高温胁迫下西洋杜鹃的生理响应及耐热性

Physiological responses of Rhododendron hybridum to high temperature and its heat tolerance

以西洋杜鹃‘铁红’、‘粉红’、‘梅红’、‘普红’4个品种(系)扦插苗为试材,分别在38℃/28℃(昼/夜)和43℃/32℃(昼/夜)下胁迫4 d,之后转入25℃/22℃(昼/夜)恢复,以研究不同高温下西洋杜鹃的耐热性及其叶片对高温胁迫的生理生化响应。结果表明,在43和38℃胁迫下,植株遭受严重形态伤害,43℃胁迫对植株造成伤害的速度和程度明显大于38℃。相对电导率、MDA含量和氧自由基含量随胁迫时间延长、胁迫温度升高而增加;叶绿素含量变化趋势则相反;可溶性蛋白含量和SOD活性呈现先升后降趋势;脯氨酸含量在胁迫4 d后与初始值相比并无显著差异,不适合应用于西洋杜鹃的耐热品种筛选。对7个单项指标的耐热系数进行主成分分析,可溶性蛋白、MDA和相对电导率3项指标的累积贡献率达96.8%。耐热性综合评价,4个供试品种(系)耐热性顺序为:‘铁红’>‘普红’>‘梅红’>‘粉红’。

Using the cuttings of 4 Rhododendron hybridum cultivars, Tiehong, Fenhong, Meihong and Puhong, as experimental materials, the heat tulerance of R. hybridum and some relative physiological indices were determined and analyzed under the stress conditions of 38 ℃/28 ℃ （day/night） or 43 ℃/32 ℃ （day/night）, the materials put into recovery at 25 ℃/22 ℃ （day/night）. The results showed as follows. After 4 days at 38 or 43 ℃, the both stresses led to serious damages in morphology of plants, and the injury caused by the stress of 43 ℃ was sooner and worse than that caused by the stress of 38℃. The relative conductivity, content of MDA and oxyradical were increased with the raise of temperature and lengthening of duration, while the content of chlorophyll was decreased, and the content of soluble protein and the SOD activitiy tended to fall after rising. However, the content of proline changed indistinctively after 4 days stress, and the result suggested that the index was not suitable for the screening of heat-tolerant cultivars. According to the main component analysis of the heat-tolerance coefficients of 7 individual indices, the cumulative contri- bution rate of soluble protein, MDA and relative conductivity reached 96.8% so that the effects of the other indices could be ignored. Results of the subordinative function analysis showed that the degree of heat tolerance of the 4 cultivars was as follows ： Tiehong 〉 Puhong 〉 Meihong 〉 Fenhong.