棉 花 学 报 Cotton Science 2007，19(1)：52-56
Effects of Removal of Early Fruiting Branches on Yield，Fiber Quality and Premature Senescence in Bt Transgenic Cotton Abstract：Our previous report has indicated that current Bt transgenic cotton varieties can be divided into two types，the early-developed (ED) and the late-developed type (LD)，according to their earliness of maturity. Therefore，it is necessary to determine the effects of removal of fruiting branches on plant growth and development，lint yield，and fiber quality in various types of Bt transgenic cotton. In the present experiments，cotton cultivars，SCRC 17 or SCRC 21(ED type)，SCRC 18 or SCRC 22 (LD type) ，and H1 or H2 (hybrids of the two types) were planted in Shanghe county in 2004，and Xiajin county in 2004 and 2005，and the effects of removal of early fruiting branches (FB) on the yield，fiber quality and premature senescence of cotton plants were determined. Averaged across two years and two experimental sites，removal of FB increased average lint yields of the ED type and the hybrids by 3.3% and 5.7%，relative to their corresponding untreated controls，while lint yield of the LD type was slightly decreased in 2004，but decreased by 6.2% in 2005 with FB removal. For the FB removed plants，the percentage of pre-summer bolls was reduced while that of summer bolls and plant height was significantly increased. Days from planting to boll opening were slightly and significantly extended in ED and LD type of cotton by FB removal，respectively. Removal of FB also increased the fiber length and strength by 2.6% and 2.3%，respectively，but decreased the micronaire value by 5.6%，did not reach the significant variation at P=0.05. Premature senescence of cotton plants seemed to be alleviated through the altered ratio of sink to source by FB removal. FB removal might be a potential way to improve cotton production for early-developed cotton plants.
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