干旱和复水对膜下滴灌棉花根系及叶片内源激素含量的影响

Effects of drought and re-watering on endogenous hormone contents of cotton roots and leaves under drip irrigation with mulch

新疆气候生态条件下,采用膜下滴灌技术,在棉花不同生育时期设置不同程度干旱处理,研究干旱和复水对棉花根系及叶片内源激素含量和叶片气孔导度的影响.结果表明:在不同生育阶段,随土壤含水率的降低,根系及叶片脱落酸(ABA)含量显著增加,玉米素(ZRs)含量减少,叶片气孔导度(gs)和光合速率(Pn)显著降低,以初花-盛花期土壤相对含水率为40%～45%处理降幅较大.土壤干旱处理结束后复水,根系及叶片ABA含量并未随土壤水分条件的改善而降低,根系ZRs含量在复水后1～3d均可恢复或超过对照,与叶片gs呈正相关,其中以盛蕾-初花期土壤相对含水率为50%～55%处理棉株叶片ZRs含量和gs恢复速度快、强度大.说明干旱后复水根系较高的ZRs含量是导致其叶片gs和Pn较高的主要原因.

degrees of Under the climatic and ecological conditions of Xingjiang, Northwest China, different drought stress were instaUed during the growth stages of cotton, and the drip irrigation with mulch was adopted, aimed to study the effects of drought stress and re-watering on the endoge- nous hormones （ abscisic acid, ABA ; and zeatins, ZRs） contents of cotton roots and leaves and the stomatal conductance （g,） of cotton leaves. With the increase of drought stress at different growth stages, the ABA contents of cotton roots and leaves increased, while the ZRs contents of cotton roots. and leaves and the g, and photosynthetic rate （Pn） of cotton leaves decreased, with greater decre- ments in the treatment of soil moisture content being 40% -45% of field capacity at early flowering- full flowering stage. After re-watering, the ABA contents of cotton roots and leaves did not have a decrease with the improvement of soil moisture regime, while the ZRs contents of cotton roots recov- ered rapidly or exceeded the control after 123 days of re-watering. There was a positive correlation between the ZRs contents of cotton roots and the gs of cotton leaves. In the treatment of soil moisture content being 50%-55% of field capacity at full budding-early flowering stage, the ZRs contents and gs of cotton leaves recovered more quickly and with greater increments. It was suggested that the higher ZRs contents of cotton roots after re-watering could be the main cause for the higher stom- atal conductance and photosynthetic rate of cotton leaves.