Science 19(488): 738-740 (1904)
THE INFLUENCE OF CLIMATE AND SOIL ON THE TRANSMITTING POWER OF SEEDS
Will W. Tracy, Sr.
Read before Botanical Club of Washington.
In speaking of the influence of soil and climate on the transmitting power of seeds, I will confine myself to certain practices which seedsmen have been taught to follow through long experience, as indicative of certain botanical facts, rather as if these facts had been established by scientific study and experiment.
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.
As an illustration in detail is a case when three large fields of very favorable soil were planted with the same stock, two of them when visited showed practically no 'offs,' nor were there many to be seen in the third field, except in a double row of circles, each about ten feet in diameter, where piles of manure had been spread, and in each of them there were twelve to twenty-five bad 'offs' more than could be found on an acre of the rest of the field.
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. An illustration was given of precisely similar results with 'American Wonder' peas when the character of soil favorable for the most desirable type is the opposite of that favorable for the best 'Extra Earlies.'
Seedsmen commonly believe that, in the case of peas, the character of the soil has a marked influence over the character of the plant, and that this influence extends to and is carried by the seed, but that such soil influence is decidedly cumulative in its effects, so that in practice they attach little importance to it for one season, but carefully avoid the use of stock seed which has been submitted to such influence for consecutive years.
Again in the case of garden beans, the tendency of rich, moist, heavy soil is to produce thick, fleshy pods slow to mature, while that of warm sandy land is to the production of flatter, less fleshy and quicker maturing pods. I can best illustrate this by experience. Some ten years ago I sent each of two growers living within a mile of each other, seed of 'Valentine' bean of precisely the same stock grown the previous year in the same field, which was a rich clay loam. One of these, whom I will call C, planted on rather heavy, rich soil, the other, S, on a light warm but rich sandy one. The next season C received seed grown by S and S seed grown by C, while a third man, M, some five miles away, on rich loam soil, received equal parts of both. When I visited the fields I noticed that in C's field, which I supposed was planted wholly with seed grown by S, there were ten rows which differed from the rest and were such as I would expect if seed from C was planted, and I tried to account for them by extra manure, etc.; but I learned that as there was not quite enough of the seed from S sent him, he had filled out with some of his own, and I had detected the exact row where the seed was used. I then visited M on loam soil, and while I could tell that one part of the field was planted with C stock and the other with S, I could not detect the line between them.
These experiences seem to indicate that in leguminous plants soil does have an influence which is carried in the seed, and is cumulative in character, but in all my experience I have never seen any influence of the climate over the seed of leguminous plants.
The only gramineous plant with which I have had a large experience is sweet corn, and here the case of legumes is reversed. I have never been able to detect any influence of soil over the character of the seed produced, but I believe that climatic condition does have a marked influence, and that the difference between stock grown east and that grown west is the result of climatic rather than soil condition. People who use large quantities of sweet corn are very positive in their belief that seed produced in the eastern states gives a better product than that grown at the west. Some seedsmen agree with them, others maintain that if eastern stock seed is used just as good corn can be grown in the west. It seems to me that that if not only undermines their contention, but shows that seedsmen have a practical belief in the cumulative influence of soil and climate.
Turning now to cucurbits, in my experience I could never detect any effect of either soil or climate on seed of cucurbitaceous plants of the same stock. I don't wish to be understood as saying that soil and climate have no influence over the fruit, for they do quite as much as with any plant, but that this difference is not carried in the seed. As an illustration the writer has knowledge of a case where seed from small but select fruits grown in Michigan was sown in Oklahoma by the side of seed from large plants of the same pedigree grown in Oklahoma, and the result was equally large fruit in both cases. Also, in another case an old and experienced grower in Michigan, who claimed that he should be paid more for seed grown in Michigan, because earlier and better, was given seed of the same stock, grown for three generations in Michigan and for four generations within 200 miles of Gulf of Mexico, to plant side by side, and told that if he could detect any difference in the crop, his request would be considered, but he was unable to do so.
I have had the same sort of results with cucumber, muskmelon and squash, and it has made me think that seed of cucurbits do not carry influences of soil and climate, even when such influence has accumulated for several generations. If time would permit I might go on and speak of tomatoes, cabbage and onion, each of which in my experience seems to have distinct habits in this respect, and considering all these cases it seems to me that plants of different natural orders differ in the degree to which influences of soil and climate are transmitted through the seed.