中文摘要：

在田间试验条件下,研究了施钾对棉花苗期生长和功能叶片生理特性的影响.试验设2个品种,4个施钾量.结果表明,施钾增加了棉花株高和单株叶片数,而对单株叶面积的影响不同,当施钾（K2O）量为180 kg/hm^2时,叶面积达最大值,继续增施钾肥叶面积减小;施钾促进了叶绿素的合成,同时增加了叶绿素荧光动力学参数Fv/Fo、Fv/Fm和qP值,降低了qN值,增加了PSⅡ的实际量子效率（ФPSⅡ）和光合电子传递速率（ETR）,从而提高了棉花功能叶的光合功能;施钾还增加了叶片中生长素（IAA）、玉米素核苷（ZR）、赤霉素（GA3）的含量,降低了脱落酸（ABA）的含量,提高了IAA/ABA、ZR/ABA、GA3/ABA比值,有利于延缓叶片的衰老.适量施钾还增强了硝酸还原酶（NR）的活性,促进了棉株氮素代谢.

英文摘要：

Knowledge of K requirement for cotton growth and development is need since it play a pivotal role cient production and fiber quality. Our present study focused on the effects of potassium nutrition on cotton on its effigrowth and leaf physiological characteristics at seedling stage. Two cotton varieties, Lu18（L18） and zhong41 （ZH41）,were used and four rates of K fertilizer were applied （K2O 0, 60, 180 and 300 kg/ha） under field condition with randomized block design. The results showed, K application increased plant height and leaf numbers per plant, but its effects on leaf area were not consistent. It appeared to reach maximum area when K application rate was 180 kg/ha, and then declined with further increasing potassium fertilizer. K application could promote the synthesize of chlorophyll. K application increased the chlorophyll fluorescence dynamics parameters, Fv/Fo, Fv/Fm and qP, and reduced qN. K application also increased actual quantum efficiency（ФPS Ⅱ ） and photosynthetic electron transport rate （ETR）, which improved the photosynthesis of cotton leaf consequently. In addition, the effects of K application on endogenous hormones were divergent. It increased the content of IAA, ZR, and GA3, while the content of ABA were reduced as the result; The lower ratio of IAA/ABA, ZR/ABA, GA3/ABA ratio indicated that senescence of leaf could be retarded. Rational application of K could promote N metabolism through increasing the activity of NR .