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

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