灌浆期高温与水分胁迫交互作用对半干旱区春玉米生长和产量的影响

The frequency and intensity of extreme weather events increased in global warming. Frequent drought and extreme temperature events appeared in spring Maize during filling stage of Chinese spring maize planting areas. The high temperature and drought disasters caused serious damage to maize. Most researchers have focused on maize growth or potted period control of moisture or temperature in growth chamber experiment, the disaster index and disaster prevention and mitigation of drought and heat temperature are restricted. The drought and extreme temperature are prone on period in spring maize during filling stage; this research would concentrate on the core issue of spring maize response to water stress and high temperature composite effect. Using field observations of soil moisture and infrared radiation to control moisture and warming, four water treatments would be set, each treatment set four kinds of warming, i.e. the day&nigh warming 3℃, day&nigh warming 5℃, day&nigh warming 7℃and not warming in growth duration, last 3,5,7 day respectively. The observations and measurements of phonological, yield, photosynthesis/respiration and environmental parameters would be acquired in filling stage. It would be find out that the impact of high temperature and drought on spring maize growth, grain quality, physiological parameters and yield. It would be clarify how different high temperature and drought may affect the growth, photosynthesis/respiration, thereby affecting the spring maize yield and grain quality. It would reveal the physiological mechanisms that how the sowing date postponed could adapt to extreme climate events.

气候变暖背景下极端气候事件发生频率和强度增加，干旱极端高温等事件主要发生在中国春玉米种植区的灌浆期,对春玉米生产带来严重威胁,以往研究集中在单一干旱、高温对玉米的影响,但干旱伴随高温对灌浆期春玉米影响机制尚不清楚,制约着灾害指标制定和干旱高温的防灾减灾；本项目围绕春玉米灌浆期水分胁迫和高温交互作用的影响机制这一核心问题,以春玉米为对象,采用大田原位试验,通过土壤水分控制场和红外线辐射器控制水分和增温,在灌浆期设置4种水分处理，每个处理设置正常温度、+3℃、+5℃、+7℃ 4 种处理,分别进行持续3、5、7天试验，观测各处理的灌浆过程、生长发育、产量等,测定环境参数和光合/呼吸作用。研究水分胁迫下，不同高温及持续时间对春玉米各生理指标影响的差异；阐明灌浆期高温干旱影响春玉米发育与产量构成的机理；揭示三因子交互作用对灌浆期春玉米生长影响中的作用和生理机制，为春玉米适应极端气候事件提供科学依据。

极端气候事件的频繁发生，高温与干旱事件对玉米生长发育造成的影响越来越严重。如何定量干旱和高温干旱交互作用对玉米生长发育、产量以及产量构成的影响等科学问题仍没有解决。本项目为弄清极端气候发生演变规律以及玉米灾损风险状况，探讨干旱与高温干旱对玉米生长发育的影响等开展研究。. 西北地区极端高温事件增多，极端低温事件减少，极端降水事件增多。极端低温、异常低温日数减少的幅度大于极端高温、异常高温日数增加的幅度，气温日较差呈减小趋势，存在非对称性增温特征。玉米的高风险区主要集中在陇东地区的东部，较高风险区分布在陇中、陇东大部分地区，河西地区通过灌溉可有效缓解旱灾，风险较低。. 春玉米拔节期受水分胁迫影响，发育后期土壤含水量较正常灌溉处理减少了约72%，造成减产约67%；抽雄期受到水分胁迫的影响，土壤含水量较正常灌溉处理减少了约57%，造成减产约55%，百粒重的减少幅度较大。抽雄期干旱直接影响春玉米的产量，造成严重的减产，并且拔节期持续干旱对春玉米的影响远大于抽雄期持续干旱的影响，株高和叶面积指数对拔节期水分胁迫处理比较敏感；不同程度干旱胁迫下春玉米叶片对光强反应差异显著，在相同光强下，正常灌溉＞轻度干旱＞重度干旱。. 玉米受高温与干旱交互作用时，土壤含水量迅速减少，并且增温幅度越大，蒸发量越大，土壤贮水量减少越多，干旱对土壤水分的影响远大于高温的影响。株高和植株含水率的变化主要受水分胁迫的影响，增温对玉米株高、植株含水率影响不大；无论轻旱还是正常灌溉，适应的温度能够促进玉米的光合作用，使得玉米增产；温度过高，导致玉米气孔关闭，抑制其光合作用从而对玉米的生理造成损伤，从而造成玉米减产。. 本研究给出了西北地区极端气候事件的发展规律以及玉米灾损的风险区划，分析了干旱对玉米生长发育影响的定量关系，弄清了高温与干旱交互作用对玉米生长发育影响的机理机制，为防灾减灾提供科学参考依据和玉米生产的粮食安全提供理论支撑。