Effects and Physiological Mechanism of Different pH Buffer on Cold Resistance of Winter Wheat at Seedling Stage

The present study was designated to explore the effects and physiological mechanism of cold resistance enhanced by different pH buffer in winter wheat.Using Jimai 22 as the material,a pot experiment was conducted to investigate the effects of different pH buffer on MDA content,electrical conductivity,antioxidative enzymes activity,relative water content and stomatal conductance of winter wheat seedlings under low temperature stress for 9 d.The results showed that the electrical conductivity and malondialdehyde(MDA) content in the seedlings increased with the prolongation of low temperature stress.But in the pH 6.5 and pH 6.0-treated winter wheat seedlings,the MDA content and electrical conductivity decreased under low temperature stress comparing with the control,the effects of pH 6.0 treatment was better after 9 d stress.The activities of SOD,POD and CAT increased at the first 1 or 4 days of low temperature stress,and then decreased.The decline of the activities of SOD,POD and CAT in the pH 6.0 treatment was obviously less than that of CK with the most significant differences.The relative water content and stomatal conductance at 6 d after spraying pH 6.0 buffer was 33.19% and 49.49% higher than that of CK,respectively.These suggested that exogenous pH 6.0 buffer could enhance antioxidant ability of enzymatic and non-enzymatic defense system and provided an optimal internal environment for intracellular material metabolism and photosynthesis to maintain the higher level of cold resistance under the followed durative low temperature stress.