低温胁迫对蓝莓枝条呼吸作用及生理生化指标的影响

为明确蓝莓枝条不同部位的耐低温能力,利用人工模拟低温胁迫的方法研究了蓝莓1年生枝条尖端、1年生枝条基端和2年生枝条对低温胁迫的生理响应。结果表明:低温胁迫下蓝莓不同部位枝条的各生理指标之间虽然具有一定的相关性,但不同生理指标的相关系数差异较大,即蓝莓枝条不同生理过程对低温的敏感性明显不同。其中,0℃时1年生枝条特别是其尖端的呼吸速率明显高于2年生枝条,但其呼吸作用对低温也特别敏感,当温度降低到-10℃时即均发生明显的降低,且1年生枝条尖端的降低幅度最大。另外,低温胁迫下1年生枝条尖端的丙二醛(MDA)含量和相对电导率增加幅度也明显大于1年生枝条基端和2年生枝条,即1年生枝条尖端对低温胁迫更为敏感。低温胁迫下不同部位枝条虽可以通过增加可溶性糖(SS)和可溶性蛋白(SP)等渗透调节物质,以及增强SOD和POD等抗氧化酶活性的方式来提高其抗寒能力,但当温度降低到-40℃时,不但抑制了蓝莓1年生枝条尖端可溶性蛋白的合成,并且1年生枝条尖端和基端的SOD活性较-20℃时也有不同程度的降低,即-40℃时1年生枝条特别是其尖端蛋白质合成的抑制以及抗氧化酶活性的降低可能是导致其蓝莓在我国北方大兴安岭地区易发生冻、干梢现象的主要原因。而1年生枝条基端和2年生枝条具有较强抗低温能力的原因除了其本身代谢活性较低,对低温不敏感外,低温下有效积累渗透调节物质和增强抗氧化酶的活性在降低其膜质过氧化程度和电解质外渗方面发挥了重要的作用。

Effects of low temperature stress on respiration,physiological and biochemical parameters of blueberry branches

In order to clarify the resistance to low temperature of different parts of blueberry branches, the physiological responses of 1-year-old branch tip and base and two-year-old stem of blueberry at low temperature were studied, through the method of artiifcial simulation of low temperature. The results showed that there was a certain correlation between the physiological indexes of different parts of blueberry stems under low temperature stress, but the correlation coefifcients have great difference between different physiological indexes. In other words, different physiological processes of blueberry stems under low temperature stress had signiifcant different sensitivities to low temperature. Among them, at 0℃, respiration rate of 1-year-old branches, especially its branches tip, was signiifcantly higher than that of two-year-old branches. But their respiration was also particularly sensitive to low temperature. When the temperature dropped to-10℃, the respiratory rate was markedly reduced, with greatest reduction in 1-year-old branch tip. In addition, increase amplitudes of malondialdehyde (MDA) content and relative electric conductivity of 1-year-old branch tip increment were signiifcantly higher than those of 1-year-old branch base and 2-year-old branches under low temperature stress, so 1-year-old branch tip was more sensitive to low temperature stress. Different parts of branches under low temperature stress could improve their cold tolerance through increasing soluble sugars (SS) and soluble protein (SP) contents, as well as enhancing activities of antioxidant enzymes (SOD and POD). When temperature dropped to-40℃, low temperature not only inhibited soluble protein synthesis of 1-year-old branch tip, but also SOD activities of 1-year-old branch tip and base were lower than those at-20℃ at different degrees. Namely, at 40℃, the inhibition of protein synthesis and reduction of antioxidant enzyme activity of 1-year-old branch tip might be the main cause of freeze and slightly dry phenomenon on blueberry stems in Daxinganling region of northern China. However, 1-year-old branch base and two-year-old branch of blueberry had stronger cold resistance. In addition to low metabolic activity and non-sensitivity to low temperature, effective accumulation of osmoregulation substance and enhancement of antioxidant enzymes activity played an important role in reducing its membrane lipid peroxidation and electrolyte leakage areas.