旱作和有限灌溉对不同耐旱性小麦耗水过程与水分利用效率影响的稳定同位素研究

Facing the challenge of shortage of agricultural water resources, it's inevitable to adopt the rained and limited irigated measures in the water management of farmland. It's crutial to determine the discrepancies of the consumption of water resources of differnent wheat cultivate and varieties under the rained and limited irigated measures. In our study, four different drought-tolerant wheat varieties were adopted among the leading wheat varieties in Shandong province. The water comsumption and water use efficiency were analyzed under the rained and limited (one to three times) irrigated measures. The key issues were as following. Discrepancies of water use process were compared by analysis of leaf water H218O enrichment resulting from transpiration based on leaf water H218O measurement. Discrepancies of water use efficiency were also compared by analysis of leaf carbon-13 depletion resulting from photosynthesis based on leaf carbon-13 measurement. The plant transpiration and soil evaporation was partitioning by the IRGA-static chamber method, thus the ratio of plant transpiration to soil evaporation, and their contribution to water use efficiency were also evaluated. Water consumption amount was estimated by the water balance method, thus water use efficiency of unit area yield was compared. Finally, adjusting mechanisms of genetic characteristic and water management on water use efficiency was elucidated by the comparison among the rainfed wheat cultivate and varieties. Our studies above would offer the basis on optimizing the water management system in wheat, and improving the water use efficiency by genetic improvement and water control approaches.

随着农业水资源越来越短缺，旱作或有限灌溉将成为农田水分管理无法回避的选择。确定不同品种在不同水分管理下水分利用规律的差异是实现麦田水分科学管理的关键。本项目拟选用4个不同耐旱性小麦品种，分析旱作、有限灌溉1～3次等4种水分管理模式对农田耗水过程和水分利用效率的影响。重点开展：以稳定性H218O方法分析气孔蒸腾导致的叶水H218O富集程度，比较植株耗水过程的差异；以稳定性13C方法分析光合作用导致的植株13C贫化程度，比较水分利用效率的差异；辅以IRGA-静态箱法分析植物蒸腾与土壤蒸发比例变化及其对水分利用效率的贡献率；并辅以农田水分平衡法测算农田耗水总量，比较分析单位产量的水资源代价。通过品种与水分条件的综合比较、耗水过程与水分利用效率的关联解析，揭示遗传差异和水分管理对耗水过程和水分利用效率的调控机制，为优化麦田水分管理制度、从遗传改良和水分调控两方面提高水分利用效率提供科学依据。

随着农业水资源越来越短缺，旱作或有限灌溉将成为农田水分管理无法回避的选择。确定不同品种在不同水分管理下水分利用规律的差异是实现麦田水分科学管理的关键。本项目以旱地冬小麦品种青麦6 号、鲁麦21和水浇地冬小麦品种济麦19、济麦22 为试验材料，设置旱作栽培，返青期、拔节期、灌浆期分别进行1～3 次灌溉（每次60 mm）等4种水分管理模式开展试验，对冬小麦全生育期的环境要素、生物要素和同位素特征过程进行了观测。分析了灌溉措施对产量和水分利用效率的影响；分析了灌溉措施对田间微气象环境的影响；对比了叶片水的δ18O 同位素特征和叶片δ13C的同位素特征；利用涡度相关技术对冬小麦农田生态系统进行水碳通量的研究，分析了农田生态系统的水碳通量日变化规律、年变化规律及其对环境因素的响应特征。结果表明：在旱作和灌溉一次的条件下，旱地冬小麦品种产量高于水浇地冬小麦品种；在灌溉2－3次的情况下，旱地冬小麦品种产量低于水浇地品种；随着灌溉量增加叶片水δ18O减小，随着灌溉量增加叶片δ13C增大，在旱作和灌溉1次条件下，旱地品种青麦6 号、鲁麦21的叶片δ13C小于水浇地品种济麦19、济麦22，在灌溉2－3次情况下，差异不显著；麦田生态系统呼吸、土壤呼吸和植物呼吸呈单峰日变化规律，植物呼吸对生态系统呼吸的贡献大于土壤呼吸，农田蒸散、土壤蒸发和植物蒸腾呈单峰日变化规律，植物蒸腾对农田蒸散的贡献远远大于土壤蒸发；在日尺度上，水碳通量的耦合关系在一天中发生明显变化，生态系统水分利用效率呈双峰日变化规律，水碳通量的不同步是造成午间水分利用效率降低的主要原因，而可能出现的“午休”现象加剧了这种趋势；在年尺度上，农田生态系统CO2通量水汽通量ET和冠层导度Gc具有良好的线性耦合关系。本研究所确立的灌溉制度在旱地小麦生产中已广泛应用。