以杜鹃花属(Rhododendron L.)5 个亚属 5 种杜鹃的 4 年生实生苗为材料,对模拟高温(30 ℃和 38 ℃ )条件下叶片丙二醛(MDA)、过氧化氢(H₂ O₂ )和脯氨酸(Pro)含量以及超氧化物歧化酶( SOD)、过氧化氢酶( CAT)和抗坏血酸过氧化物酶(APX)活性进行了测定分析,对各指标进行了相关性和主成分分析;在此基础上,采用隶属函数法对 5 种杜鹃的耐热性进行了综合评价,并通过建立最优回归方程对综合评价结果进行检验。 测定结果表明:与对照(22 ℃ )相比,5 种杜鹃幼苗的 MDA、H₂ O₂和 Pro 含量以及 CAT 和 APX 活性均随胁迫温度的升高而增加;SOD 活性则表现为在 30 ℃条件下小幅增加、38 ℃条件下下降的趋势。 CAT 活性与 H2 O2和 Pro 含量及 APX 活性均呈极显著正相关关系(P<0. 01),APX 活性与 Pro 含量和 SOD 活性分别呈显著的正相关和负相关关系( P<0. 05)。 通过主成分分析可将测定的 6 个单项指标转换成 3 个相互独立的综合指标,累计贡献率达 87. 52% 。 根据综合评价值(D),可将 5 种杜鹃的耐热性分为 4 个等级:白花杜鹃[ R. mucronatum ( Blume) G. Don]的耐热性最强,毛棉杜鹃(R. moulmainense Hook. f.)和羊踯躅[R. molle ( Blume) G. Don]耐热性较强,红滩杜鹃( R. chihsinianum Chun et Fang)耐热性较弱,红棕杜鹃(R. rubiginosum Franch.)的耐热性最弱。 利用所建立的最优回归方程对供试种类进行耐热性预测,预测值与 D 值的次序完全一致,表明综合评价法可用于杜鹃苗期耐热性的评价。

 

Using four-year-old seedlings of five species belonging to five subgenera in Rhododendron L.as experimental materials, contents of malondialdeyde (MDA), hydrogen peroxide (H2 O2) and proline (Pro) and activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were determined and analyzed under condition of artificial simulated high temperature (30 ℃ and 38 ℃ ), and correlation and principal component analyses of above indexes were also conducted. On this basis, comprehensive evaluation of heat tolerance of the five species was performed by subordinate function method, and comprehensive evaluation results were tested by means of the established optimum regression equation. The determination results show that compared to the control (22 ℃ ), contents of MDA, H ₂ O₂, Pro and activities of CAT, APX of the five species seedlings all increase with rising of stress temperature, and SOD activity appears the trend of less increasing under 30 ℃ condition while decreasing under 38 ℃ condition. CAT activity has extremely significant positive correlation with contents of H ₂ O₂ and Pro and APX activity ( P <0. 01), and APX activity has significant positive or negative correlations respectively with Pro content and SOD activity (P<0. 05). Six single indexes tested of all species are converted into three independent comprehensive indexes with an accumulative contribution rate of 87. 52% by principal component analysis. According to the comprehensive evaluation value (D), heat tolerance of the five species can be divided into four classes: heat tolerance of R. mucronatum (Blume) G. Don is the strongest, that of R. moulmainense Hook. f. and R. molle (Blume) G. Don is stronger, that of R. chihsinianum Chun et Fang is weaker, and that of R. rubiginosum Franch. is the weakest. The heat tolerance of the five species can be predicted using the optimum regression equation established and the prediction value order is completely in accordance with D value order, indicating that the comprehensive evaluation method can be used to evaluate heat tolerance of different species of Rhododendron L. at seedling stage.