Abstract: During the radish sowing season in Chongqing and its surrounding areas，radishes often face the combined stress of high temperature and drought.To establish a multi‐index comprehensive evaluation system for radish drought tolerance under combined high temperature and drought stress and screen drought‐resistant radish genetic resources，11 radish varieties（lines）were used as materials.After 40 ℃ high temperature and water cessation treatment for 0，2，6，12，24，and 48 h in 5—6 leaf radish seedlings，the plant height，aboveground fresh weight，underground fresh weight，superoxide dismutase（SOD），ascorbate peroxidase（APX），catalase（CAT），peroxidase（POD）activities，malondialdehyde（MDA）content，and chlorophyll fluorescence parameters（F₀，F_m，F_v/F_m）were measured.The drought tolerance of radishes under combined high temperature and drought stress was comprehensively evaluated by using the membership function analysis and principal component analysis.The results showed that all radish varieties（lines）died after 48 h of stress. With the intensification of high‐temperature and drought stress，the relative plant height，aboveground fresh weight and underground fresh weight of different radish varieties（lines）showed a downward trend.The relative activities of APX，POD and SOD first increased，then decreased and then increased again，while the relative CAT activity first increased and then decreased.The relative MDA content first increased，then decreased and then increased again.The 6—12 h of stress was the key response period.The relative APX and CAT activities were the highest at 6 h of stress，the relative SOD and POD activities significantly decreased after 2 h of stress and then increased after 12 h of stress，and the relative MDA content decreased to the lowest at 6 h.The relative F_v/F_m and Fm decreased to the lowest after 24 h of drought.According to the comprehensive evaluation results of all indicators，the drought tolerance of the 11 radish varieties（lines）from strong to weak was Fuling wild radish，Changshou wild radish，BZ2，Lanhuazi，Hongxing cherry radish，ZY228，Baidingshui radish，Changhong No.1，Xichang white，ZY147，and ZY4.The constructed multi‐index evaluation system can effectively identify the drought tolerance of radishes under combined high temperature and drought stress and screen drought‐resistant varieties. Chlorophyll fluorescence parameters（F₀，F_m），SOD，CAT activities can be used as important traits for rapid identification of radish drought tolerance in areas with frequent high temperature and drought.

Key words: Radish, High‐temperature and drought stress, Physiological and biochemical indicators, Comprehensive evaluation, Drought‐tolerant variety

摘要： 重庆及周边地区萝卜播种季节，常面临高温干旱复合胁迫。为建立高温干旱复合胁迫下萝卜多指标综合耐旱性评价体系，筛选抗旱萝卜基因资源，以11份萝卜品种（系）为材料，5~6叶期萝卜苗在40 ℃高温与停止浇水处理0、2、6、12、24、48 h后，测定株高、地上鲜质量、地下鲜质量、超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）活性、过氧化氢酶（CAT）活性、过氧化物酶（POD）活性、丙二醛（MDA）含量和叶绿素荧光参数（F₀、F_m、F_v/F_m）等指标，采用隶属函数分析和主成分分析对萝卜在高温干旱复合胁迫下的抗旱性进行综合评价。结果表明，萝卜品种（系）在胁迫48 h后全部死亡，随着高温干旱胁迫的加剧，不同萝卜品种（系）的相对株高、地上鲜质量和地下鲜质量呈下降趋势，相对APX、POD和SOD活性先上升后下降再上升，相对CAT活性先上升后下降，相对MDA含量先上升后下降再上升。胁迫6~12 h为关键响应时期，相对APX、CAT活性在胁迫6 h最高，相对SOD、POD活性在胁迫2 h后显著下降，在胁迫12 h后上升，相对MDA含量在6 h降至最低，相对F_v/F_m和F_m在干旱24 h后降至最低。根据各指标的综合评价结果，11份萝卜品种（系）抗旱性由强到弱为涪陵野萝卜、长寿野萝卜、BZ2、蓝花籽、红星樱桃萝卜、ZY228、白丁水萝卜、长红1号、西昌白、ZY147和ZY4。构建的多指标评价体系能有效鉴定萝卜在高温干旱复合胁迫下的抗旱性，筛选出抗旱品种，叶绿素荧光参数（F₀、F_m）、SOD、CAT活性等关键指标可作为高温干旱频发地区萝卜抗旱性快速鉴定的重要性状。

关键词: 萝卜, 高温干旱复合胁迫, 生理生化指标, 综合评价, 耐旱品种