Bureau of Plant Industry—Bulletin No. 159 (1909).

Local Adjustment of Cotton Varieties
O. F. Cook


The method of testing the second and third generations of n variety of cotton in a new place has been to compare these generations with plantings of the same original stock of seed held over for this purpose. While it is difficult to see how a direct test could be made in any other way the plan might be open to objection if it could be shown that plants raised from old seeds were more diverse than those that come from seeds raised in the previous year. Though no formal test of the relation of age of seed to diversity has been made, it may be said that neither from our experiments with cotton nor from what is known regarding other plants is there any indication that old seeds are likely to yield more diverse progeny than are new seeds.

The evidence, such as it is, seems to be more favorable to the opposite idea that less diversity appears in plants raised from old seed. Our nearest approach to a definite test was at Kerrville, Tex., in 1901, where a row test with old Lockhart seed of Triumph cotton stood adjacent to a field planted with new seed from Lockhart. The plants raised from the. old seed appeared distinctly better and more uniform than those from the new, though the experiments were not of such a character as to completely exclude the possibility of influence from differences of soils or dates of planting.

It has also happened in several of our experiments with the Central American types of cotton that seed 2 or 3 years old gave more fertile plants than had been secured from the first plantings of the same stocks in the same places. Though the possibility that more favorable seasons may he responsible for these differences is not to he excluded, the better results from the old seeds are at least worthy of note. If the undesirable diversity can be avoided or diminished by merely holding over old seed, an advantage might he gained in the acclimatization or local adjustment of varieties.

It seems rather remarkable that this question of differences between old and new seed has not been more carefully tested. The idea that old seeds are better, at least in the sense of being likely to yield more uniformly productive plants, is firmly established in the popular mind, especially among growers and dealers in the seeds of melons and cruciferous plants. The difficulty is to distinguish between the possible influence of the factor of age and that of the factor of difference between crops of seed of the same variety.

a "Seed of the same stock and equally well grown, by the same cultivator, in the same location, differ in the variant tendency and the degree to which their product will be of the desired type in different seasons. The crop of seed of Green Globe Savoy cabbage produced by a certain grower in 1893 gave much more evenly typical plants and heads than any subsequent crop produced by him of the same strain, though he took the greatest care in selecting stock and growing the plants, even setting them in the same field that gave the superior crop. I have known a practical seedsman, one not likely to waste money on a mere theory, to pay treble the market price for a certain strain of peas produced by him four years before, though he had an abundance of seed of the same strain grown by himself in succeeding years—none of these later crops giving such good results as seed of that particular season." See Tracy, W. W., sr., Variant Tendency and Individual Prepotency in Garden Vegetables, in Memoirs of the New York Horticultural Society, vol. 1. p. 77, 1902.

It is stated by Mr. W. W. Tracy, sr., that seed dealers often come to recognize particular crops of seed as setting standards of excellence which later generations of the same stocks are not able to attain. A particular crop of seed of a variety of Savoy cabbage which came tinder the personal observation of Mr. Tracy gave progeny of greater and more uniform excellence than any other stock of seed that could be secured, not excepting the seeds grown from progeny of this same original lot, even when grown in the same field. The second generation, or grandchildren, was never equal to the first generation that came from the special stock of seed.a

Whether the retention of the later lots of seeds to an equal age would have given them the same excellence was not determined. Indeed, such a test would be Very difficult in view of the fact that differences of age could never he equalized. Even though the popular idea of the superiority of old seed should be found to rest on the superiority of particular crops the continued excellence of these superior crops would still show that the increased age of the seed should not be supposed to make the progeny more diverse. It is to be expected that different crops of Triumph cotton raised at Lockhart might show differences of behavior at Kerrville. or even at Lockhart, but there is no reason to believe that this factor is of serious importance in comparison with local adjustment. The amount of diversity that appears at Kerrville is out of all proportion to the diversity that appears at Lockhart.

b East. E. M. A Study of the Factors Influencing the Improvement of the Potato. Bulletin 127, Illinois Agricultural Experiment Station. 1908.

A similar idea, that uniformity increases with the age of the stock, is said to exist among breeders of new varieties of potatoes, who believe that bud variations are much more likely to occur in new varieties recently developed from seedlings than in old, long-established varieties.b

Still further back, we find a similar idea in the theories and methods applied by the Belgian horticulturist Van Mons to the breeding of pears and other fruits a century ago. Van Mons made a practice of sowing the seeds of the first fruits of his seedlings, which were supposed to deviate more readily from the parental type than seedlings obtained from mature trees. Though horticulturists admit that Van Mons was able in this way to produce a large number of superior varieties, some of which are still popular, the value of the system has remained in doubt. Some have believed that it did produce a rapid amelioration as claimed, while others have ascribed the results to accidental hybridization as likely to be of frequent occurrence in his gardens, where large numbers of different types of fruits were crowded together with no protection against cross-fertilization by insects.

a "The first colonists here, who brought with them many seeds gathered from the best old varieties of fruits, were surprised to find their seedlings producing only very Inferior fruits. These seedlings had returned by their inherent tendency almost to a wild state. By rearing from them, however, seedlings of many repeated generations, we have arrived at a great number of the finest apples, pears, peaches, and plains." See Downing, A. J., The Fruits and Fruit Trees of America, 1845, p. 7.

To explain the supposed worthlessness of the seedlings of old and superior sorts, Van Mons advanced the idea that the improvement had distinct limits and then suffered a sudden and complete decline. This idea appears to have been based largely on the inferiority of seedlings of some famous old southern varieties which had been carried into more northern regions. It is quite conceivable from the standpoint of the behavior of cotton that the change of conditions might render the seedlings of southern varieties inferior to those that Van Mons was able to derive from native Belgian stocks. A statement made by Downing in his discussion of Van Mons. that there was a marked and unexpected decline in the quality of seedlings raised by colonists in New England. also suggests the possibility that factors of acclimatization and local adjustment may have to be considered in the breeding of fruits as well as in annual crops.a

Cook bibliography