Cold tolerance of native Bermudagrass germplasms in southwest China

The cold tolerance of Bermudagrass (Cynodon dactylon), including 50 native accessions in Southwest China and 2 introduced varieties (“Tifway” and “Tifeagle”), was studied using methods including the green period, semi-lethal temperature, and stolon regrowth experiments. The following results were obtained: 1) A green period for the 52 accessions ranging from 277 days to 306 days, with Sau02033 (Yuexi) and Sau02040 (Zigong) having the longest green periods; 2) Semi-lethal temperatures (LT₅₀) ranged from –9.00 ℃ to –1.72 ℃, and the LT₅₀ of Sau02014 (Jinchuan) and Sau02040 (Zigong) were the lowest; 3) Survival rates ranged from 18.05% to 42.36%, and the survival rates of Sau02012 (Jinchuan) and Ly97021 (Suining) were the highest among all accessions; 4) The results of the partial correlation analysis indicated that there was a significant correlation between the cold tolerance and altitude (P < 0.05); 5) 52 bermudagrass accessions were clustered into three groups: A, B, and C, in which the cold tolerance was A > B > C. Both “Tifway” and “Tifeagle” were clustered into group C, whereas most of the native accessions showed a higher level of cold tolerance compared to the two introduced ones; 6) According to the comprehensive results of the three methods, Sau02040 (Zigong), Sau02013 (Jinchuan), Sau02014 (Jinchuan), and XZ2 (Tibet) were the top performers, from which excellent forage and turfgrass can be obtained. The cold tolerance of bermudagrass could be better evaluated using the three reference indicators above.