Evaluation of frost tolerance among a large number of bermudagrass (cynodon spp.) Ecotypes collected from different climatic zones

As a warm-season grass, bermudagrass (Cynodon spp.) has been widely used as turf and/or pasture in most parts of the world, however, frost is one of the most important factors to reduce growth and performance. Frost tolerance of 466 bermudagrass ecotypes collected from four climatic zones of Australia was assessed in a single field experiment in Southeast Queensland, Australia. In a second field experiment 12/466 ecotypes were assessed in a separate Southeast Queensland, location. Leaf death was scored after 7 frosts had occurred in each location over a 15-day period. For the evaluation of 466 entries, the ecotypes collected from regions with 30-40 and 40-50 potential frost days (PFD) based on 30-year climate data had over 50% lower leaf death than the ones from 0-10, 10-20 and 20-30 PFD. Ecotypes from the tropical rainy climatic zone had over 26% higher leaf death than the other climatic zones sampled in this study. In addition, there was a significant positive correlation between leaf death and plant height (r=0.84) and leaf death and clipping yield (r=0.96). The frost tolerance rating of 12/466 was validated at the second location. These results indicated that ecotypes from the geographic areas with longer period of PFD had superior frost tolerance. We suggest that the frost tolerant ecotypes were able to enter cold acclimation earlier than susceptible ones