Dynamic changes of the aboveground biomass of several forages in karst rocky desertification area

The aboveground biomass dynamic and the relationship between plant height and yield of Cichorium intybus, Pennisetum americanunP.pureum, Zea diploperennis, Lolium perenne, Medicago sativa, Trifolium repens, mixed cultivation of C. intybus, P. americanunP.pureum and Stylosanthes guianensis cv. Reyan No. 2 were studied in karst rocky desertification area to provide a scientific basis for selecting the suitable forage species and cultivating techniques. The results showed that the harvesting height significantly affected the yields of P. americanunP.pureum, Z. diploperennis, L. perenne and T. repens, but little influence on that of C. intybus, the mixed cultivation and M. sativa. The difference of fresh and dry matter yields at different harvest times was significant, indicating that both fresh yield and dry yield had obvious seasonal variation. In which, C. intybus was a high productive forage. P. americanunP.pureum was productive and high quality and suitable fro making silage. The yields of Z. diploperennis in August and October accounted for only 50％ and 30% of C. intybus and P. americanunP.pureum respectively. The yield of mixed cultivation was stable compared with the monoculture. L. perenne, M. sativa and T. repens could be used as rotation crops for fully using the land resource and increasing the forage supply in spring and autumn.