Abstract: The effects of different grazing intensities, on leaf numbers of perennial ryegrass and whiteclover and their total leaf numbers of mixed pasture are no significant difference in same season and the leafnumbers per tiller of each species are also no significant differeacc.There is a decreasing tendency of the leafnumbers of perennial ryegrass and increasing tendency of leaf numbers of white clover during growing seasons.In July and August, the LAI of each species under medium and low grazing intensities is bigger thanthat under high grazing treatment, and the difference is siginificant (P<0.05).The each leaf area of perennial ryegrass are more obviously influenced by the seasonal change.The regression analysis between LAI andbiomass has showed that the LAI of white clover is strong positive correlation with biomass under medium andlow grazing intensity (P<0.01 ), and positive correlation under high grazing intensity(P<0.05).The strongpositive correlation appeared between the LAI and the biomass of the swards under medium grazing intensity(P<0.01), and then the positive correlation appeared between the LAI and biomass of perennial ryegrass(P<0.05 ) .

Key words: Grazing intensity, Perennial ryegrass, White clover, Leaf area index, Leaf area

摘要： 不同放牧强度在同一季节对黑麦草和白三叶的叶片数及单位面积总叶量的影响均不显著,单枝叶片数也不显著。随着季节的变化黑麦草叶量减少而白三叶则增加,但草地总叶量呈减少趋势。在7～8月两种草的叶面积指数在中、低放牧强度下显著(P<005)高于高放牧强度。黑麦草的单叶面积受季节影响较大。叶面积指数与生物量的回归分析表明,白三叶在中、低放牧强度下呈强正相关(P<001)。在高放牧强度下则呈显著相关(P<005)。草地总叶面积指数与生物量在中等放牧强度下呈强正相关(P<0.01),这与此时黑麦草的叶面积指数与其生物量间相关显著(P<005)有关。

关键词: 放牧强度, 多年生黑麦草, 白三叶, 叶面积指数(LAI), 叶面积