中文摘要：

为了探讨豆科牧草在遮阴条件下生态适应性及寻求适度的遮阴比例,系统研究了不同程度的遮阴处理（0%,48%,70%,95%）对3种豆科牧草的光合特性和叶绿素荧光参数的影响。结果表明,随着遮阴强度的提高,白三叶的光补偿点和光饱和点减小,紫花苜蓿与草木樨在适度遮阴条件下可维持较低的光补偿点和光饱和点;3种豆科牧草叶片叶绿素a、叶绿素b和叶绿素a＋b的含量逐渐降低,且相同遮阴处理下白三叶均高于其他2种豆科牧草,紫花苜蓿在Y3处理条件下表现为叶绿素a/b值最大;3种豆科牧草PSⅡ受到损伤的程度为紫花苜蓿〉草木樨〉白三叶;遮阴会使白三叶与草木樨的ΦPSⅡ和qP略有降低,但在Y3处理条件下,白三叶的ΦPSⅡ和qP会略有增加,而紫花苜蓿随着遮阴强度的提高,其ΦPSⅡ和qP呈先增加后减小的趋势。3种豆科牧草的耐阴强度顺序为：白三叶〉草木樨〉紫花苜蓿,其中,白三叶在70%以上的遮阴强度下仍然可以长势良好,而草木樨在48%的遮阴强度下有利于生长,紫花苜蓿则受遮阴影响较大。

英文摘要：

To investigate the ecological adaptability of leguminous forage under different shade conditions and seek appropriate shading proportions, the photosynthetic characteristics and chlorophyll fluorescence parame- ters of three kinds of leguminous forage were determined under three shade conditions （0%, 48%, 70%, 95%）. The results of the experiment showed that the light compensation point （LCP） and light saturation point （LSP） of Trifolium repens were at a low level. Medicago sativa and Melilotus suaveolens could maintain low LCP and LSP in the appropriate shade conditions, but they decreased with an increase in shade. The con- tent of chlorophyll a, chlorophyll b and total chlorophyll a＋b ratio in leaves decreased with increasing shade and the levels in T. repens were higher than those in the other two f legumes in the same shading treatments. The chlorophyll a/b ratio maximum performance of M. sativa was in the Y3 treatment. The order of legumi- nous forage for sensitivity to PSII injury was： M. sativa〉M, suaveolens〉T, repens; The ΦPS II and qP of T. repens and M. suaveolens were slightly reduced with shading, while those of T. repens were slightly in- creased under Y3 treatment conditions, and the M. sativa initially increased but then decreased with an in- crease of shading. The shading intensity sequence of the three kinds of leguminous forage was： T. repens〉M. suaveolens〉M, sativa. T. repens could still grow well in more than 70% shade, M. suaveolens were grew well under 48% shade, and M. sativa was greatly affected by shade.