| The experiment was conducted at Plant Protection Station experimental field of Agricultural Technology Promotion Center in Xinjiang's Aksu City, in 2009, selected the specific strength of high, medium and low three types of cotton varieties: No 46, No 49 and No 43 were chose to be tested materials. Through setting a different time in planting field,thus made all varieties of cotton bolls at different temperature conditions, analyzed and discussed from dry boll dry matter accumulation, boll size and diameter changes, dry matter accumulation of cotton fiber, cotton fiber quality and other physiological and metabolic aspects to explore the moderating effect of different temperature conditions on the cotton bolls and cotton fiber development process, proved the key temperature factors of impacting fiber quality characteristics, the main conclusions are as follows:Boll size increased rapidly at 14 days from flowering to boll, and B2 treatment had the largest initial volume of cotton bolls at boll age of 14 days, and their size showed B2> B3> B1. When the volume tended to stereotypes, the volume of cotton bolls in B2 treatment showed the minimum, cotton boll diameter increased rapidly from 14 to 21 days in the same sowing date treatment, Among boll daily growth volume of the No.49 increased the fastest, on the condition of B2 treatment, the cotton boll diameter changes of three varieties were relatively uniform. Boll dry matter accumulation was "S" curve, better simulated by quation, boll dry matter accumulation characteristics of each species was not obvious before 35 days in the boll. But along with the delayed sowing date,cotton boll dry matter accumulation of the same species was decreased, the emergence of time (t0) of the maximum dry matter accumulation rate (Vmax) was advanced,△t became shorter.In the appropriate planting time,boll dry matter accumulation schedule trended shorter in late-sowing.In the development process of the cotton boll,boll shell ratio decreased along with bell age, No.49 had higher boll shell rate that the boll shell tended to stereotypes. Boll shell ratio of B1 showed higher in early development of fiber,decreased significantly in later stage. With the sowing date postponed,all varieties showed the number of boll increased in the upper plant and decreased in the lower plant.Dry matter accumulation in cotton fiber and accumulation rate made difference among the varieties, and No.49 was obviously different from the other two varieties. In different sowing dates,at boll age of 14 days, dry matter accumulation characteristics in cotton fiber showed:B1>B2>B3. With the sowing date postponed, bell maturity average temperature dropped and the accumulation of friber dry matter became smaller, the appeared time of the maximum accumulation rates delaied,the maximum accumulation rate decreased. The soluble sugar content of cotton fiber reached the highest at boll age 14 days, then decreased.In different sowing dates,along with the delayed sowing date, 14 days in boll age,soluble sugar content showed B1 B2> B1.IAAO activity in the B2 treatment for 14 days under the boll higher activity than the B1 treatment has been ahead of the peak,and showed maximum at 28 days in boll age, IAAO activity change in B3 treatment was stable, in different sowing dates, activity peak value closed. With the detention in sowing date, the average POD activity declined in the secondary wall thickening, and the same behavior in the final fiber strength. Within 49 days in boll age,stable POD activity change of 46 was the key to the formation of high specific strength. IAAO activity was stable in the thicking stage, the IAAO activity peak value of No.46 appeared significantly higher than the other two varieties, provided guarantee for the formation of high specific strength cotton fibers. 22.5~24℃is the appropriate temperature of stable POD activity,with the delayed sowing date,boll maturity average temperature increasingly declined,appeared time of the POD activity peak value in No.46 and No.49 delayed, Temperature effect on the IAAO activity was less than POD, bell of temperature between 20~24℃, IAAO activity had showed more stable change trend.
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