Abstract: Natural grassland in China is mainly distributed in North China drought and semi -drought regions and in high altitude and cold Qinghai-Tibet Plateau. Its grass growth is greatly influenced by meteorological conditions. In this pap er, a meteorological condition index reflecting the influences of precipitation, air temperature and sunlight on the grass growth were developed, and its relatio nship with the grass yield of main natural grasslands in China was analyzed, bas ed on the grass biomass observation data from animal husbandry meteorological st ations in 1994〖KG-*2〗-〖KG-*7〗2005. For the main natural grasslands in China, there was a clos e relationship between the meteorological condition index and the grass yield du ring the growth period from March to September. The fresh and dry grass yields o f North China natural grasslands had close correlations with the meteorological condition index from March to August, and a high correlation coefficient was obt ained in the periods of time from March to May and from August to September in Qinghai-Tibet Plateau natural grasslands, with a higher correlation coeffi c ient between the fresh and dry grass yields and the meteorological condition ind ex from August to September than from March to May. Comparing with dry grass yie ld, the fresh grass yield in the two main grassland regions had a higher correla tion with the meteorological condition index. Historical simulation and extensiv e prediction examination showed that using this meteorological condition index t o predict grass yield had a higher accuracy, being available in operational pred iction.

Key words: Campylomma chinensis, Lantana camara, Volatiles, Olfactory stimuli, Floral colors, Visual stimuli