Abstract: Water resource shortage is an important factor restricting the product development of the Loess Plateau region,and improving the water use efficiency of crops is an important way to alleviate water scarcity. This experiment relied on the alfalfa-wheat rotation system platform of the Grassland College Experimental Station of Shanxi Agricultural University,to explore the effects of water and fertilization addition on the water use efficiency of winter wheat leaves. The results showed that water addition only significantly reduced the leaf water use efficiency by 7.1% from greening period to filling period with a significantly reduced leaf water use efficiency in the booting stage. However,fertilization and water+fertilization treatments did not affect the leaf water use efficiency,except fertilization addition significantly increased it in the greening stage. The study found that water addition affected the leaf water use efficiency of winter wheat by changing the leaf photosynthetic rate,transpiration rate,intercellular CO₂ concentration and soil temperature,of which the transpiration rate was the main regulatory factor. Fertilization addition did not significantly affect the leaf water use efficiency,which might be due to nitrogen fixation effect of alfalfa,making the water and carbon cycles of winter wheat insignificant to fertilizer. The study indicates that introducing alfalfa into the rotation system is helpful to alleviate the water shortage problem.

Key words: Alfalfa, Fertilization addition, Water addition, Water use efficiency, Winter wheat

摘要： 水资源匮乏是制约黄土高原地区生产发展的重要因素，通过提高作物的水分利用效率是缓解其水资源匮乏问题的重要途径。本试验依托山西农业大学草业学院试验站苜蓿(Medicago sativa L.)-小麦(Triticum aestivum L.)轮作系统平台，探究增水和施肥对冬小麦叶片水分利用效率的影响。本试验结果显示仅返青期—灌浆期增水显著降低叶片水分利用效率7.1%，其中孕穗期增水显著降低了叶片水分利用效率，但是施肥以及增水+施肥处理未显著影响叶片水分利用效率，仅在返青期施肥显著提升了叶片水分利用效率。研究发现增水通过改变叶片光合速率、蒸腾速率、胞间CO₂浓度和土壤温度影响冬小麦叶片水分利用效率，其中蒸腾速率为主要调控因素；施肥并未显著影响叶片水分利用效率，可能是由于紫花苜蓿的固氮作用，使得冬小麦的水碳循环过程对肥料响应不显著，说明将紫花苜蓿引入轮作系统有助于缓解水资源匮乏问题。

关键词: 紫花苜蓿, 施肥, 增水, 水分利用效率, 冬小麦