Abstract: In order to discuss the physiological mechanism of postponing cotton leaf senescence after topping, and effects of plant growth regulators on cotton stem leaves senescence, yield and quality, a field experiment was conducted to study the effects of plant growth regulators on cotton leaf senescence physiological characteristics, yield and quality of conventional cotton variety Guoxin 3 and hybrid cotton Guoxin 8 at different growing stages in 2010-2011. Chlorophyll a and total chlorophyll contents in stem leaves from topping to boll opening metaphase of both Guoxin 3 and Guoxin 8 were significantly increased under plant growth regulator treatment. Net photosynthetic rate of both Guoxin 3 and Guoxin 8 was improved from full-bloom to initial boll opening stage, especially at full-bloom stage. The activities of POD from topping to boll opening metaphase of both Guoxin 3 and Guoxin 8 were significantly increased under plant growth regulators (Miantaijin，DPC tablet，DPC powder) treatments. The activities of SOD in Guoxin 3 at the pre-boll opening stage and Guoxin 8 at the post boll opening stage were also improved. However, the activities of CAT were unaffected. Carotenoid contents were significantly increased both in Guoxin 3 and Guoxin 8 at pre-boll opening stage and post boll opening stage, respectively. Peak of oxygen free radicals and MDA contents at initial boll opening stage was significantly reduced in both Guoxin 3 and Guoxin 8. The number of green leaves at boll opening metaphase, and total cotton yield was increased under plant growth regulators treatment. Plant growth regulators treatment also improved upper half staple length, specific breaking strength and uniformity of Guoxin 3 in 2010 and Guoxin 8 in 2010 and 2011. Micronaire value of Guoxin 3 was increased in both 2010 and 2011. Plant growth regulators increased the chlorophyll a and total chlorophyll contents in stem leaves from topping to boll opening metaphase, and increased the photosynthetic rate from full-bloom stage to initial boll opening stage. Plant growth regulators increased number of green leaves at boll opening metaphase and prolonged photosynthetic time, increased the flowering rate of cotton before frost, average boll weight and total cotton yield, and also optimized the cotton quality by certain portion.

Key words: plant growth regulator, leaf senescence, photosynthetic fluorescence, yield and quality

摘要： 为探讨植物生长调节剂延缓棉花打顶后主茎叶衰老的生理机制及对产量与品质的影响，2010-2011年采用大田试验，研究了调节剂与对照对常规棉国欣3号与杂交棉国欣8号打顶后棉花主茎倒2叶衰老生理特性、产量与品质的影响。调节剂（棉太金、DPC片剂、DPC粉剂）处理较对照增加了2品种打顶后至吐絮中期主茎叶叶绿素a及总叶绿素含量，提高了2品种盛花期至初絮期单株棉花光合速率，尤其在盛花期较为明显；显著提高了2品种的打顶后至吐絮中期主茎叶的POD活性，提高了国欣3号吐絮前与国欣8号吐絮后主茎叶SOD活性，而对CAT活性影响不明显；2品种主茎叶类胡萝卜素含量分别在吐絮前有所提高及在吐絮后明显提高，明显降低了2品种初絮期的活性氧最高峰值与MDA含量，提高了吐絮中后期单株绿叶数；增加了2年2品种的籽棉总产量，显著提高了2010年国欣3号与2年内国欣8号上半部平均长度、断裂比强度、整齐度，提高了2年国欣3号马克隆值；增加了2品种打顶后至吐絮中期主茎叶叶绿素a及总叶绿素含量，提高了此时期的单株光合速率，增加了吐絮中后期单株绿叶数，延长了后期光合时间，增加了霜前花率、平均铃重及籽棉总产量，且优化了部分籽棉品质。

关键词: 调节剂 , 叶片衰老, 光合荧光, 产量与品质