以美洲黑杨品种‘2025’ ( Populus × deltoides ‘2025’) 及其 2 个芽变彩叶品种‘全红杨’ ( P. × deltoids ‘Quanhong’)和‘中红杨’(P. × deltoides ‘Zhonghong’)当年生嫁接苗为实验材料,对土壤干旱胁迫 0、4、7、14、21 和28 d 以及复水7 d 后叶片中 MDA 含量及 PPO、SOD、CAT 和 POD 活性的变化以及 MDA 含量与4 种酶活性的相关性进行了分析,并采用隶属函数法和灰色关联分析法对 3 个品种的抗旱性进行综合评价。 结果表明:随干旱胁迫时间的延长,3 个品种的 MDA 含量总体呈增加趋势,并在处理的中期和后期显著或极显著高于各自的对照;PPO 和SOD 活性总体上先升高后降低,均在处理的前期和中期高于各自的对照;‘中红杨’和‘2025’的 CAT 活性先升高后下降,而‘全红杨’的 CAT 活性持续下降,均在处理 14 d 后极显著或显著低于各自的对照;‘全红杨’和‘2025’的POD 活性先降低后升高且均低于各自的对照,而‘中红杨’的 POD 活性则呈波动趋势但总体上与对照无显著差异。复水 7 d 后,3 个品种的 MDA 含量均有所降低,而 PPO 和 CAT 活性均有所提高;‘全红杨’和‘2025’的 SOD 和 POD活性升高,而‘中红杨’的 SOD 和 POD 活性则降低。 在土壤干旱胁迫条件下,仅‘全红杨’的 PPO 和 CAT 活性与MDA 含量以及‘中红杨’的 CAT 活性与 MDA 含量呈极显著负相关,各品种的其他酶活性与 MDA 含量均无显著相关性。 ‘全红杨’、‘中红杨’ 和‘2025’ 的平均隶属函数值分别为 0. 482、0. 527 和 0. 533,据此判断 3 个品种中‘2025’的抗旱性最强、‘全红杨’的抗旱性最弱。 3 个品种抗旱性与各生理指标的关联度均大于 0. 64,其中与 CAT和 PPO 活性的关联度分别为 0. 793 和 0. 761,因而,可将 CAT 和 PPO 活性作为评价杨树品种抗旱性的首选指标。

 

Taking annual grafted seedlings of Populus × deltoides ‘2025’ and its two bud mutation color-leaf cultivars of P. × deltoides ‘Quanhong’ and P. × deltoides ‘Zhonghong’ as experimental materials, changes of MDA content and activities of PPO, SOD, CAT and POD in their leaf after drought stress for0, 4, 7, 14, 21 and 28 d and rewatering for 7 d and correlations between MDA content and four enzyme activities were analyzed, and drought resistance of three cultivars was comprehensively evaluated by subordinate function method and grey relational analysis method. The results show that with prolonging of drought stress time, MDA content of three cultivars appears a generally increasing trend and is significantly and extremely significantly higher than that of their respective controls at the middle and later treatment stages. On the whole, PPO and SOD activities firstly increase and then decrease and are higher than those of their respective controls at the earlier and middle treatment stages. CAT activity of ‘Zhonghong’ and ‘2025’ firstly increases and then decreases, while that of ‘ Quanhong’ decreases continuously, and is extremely significantly and significantly lower than that of their respective controls after treated for 14 d. POD activity of ‘Quanhong’ and ‘2025’ firstly decreases and then increases and is lower than that of their respective controls, while that of ‘Zhonghong’ appears a fluctuant trend but overall with no significant difference in comparison with that of its control. After rewatering for 7 d, MDA content of three cultivars all decreases, while PPO and CAT activities all increase. SOD and POD activities of ‘ Quanhong’ and ‘2025 ‘ increase, while those of ‘ Zhonghong’ decrease. Under soil drought stress condition, there are only extremely significantly negative correlations between PPO and CAT activities and MDA content in ‘ Quanhong ‘ and between CAT activity and MDA content in ‘Zhonghong’, there is no significant correlation between other enzyme activities and MDA content in all cultivars. Subordinate function average value of ‘Quanhong’, ‘Zhonghong’ and ‘2025’ is 0. 482, 0. 527 and 0. 533, respectively. Accordingly, among three cultivars, drought resistance of ‘2025’ is the strongest, while that of ‘ Quanhong’ is the weakest. Correlation degree of drought resistance of three cultivars with physiological indexes all is higher than 0. 64, in which, that of drought resistance with CAT and PPO activities is 0. 793 and 0. 761, respectively. Therefore, CAT and PPO activities can be regarded as main indexes for evaluating drought resistance of cultivars of Populus.