中文摘要：

以50个两系（三系）杂交水稻组合为供试材料,以旱稻1255和旱稻297为对照材料,分别在发芽期用20%的聚乙二醇6000（PEG6000,-0.49MPa水势）模拟水分胁迫,在4叶期进行干旱和复水处理,在抽穗期田间晒田条件下无损测定叶片的最大光化学效率（Fv/Fm）,平行测定超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）3种抗氧化酶活性,并在收获后考察其结实率。结果表明：不同水稻材料在不同生育期耐旱性表现不相同,通过聚类分析,结合发芽率、抽穗期田间晒田条件下Fv/Fm值以及后期结实率的联合筛选,将水稻耐旱表现型分为3类,即耐旱型、干旱敏感型以及中等耐旱型;不同耐旱类型在不同生育时期的筛选指标的平均值也不同;在抽穗期晒田条件下,叶片的Fv/Fm值与芽期发芽率、SOD活性有极显著的相关（相关系数分别为-0.382＊＊和0.349＊＊）,可见抽穗期晒田条件下叶片的Fv/Fm值可作为田间栽培条件下水稻水分胁迫无损筛选指标。

英文摘要：

Using two high yield hybrid rice（Shanyou 63 and Liangyoupeijiu） and two rice varieties（1255 and 297） as control,some growth and physiological characteristics such as the germination rate,SOD activity,POD activity,CAT activity and Fv/Fm of 50 hybrid rice varieties（744-791） were measured at seedling stage with 20% PEG6000 as simulated drought stress and at flowering stage in the field.The different indexes of rice varieties in different growth periods were studied by cluster analysis according to the performance of drought resistance.Performances to drought which varied in different stages were classified into 3 types,which were drought tolerant,susceptible,and medium tolerant.Among these indexes measured,the correlation coefficient between Fv/Fm at heading stage in the field and the germination rate under drought,SOD activities in the leaves of rice were-0.382＊＊ and 0.349＊＊,respectively.So Fv/Fm at heading stage can be an important non-traumatic identification index to drought stress in rice under field condition.