喀斯特山区混播草地草本植物的光合特性

摘要

The photosynthetic characteristics of Trifolium repens/Loliumn perenne, Eragrostis perenans and Paspalum dilatum conducted by Li-6400 portable photosynthetic instrument showed that the net photosynthesis rate, transpiration rate and stomatal conductance of the four herbaceous plants were double-peak curves with “midday rest” phenomenon. the “midday rest” phenomenon of Trifolium repens,Lolium perenne and Eragrostis perenans was mainly affected by non-stomata limiting factors while that of Paspalum dilatum was affected by stomata limiting factors. The “midday rest" phenomenon was due to the partial closure of stomata. The water use efficiency of Paspalum dilatum and Eragrostis perenans were significantly higher than that of Trifolium repens and Lolium perenne. Therefore, mixed sward of Trifolium repens/Lolium perenne production could be improved and its degradation could be reduced by irrigation, at the same time, Paspalum dilatum and Eragrostis perenans are the main alternative to grass in mixed sward of Trifoliur repens/Lolium perenne in Karst mountainous area, where the soil moisture retention capacity was poor.%为了解混播草地草本植物的光合特性,用Li-6400型便携式光合仪观察白三叶/多年生黑麦草混播人工草地中4种草本植物的光合特性.结果表明:4种草的净光合速率、蒸腾速率和气孔导度日变化均为双峰型,有明显的光合"午休"现象,其中白三叶(Trifolium repens)、多年生黑麦草(Lolium perenne)和宿根画眉草(Eragrostis perenans)的光合"午休"现象由非气孔限制因素引起;毛花雀稗的光合"午休"现象由气孔限制和非气孔限制因素引起,而气孔限制因素占主导.蒸腾速率"午休"主要由气孔出现部分关闭所致.毛花雀稗和宿根画眉草比白三叶和多年生黑麦草有相对较高的水分利用率,因此,通过灌溉可以提高白三叶/多年生黑麦草混播人工草地的产量和减少其退化,同时在土壤水分保持力较差的喀斯特山区建植白三叶/多年生黑麦草混播人工草地,毛花雀稗和宿根画眉草是其主要的演替草种.