关键词: 美洲黑杨, 干旱胁迫, 色素含量, 光合特性, 抗旱性

Abstract: [Objective] In this paper, we studied physiological responses of poplar 2025 and its two bud mutation colored-leaf varieties to continuous drought stress and compared drought resistance of the three varieties, to provide a theoretical basis for the promotion of new varieties of color-leaf poplar.[Method] The graft seedlings of 2025 poplar and its two bud mutation colored-leaf varieties (P.deltoides cv. Zhonghong, P.deltoides cv. Quanhong) were used as experimental materials. A randomized block design was used to simulate drought environment in a potting experiment. The seedlings were subjected to drought stress for different time (7, 14, 21 d, and 28d, as well as 7 d after rewatering), and the changes of phenotype, photosynthetic characteristics and the effects on chlorophyll and anthocyanin content of three poplar leaves were measured. The normal watering served as the control.[Result] With the aggravation of drought stress, the leaf pigment content and photosynthetic physiological indexes of the three poplar varieties were significantly decreased (P<0.01). At the later stage of stress, P_n and WUE appeared negative. The leaf P_n and Tr all were positively correlated with SWC. The determination coefficient (R²) of P_n-Tr simulation equation was more than 0.8. Meanwhile, leaf pigment content of P.deltoides cv. Quanhong showed a significant positive correlation with SWC. The content of anthocyanin, the main influencing factors of leaf color, also decreased significantly (P<0.01), showing a certain explanation for the Pn change. The subordinate function analysis showed their drought resistance from strong to weak was 2025, P.deltoides cv. Zhonghong, P.deltoides cv. Quanhong (P<0.05). The grey correlation analysis showed chlorophyll a, b and carotenoids were the primary indexes to evaluate the drought resistance of cultivars.[Conclusion] Under drought stress, the change of physiological indexes of the 3 poplar varieties had significant differences. The P_n, and Tr of 3 varieties of poplar were significantly and positively correlated with soil water content. The determination coefficient (R²) of P_n-Tr simulation equation was more than 0.8. Based on the analysis of the external morphology and photosynthetic physiological indicators, the drought resistance of the three poplar varieties was found to be remarkable difference with the order of:2025 > P.deltoides cv. Zhonghong > P.deltoides cv. Quanhong.

Key words: Populus deltoides, drought stress, pigment content, photosynthetic characteristics, drought resistance