【摘要】 报道了４种热带亚热带禾本科牧草植物的蒸腾速率、水分利用效率的日变化图式，并就它们与叶面光强、叶面温度、气孔导度等参数之间的相关关系进行了分析．结果如下：（１）蒸腾速率因牧草种类不同而有差异，墨西哥玉米、矮象草．杂交狼尾草、皇草的日平均蒸腾速率分别为２．４７、１．３８、２．５３、２．９０ｍｍｏｌ ｍ－２ｓ－１；（２）正午前后（１０：００－１４：００）是４种牧草植物蒸腾耗水的主要时期；（３）虽然矮象草的净光合速率和蒸腾速率的日变化图式与其它３种牧草之间存在较大的差异，但水分利用效率日变化差异则很小；（４）不同牧草种类对正午前后高光强高温的适应策略存在差异，墨西哥玉米、杂交狼尾草、皇草采用了相同或相近的适应策略，即通过维持气孔扩张最大程度地蒸腾水分以降低叶温，矮象草则通过关闭气孔以减轻因水分过度消耗带来的伤害（５）４种禾本科牧草植物具有忍受或适应华南夏季炎热高温气候的能力或潜力，在热带亚热地区有推广价值和发展前景．更多还原

【Abstract】 Diurnal changes in transpiration rate (E) and water use efficiency (WUE) of four tropical-subtropical forage grasses were revealed in this paper. Analyses on the relationships between E (or WUE) and other relevant parameters (Qleaf-leaf incident light, Tleaf-leaf temperature, gs-stomatal conductance) were also made. The transpiration rate differed remarkably among species, with the daily average values of 2.47, 1 .38, 2.53 and 2.90 mmol m-2s-1 for teosinte (Zea mays subsp. mexicana), elephant grass (Pennisetum purpureum), hybrid pearl millet (Pennisetum glaucum× P. purpureum), and hybrid elephant grass (Pennisetum purpureum ×P. glaucum), respectively. Major part of water depleted through transpiration occurred during 10:00-14:00. The daily changes in water use efficiency were quite similar among species, although significant differences in Pn (net photosynthetic rate) and E were found between Pennisetum purpureum and the other three. Evidence from stomatal behavior showed different acclimation strategies for different species to strong light intensity and high temperature at noontime, i.e. hybrid elephant grass, hybrid pearl millet and teosinte sufficiently maintained transpiration through maximum stomatal opening to decrease leaf temperatures, but elephant grass adopted stomatal closure to reduce possible damages induced by excessive water loss through transpiration. All the studied species demonstrated capacities to tolerate or acclimatize to the hot summer climate-strong light irradiation and high temperature, and showed potentials to be extended in tropical and subtropical areas.更多还原