中文摘要：

早衰是棉花生产中普遍存在的问题。本试验选用2个棉花品种冀优01和国欣3号,研究蕾期不同水分条件对棉花早衰和内源激素含量的影响。结果表明,蕾期干旱显著提高了棉花叶片和根系中丙二醛（MDA）的含量以及早衰指数,降低了棉花干物质积累和籽棉产量,是棉花早衰的主要诱因,而蕾期浇水能够明显缓解棉花早衰;棉花早衰始于根系,是蕾期干旱条件下根系向叶片中输送的ABA含量的增加及CTK含量减少引起的,推测叶片中ABA/CTK比值的提前升高是启动棉花早衰的激素信号。

英文摘要：

Premature Senescence is a common problem in cotton production. The effects of squaring stage irrigating on premature senescence and endogenous hormones in cotton have been studied with two cultivars,Jiyou 01 and Guoxin 3,and the mechanism of cotton premature senescence was also discussed. The senescence index and malondialdehyde（MDA） concentrations of cotton leaves and roots were increased,and the dry matter and yield were decreased by drought stress of squaring stage,which was the primary cause of premature senescence and obviously mitigated by squaring stage irrigating. Cotton premature senescence was started at roots caused by increasing ABA and decreasing CTK transported from roots to leaves under drought stress at squaring stage. The earlier raise of ABA /CTK ratio could be the original signal to start cotton premature senescence.