THE MARYLAND AGRICULTURAL EXPERIMENT STATION, BULLETIN No. 173. (JANUARY, 1913)

TOMATO VARIATIONS INDUCED BY CULTURE
By THOS. H. WHITE

INTRODUCTION

The common occurrence of variation in plants under culture would seem to indicate that some part or parts of the practice of that culture has a bearing upon this matter. The work reported herein was taken up with reference to three phases of this question, namely: pruning, feeding and temperature. It was thought that this would cover some of the most important conditions to which plants are subjected when brought under cultivation.

The phase of the work which had to do with the feeding with chemicals seemed to give such interesting results as to be worthy of publication at this time. The experiments relating to temperature have been continued through four generations. The pruning work was not carried further than the the first generation.

THE CHARACTER OF THE EXPERIMENTS

  1. A study of the effect of excessive amounts of Nitrogen, Phosphoric Acid and Potash, separately and in combination, on the variation of tomatoes and beans.
  2. A study of the effect of temperature on Acme tomato variation.
  3. A study of the effect of pruning on sweet peas and tomatoes.
  4. A study of the effect of Dried Blood, Dissolved Phosphate Rock, Sulphate of Potash, separate and combined, on Red Cherry tomatoes, also effect of Iron filings on the same.
  5. A study of the effect of cross-pollination upon well fed and starved plants.

HISTORY OF EXPERIMENTS

The first of these were commenced in the fall of 1906. The plan was to treat soils with excessive amounts of Nitrogen, Phosphoric acid and Potash, separate and in combination. Seeds were to be saved from all the fruits and all the plants on the several plots. From these a composite sample representing each plot would be drawn and sown for the next generation. Small individual variations that can be found in any variety of tomatoes were not to be considered.

Seven plots, each six square feet in size, were laid off on a green house bench and filled with rich soil. These were treated as follows:

    Applied at the
rate per acre of
Plot 1: Dried Blood
Dissolved Phosphate Rock
Muriate of Potash
2000 lbs.
2000 lbs.
500 lbs.
Plot 2: Dried Blood 2000 lbs.
Plot 3: Dissolved Phosphate Rock 2000 lbs.
Plot 4: Raw Phosphate Rock 2000 lbs.
Plot 5: Muriate of Potash 500 lbs.
Plot 6: Sulphate of Potash 500 lbs.
Plot 7: Nothing.  

 

*The Acme tomato was chosen for this work because Dr. Chas. A. White of the Smithsonian Institute had published in Popular Science Monthly, Jun. 1905, a report of a peculiar variation. This variation was so different that it was considered a new variety. Dr. White named this variety the "Washington" and distributed seed. The variety as it developed here was very similar to, if not identical with, the Dwarf Champion.

Seeds of the Acme* variety of tomato were sown in the plots on October 2, 1906. These were thinned so that six plants were left standing on each plot. They were trained to a single stem and the flowers were self pollinated. The first lot of seeds from these were saved March 1, 1907. These were planted on another set of plots, prepared in the same way, out in the field, the first week in May, 1907. The soil of these plots was a heavy loam. quite fertile. Each plot contained four hundred square feet.

Some beans of the variety Wardwells Kidney Wax were also planted on these plots. The seed was sown in a row and the plants thinned to six inches apart; this left about eighty plants to the plot. The annual succession of these plantings has been uninterrupted since that time. The plots have also received their several kinds and amounts of fertilizers annually. The seed has been carefully saved from a number of different fruits and a composite sample of each taken and sown each time. The noticeable temporary effect of the fertilizers has been the same each year and is as follows: The plants growing on the complete fertilizers make a strong, vigorous growth. On the dried blood the same but with a decidedly darker color. The plants growing on the dissolved phosphate rock are usually an extremely light green in color, and the fruit ripens somewhat earlier.

There is never very much difference between the other plots, all being rather a light green in color. The fruit is all about the same. except that it is rounder and smoother on the dried blood plot, and apparently a trifle more irregular than normal on the potash plots. These differences, however, disappear when samples are planted on soil which has not been given any of the special treatments. Samples of seed of the sixth generation were planted in rows in the field under ordinary conditions and no extraordinary differences were noted.

By planting samples of seed this way in rows in the field it was thought that if there were any striking variations they would be easily detected, so far, however, none have been noted.

EXPERIMENT II—THE EFFECT OF TEMPERATURE ON TOMATO VARIATION

In the fall of 1908 plots duplicating exactly those of Experiment I, were made up in a cool greenhouse. The heat radiating surface in this house was not more than sufficient to keep out frost in severe weather. The seeds taken from the stock of the out-door plants were sown and the plants thinned to twenty plants to the plot. The area of each of these plots was twenty square feet. They were made up on the ground, enclosed by cement walls one foot deep. Six inches of coal ashes was placed below for drainage. The top soil was a rich loam. The same temporary differences were noted regarding the color of the foliage as in the out-door plots. Also during the coldest weather the plants on plots 3, 4, 5, 6 and 7 would turn a deep bluish color. This would change, however, as the temperature rose and the days lengthened. As in the out-door work this succession has been continued without interruption for four generations. There have been no marked general variations. An exceptional variation, however, appeared on plot six the first generation after the plants were brought in from the outside. This, was one plant, which. produced fruit of a scarlet color (Acme is purple). The seed of this plant, however, was not allowed to go into the stock to be saved, for unless all the plants on a plot varied in the same way it could not be considered the result of the treatment.

Seeds of this variation were planted and produced in the second generation some Acme among the progeny. This was undoubtedly an accidental cross.

The conditions in the greenhouse have not been exactly what was desired, however, in that the temperature was so low that there was no pollen ripened; in fact, the anthers were not normal, having a dried, twisted appearance. For this reason no fruit was secured during the coldest part of the season. Some of the plants will be grown in pots hereafter so that if necessary they can be placed in a slightly higher temperature to develop the pollen.

EXPERIMENT III—EFFECT OF PRUNING OF TOMATOES AND SWEET PEAS

Desiring to note the effect of pruning on the variation, some seeds of the tomato variety Red Cherry were sown. Several plants from these were set in a bed of good rich soil in the greenhouse. The plants were supplied with an abundance of plant food and trained to a single stem. After four clusters of fruit had formed the tops were taken out so that all the energy of the plant could go into the four clusters of fruit. The leaves were also trimmed off one-half. The effect was very pronounced, and the plants grew extremely large. The foliage was very much increased in size and in some cases laterals started from the mid-ribs of the leaves. The fruit corresponded proportionately. Figure I is a photograph of two of the clusters of fruit. In the upper left-hand corner is seen a many-celled fruit that was very much increased above the size of a normal fruit of the same character. It can also be seen that nearly all the fruits have increased in size, and are somewhat flattened and irregular in shape. The normal size and shape of Red Cherry is like the three fruits near the stem, in the lower part of the plate.


Fig. 1.—Two clusters of fruit from pruned Red Cherry. Note the large many celled fruit
in upper left-hand corner. Common Red Cherry is similar to the three fruits in lower center.

Seeds were saved from this many-celled fruit and planted in the greenhouse. Part of them in a warm house and part in a cooler one. Eighty plants in all were grown from these seeds. Sixty-three of these plants showed a few fruits of the many-celled type. None, however, were out of the ordinary for size. Sometimes two or three but usually only one to each plant. This fruit would often be the first fruit on the first cluster, but not invariably, as sometimes three or four dusters would be set before the many-celled type showed. The other seventeen plants gave all round fruits. In other work with Red Cherry there has been noticed fruits of the many-celled type, so it may be considered that a percentage of many-celled fruit is normal with this variety. In the work with sweet peas several plants of the variety Christmas Pink were pruned to a single stem. After several pods had set the terminal shoot was cut off just above the pods. The laterals also were kept from growing. The effect of this was an increase in the size of the pods and seed, also the foliage. At the same time the foliage took on a very dark green color. Fifty seeds were saved and were planted the following year. All the plants growing from these seed produced normal blossoms.

As the pruning work did not seem to have any effect on the succeeding generation of the plants worked with, it was not continued further.

EXPERIMENT IV—THE EFFECT OF DRIED BLOOD, DISSOLVED PHOSPHATE ROCK
AND SULPHATE OF POTASH SEPARATE AND COMBINED ON RED CHERRY TOMATO

After working two seasons with the Acme tomatoes and Wardwell Kidney wax bean on beds of soil where there was nothing to check leaching, it was thought more positive results might be obtained by growing plants in pots where greater control could be maintained.

Seeds of the Red Cherry tomato were obtained from W. Atlee Burpee & Co., and a new series were started in pots. In addition to the fertilizers another pot was added to which iron filings were applied. The amounts of fertilizers applied were approximately the same as in the out-door plots for the Acme tomato and Wax beans. The amounts were not strictly adhered to, however, as consideration of the health of the plants had to be taken into account. The aim was to give the plants just as much as they could stand. It was found that this would vary according to the time of year and temperature. The plants would remain healthy and thrive on an amount of fertilizer in cool weather that would sicken and kill them in hot weather. Ordinary six-inch flower pots were used. These were filled with potting soil and the amounts and kinds of fertilizer, as stated for Experiment I, were mixed with it. For the pot of iron filings about one-fifth of the bulk of the pot of soil was used. The iron filings were borings and chips from the machine shop. The pots when filled were set in saucers in the greenhouse. Thirty to forty seeds were sown in each pot. These were carefully thinned down until only one was left in each pot. As the pots became filled with roots and grew down into the saucers more fertilizers were applied, both on the surface of the soil and among the roots in the saucers.

The growth of these plants was quite similar to those of the outside plots, only a good deal more pronounced.

The plants grown in the soil treated with iron filings were dwarfer than the others with very dark green foliage and purplish stems.

After the plants had grown for six months and several fruit clusters had set the fruit was gathered and the seed saved. The seeds and pulp were pressed out into small bottles and allowed to ferment for forty-eight hours. They were then dried in wire sieves. The pots were also allowed to dry out thoroughly after which the old plants were shaken out of the soil. The soil was then dumped from each pot and after having another portion of fertilizer mixed with it was put back into the pot from which it was removed. The seeds were again sown in their respective pots and the treatment continued.

After four generations had been grown in this way some of the surplus seed was sown under normal conditions in a greenhouse bed. As soon as the plants were up it was at once remarked how dark green and vigorous looking were the plants from the Dried Blood treatment. Those from the Iron filings also showed a change, in that they were somewhat stunted and of a dark green color with a great deal of purple color in the stems.

Those from the Dissolved Phosphate Rock and Sulphate of Potash were very much lighter green. This method of treating the plants was continued without interruption, the same soil and same pots being used, until the sixth generation. In order to see if the changes were becoming permanent some seed of the fifth generation were taken and sown in good soil under normal conditions. The same differences in character were observed. Also that the plants grown from the seed of the pot receiving dried blood were not only darker green but had increased strikingly in vigor and size of fruit. Three generations of these were grown under normal conditions, without any applications of fertilizers and the third generation which are now several inches high show the same differences.

In samples of the sixth generation, of the original series under the fertilizer influence, some startling differences appeared. They were from the plants that had received the dried blood. Figure 2 shows one of these. Until the time that the plants were about to show the first cluster of blooms the seedlings appeared to be alike; but at this period of their growth instead of producing a cluster of six to eight flowers there was only one and this appeared to be united with the leading shoot. This resulted in the production of a single blossom setting in a calyx of which the sepals were very abnormal, having the appearance of small leaves. The ovary was somewhat flattened and distorted. The pistils and anthers seemed the normal, only somewhat twisted and shrunken. Only one of these flowers was successfully pollinated. This produced two seeds, one of which has been grown into a plant that has grown well and produced fruit in the normal condition.


Fig. 2.—Shows plant of sixth generation Red Cherry treated with Dried Blood, having the peculiarly united flower cluster and terminal shoot.

After noticing this peculiarity, more of the same seed was sown so that an accurate count could be made of the seedlings having the abnormal growth. In an examination of two hundred and fifty there were found twenty plants with this abnormality; this equals eight per cent.

Desiring to more clearly note the differences between the plants growing on the different fertilizers a sample from the dried blood, complete fertilizer, and dissolved phosphate rock were set in a greenhouse bed and trained to single stem. A photograph of these plants is shown by Figure 3.


Fig. 3.—Shows plants of Red Cherry grown off Dried Blood (left); Dissolved Phosphate rock (center); Complete fertilizer (right).

While this work had been carefully conducted and enough seed sown each time, so that by thinning them the chance of error from individuality would not be serious, it was thought that a check on this would be valuable. Therefore, seeds of the second generation which had been preserved, were sown in a flat box of soil. Some seed of the sixth generation was also sown in the same way. After the plants were of a size to transplant they were set outside in the garden all under exactly the same conditions as nearly as possible. The growth they have made is shown by photograph Fig. 4. Between the two stakes to the right can be seen the plants of the sixth generation and on the left those of the second. As these seeds all came from the same parent originally, the difference can be fairly attributed to the influence of the different fertilizers.


Fig. 4.—Shows Red Cherry tomato growing outside. Second generation on the left of center stake and sixth generation on right. Note the increased
vigor of plant on extreme right. This is from Dried Blood treatment. The fourth plant from left is from same parents but is of the second generation.

The plant on the extreme right is the one from the dried blood treatment in the sixth generation. The plant corresponding to this from the second generation is the fourth from the extreme left. It is unfortunate that several of the plants set in this row were destroyed. As it is believed that it would also show that there is a stunting of the growth in the case of the treatment by dissolved phosphate rock. This, in fact, was very marked in the plants grown in greenhouse. (See photograph on Page 129.) The plant from the dissolved phosphate rock was set at extreme right. Unfortunately this was destroyed by a cut worm.

Measurements of these plants show that the plants of the sixth generation grown under the influence of the dried blood are one-third larger in height, length of leaf and size of fruit, than those of the second. (See Fig. 5). The fruit also is improved in quality and flavor. There is more fibre in the pulp and less acid to the taste in the juice of the improved fruit than in the earlier generations.


Fig. 5.—Leaf and cluster of fruit of Red Cherry of the second generation (left) same of the sixth generation (right).

In his book on "Tomato Culture," page 7. Will. W. Tracy says: "I have given a true stock of Cherry most careful cultivation on the best of soil for twenty consecutive generations without any increase in size or change of character in fruit."

EXPERIMENT V—CROSS POLLINATION OF WELL-FED AND STARVED PLANTS

The two varieties of tomatoes, Red Cherry and Yellow Plum, were used in this work. One pair of parents were well-fed and the other pair starved. The pair that were starved were grown in pots in rather poor soil, and nothing but water supplied to them. The other, the well-fed pair, were set in a rich bed of soil in the greenhouse and were watered and fed all they would stand. The resultant growth was commensurate with the treatment. The well-fed parents grew very luxuriantly; so much so that one of the fruits of the yellow plum took on a flattened and ridged appearance. Reciprocal crosses were made, that is, the well-fed Cherry was crossed by Yellow Plum and vice versa. The same thing was done with the two starved parents.

Two hundred plants were grown from the seed saved from these crosses. These were to all appearance practically Red Cherry in the color of fruit. The shape was generally Red Cherry but some had the shape of the Yellow Plum. The stem and leaves seemed to have more of the characteristics of the Yellow Plum. Eighty plants from seed of this, F.1 generation, were grown to maturity. These broke up, in the F.2 generation, in the following order:

Red Cherry X Yellow Plum—Starved   Red Cherry X Yellow Plum—Well-Fed
Red Cherry 8     15
Yellow Cherry 5     0
Red Plum 3     0
Yellow Plum 4     0
Other forms 0     0
Yellow Plum X Red Cherry—Starved   Yellow Plum X Red Cherry—Well-Fed
Red Cherry 12     13
Yellow Cherry 4     9
Red Plum 2     2
Yellow Plum 1     1
Other forms 0     1

As will be noticed from the table the color and shape characters combined about as would be expected, and the treatment had no appreciable effect on the progeny.

Seed was saved from the plant bearing fruit listed as "other forms." These were planted and have fruited. They have broken up in such a way as to show there was accidental pollination with some Acme planted in the same field.

CONCLUSIONS

From the work done it would appear that only one of the treatments, that of the fertilizers on Red Cherry tomato, made any permanent changes in the character of the plants worked with. There can be no doubt, however, that in the case of Red Cherry, treated with Dried Blood, there is permanent variation to the third generation.

Mutilation as in the pruning, also starvation and high feeding, as in the well-fed versus starved, do not seem to have had any permanent effect. In following this work it is evident that there is better control of conditions when plants are grown in pots. In the out-door work where rainfall is variable, control is difficult.