不同灌溉处理下紫花苜蓿光合特性、叶绿素荧光参数及生物量的变化

为了在永昌荒漠化灌区获得紫花苜蓿（Medicago sative）的高产节水技术，本研究以甘农3号紫花苜蓿为试验材料，在地下滴灌方式下，采取人工控制土壤水分的方法，对不同水分胁迫下紫花苜蓿的光合特性、叶绿素荧光参数及地上生物量进行研究。结果表明：随着水分胁迫的加剧，影响紫花苜蓿的光合特性的因素由气孔限制逐渐转变为非气孔限制，水分利用效率（water use efficiency，WUE）呈先上升后下降趋势，在10：00和16：00左右时轻度水分胁迫的WUE显著大于充分灌溉的；随着水分胁迫的加剧，叶绿素总含量均先升高后降低，表明在轻度水分胁迫下更有利于叶绿素的合成；随着水分胁迫的加剧，紫花苜蓿的叶绿素荧光参数下降幅度逐渐加大，干草产量也逐渐下降，严重的水分胁迫会抑制了PSⅡ的光化学活性，从而影响了紫花苜蓿的干草产量；轻度水分胁迫与充分灌溉之间无显著差异，这体现了在轻度水分胁迫下也能够达到高产的目的。

Photosynthetic Characteristics,Chlorophyll Fluorescence Parameters and Biomass of Alfalfa under Different Irrigation Treatments

In order to obtain the high-yield water-saving technology of alfalfa in Yongchang desertification irrigation area,the photosynthetic characteristics of Gannong 3 alfalfa under different water stress were studied. Soil moisture was artificially controlled using subsurface drip irrigation. Chlorophyll fluorescence parameters and aboveground biomass were analyzed. The results showed that with the increase of water stress,the factors affecting the photosynthetic characteristics of alfalfa gradually changed from stomatal limitation to non-stomatal limitation,and the water use efficiency (WUE) increased first and then decreased,at 10:00 and 16:00. The WUE of mild water stress was significantly greater than that of full irrigation. With the increase of water stress,the total content of chlorophyll increased first and then decreased,indicating that it is more favorable for chlorophyll synthesis under mild water stress;The chlorophyll fluorescence parameters of alfalfa and the yield of hay gradually decreased. Severe water stress inhibited the photochemical activity of PSII,which affected the hay yield of alfalfa;There is no significant difference between mild water stress and full irrigation,indicating the possibility of achieving high yield and water saving under mild water stress.