Carbohydrate Profiles During Cotton (Gossypium Hirsutum L.) Boll Development And Their Relationships To Boll Characters

The dynamics of non-structural carbohydrates(NSC) in various fractions of cotton boll might have significant impact on within-boll lint and seed yields. The objective of this research was to determine how NSC in the three fractions of cotton boll(the fiber, the seed, and the bur)fluctuated at various stages of development and assess whether there was any association between carbohydrate profiles and boll characters. This experimengts were conducted in 2011 and 2012.Field experiments was arranged in random design with three replicates in each treatment.Each plot consisted of rows,which were 10 m in length and 1m apart from each other.On the day of anthesis in full-blossom period, white flowers were tagged.Boll samples were harvested at 10, 17, 24, 31, 38, 45, and 52 days post anthesis(DPA).At each harvest,eight to ten tagged fruits per plot brought to the laboratory, where bur,fiber and seed fractions were immediately separated from the fruit samples and dried at 110℃ 30 min and at 50℃ to constant weight.These tissues were ground with a mill until they couldpass through a 32-mesh sieve for analysis of glucose, fructose, sucrose and starch with the method of Enzymatic colorimetry and anthrone colorimetry. The starch concentration in those fractions from all genotypes was characterized by a declining trend with a faster decrease during the first 24 DPA than during later stages of boll development in both years. The sucrose concentration in embryos increased to the first peak from 17 DPA to 24 DPA and then declined down to a valley at 38 DPA corresponding the beginning of embryo desiccation. Thereafter, the sucrose concentration increased linearly, to form a second peak observed at 52 DPA. It indicted that the accumulation of sucrose may be association with the synthesis of raffinose and stachyose al storage materials. The sucrose, glucose and fructose concentrations in fibers presented as single-peak curves during fiber development with the maxima occurring at either 17 or 24 DPA, corresponding to the transition phase from primary to secondary wall formation or to the beginning of massive secondary cell wall formation. then fast decreasing. Boll characters(boll size, lint percentage, and lint mass per boll) were more related to the starch and sucrose changes in embryos than in fibers. Sucrose might withdraw from either seeds or fibers to burs by maturity.