关键词: 苜蓿, 沙打旺, 水分利用效率, 根冠比

Abstract: A study comparing water use efficiency and root biomass/shoot biomass ratio of Alfalfa and Astragalus adsurgens at seedling stage in growth chambers with two levels of soil water content treatment shows that the instantaneous leaf WUE of Aa is higher than that of Alfalfa at each growing stage with accorded soil water content.The root biomass/shoot biomass and root length/plant height of Aa are also much fuller than those of Alfalfa,more particularly,even a low level soil water treatment,alfalfa yields larger biomass with a higher per unit water consumption rate and decreases biomass growth with the decrease of soil water content.Consequently,Alfalfa exhibits a high transpiration rate as well as a high rate of root extension,resulting in quick soil water consumption.Generally,high soil water content effects the productive efficiency of Alfalfa.As for Aa,however,the variable soil water content does not affect its growth significantly.Based on the year-on-year research data and the undulating land condition of the Loess Platea,we propose to cultivate grassland in the area by planting Aa on the mountainous slopes and Alfalfa on the more or less level land with relatively more water supply.

Key words: Alfalfa, Astragalus adsurgens, Water use efficiency, Root biomass/shoot biomass ratio