The comprehensive evaluation of heat tolerance of 18 trifolium varieties

The heat tolerance of 18 trefoil varieties were compared and evaluated comprehensively combined with germination and seedling field experiment. The results showed that the germination rate and the germination index declined with the temperature increasing. The seeds from all trefoil varieties could not germinate at the 40℃. The leaf firing rate, the survival rate of seedling and the leaf relative water content were different greatly in all varieties. The results of comprehensive appraisal indicated that the varietyTetri was the highest tolerant to heat, the variety New Zealand was higher tolerant, and the varieties Haifa，Huia，G18，Gollum,Retor，Badong，Pawera，Emu No 1 and so on were midtolerant to heat, Crau,Pitau,Aurora,Tetra were the varieties with lower tolerance to heat, while the tolerance to heat of variety Louisiana was the lowest. It was suggested that the varieties with higher heat tolerance should be planted in Yangtze River and its south region of China.