Author: Wang Shih-chih, Chu Te-hui, Fong Chen-liang and Sa Hong-wu
J Integr Plant Biol 1974, 16 (1): -.
Experiments have been carried out in Peking in 1962–1963 with 3 varieties of winter wheat: "A. U. 183", "Peking Ⅵ" and "B. M; Ⅰ". After they have turned green in the spring, they were treated with ammonium sulphate and watered at three different stages: Stage Ⅰ, March 20th; Stage Ⅱ, March 30th; Stage Ⅲ, April 18th. The purpose is to study the interrelationship between the plant growth, organ development, the accumulation & distribution of dry matter and carbohydrates under different treatments, and to study the effect of their relation to the growth of ears and yields. Results on yields: All three varieties have the highest yields with Treatment Ⅲ, giving on increase in production of 16.1%, 6.5% & 5.9.% respectively, as compared with that after Treatment Ⅰ. In Treatment Ⅲ, the number of ears per mu is less, the average number of grains per ear & the weight of the grains increased more than in the other treatments. The main results after the testing & analysis of the main stalk of “A. U. 183” are as follows: 1. With early treatment in spring, the leaves, sheathes, middle & lower nodes grow faster, longer and with bigger volume, but delay the growth rate of the later-growing organs, including the ear. The upper most node, ear & grains are smaller. On the contrary, when the treatment is delay, the early-growth organs are smaller, but the growth rate of the later-growing organs and the appearance of ears quicken, the upper nodes grow longer. Concurrently grains & the weight of grain increase. Through different treatments, it was noticed that the growing condition of early organs are closely related to the sizes of the later growing organs. The different conditions of fertilizers & watering produce apparent difference in the relation between different treatments. 2. During the growth of a wheat plant, some organs grow faster, while others slower. During the entire period of development, the same organ, it sometimes grows faster & sometimes slower. This illustrates that the growth of a plant & its various organs is not homogeneous & unbalanced. This unbalanced condition reflects the interrelationship of the growth of organs & the effect of different treatments. 3. The dry matter of the entire plant increases during its growth. But the dry weight of the same vegetative organ, sometimes increases & sometimes decreases, in accord with the difference of the conditions of additional fertilizer and watering. From the time when wheat turns green to the stage of ear-formation, the decrease of dry matter in the lower leaves in treatment Ⅰ is the highest, while in treatment Ⅲ, the dry matter decreased, in the lower sheathes is the highest. The sheaths are the organs for storing carbohydrates during the early growth stages. The decrease of dry matter of sheath can be considered as the supplier of storage matter to the later-growing organs. Present experiment proves that with larger amount of decrease of the dry matter in the sheaths during this period, the growth of the upper node, ears & grains are comparatively better. Leaves are not the main storage organs. The decrease of dry matter only means leaf senescence. 4. Before earing, the content of the soluble sugar & starch in the sheath is more than other organs and may increase or decrease markly. After heading, the stalk keeps the maximum dry matter content and decreases in large quantity since the mid- die stage of grainfilling. At that time, most of the content accumulates in the ears. There is the difference between the changes of the sugar content & the starch. Starch is a quite stable material for storage. Marked decrease appears at the times when wheat has turned green & during the early stage of node elongation, though there is no marked change in treatments. While sugar content decreases rapidly after applying fertilizer & watering, and increase rapidly when fertilizer & water are under controlled conditions. During the period from shooting up to earing, both sugar and starch decrease greatly in the sheath in all 3 treatments. The increase or decrease of sugar & starch corresponds to the change of dry weight. Therefore it can be assumed that the change of the dry weight mainly reflects the increase or decrease of the carbohydrates storage. 5. In the course of the wheat growing, the increase in volume of plant does not correspond with the increase of dry weight. Therefore the dry weight per unit volume, the specific gravity, varies apparently. During the period of wheat green- resuming to the stage of stem-extension, the increase of volume is faster than that of the dry weight so that the specific gravity of wheat plants of all 3 treatments decrease markedly, & continues to decrease until the stage of node elongation. After shooting, the specific gravity begins to increase. While the grains are in formation, the specific gravity rises immensely. The comparison of the treatments shows: before node elongation the specific gravity of treatment Ⅲ is the highest, treatment Ⅱ, the second, & treatment Ⅰ the lowest. It indicates that when the fertilizer & water are applied later, the volume of plant increases slower, while the dry matter accumulates faster. Whitehead (1962) initiated the experiment taking "Surplus material" as the relation between dry weight & leaf area. We use the formula as follow: α=loge W2/V2-loge W1/V1 S= α·1/2(W1+W2) α, is the average comparative increase of specific gravity between 2 sampling periods; S, is the quantity of comparative "surplus material"; W, is the dry weight & V, is the volume of the plant. There is a close relationship between the change of comparative "surplus material'' & the change of the daily growing rate of average volume. Treatments show a common tendency from the time the plant has been turning green until all its organs developed, that is, when the growth is faster, the "surplus material" will be lesser; and as the previous stage grows faster, the plant has less "surplus material", the growth of the later stage will be slower, & the "surplus material" increases, then the tempo of the growth of the next stage will be faster, & "surplus material" will decrease. The whole process of the growth of the wheat plant is wave-like, faster & slower, rises & falls, while the rise and fall of the "surplus material" is vise versa. 6. In wheat production, seedling stunting (to reduce or delay in applying fertilizer & watering during the period from the wheat is turning green up to the elongation of node) is often used to control the growth of the plant. Under the conditions of high rate of fertilizer & high density in the field, to induce the tillers develope towards two different directions. That is to say, one portion grows to shooting and earing rapidly & let the rest remain sterile, in order to reduce the density & at the same time, keep the growth of wheat plant to conform with its level of assimilation, to unify the contradiction between the vegetative growth & reproductive growth. Then it will help to increase the number and weight of grains & stronger the stalks to resist lodging. Under the condition of the lower rate of fertilizer the vegetative organ does not grow as desired, then it is necessary to apply fertilizer & water in time during the period from the wheat turns green to elongation of node in order to enhance the vegetative organs grow faster & larger & achieve high crop production.