椒-草种植模式下5种牧草的光合生理特征分析

以白三叶、光叶紫花苕、一年生黑麦草、多年生黑麦草、紫花苜蓿5种牧草为试验测试对象，采用u．6400便携式光合测定系统分别测定椒～草种植模式下5种牧草在生长盛期的净光合速率（Pn），以探讨不同牧草的光合生理特性．试验结果表明：不同牧草的净光合速率日变化特征参数存在明显差异，苜蓿和一年生黑麦草的净光合速率日变化呈双峰曲线，有“午休”现象；白三叶、多年生黑麦草、光叶紫花苕没有“午休”现象；净光合速率值对光照日变化的反应差异也较大，在生产中需要调整花椒林冠层分郁闭度以便营造适宜不同牧草生存的林下光环境，既达到坡地植被水土保持效益，又满足花椒经济林和牧草生产两不误的植被建设需求．

Photosynthetic Physiological Characteristics Analysis of Five Forage Grasses under Zanthoxylum-Grass Plant Pattern

Taking five forage grasses, including Trifolium repens L., Vicia bengbalensis, Lolium muhiflou- rum L., I_ohum perenne L., and Medicago sativa L., as the experimental test objects, this paper uses the LI-6400 portable photosynthetic system to measure individually the net .photosynthetic rates of five forage grasses under Zanthoxylum-grass plant pattern during the growing peak season in order to study the photo- synthetic characteristics of five different forage grasses. The analysis results show that the diurnal variation parameters of the net photosynthesis rates（Pn） of five different forage grasses have significant differences. The curves of Medicago sativa L. and Lolium multiflourum L. leaf photosynthesis show double peaks, which have ＂sleep-at noon＂ phenomenon obviously. The curves of of Trifolium repens L., Lolium pereune L., and V＂ atropurpurea leaf photosynthesis show one peak, without ＂sleep-at noon＂ phenomenon. With diurnal vari- ation of illumination, the net photosynthesis rates show large differences. We need to adjust Zanthoxylum canopy to build understory light environments for different forages, which can achieve the soil and water conservation benefits of the slope vegetation and meet the vegetation construction needs of Zanthoxylum and forage grass production.