西北雨养旱作区地膜增温对春玉米根冠早衰的影响机理及调控途径

In the rainfed area of northwest of China, the phenomenon of premature senescence had a serious impact on the formation of grain yield of maize which film mulch maize grow on late stage. Clear maize senescence causes, it plays an important role in promoting high yield and efficiency of film maize. At present, the study of soil temperature control technology and mechanism on film mulch maize was litter, and the mechanism of water and nutrient in soil absorbed and utilized by maize root was still not clear under change of soil temperature. The principle of soil water movement and absorption under different soil temperature needed to be further explored. In this study, the effect of film mulching on soil warming was taken as the breakthrough point, using effective measures to adjust film temperature, studying on effect of temperature on soil physicochemical properties, root growth and aging of key enzyme activity of maize. Reveal morphological characteristics and changes of endogenous hormones of maize root and leaf aging under film warming. The relationship between the plastic film warming and soil environment, the soil environment and the development of maize root system, the secretion of endogenous hormones, the development of root system and morphology and internal activity of leaves were studied. From two aspects of soil environment and root physiological metabolism, to clarify the mechanism of film temperature on soil environment and corn root leaf aging, and seek to a new way and method of increasing yield and prevention sensecence for of maize.

在西北雨养旱作地区，地膜春玉米后期早衰现象普遍，严重制约玉米籽粒产量形成。明确玉米早衰形成原因，对促进该区地膜玉米增产增效具有重要作用。目前，有关地膜玉米的土壤温度调控技术及作用机理研究较少，土壤温度改变后玉米根系对水分和养分吸收利用的内在机制仍不清楚，不同土壤温度变化下的土壤水分运动与吸收利用规律有待深入探究。本研究以地膜对土壤的增温作用为切入点，采取有效的地膜调温措施，研究增温对土壤理化性状、玉米根冠发育及衰老关键酶活性等的影响。揭示地膜增温下玉米根冠衰老形态特征和内源激素变化规律；明确地膜增温与土壤环境、土壤环境与玉米根系发育及内源激素分泌、根系发育与叶片形态及内部活性等之间的互作关系。从土壤环境和根冠生理代谢两个方面，系统阐明地膜增温对土壤环境和玉米根冠衰老的作用机理，探寻玉米防衰增产的新途径和新方法。

早衰现象严重影响作物产量和品质，在西北雨养旱作地区，随着近年来全球气温的不断升高，地膜春玉米后期早衰现象普遍，严重制约玉米籽粒产量的形成；明确其早衰原因及防控机理，对促进该区玉米增产增效具有重要作用。本研究以地膜增温后的土壤环境、玉米根系活力与内源激素分泌、植株代谢与叶片内部酶活性等互作关系为主要研究对象，系统分析地膜增温对玉米根区土壤理化性状和根冠早衰的影响。结果发现，（1）由于西北雨养旱作地区光热资源丰富，地膜的主要作用是保水；在玉米出苗后，随着环境气温的快速升高，膜下过高的土壤温度导致玉米根区土壤紧实度、有效养分含量等理化性状变差，显著影响了玉米根系对水分和养分的吸收利用，造成玉米后期根系生长量减少，根系衰老提前。（2）膜下过高的土壤温度导致玉米根系活力降低，根系内源激素和保护酶活性下降，根系对养分和水分的吸收与运转功能变差，进而影响了玉米地上部生长，造成玉米地上部植株生长受阻，干物质生长量显著减少，玉米的叶片光合能力下降，后期叶片的保护性酶活性降低，叶片出现早衰。（3）适当的膜下降温覆盖方式可以显著提高玉米的叶片光合能力，延缓根冠衰老，延长玉米灌浆时间，提高玉米千籽重和籽粒产量，农田水分利用效率显著提高。本研究结果从地膜覆盖的作用效果方面，深入解析了雨养旱作区地膜覆盖下玉米早衰的内在原因，并从栽培技术方面研发形成了缓解地膜玉米早衰的膜下土壤降温覆盖措施，在有效缓解雨养旱地玉米根冠衰老，促进玉米增产增效方面效果显著。项目形成的以黑色地膜为覆盖方式的玉米防衰高产栽培技术，将为保障我国西北雨养旱地玉米的持续高产稳产发挥重要作用。