新疆干旱区膜下滴灌棉花早衰的水钾耦合调控效应及机理

Physiological premature senescence in cotton caused increasingly serious damage under mulched drip irrigation in arid area of Xinjiang,the cotton premature senescence is closely related to the root characteristics and potassium nutrition,as yet,little information has been available on the interaction effect of the water and potassium on cotton root and premature senescence in cotton,and the mechanism of water-potassium coupling regulation to premature senescence in cotton. The fields experiments will be designed to investigate the relationship between soil waterr-potassium features in drip-irrigated cotton field,the characteristics of root,root-shoot balance, source-sink,plant physiological characteristics and crop growth of cotton,the compensation of cotton under Regulated Deficit Irrigation,response of raising water use efficiency by suitable application of potassium, response of the cotton premature senescence to water and fertilizer interactions,analysis the dynamics of root caused by various root zone moisture and potassium.To carry out the trial we will reveal the physiological mechanism of premature senescence of cotton and high water use efficiency and water-potassium use efficiency caused by drip irrigation regulation, clarify the ecophysiological mechanism of premature senescence of cotton with water-potassium coupling,look for the optimal pattern of mulched drip-irrigation and regulatory pathways with moisture and potassium integrated,which raising water use efficiency by suitable application of potassium,draw up the reasonable mulched drip-irrigation, by which premature senescence in cotton will be inhibited in arid area of Xinjiang.Therefore it will have important theoretical and practical significance in reveling the water and fertilizer regulation mechanism of premature senescence in cotton,and the water and fertilizer saving cultivation theory and mulched drip irrigation technology of cotton.

新疆干旱区膜下滴灌棉田早衰现象日益严重，棉花早衰与根系分布和钾素营养有密切关系，但关于水、钾对棉花根系及早衰的调控效应，及早衰的水钾耦合调控机制研究很少。本项目开展滴灌棉田间根层土壤湿润体水肥特征与根系特征、根冠动态平衡、源库特征、植株生理特征、发育进程的关系，调亏滴灌下棉花的补偿效应，钾的以肥调水效应,水钾交互作用对早衰的调控效应等研究，分析膜下滴灌棉田水钾对根系变化规律，揭示膜下滴灌棉花水钾高效利用特征及棉花早衰的生理机理，确定棉花早衰水钾耦合调控的生理生态机制。寻找棉花早衰优化滴灌模式、“以肥调水”的水钾一体化调控途径。提出适宜于新疆干旱区膜下滴灌的高效抑制棉花生理性早衰的滴灌制度，为生产实践提供理论依据。另外，开展本项目研究，有助于从理论上认识膜下滴灌棉花早衰的节水节肥调控机制，对于补充干旱区膜下滴灌棉花节水控肥栽培理论具有重要意义。

新疆是中国最具比较优势和发展潜力的宜棉区，同时也是全国最大的优质棉产区，早衰现象严重是目前棉花生产上亟待解决的问题。对于棉花早衰的生理机制尚不明确，并缺少有力的试验论证。本项目通过水钾耦合调控试验和调亏滴灌施钾试验，研究根区水分、植株钾素营养代谢规律与棉花根系发育、早衰的关系，以及相应的根冠、源库调节效应、光合和生理生化特性，并进行水钾交互作用的水肥利用效率分析。初步阐明：.1.滴灌水分亏缺处理易呈现不同程度衰老特征，并对产量产生影响。.2.棉花生育期内确保充足水分供应，使棉花生育前期具有较高的抑制衰老早衰相关酶类活性，根系ABA含量处于较低水平，植株叶绿素含量较高，避免了前期植株早衰。而且足够的水分供应为同化物质由源向库的运输为产量形成提供了基本保障。限量灌溉产量大幅下降的同时水分利用率显著降低。.3.生育前期轻度水分调亏配合适量施钾可显著缓解早衰并有助于提高棉花产量；蕾期轻度水分调亏不施钾，重度调亏施钾水分利用率最高。.4.水钾互作下过量施用钾肥影响水分利用率，生育前期调亏灌溉中过量施钾有进一步诱发早衰的倾向。.5.蕾期两种水分调亏处理后在花铃期叶片ABA/CTK水平仍处于显著低于对照的激素水平；虽然生育前期水分调亏根系活力低于后期调亏处理，但由于生育前期轻度水分调亏后复水产生的补偿效应，使产量器官干物重、单株干物重显著增加，产量显著提升。.6.生育前期轻度水分调亏配合适量施钾可显著缓解早衰并有助于提高棉花产量，高于生产上常规施肥用量施钾用量有进一步诱发早衰的倾向。