Abstract:

To provide a reference for sugarcane cold−resistance cultivation, parent selection, resistance breeding, etc. 59 global sugarcane varieties were grown in the sugarcane germplasm resource nursery of Guangxi Academy of Agricultural Sciences. The early morning maximum photochemical efficiency of photosystem II (Fv/Fm) was measured in autumn and winter. The temperature data from 1970 to 2000 for each sugarcane region were collected and the correlations between them and Fv/Fm values were analyzed. More over, the correlations between the Fv/Fm values in the early morning of winter and the temperature of 24 varieties of sugarcane originally from the United States after planting in Nanning also were analyzed. The results showed that the Fv/Fm values of the 54 sugarcane varieties were less than 0.7 in the early morning of the chill season, indicating a significant chilling photo−inhibition. A highly significant negative correlation between the early morning Fv/Fm values and the mean temperature of warmest season (MTOWS) , mean temperature of coldest season (MTOCS) , as well as annual mean temperature (AMT) was observed in these varieties. Meanwhile, the early morning Fv/Fm values was significantly positively correlated with the mean temperature difference between hot and cold season(MTDBHACS). Additionally, a highly significant positive correlation was observed between the differences in Fv/Fm values from autumn to winter and the MTOWS, MTOCS, as well as AMT. Meanwhile, the differences in Fv/Fm values from autumn to winter was significantly negatively correlated with the MTDBHACS. For the 24 varieties of sugarcane from the United States, a highly significant negative correlation was identified between the Fv/Fm values in the early morning of winter and the MTOCS during breeding, as well as a significant negative correlation between the Fv/Fm values in the early morning of winter and the AMT of the origin region. Besides, a significant negative correlation was also observed between the Fv/Fm values in the early morning of winter and the MTOCS during planting in Nanning. Meanwhile, no significant correlation was observed between the Fv/Fm values in the early morning of winter and the AMT. Furthermore, the differences in Fv/Fm values from autumn to winter was highly significantly positively correlated with the MTOCS during breeding. Additionally, it had a significant positive correlation with the AMT of the origin region. Meanwhile, it was also significantly positively correlated with both the MTOCS and the AMT during the planting period in Nanning. Overall, the sugarcane population demonstrated typical thermophilic behavior and sensitivity to low temperature. The cold resistance of sugarcane was closely linked to the temperature of the cold season and the temperature difference between the hot and cold seasons in the region of origin. Besides,this characteristic remained consistent even after long-term cultivation in various locations. 

Key words: Sugarcane, Cold resistance, ChlorophyⅡ fluorescence, Temperature in original breeding location