不同叶龄期水稻秧苗对水分亏缺反应的探讨

水分亏缺对秧苗生长影响的研究甚多,但有关水稻秧苗本身对水分亏缺反应的研究报道尚不多见。本研究着重探讨了水稻不同叶龄期秧苗对水分亏缺的敏感程度、忍耐力及其生物学原因,为合理掌握旱秧育秧期水分管理提供理论依据。1 材料与方法选用杂交中籼汕优63和早熟晚粳武育粳2号为材料,在塑料顶蓬内的盆钵中进行。供试土壤为砂壤土,最大持水量为29.6%。1) 分期播种,培育不同叶龄的旱秧。从6月28日至7月23日,每隔3～6d播一期,共计6期。7月23日播最后一期后,各期秧苗全部停止水分补给。在此之前,适当给水,保持表土潮湿,以保证秧苗正常生长。2) 各播期分别设置浅土层和深土层两个处理:“浅土层”处理的土层厚度为5cm,5cm以下用塑料膜隔开,防止深层土壤水分上升及秧根下扎,用以探讨秧苗对水分亏缺的生物学反应。“深土层”处理的土层厚度为25cm,模仿旱地育秧的生长环境,用以探讨秧苗对水分亏缺的农学反应。

Response of Rice Seedling to Water Deficit at Different Leaf Age

The responses of different leaf age seedlings to water deficit for two cultivars (Shanyou 63 and Wuyujing 2) were studied in test pots. The whole process from growth stagnate, leaf curl to seedling death was observed. The results show that the sensitivity and tolerant ability to water deficit have obvious difference at different leaf stages of rice seedling. Besides extreme sensitiveness at bud stage, the sensitivity of seedling to water deficit enhances with leaf age increase, but tolerant ability is the most weak at stage of 2-3 leaf age of seedling. These response differences above-mentioned depened mainly on the size of leaf area of seedling, cultivar types and thickness of soil layer.