覆盖耕作模式对旱地冬小麦籽粒品质形成的影响及其氮素调控

Mulching tillage, which improved significantly soil environments consisting of water,fertilizer,air and temperature, have been considered as an effective plant model to increase wheat yield in semi-arid rainfed agricutural area of Northwest China.Although most of experiments have been conducted to study the effect of mulching tillage on soil environments and plant metabolism in the past few decades,few studies have focused on the effect of mulching tillage on wheat grain quality.Consequently,field experiments were designed by selecting different mulching tillages and nitrogen applications in Longdong semi-arid rainfed agricutltural area.Systematical research will be aimed at the effect of mulching tillages, nitrogen applications and interaction between them on soil water and fertilizer dynamic,above-ground metabolism of carbon and nitrogen, as well as wheat grain quality.Research will deeply analyze intrinsic relationship between grain quality formation and enzyme ability related to metabolism of carbon and nitrogen.The objectives of this study are to make clear the storage substance redistribution in vegetative organs, the accumulation of starch and protein in wheat seeds and the physiological mechanism of wheat grain quality formation under different mulching tillages.Nitrogen adjustment strategy of dryland seed quality formation will be also established by systematical study.Results will be an important theorical proof to develop winter wheat quality with high yield,good quality and high effiency in Longdong semi-arid rainfed agricultural area.Moreover,it is also meaningful to deepen and broaden the physiological mechanism of grain quality formation of dryland winter wheat under different mulching tillages.

覆盖耕作因改善土壤水、肥、气、热环境，大幅度提高小麦产量，近年来在西北半干旱雨养农业区得到大面积推广。目前，就覆盖耕作对土壤微环境和植株代谢进程的作用已基本明确，但就覆盖耕作对小麦籽粒品质形成的影响报道较少。本项目拟在陇东半干旱雨养农业区选择典型的覆盖耕作模式，设计不同的供氮水平，系统研究覆盖耕作模式、氮素及模式氮素互作对冬小麦土壤水肥动态、地上部碳氮代谢特点及籽粒品质形成的影响，解析碳氮代谢相关酶活性与籽粒品质形成的机理关系，以期明确不同覆盖耕作模式下旱地冬小麦营养器官储存物质再分配及籽粒淀粉、蛋白质累积规律，阐明不同覆盖耕作模式影响籽粒蛋白质、淀粉形成的生理机制，确立不同覆盖耕作模式旱地冬小麦品质形成的氮素调控方案。研究结果将为西北半干旱雨养农业区冬小麦高产、优质、安全、高效栽培提供理论依据和技术途径，对深化和拓展不同覆盖耕作模式下旱地冬小麦品质形成的生理机制有重要的理论和现实意义。

覆盖耕作对土壤微环境和植株代谢进程的作用已基本明确，但对小麦籽粒品质形成的影响报道较少。本项目选择常规耕作（CT）、秸秆深松还田（CTI）、全膜覆土穴播（PFM）、免耕秸秆覆盖（NTS）4种耕作方式和75（N1）、150（N2）、225（N3）、300 kg ha-1（N4）4个氮肥水平，在典型的半干旱雨养农业区进行连续4年的大田试验，测定蛋白质和淀粉品质，监测土壤水温参数，测定地上部碳氮代谢指标，目的是明确不同覆盖耕作模式和供氮水平对旱地冬小麦谷物产量和品质的影响及其生理生态机制。研究结果表明，耕作方式和供氮水平对谷物产量和品质均有显著影响。在4种耕作模式中，PFM谷物产量、千粒重、蛋白质、沉降值最高，湿面筋较高，延伸性较好，稳定时间和抗延阻力最低；NTS谷物产量、千粒重、蛋白质、湿面筋最低，延伸性最差，稳定时间、形成时间、抗延阻力最高；CTI抗延阻力、千粒重、蛋白质、稳定时间较高，湿面筋、沉降值较低，延伸性较差；CT延伸性最好，湿面筋最高，但沉降值最低，千粒重、蛋白质、稳定时间、抗延阻力均处于较低水平。随着施氮水平的增加，谷物产量、蛋白质、沉降值、湿面筋、面团吸水率、延伸性显著增加，N4条件下蛋白质、沉降值、湿面筋、面团吸水率、延伸性分别为12.78%、31.06ml、32.32%、61.06%、162.42mm，比N1分别增加23.84%、49.83%、35.31%、5.95%、18.01%。相反，施氮显著降低了面团的稳定时间和抗延阻力。比较N1，N4面团稳定时间和抗延阻力分别降低20.12%和6.35%。CT、CTI、PFM、NTS产量依次为5021.48、4870.38、5815.61、4510.50kg ha-1； N1、N2、N3、N4依次为4650.50、 5134.20、 5209.25、5224.03kg ha-1。耕作方式和施氮水平也改变了土壤水热动态和物质转移、累积、再分配规律。综上可知，在半干旱雨养农业区实施全膜覆土穴播栽培，并施氮150 kg ha-1，既能大幅度增加小麦谷物产量，也有利于加工品质的改善，是该地区小麦生产实现高产和优质的最佳耕作和供氮模式，研究结果为该区域旱地冬小麦的高产、优质栽培提供了理论参考。