西瓜幼苗10℃和15℃低温处理下相关生理指标的比较分析

Comparative Analyses of Some Physiological Characters of Watermelon Seedlings under 10℃ and 15℃ Low Temperature Treatments

以四叶一心期的西瓜幼苗为材料,研究了10℃和15℃低温处理下西瓜幼苗的叶绿素荧光强度、脯氨酸、可溶性糖、POD和APX的变化规律。结果表明,4、6号品种的相对光化学反应活性值低于同时期的2、5号品种,前者在15℃低温处理的初期就积累了大量的可溶性糖和脯氨酸,而后者在10℃低温处理较长时间后体内才积累大量可溶性糖和脯氨酸,并且它们的增加幅度小于前者。POD和APX呈现15℃比25℃(对照)增加,10℃又下降的一般趋势,后者的变化幅度小于前者。综合实验中各项指标可以认为,2、5号品种是耐冷性品种,4、6号品种是相对敏感品种,同时叶绿素荧光强度、可溶性糖、脯氨酸可作为评价品种耐冷性的主要指标。

In order to analyze the effects of 10℃ and 15℃ low temperature treatment on watermelon seedlings, some physiological characters such as the light reaction activity, soluble sugars, proline content and the activities of POD （peroxidase） and APX （ascorbate peroxidase ） were investigated in watermelon seedlings at the age of four leaves after low temperature stress. The results indicated that, the relative light reaction activities of varieties No. 4 and No. 6 are lower that of varieties No. 2 and No. 5, the content of soluble sugar and proline in the former two varieties increased rapidly at early time point of 15℃ stress, but that of the later two varieties increased steadily long after treated under 10℃ low temperature. Compared with the respective control, the activities of POD and APX displayed a trend to increasing at 15℃ stress declining at 10℃ stress, and APX changed less than POD to some degree centigrade. Considering all the comprehensive physiological indices in this experiment, varieties No. 2 and No. 5 are relatively chilling-tolerant and varieties No. 4 and No. 6 are chilling-sensitive ones. Meanwhile, the light reaction activity, the contents of soluble sugar and proline could be applied to evaluated watermelon chilling tolerance as the main physiological performance.