Abstract: Two rice varieties Handao 297 (upland rice) and Koshiyutaka (lowland rice) seedlings were employed to study the effect of plant growth substance coronatine on leaf water content, membrane permeability, osmotic adjustment substances (proline, soluble sugar and soluble protein) and endogenous hormones (ABA, IAA and GA3) contents under 20% PEG-simulated drought stress. The results showed that coronatine treatment could maintain leaf relative water content of Handao 297 (0.01 μmol/L) and Koshiyutaka (0.1 μmol/L) at a higher level, enhance the accumulation of proline, soluble sugar and soluble protein, decrease the membrane permeability and maintain the integrity of their plasma membrane structure under drought stress. Coronatine treatments (0.01 and 0.1 μmol/L) also significantly promoted the accumulation of ABA and changed the content and proportion of IAA and GA, in Handao 297 and Koshiyutaka under drought stress. This proved that the coronatine treatments could improve the capacity of the drought tolerance of upland and lowland rice seedlings, with the optimal concentrations in tolerance induction at 0.01 μmol/L and 0.1 μmol/L for upland and lowland rice varieties, respectively.

Key words: upland rice, lowland rice, coronatine, drought stress, membrane permeability, endogenous hormones

摘要： 以旱稻 297 和水稻越富幼苗为材料，在 20% PEG 模拟干旱条件下，研究了植物生长物质冠菌素处理对叶片水分状况、质膜透性、渗透调节物质（脯氨酸、可溶性糖和可溶性蛋白）及内源激素（ABA、IAA 和GA3）含量的影响。干旱胁迫下，冠菌素处理可以维持旱稻 297（0.01 μmol/L）和越富（0.1 μmol/L）较高的叶片相对含水量，促进幼苗叶片中脯氨酸、可溶性糖和可溶性蛋白的积累，降低质膜透性，维持细胞质膜的完整性；同时，冠菌素（0.01 和0.1 μmol/L）处理明显促进旱稻 297 和越富幼苗叶片中ABA的积累，并改变了 IAA 和GA3 的浓度及比例。冠菌素处理能改善旱稻和水稻幼苗耐干旱胁迫的能力，最适浓度分别为0.01 μmol/L和0.1 μmol/L。

关键词: 旱稻, 水稻, 冠菌素, 干旱胁迫, 质膜透性, 内源激素, 渗透调节