Physiological responses and cold resistance evaluation of peanut under low-temperature stress

In order to investigate and comprehensively assess the cold resistance of peanut varieties planted in Heilongjiang Province, four peanut varieties including Jihua No. 3 (JH3), Silihong (SLH), Baisha 1016 (BS1016) and Honghua No. 1 (HH1) were used as test materials to determine the indexes of emergence rate, emergence time, physiological and biochemical characteristics under different temperatures. The results showed that with the aggravation of low-temperature stress, emergence days (ED) were prolonged with emergence rate (ER) reduced, moreover, malondialdehyde (MDA) and osmotic adjustment substances were accumulated, and the relative membrane permeability (RMP) and the activities of anti-oxidases of four peanut cultivars were gradually increased with decreasing of the temperature. Furthermore, it was confirmed that ED of SLH was shortest and ER was highest as well as the contents of osmotic adjustment substances compared with the other three cultivars. Comprehensive assessment by Membership function showed that SLH had the strongest cold resistance, and followed the order of JH3 > BS1016 > HH1. Correlation analyses demonstrated that integrated assessment value of cold resistance had significantly positive correlation with the content of SP, SOD and CAT activity as well as the contents of Pro, SS, POD and ER, while it had significantly negative correlation with the content of MDA, as well as RMP and ED. Thus, these indexes could be used as the evaluation indexes of cold resistance in peanut. Comprehensive assessment of cold resistance and the results of physiological and biochemical indexes indicated that multigrain SLH has strong cold resistance and was suitable for planting climatic conditions in Heilongjiang Province. This study revealed the effects of low-temperature stress on physiological response of these four peanut cultivars. In addition, the data of germination and physiological parameters evaluated the cold resistance between these peanut cultivars and provided a theoretical basis for peanut germplasm innovation and breeding. (authors)