effects of male parent are equated with heritable genetic variation.
Sexual Plant Reproduction 7(4): 215-220 (July 1994)
Effects of soil phosphorus on pollen production, pollen size, pollen phosphorus content, and the ability to sire seeds in Cucurbita pepo (Cucurbitaceae)
Tak-Cheung Lau and Andrew G. Stephenson
To determine the effects of soil phosphorus on pollen production, pollen grain size, phosphate concentration per pollen grain, and the siring ability of pollen, two cultivars of the common zucchini (Cucurbita pepo) were grown under two soil phosphorus conditions in an experimental garden. Overall, soil phosphorus availability had a significant effect on reproductive output through the female function and on traits affecting the male function of plants (staminate flower production, pollen production per flower, and pollen grain size). In addition, pollen produced by plants in the high phosphorus soils had a higher phosphate concentration than pollen produced by plants in the low phosphorus soils. A pollen mixture experiment revealed that pollen produced by plants in the high phosphorus treatment sired significantly more seeds than pollen produced by plants in the low phosphorus treatment. This study showed that growing conditions such as soil phosphorus can influence the size of a pollen grain and its chemical composition, which, in turn, can affect its ability to sire mature seeds.
Philos Trans R Soc Lond B Biol Sci. 358(1434): 1009–1018. (June 29, 2003)
Pollen performance before and during the autotrophic-heterotrophic transition of pollen tube growth.
Andrew G Stephenson, Steven E Travers, Jorge I Mena-Ali, and James A Winsor
We found that the ability of the paternal sporophyte to provision its pollen during development significantly influences pollen performance during the autotrophic growth phase. Consequently, under conditions of pollen competition, pollen selection during the autotrophic phase is acting on the phenotype of the paternal sporophyte. In a field experiment, using Cucurbita pepo, we found broad-sense heritable variation for herbivore-pathogen resistance, and that the most resistant families produced larger and better performing pollen when the paternal sporophytes were not protected by insecticides, indicating that selection during the autotrophic phase can act on traits that are not expressed by the microgametophyte.
Sexual Plant Reproduction 11(5): 265-271 (November 1998)
Variation in sporophytic and gametophytic vigor in wild and cultivated varieties of Cucurbita pepo and their F1 and F2 generations.
M. H. Jóhannsson and A. G. Stephenson
This study examines sporophytic and gametophytic vigor in wild and cultivated varieties of Cucurbita pepo L. and their hybrids in order to determine whether hybrid vigor extends to the microgametophyte generation. It also examines the variation in sporophytic and gametophytic vigor to discern the non-genetic influences of pollen provisioning by the sporophyte on pollen performance from the genetic influences of the microgametophyte's own genotype on pollen performance. A cultivated and a wild C. pepo and their F1 and the F2 generations were grown under field conditions and flower and fruit production were monitored over one summer. We found that the four types of plants differed significantly in the number of male and female flowers and the number of fruits they produced. The F1 plants produced significantly more male flowers and marginally more female flowers and fruits than the parental lines. To estimate gametophytic vigor pollen was germinated in vitro and pollen tube length measured after 30 min. We found that pollen tubes from the F1 plants had significantly greater growth than tubes from the parental lines or the F2 generation, indicating that hybrid vigor extends to the microgametophytic generation. By partitioning the variance of pollen tube growth into 'within' and 'among' plant components of variation, we were able to show that the genotype of the microgametophyte influences pollen performance in vitro, but that expression of hybrid vigor in the microgametophyte is likely to be due to an environmental effect related to provisioning of the pollen grains during development.
Sexual Plant Reproduction 14(2): 77-83 (September 2001)
The performance of microgametophytes is affected by inbreeding depression and hybrid vigor in the sporophytic generation
A. G. Stephenson, C. N. Hayes, M. H. Jóhannsson, J. A. Winsor
Inbreeding reduces the level of heterozygosity, thereby exposing deleterious recessives to selection and simultaneously reducing the number of loci expressing heterosis (overdominance). In contrast, hybridization increases the level of heterozygosity, thereby masking deleterious recessives and simultaneously increasing the number of loci expressing heterosis. Most studies of inbreeding depression/hybrid vigor have focused on sporophytic performance such as survivorship, vegetative growth rates, fruit and seed production and (rarely) pollen production. Because the genetic mechanisms that underlie inbreeding depression/hybrid vigor are relevant only to the diploid stage of the life cycle, most studies have tacitly assumed that they have no effects on pollen performance (pollen germination, pollen tube growth rate, ability to achieve fertilization under conditions of pollen competition). However, we reasoned that because pollen is dependent upon the sporophyte for the resources necessary to develop, germinate and initiate tube growth, the level of heterozygosity (vigor) in the pollen-producing parent can affect pollen performance by affecting the ability of the sporophyte to provision its pollen. In a series of studies conducted under field conditions over 7 years, we experimentally varied the level of heterozygosity in wild gourd (Cucurbita pepo) plants (four levels of inbreeding, f = 0.75, 0.50, 0.25, 0 and a zucchini x wild gourd F1). We found that sporophytic vigor (e.g., flower and fruit production) increased with the level of heterozygosity and that the level of heterozygosity of the sporophyte affects the in vitro and in vivo performance of the microgametophytes it produces. These findings are analogous to the ”maternal environmental effects" frequently observed in seeds.
Tull: Climate changes plants (1751)
This beneficial Change of Individuals seems rather to be from the forementioned Causes, than from Change of Food; and these Causes shew their Efficacy, chiefly in the Generation or Foetation of those Seeds; as Flax-seed brought from Holland, and sown here, will bring as fine Flax as there; but the very next Generation of it coarser, and so degenerating gradually, after Two or Three Descents, becomes no better than the common ordinary Sort; yet its Food is the same, when the Flax is fine, as when 'tis coarse.
Khan, R. A., and H. M. Laude (1969) Influence of heat stress during seed maturation on germinability of barley seed at harvest. Crop Sci. 9: 55-58
Riaz A. Khan and Horton M. Laude
A germination response to high temperature stress at stages of seed maturation is demonstrated in barley (Hordeum vulgare L.). The germination of freshly harvested seed is depressed following heat stress at 7 to 10 days after awn emergence, but is enhanced by the same stress applied 3 weeks after awn emergence. The depression is attributed to reduced viability associated with thermal injury. The stimulation following stress at more mature stages of seed development is related to a thinner seed coat, increased permeability as evidenced by faster imbibition rate, and decreased water-soluble inhibitor content of the seed. These effects of environmental stress during seed maturation aid in explaining differences noted in the germinability at harvest of seed produced in successive years or produced in the same year at different locations.
American Journal of Botany. 88:242-257. (2001)
Mechanisms of differential pollen donor performance in wild radish, Raphanus sativus (Brassicaceae)
Diane L. Marshall and Pamela K. Diggle
The process of pollen tube growth and fertilization differed substantially among maternal watering treatments, with many early events occurring more quickly in stressed plants. Seed paternity, however, was somewhat more even among pollen donors used on stressed maternal plants, suggesting that when maternal tissue is more competent, mating is slowed and is more selective.
Michurin: Principles and Methods (1929)
The age and health of the parent plants chosen for the crossing are of very great significance in practice. Young hybrid plants in their first bearings, or older plants that have been bearing for many years but which were weakened by a dry or unusually cold spring during the given vegetation period, possess a weaker individual capacity for hereditarily transmitting their properties, and, conversely, plants belonging to pure species and, particularly, wild forms in their prime, possess the greatest capacity of handing down their properties to the hybrids.
Babcock: Remarkable Variations in Tarweeds (1924)
DURING the course of a genetical investigation of two of the Hayfield Tarweeds a number of interesting variations have appeared among populations only one, two, three, or four years removed from the wild state. Some of the variations which were found among about 400 plants during the first season of garden culture are the following: Size of plant, habit (form) of plant, color of flowers (corolla and stamen tube), structure of flowers (petallody), size of leaves (width and length), pubescence on leaves (long, appressed or short, spreading), and other less striking differences. From the first year garden cultures numerous pairs of plants were chosen and crossed because the individual tarweed, like the individual sunflower, is self-sterile. From their progeny similar pairs were again chosen and crossed, and this was repeated, so that inbreeding by brother and sister mating was practiced in some strains for two or three years, when these strains became so weakened that very few progeny were obtained. It was in these inbred strains that most of the other variations herein described were found.
Worsley: The Brunsdonnas (1926)
An account of B. x Parkeri appeared in Journal R.H.S., November 1909. By that time I had twice obtained fruit from it. It first flowered with me in August 1897. I raised fruit upon it in 1899, and again in 1904. Only two of the seedlings from these fruits have yet flowered, and both proved typical B. x Parkeri.
B. x Parkeri alba was raised by self-fertilizing a multi-petalled flower of B. Parkeri in 1904, and it flowered for the first time in September 1911, when it received an A.M. Two bulbs from this batch have proved to be B. x Parkeri alba, and two others were B. x Parkeri.
B. x Parkeri alba varies from B. x Parkeri in several respects besides colour. In a general sense it varies as Crinum Powellii alba varies from the original C. Powellii, the flowers being larger, shorter in the tube-shaped part of the limb, and more recurved.
The seeds producing B. x Parkeri alba were discernible from those of bulbs that have produced coloured flowers. On dehiscence of the fruits these seeds were colourless ; the type, coloured pink.
Hurst: Mechanism of Creative Evolution (1932) pp. 112-113
Several external factors may be the cause or occasion of this duplication of chromosomes. A severe frost, for example, will temporarily suspend divisions in the pollen grains and cause some germ-cells to form (provided the frost has not been too severe), bearing twice the normal number. These on fertilising normal egg-cells will produce triploids or, if the egg-cells have been similarly affected, tetraploids. In gardens where many plants are out of their natural environment, having come from countries with more regular climates, such occurrences are not infrequent. In their own country, once the winter is over, they produce their flowers with no set-backs, but in England, where we get a warm spell in the spring long enough to bring out the flowers, often followed by a severe frost for several nights just as the flowers are forming, many aberrations and abnormalities arise. Similarly in a wild state, an unusual season may upset many of the normal mechanisms of the plant. De Mol has discovered that many of the different chromosome types in bulbous plants have been due to the custom of drying off the bulbs after the flowering season and, in the case of bulbs for commerce, the subsequent forcing to produce early-flowering for culture in pots. These bulbs, being subjected to various degrees of temperature at the time of the formation of their germ-cells (these being formed deep down in the bud during the previous summer or autumn before flowering), produce various irregularities of division. Many of these irregularities fail to carry on but the few that struggle through will give rise to new races, sometimes of great beauty, for our gardens.
Michurin: Principles and Methods
4. The age and health of the parent plants chosen for the crossing are of very great significance in practice. Young hybrid plants in their first bearings, or older plants that have been bearing for many years but which were weakened by a dry or unusually cold spring during the given vegetation period, possess a weaker individual capacity for hereditarily transmitting their properties, and, conversely, plants belonging to pure species and, particularly, wild forms in their prime, possess the greatest capacity of handing down their properties to the hybrids. Thus, for example, from the cross of the Crimean Kandil Sinap with the Siberian crab apple [Malus baccata Borkh.] hybrids were obtained with fruits the size of our ordinary orchard Kitaika [Malus prunifolia Borkh.], whereas the cross between Kandil Sinap with the seedlings of our orchard Kitaika in its first blossoming produced fruits of an excellent taste. In this case the maternal parent was the young seedling of the Kitaika, not the pure type of course, but a hybrid; this became evident later from the larger size of its fruit as compared with the ordinary size of the Kitaika. That is why its resistance properties were not transmitted with due intensity, and as a result the shoot ends of the seedlings obtained from this cross suffered from the frost. To eliminate this shortcoming the hybrids had to be placed once again under the influence of their female parent—Malus prunifolia Borkh.—by grafting cuttings of the seedling into the crown of the maternal tree, which soon gave the required degree of resistance to the new variety. This circumstance should be taken into consideration when choosing the parent plants.
It has been likewise remarked that flowers chosen for fertilization on the maternal plant, if placed nearer to the main vertical branches of the trunk, give better hybrids with larger-sized fruit but such that tend to deviate considerably in structure in the direction of the maternal plant, and, conversely, flowers on the horizontal branches, placed nearer to the periphery of the crown generally give hybrids with fruit of smaller size and such that deviate in the direction of the male parent. The shady side of the maternal plant yields hybrids of poorer quality as compared to the sunny side. This is particularly clearly expressed by the depth of the outer colouring of the fruit and by the amount of sugar in the pulp.
Marshall & Whittaker: Am. Jour. Bot. 76(7): 1081-1088 (July 1989)
Effects of pollen donor identity on offspring quality in wild radish, Raphanus sativus
There were significant effects of paternity on two measures of early growth: leaf number and plant height. Paternal effects on three measures more closely related to fitness; final plant weight, day of first flower production, and total flower number were also significant. Under the conditions of this experiment, final plant weight was probably the best predictor of fitness. The pollen donor that sired the largest seeds in the previous experiment sired offspring that were largest after 8 weeks of growth. Half of the plants were grown under low-water conditions. Paternal effects on growth were not masked by the environmental effects. In fact, some paternal effects became stronger under stress.
Galloway: Ecology 82: 2781-2789. (2001)
Parental environmental effects on life history in the herbaceous plant Campanula Americana.
Maternal light environment also did not affect percentage germination (Table 2). However, the paternal light environment did influence germination percentage (Table 2). Seeds whose fathers grew under low-light conditions germinated in larger numbers than seeds from fathers in which light was not as limited (Fig. 2).
Evolutionary Ecology 19(3): 275-288 (May 2005)
Effects of Nutrient Level on Maternal Choice and Siring Success in Cucumis sativus (Cucurbitaceae)
Teklehaimanot Haileselassie, Margaret mollel and Io Skogsmy
In this paper we address the question of weather nutrient availability for the female affects the outcome of pollen competition between two pollen donor cultivars of Cucumis sativus. We do this by carrying out controlled crosses of female plants grown at three different nutrient levels. We separated the effect of a specific donor from the effect of pollen tube growth rate by using reversed crosses of fast and slow pollen. Our results show that female effects on siring ability vary with nutrient level. Pollen with a high pollen tube growth rate was more successful when nutrient availability for the female was high. This could be the result of selection on the female to adjust preference according to environmental circumstances. Pollen tube growth rate was measured under nutrient rich circumstances, thus high performers possessed traits adapted to a nutrient rich situation. Due to trade-off effects, these traits might not be advantageous in poor environments. Instead, individuals adapted to low nutrient circumstances will have a higher pollen tube growth rate. If siring ability varies with the environment of the recipient plant, this means that assessments of gene flow must account for this variation and include both pollen donors and recipient plants subjected to a range of environmental circumstances.
Oecologia 102(3): 353-360. June 1995
Differences in phenotypic plasticity between plants from dimorphic seeds of Cakile edentula
Cakile edentula produces upper and lower dimorphic seeds which disperse long and short distances, respectively, from the parent. Canonical discriminant analysis was used to determine the differences between plants from the two seed morphs in both the amount and direction of their overall plastic responses to major environmental factors. In general, plants from the long-distance dispersal seeds were less plastic than those from the short-distance dispersal seeds in response to soil moisture and sand burial. This is probably a result of broader ecological amplitude of the plants from the long-distance dispersal seeds due to their larger seed masses. Differences in the direction of overall plasticity between plants from the two seed morphs are not likely to be adaptive. However, phenotypic selection may affect the relative contribution of plants from the two seed morphs to the next generation
|1In this connection it is of interest to note that various parasites (as Hydnora, Rafflesia, and Balanophora) and mycophytes (as Monotropa and the orchids) have minute seeds with rudimentary undifferentiated embryos and almost no food, nutritive dependence upon other plants being necessary very early, in most cases even in the earliest stages of germination.|
A Textbook of Botany for Colleges and Universities: Ecology, p. 918 (1911)
John Merle Coulter, Charles Reid Barnes, Henry Chandler Cowle
Variations in the size and the structure of fruits and seeds.— Probably no other plant organs are as invariable as are fruits and seeds, and for this reason the few variations which are known have an unusual interest. Seeds which develop singly or which are not crowded during development are likely to be spherical, while crowded seeds commonly are angular. In the two-seeded fruits of Xanthium and Cakile, each seed differs considerably in shape and in size from the other. In certain composites the achenes of the ray flowers and of the disk flowers differ strikingly in shape. In the parasitic Scrophulariaceae it has been discovered that vigorous plants give rise to larger seeds than do weak plants, and that the large seeds give rise in turn to more vigorous plants than do the smaller seeds; furthermore, the larger seeds are more likely than are the others to grow into autophytic individuals, while the plants coming from small seeds in order to thrive, apparently must be parasitic.1 The achenes of hemp vary considerably in size and in weight, those produced in moist habitats being larger and heavier than those produced in dry habitats. The larger achenes germinate more quickly than do the others, forming stronger plants. Similar differences have been observed in the seeds and seedlings of tobacco. In a crowded group of natural seedlings such a difference in size might be of great significance, since the stronger seedlings would tend to crowd out the others. The influence of grafting upon the character of fruits has been noted elsewhere, but it may be recalled that changes in the size and in the flavor of cultivated fruits often result from the reciprocal influence of the stock and the scion. Pollination may affect the character of the fruit; for example, when the flowers of watermelons are pollinated by cucumber pollen, the resulting fruit is very poor in sugar.
Seed variations manifested in behavior.— Seeds of the same species, though apparently alike in structure, in reality may be very different. Perhaps the best instance of this is seen in a comparison of seeds raised in different climates. Farmers in the United States have long known that northern-grown seeds produce crops that ripen earlier than do crops raised from seeds grown farther south. It appears as if the progeny of the northern plants have inherited from them their short maturation period, thus furnishing evidence in favor of the theory of the inheritance of acquired characters (p. 947). After a few years, however, it is necessary once more to use northern seeds, since the progeny of northern-grown plants come to have the same period that is characteristic of the climate to which they are transferred.
Proceedings of the American Seed Trade Association (1902) pp. 29-46
C. L. Allen
Take as an illustration the climate of Sweden, where there is but nine weeks of spring, summer, and autumn, yet the active principle of growth is so intense during that short period that their meadows yield two crops of the most nutritious grass, and their gardens two crops of the most delicate and delicious vegetables.
Do not understand me that they can take seeds grown in a more southernly clime and get such results at first; they cannot; but by slow stages the plants have become adapted to localities where rapid growth is required, until the results are as stated.
On the contrary, seeds grown in Denmark will, if planted in a more southern locality, make for a season a much more rapid growth, but a second or third generation will take the full time allowance for reproduction.
Corn has been and is being grown to a profit where there is rarely a month in the year without a frost. I have seen it growing in the province of Quebec where such climatic conditions existed. The stalk did not exceed more than four feet in height and was proportionate in diameter, yet nearly all of them produced each two small ears of sound yellow corn of most excellent quality.
Some of this corn was taken to central New York and given every attention necessary for the production of a crop, and never did plants respond more freely to good treatment. The growth was no larger than the same made in Quebec, and the harvest was made in about the same number of days after planting the crop, being harvested before the middle of August.
The seed product was all used for planting the following season, but its consciousness having found that in the climate of its adopted home it had twice as long a time to mature, it took it all and grew as high and strong as the yellow flint corn there generally grown, and produced as large ears. Its identity as an early type or variety was lost, but the lesson taught was instructive and valuable, showing how readily the plant adapted itself to the conditions as found and how readily all plants accept the situation given them and cheerfully perform their alloted work.
Species and Varieties (1906)
Hugo De Vries
The production of varietal and of atavistic leaves is dependent to a high degree on external conditions. It agrees with the general rule, that favorable circumstances strengthen the varietal peculiarities, while unfavorable conditions increase the number of the parts with the atavistic attribute. These influences may be seen to have their effect on the single individuals, as well as on the generations growing from their seed. I cannot cite here all the experimental material, but a single illustrative example may be given. I divided a strong individual into two parts, planted one in rich soil and the other in poor sand, and had both pollinated by bees with the pollen of some normal individuals of my variety growing between them. The seeds of both were saved and sown separately, and the two lots of offspring cultivated close to each other under the same external conditions. In the beginning no difference was seen, but as soon as the young plants had unfolded three or four leaves, the progeny of the better nourished half of the parent-plant showed a manifest advance. This difference increased rapidly and was easily seen in the beds, even before the flowering period.
Science 19(488): 738-740 (1904)
The Influence of Climate and Soil on the Transmitting Power of Seeds
Will W. Tracy, Sr.
Speaking first of leguminous plants, in the 'Extra Early' varieties of garden peas the desirable form of vine is one eighteen to forty inches high, and of a determinate growth, by which term I mean a vine that before the lowest and first formed pod has become too large for use as green peas, has completed its elongation and has its apex crowned by a well-formed pod or at least one well out of the blossom. The objectionable form is a vine twenty-four to sixty inches in height, which even when the lowest pod is fully ripe is still growing having its apex covered with blossoms and buds. Such plants as these last are called by seedmen 'wicks' or 'offs,' and a stock of 'Extra Early' peas is valued in inverse proportion to the number of such plants it produces. I never have seen a stock which did not occasionally produce them, and in number varying with different conditions of cultivation. On very rich soils, or those which have been recently fertilized with stable manure, there will be a great many more such plants developed than on a poorer soil. A stock which, when grown on a white clay soil of uniform composition, will ripen down very uniformly and not show more than a dozen such 'offs' to the acre, will, when planted on a mucky soil or one which has been enriched by fresh stable manure, give a dozen 'offs' to the square rod.
... Seedsmen find that if the seed from such 'off' plants grown from good stock is planted on soils favorable for the development of the true type, it will produce few, very few, often no more 'off' plants than seed from plants of the true type grown from the same stock; but if seed from the 'off' plants is sown on soil favorable for the development of 'off' plants, they will produce more 'offs' than seeds from the true type, and this tendency to produce 'off' plants on either favorable or unfavorable soil increases very rapidly with the number of consecutive generations of 'off' plants back of the seed in question.
Herbert: Camellias (Amaryllidaceae, p. 367. 1867)
I have had greater success than any other person in raising from seed double camellias of various tints and appearance, and some of the best have been produced either from single flowers or plants raised from single ones, impregnated by the pollen of double flowers, preferring, where it can be got, the pollen that is borne on a petal. The new seedlings that flowered with me in one spring for the first time were nine full double; three semi-double, of which one was very fine, and only three single; but such an unusual result is not to be obtained without particular attention to the mode of treating the mother plant while in flower and seeding: the method which I have adopted being to keep it in confined air, with a superabundance of water, even to the detriment of its health, and to prevent it from making young shoots, in a great measure, if not entirely, by which means an exuberant degree of nutriment is forced to the seed-vessel. The reason that the seedlings raised by some nurserymen are so very inferior is, that their plants are in the most luxuriant growth; and it cannot be expected that seed gathered from individuals growing with freedom and vigour, should not be more disposed to reproduce the natural form of the plant, than to yield the fine cultivated varieties, which are to be obtained from them when almost diseased by repletion.
Herbert: Camellias (Amaryllidaceae, p. 369. 1867)
I have no difficulty in obtaining seed from any given flower of the Pompone or Middlemist's Camellia, by putting it in a house rather warmer, and with less admission of air, than suits greenhouse plants in general; impregnating the stigma, and taking off the corolla before it begins to decay, and cutting away the petals that adhere to the germen or young seed-vessel, that the air may have free admission to it; without which precaution it will perish in most cases from damp. The striped sorts have usually more white in their flowers when they flower earliest in the spring, and it seems that the seed ripened earliest in the year is the most apt to yield white or pied seedlings.
Tree Biotechnology, 2003
The maternal temperature during zygotic embryogenesis influences the adaptive properties of Norway spruce progenies; a "memory" involving DNA methylation and differential transcription of phytochrome genes?
Øystein Johnsen, Carl Gunnar Fossdal, Ruediger Baumann, Jørgen Mølmann, Ola Gram Dæhlen, David Clapham and Tore Skrøppa
Survival and competitive successes of boreal forest trees depend on a balance between exploiting the full growing season and minimising frost injury through proper timing of hardening in autumn and dehardening in spring. Our research has shown that the female parents of Norway spruce adjust these timing events in their progeny according to the prevailing temperature conditions during sexual reproduction. Reproduction in a cold environment advances bud-set and cold acclimation in the autumn and dehardening and flushing in spring, whereas a warm reproductive environment delays these progeny traits by an unknown non-Mendelian mechanism. We have performed identical crosses in combination with timed temperature treatments during shorter and longer periods from female meiosis, pollen tube growth, syngamy and embryogenesis, tested the progenies for bud-set and frost hardiness, and concluded that the effect of temperature most likely is a response to accumulated heat during embryogenesis and seed maturation. Our first attempt to look for a molecular mechanism has revealed that transcription of PHYO, PHYP and PHYN (using RealTime PCR) all show higher transcription levels in progenies reproduced under cold conditions than their full-sibs developed under warmer conditions. This result is consistent with preliminary findings that methylation of cytosine in total DNA is higher in progenies reproduced under warm conditions than their colder full-sib counterparts. If these observations are related to methylation of phytochrome genes, we may explain why progenies with a memory of a past time cold embryogenesis are more sensitive to short days than their full-sibs with a warmer embryonic history.
Tree Physiology 15: 551-555 (1995)
Sexual reproduction in a greenhouse and reduced autumn frost hardiness of Picea abies progenies.
Øystein Johnsen, Tore Skrøppa, Gunnar Haug and Inger Apeland
In 1989, identical crosses (2--3 females within males) were performed with Picea abies (L.) Karst. in a greenhouse seed orchard at Biri nursery and in an outdoor seed orchard at Huse, 32 km north of Biri. Pollination began 17 days earlier in the greenhouse than outdoors at Huse. The potted grafts in the greenhouse were moved outdoors when the seed cones were no longer receptive. Twelve full-sib family pairs (Biri and Huse) from these crosses were grown in a phytotron and tested for height and autumn frost hardiness during their first growing season. No significant difference was found between the indoor (Biri) and outdoor (Huse) progenies for height growth. However, the progenies from the greenhouse seed orchard were significantly more susceptible to frost than their full-sibs from the outdoor seed orchard. There was no significant interaction between males and the flowering environment, but a significant female x flowering environment interaction was present as a result of greater differences in frost hardiness between progenies from females in the greenhouse seed orchard than in the outdoor seed orchard. Although seeds from the outdoor seed orchard generally had a greater biomass than seeds from the greenhouse seed orchard, the difference in seed weight did not explain the difference in frost hardiness. We hypothesize that temperature and photoperiod during pollination and fertilization affect the frost hardiness of the progenies.
Adaptation in Plant Breeding, 1995: 84
Adaptive properties of Picea abies progenies are influenced by environmental signals during sexual reproduction
Øystein Johnsen & Tore Skrøppa
Virtually no information is available about rapid genomic changes or epigenetic effects in spruce. Genomic imprinting is, however, being increasingly accepted as a fundamental and widespread process that determines, in ways not predicted by the laws of Mendelian inheritance, whether a particular gene will be expressed or not (Matzke & Matzke, 1993). Interestingly, Meyer et al. (1992) found that environmental factors influenced 35S promoter methylation of a maize A1-gene construct in transgenic petunia and its colored phenotype. While blossoms on field-grown plants flowering early in the season were predominantly red, later flowers on the same plants showed weaker coloration. The reduction of the A1-specific phenotype correlated with methylation of the 35S promoter. Moreover, they found that the stability of pigmentation correlated with the time of seed production. The A1-gene construct was insensitive to methylation in progeny from flowers of young parental plants produced early in the season, but became susceptible to methylation within progeny from subsequent later crosses. Similar observations have been made in non-transgenic Zea mays where methylation was more pronounced in upper ears and tassels (Federoff & Banks, 1988). So far, we can only speculate that such gene regulation, caused by activation or deactivation of certain genes by environmental conditions during reproduction, regulate the phenotypic expression of adaptive traits in Norway spruce.
Euphytica, 92(1-2): 67-71 (1996)
Adaptive properties of Picea abies progenies are influenced by environmental signals during sexual reproduction
Øystein Johnsen & Tore Skrøppa
Several independent tests have shown that climate and weather during sexual reproduction influence the adaptive properties of the Picea abies progenies. This phenomenon is expressed in seed orchards established by moving parent trees, propagated as grafts, from north to south, from high to low elevation, or from outdoor to indoor greenhouse conditions. The progenies exhibit delayed flushing in the spring, later growth cessation of leader shoots in the summer, delayed bud-set, higher frequency of lammas shoots and delayed development of frost hardiness in the autumn compared to progenies reproduced in the colder native environment. The altered performance is persistent. We have found no effect on progenies of photoperiod and temperature treatments given to the males during meiosis and pollen production. However, when crosses were made in early spring (March), inside a heated greenhouse (short day, high temperature), the progenies are less frost hardy during cold acclimation than progenies from identical crosses performed in late spring (May; long day high temperature) in the greenhouse. The most hardy offspring were from crosses performed under outdoor conditions in May (long day, low temperature). These results indicate that some stages in reproduction, such as female meiosis, pollen tube growth, syngamy and early embryo development, are sensitive to temperature and/or photoperiod which then alter the phenotypic performance of the offspring. The most likely explanation is the existence of a regulatory mechanism affecting the expression of genes controlling adaptive traits. If this is true, it must have implications for the genetic interpretation of provenance differences in Picea abies.
Annual Report of the Secretary of the Board of Agriculture for 1885, 33: 110 (1886)
The Garden Fence
Prof L. H. Bailey
Seeds from young plants appear to produce a better and more variable offspring than those from old plants of the same species. Dr. Van Mons of Belgium, inspired by this fact, built for himself a permanent name in the science of horticulture. He selected seeds from the first fruits of young trees, especially from young trees of new varieties, and planted them. From the first desirable fruits of the seedlings obtained, he again selected seeds and planted, and so continued to do for several generations. Each succeeding generation fruited sooner than the preceding ones and produced better fruit, until about the fifth generation, beyond which there was no increase. The fifth generation of pears bore at three years from the seed. Van Mons proved that by selecting seeds from these young plants, which are in "a state of variation," whose characters are not yet fixed by age, we shall rear the best seedlings. And here another question arises. If the characters of young trees are not yet fixed, will the first fruits be the same as those which the tree will bear in maturer years? Are the habits of the boy the same as those of the man into which he grows? We know that in many cases they are not. But here we find a fact that we should not expect from the conclusions of Van Mons; the first fruits of the tree, if they vary at all, are commonly inferior to the later fruits. Still these same inferior fruits give a superior progeny! Would it be possible by root-grafting scions from a seedling at different times during the first four or five years of its existence to secure different varieties of fruit? We shall try it.
[CybeRose note: seedlings raised from seed of the first fruit tend to be more variable than those raised from the same trees later in life. This increased variability allows that some of the seedlings will yield superior fruit; others will not. The quality of the fruit is not a clear indication of the potential of the seeds they contain.]
Weston: Theorie Van Mons (1836)
Upon this basis, he established his theory of producing new varieties of fruits, viz. that when we have produced a variation by removal or cultivation in any tree, let the first seeds be planted, and upon first production of fruit by the new generation, let its first seeds be planted, and so on without interruption as it is expressed from parent to son, and at each remove it is found that the character of the tree becomes more like those of the old known and approved variety and the fruit advancing to perfection.
Journ. of Genetics 48: 80-98. (1947)
Heterochromatization as a change of chromosome cycle
A. A. Prokofyeva-Belgovskaya
(5) The influence of parental age
It was found that the ageing of the parents causes a progressive heterochromatization in their progeny of the most sensitive inert regions and of the active ones in their vicinity. There is reason to suppose that ageing causes a progressive heterochromatization of the cell nuclei in the parents, and that this process tells upon the condition of the most sensitive regions in their progeny. A comparison of this evidence with that on the influence of age on crossing-over (Bridges, 1927, 1929) leads to the belief that the two phenomena are parallel. Ageing is accompanied by a reduction of the capacity of the chromosomes for conjugation and by a drop in the percentage of crossing-over.
(CybeRose note: This paper deals with fruit flies, but the parallel with the previous item is noteworthy.)
Journal of Horticulture and Practical Gardening – n.s. 2(42): 309-310 (January 14, 1862)
Progress in cross-breeding among florists' flowers
By its own pollen all seedlings of [Pelargonium] Punch in this garden come without a speck of white, but they vary from the parent very much, and not one in fifty of them is like it; whereas on the chalk Punch is all but a botanical species, reproducing itself at the rate of from 70 to 80 per cent.
Cook: Kinetic Evolution (1907)
Differences under New Conditions (Neotopism).— Variations induced by the transfer of organism to new and unwonted conditions. Three stages of new place effects may be distinguished, (1) those in which there is merely a stimulation of growth, (2) those in which there is also a definite mutative change of the hereditary characteristics of the variety, (3) those in which the new conditions call forth a promiscuous mutative diversity.
Size and Condition of Seeds and Fruit
Crandall: Influence of fruit size on viability of apple seedlings (1918)
In general, seedlings from seeds of large fruits are somewhat more resistant to adverse conditions and possess a higher degree of vitality than do seedlings from seeds of small fruits.
Zavitz: Influence of seed size on yield (1910)
From the numerous experiments which have been conducted at the Ontario Agricultural College within the past fourteen years, it seems very evident that large seeds will give a greater yield than an equal number of small seeds, in the case of each of at least twelve different classes of farm crops.
Cummings: Large seed a factor in plant production (1914)
The trials reported upon herewith show that a distinct advantage follows the use of heavy or large seed. The results attained with seed sorting with sundry plants are of assistance in the explanation of several points relating to the differences in maturity, lack of uniformity in size, season, and quality of production.
Highkin: Temperature-Induced Variability in Peas (1958)
The low level of activity reached in the later generations of plants grown at a constant temperature is not immediately reversible. That is, plants which have been raised for several generations under the detrimental constant temperatures will give rise, on return to fluctuating temperatures, to inferior plants as compared with controls grown for the preceding generations in the more favorable fluctuating temperatures. This fact in itself may not be surprising since one could expect that seed produced in an unfavorable environment might be less vigorous than those produced in a favorable environment. What is surprising is the fact that there appears to be an hysteresis phenomenon. When seeds from the less vigorous plants are grown for two generations in fluctuating temperatures, they do not differ phenotypically from the control plants which have been grown for many generations in fluctuating temperatures. When seeds from the originally less vigorous plants are reintroduced into the constant temperature, the difference becomes immediately apparent, despite a two-generation sojourn in the favorable fluctuating conditions. The fact that this difference persists for at least three generations, although decreasing somewhat each generation, indicates a strong analogy with the phenomena of "Dauermodifikation" as described by Jollos (1921).
Highkin: Vernalization & Heat Resistance in Peas (1959)
It was found that there is a marked increase in heat resistance as a result of a cold treatment. The induction of heat resistance as a result of vernalization appears to be independent of the induction of the floral stimulus resulting from such a treatment.
Reychler: Traumatic Pollination (1926)
The possibility of fertilising the ovules after operation direct in the ovary at a time when it is not effected by nature suggested the following thought to my mind: We note the posibility of premature fertilisation. How do the seeds themselves act? Does their apparent maturity correspond with the optimum point possible of germination? I immediately made experiments and again it was the Impatiens sultani of which I made use.
I fertilised the specimens normally. In a greenhouse the seeds take (June-July) twenty-three to twenty-four days to mature. From the seventeenth day, I open the ovaries and sow the seed, still green, on very wet Sphagnum. After one or two days, the green colour changes, the seeds assume the brown tone of ripe seeds, then they germinate and yield plants more puny than the normal type.
I then take still younger ovaries, some even perhaps too young, and sow all the seeds pell-mell. The germination takes place very slowly and produces very puny specimens. They revive, however, after a time and become perfect plant, among these, there are some the flowers of which seem to have a colour that I believe to be new; but this I cannot, however, vouch for. Several other plants, on the other hand, especially two, produced flowers of a clearly different shape, not opening so well, of a rounder form and with petals showing curly edges (see photo.) Here, also, I observed physiological disturbances, but only with the flower, the plants being vigorous and the leaves normal. I kept these two individuals: they produced, by self-fertilisation, offspring showing the same phenomena. Here, once more, the morphological changes were definitely established in the offspring (fig. 6).
HortScience 37(1): 206-207 (2002)
Cercis canadensis L. Seed size influences germination rate, seedling dry matter, and seedling leaf area
Gary A. Couvillon
The author found that the larger seeds of C. canadensis gave higher germination, more uniform and more vigorous seedlings. His results agreed with other research cited involving lettuce, sweet corn, wheat, oats and Lima beans.
One slightly curious result was that small seeds gave more uniform seedlings when planted separately from the large seeds, rather than mixed in with them.
Annals of Botany 86: 1185-1192 (2000)
Influence of Seed Size on Seedling growth of Albizia procera Under Different Soil Water Levels
Khurana and Sing
Our results demonstrated that the effect of seed size on the growth of A. procera seedlings persisted throughout the experimental period; seedlings derived from large seeds were taller and heavier and had a greater leaf area than those from small seeds.
Soil Science 3(4): 393-398 (1917)
The Influence of Soil Temperature Upon Seedling Corn
Byron D Halsted and Selman A Waksman
Table VIII indicates that, first of all, variability is somewhat inborn, as may be seen by making a comparison of the second and third cross, the former being less variable than the latter in each of the six tests. From the average it is found that the autumn-grown crop is over twice as variable as the summer one, which had the more favorable temperature and made the larger development. In like manner, the plants from the sugary are more variable than those from the starchy grains.
As an extreme instance, not shown in the tables, the average variability in length for the summer-grown plants from starchy large grains is only 0.89 per cent, while the sugary smaller grains grown in autumn gave a range of 2.85 per cent, showing, in other words, three times as much variability.
Botanical Abstracts, 5:133 (1920)
948. Andronescu, Demetrius Ion. Germination and further development of the embryo of Zea Mays separated from the endosperm. Amer. Jour. Bot. 6: 443-152. 1 pl. 1919.— Embryos of corn (with their scutella) were separated from their endosperms and germinated in water and in various culture media, of which 1 and 2 per cent sucrose solutions produced the best results. The young plants thus obtained were considerably smaller than those produced by whole kernels, but were otherwise identical with them. When the scutellum as well as the endosperm was removed, growth was very much reduced and the seedlings were unable to develop far.—Seedlings grown from embryos only and those grown from whole kernels were transplanted into soil and the plants obtained were essentially similar, except that the former were somewhat smaller than the latter. The author concludes that in germination and development the presence of endosperm is not essential, but is beneficial.—E. W. Sinnott.
Australian Journal of Experimental Agriculture 28(6) 765 - 770
High phosphorus concentrations in seed of wheat and annual medic are related to higher rates of dry matter production of seedlings and plants
M D A Bolland and M J Baker
Seed of 2 cultivars of wheat (Triticum aestivum) and 1 burr medic (Medicago polymorpha) with increasing phosphorus (P) concentrations (wheat 1.4-3.7 g P/kg dry matter, medic 3.3-7.9 g P/kg dry matter) were collected from field experiments with variable levels of applied superphosphate (wheat 0-577 kg P/ha, medic 0-364 kg P/ha) in south-western Australia. These seeds were used in further experiments to examine the effect of seed P concentration on the subsequent dry matter (DM) production of seedlings and plants in 3 glasshouse pot experiments and 1 field experiment. Seed of the same size (wheat, 35 mg/seed; medic, 3.6 mg/seed) but with increasing P concentration produced substantially higher DM yields in the absence or presence of freshly applied superphosphate P up to 28-35 days after sowing in the pot experiments and 67 days after sowing in the field experiment.
Bulletin, Volume 2: 209-219 (1901)
Experiments on cutting off parts of the cotyledons of pea and nasturtium seeds
Abegail C. Dimon
The effect, it would seem, of removing a part of its food supply from the seed is not merely a transient one, but is one that can be traced through the whole life of the plant, and even increases as the plant grows older. The amount of food supply in the cotyledons influences, perhaps, the early stages of growth, while as the plant increases in size it becomes more and more vigorous and tends to grow more and more rapidly; so that a plant that is given an advantage over its fellow at the start will increase this advantage during subsequent development.
Michurin: Selected Works (1949)
Premature loss of, or partial injury to, cotyledons has a very harmful effect upon the development of seedlings: the growth is retarded, the shape of all parts of the plant deviates towards wild forms; it is therefore essential to take good care to safeguard the cotyledons from injury until they have completed the process of nourishing the young sprout, when they drop away by themselves.
Annals of the Missouri Botanical Garden, 7:291-298 (1920)
The Nutritive Value of the Food Reserve in Cotyledons
B. M. Duggar
The importance of the cotyledons in the vigorous development of the seedling is an ancient observation. Bonnet (1754) demonstrated that beans and buckwheat grew less rapidly when the cotyledons were cut off, and more important still, he observed the persisting effect of this early difference, stating the matter in the following words: "La meme différence, ou une différence analogue, a subsisté entre ces Plantes pendant toute la dureé de l'accroissement. Il a toujours été facile de distinguer les unes des autres." [The same difference, or a similar difference, remained between these plants during all the duration of growth. It was always easy to distinguish one from the other.]
New Phytol. (1998) 140:655-665
Ali El-Keblaw and Jon Lovett-Doust
Persistent, non-seed-size maternal effects on life-history traits in the progeny generation in squash, Cucurbita pepo.
Maternal-environmental effects on subsequent progeny life-history traits were evaluated in squash (Cucurbita pepo L,) in terms of the amount of time available for seed development and the timing of fruit production. Progeny arising from three kinds of fruit were compared. Plants from which fruits were removed 3 d post-pollination throughout the growing season developed only 'late' fruits (during 10-15 d) at the end of the growing season; on control plants both 'early' and 'late' fruits developed (both types allowed to ripen fully). Seed from each type of fruit was weighed individually and categorized into three size classes, then germinated and raised to maturity, including regular harvesting of all fruits 3 d post-pollination. Maternal effects were evident for both vegetative and reproductive traits and carried over to later stages. In contrast, effects due simply to seed size disappeared by day 30 for leaf variables and day 60 for male flower production. Within a seed-size class, progeny arising from fruit of treated plants produced significantly more leaves, with greater size, and more male flowers than those arising from fruit of control plants, while the reverse was true for fruit number and fruit mass. This result is discussed in terms of possible gibberellic acid involvement. In control plants, progeny arising from seeds in the large, fully mature 'early' fruits produced significantly more, and larger leaves by day 30 than did those from late fruits (suggesting differential provisioning in seeds during development). Male flower production had a highly significant positive correlation with vegetative mass and a significant negative correlation with fruit production.
Klippart: The Wheat Plant (1858)
Grain which ripens in cold weather, late in August or September, will be heavier ordinarily than that which is hastened to maturity in hot weather. By grain is meant spring wheat. From this it might be inferred that spring wheat should be sowed late, without reference to the grain worm; and yet before the appearance of that insect, it was found that early sown wheat was ordinarily the best. This may be remedied, and late sown wheat rendered a certain and uniform crop. When the wheat grows rapidly with a large straw and broad leaf of a peculiar deep green color, having the appearance of that which grows about burnt places, the straw will rust, and the grain blast. Grain sown the 1st of May or June will be more luxuriant, with a greater growth of stalks and straw than when planted early. It follows, therefore, that so long as spring wheat is obliged to be sown late to avoid the grain worm, there is more certainty of a crop to sow it on medium soil which will yield from 15 to 18 bushels per acre, than to sow it on very rich land.
Hector: Photoperiodism and Vernalization in Relation to Habit (1936)
In winter rye, the differentiation of flower primordia was found to be subject to an interaction between day length and the temperature during germination, these factors determining both the minimal number of leaves formed before differentiation of flowers began, and the rate of growth of the meristematic tissue. As a consequence of this interaction, low temperature germination hastened flower inception in winter rye under long days, but produced no effect under short days. At the same time, after germination at high temperatures, short-day treatment led to earlier differentiation of flower primordia than did long-day treatment. No temperature after-effect was found in spring rye, but short days retarded the differentiation of flower primordia. Once the differentiation of primordia had taken place, however, further development was always hastened by long days. Hence if ear emergence be taken as the criterion of flowering, all types of rye may be regarded as "long-day" plants; but if differentiation of flower primordia be taken into consideration, winter rye germinated at high temperatures behaves as a short-day plant; germinated at low temperatures, it behaves as does spring rye.
Bot. Gaz. 69 : 97-126. 18 fig. 1920.
Formative effect of high and low temperatures upon the growth of barley: A chemical correlation.
Walster, H. L.
Maize Newsletter Issue 21 (1947)
Maize and Heat
D. F. Jones
Varieties of corn grown in the Northeast and in the Middle West at the same latitude are noticeably taller in the East. Several environmental conditions are involved in this growth difference, principally light intensity and temperature. Plants of many species, including maize, grown under tobacco shade cloth are significantly taller and broader in leaf than plants from the same lots of seed grown in full sunlight. Under the cloth shade the temperature is the same as outside but the humidity is higher and the light intensity is lower. The same effect is noticed in the field where short-stalked varieties of corn are grown in single rows between taller varieties. Where there is a wide alley between ranges the plants at the ends of the rows are shorter than those in the center of the rows, the plants graduating in height. Here humidity and temperature are the same but light intensity varies.
Some corn seedlings started in the greenhouse and set outdoors were shorter at maturity than plants from the same seed started outdoors. This indicated that temperature in the early stages of growth had an effect. To test this, seeds of a uniform, vigorous, first generation hybrid (Wf9 x P8) were germinated in an incubator at about 30° C. until the shoots and roots were from one fourth to one half inch long. Three different lots of sprouted seedlings were held at 40, 50 and 60° C. for one hour. They were then planted in pots and left in the greenhouse until it was certain the plants would grow. They were then set in the field alongside plants from the same lot of seed sown in the open ground at the same time the treated seedlings were started in the incubator. Some of the treated seedlings died but enough were started in each lot and later thinned to give an even stand of plants in the field.
All three lots of heat-treated seedlings were shorter in height, less vigorous in growth throughout the season and later in flowering than the [un]treated plants. All lots grew to full maturity and were measured after growth had ceased. The results are: Control 101: 40° C. 87; 50° C. 89; 60° C. 93 inches in height. The differences between the three temperature treatments are small. All three averaged 90 compared to 101 inches in height for the control.
The result that was not anticipated was the pollen sterility in all treated lots. Normal tassels were produced with well-developed florets but the anthers were small and shriveled and for the most part remained enclosed in the glumes. In view of the fact that high temperatures sterilize the male germ cells in animals, from amphibians to mammals, these results are highly significant. This influence on growth is an anti-vernalization effect and may have wide usefulness in the production of hybrid seed especially if shown by other plants as well as maize.
Plant Physiol. 1935 April; 10(2): 269-289.
Temperature as a predeterming factor in the development of Avena sativa.
Thora M. Plitt
APPEL and GASSNER (1) reported that both summer and winter cereals were injured if their germination took place at unfavorably high temperatures. GASSNER (10) brought out the fact that certain types of oats lodged if they were germinated at 25°C. and then transplanted to the field. Lodging occurred even if the 25° temperature prevailed only during the first two days of germination. In either case indications of lodging appeared about five weeks after germination. Under these conditions the oats also failed to head and consequently to yield any grain. The detrimental effects brought about by high temperature were apparently due to disturbances in the very complex chemical reactions in the plant. These findings are confirmed by those of MAXIMOV (19). WALSTER (24), as a result of an investigation on the formative effects of high and low temperatures on the growth of barley, suggested that the course of development of barley is to a large extent predetermined at a very early stage in growth by the chemical equilibria within the seedling, especially the carbohydrate-nitrogen ratio.
Mutation Theory (1910) vol. II p. 322
Prof. Hugo de Vries
Zea Mays forms more bi-sexual panicles and ears when the seed has germinated at high temperature.
Value of Old Seeds