Studies On Boll Sucrose Metabolism And The Relation Of Fiber Strength Formation In Xinjiang

Fiber strength is an important factor to measure fiber quality, and the formation of it depends on the cumulative properties of cellulose during cotton fiber thickening development and metabolism and regulation process of sucrose. With the Machine-plucking technology promotion of xinjiang cotton, the cotton fiber strength formation has been great influenced by defoliant. Aiming at the existing problems in the cotton production in Xinjiang, the relationship of transfered characteristics of carbohydrates in the boll-leaves system, cellulose accumulation characteristics and fiber strength were studied, the purpose is to explore the mechanism of boll bur carbohydrates and fiber strength under reducing photosynthetic source. Additionally, the results obtained can offer an important strategy for high-yielding and high-quality in cotton. Below are the main results in this thesis. 1. Cotton boll development characteristics and Boll shells, fiber and cotton seed dry matter accumulation and distribution of different genotypes of cotton, The distribution of the carbohydrate and it affects the cellulose synthesis(1) Nine different genotypes cotton varieties were taken as test materials, the relationship between rapidly increasing period duration of the cotton boll and boll weigh were studied. The results showed that the growth rate of cotton boll length, diameter and volume appeared in the 0-22 DPA, and the greatest drop appeared in the 0-15 DPA. The growth rate of boll weight increased(0-22d) at first and then descend within 36-46 DPA, the duration and maximum rate of the boll weight rapid growth was the decisive key factor to boll weight. Path analysis further showed rapidly increase duration of boll length had largest direct effect on boll weight and rapidly increase duration of boll volume had secondly indirect effect on boll weight. This shows boll length and volume as an index to the breeding of cotton varieties has certain guiding significance to improve the single boll weight.(2) Boll shells, fiber and cotton seed dry matter accumulation and distribution of physiological mechanism and the boll shells in the role of the transport were analyzed. Boll shell dry matter had fastest accumulated rate from 0 to 29 DPA, and began to fall with the increasing of the days post-anthesis after 39 DPA; there were two periods of fibre and cotton seed dry matter accumulation from 0 to 29 and 20 to 30 DPA, as well as cotton seed material accumulation faster than the fiber, the latter stage of growth of cotton seed inosculated with the period of reducing boll shell matter. The distribution of boll shell dry matter has mainly occurred at 15-29 DPA, there is difference for shell nutritions among three varieties and cotton seed and fiber had more organic material of strong strength cotton. Cotton seed rate were higher percentage 15 than fiber, It Shown that cotton seed and fiber had a strong apply ability for photosynthesis product under the circumstances of less shell dry matter. So extending the duration of the rapid increase of dry matter was to improve the quality of dry matter, and increasing the capacity of advantage was to promote nutrient flux efficient transit among boll shell, cotton seed and fiber in cotton cultivation.(3) In the late period of cotton boll growth and development, It is commonly used defoliant that insufficient leaves source effected the leaf photosynthate synthesis and transshipment. Cotton fiber strength changes through analyzing the impact of boll bur and fiber sucrose metabolism of studying under insufficient leaves source, which is an effective way to improve the cotton fiber quality. The results showed that boll burs sucrose, fructose and starch content had seen a decline after 15 DPA, and boll burs sucrose content accounted for a largest proportion in the total bur carbohydrate. The dynamic change of fiber sucrose, fructose and glucose contents showed a unimodal curve, the peak appeared in 15 DPA. The boll bur sucrose content is the main factor for affecting the soluble sugar content in the fiber, bur fructose directiy effected on the cellulose content, Cotton fiber carbohydrate completely changed into amorphous cellulose when fructose thoroughly and quickly transfered in the seed cotton, and had much amount of cellulose deposition. 2. Limited cotton leaves Affects Sucrose Metabolism of Cotton Boll and Related with Fiber StrengthUnder the condition of spraying defoliant, Limited cotton leaves affected leaf photosynthesis in Xin Jiang. It is of great significance to explore the technical approach to reveal underlying mechanisms contributing to cotton fiber strength changes through analyzing the impact of boll bur sucrose metabolism under insufficient leaves source. The impact of spraying defoliant during different periods on sucrose metabolism in cotton fiber, and cotton fiber strength changed under reducing photosynthetic source. Compared with the control, the application of defoliant lead to the transformation delay 3.8 days of bur sucrose and the duration of the fast accumulation cut by half, thus boll bur sucrose content had low. It is 14.9 days in advance of reaching peak value of fiber sucrose content by using defoliant, the rapid accumulation time of cellulose was shorten and carbohydrate did not fully change in to cellulose, which was by 13.2 % and affected the formation of fiber strength. Sucrose content in the boll bur is the main factor affecting the fiber sucrose content. the application of defoliantreduced the sucrose content in the boll bur which leaded to the reduction peak value of fiber sucrose content, and fiber strength was eventually decreased.