Abstract: In order to explore the physiological characteristics of drought stress-induced flower bud differentiation in Erythrina sykesii, the physiological response of E. sykesii to drought stress and its flowering induction characteristics were analyzed. The physiological indicators such as the contents of photosynthetic pigments, soluble sugar, malondialdehyde and endogenous hormones, and the activities of superoxide dismutase (SOD) and peroxidase (POD) in the leaves of 8-year-old E. sykesii under drought stress were determined. The results showed that the photosynthetic pigment and endogenous hormone contents and antioxidant enzyme activities in the leaves of E. sykesii exhibited a trend of first increasing and then decreasing with the increasing degree of drought stress. The contents of chlorophylls and carotenoids, starch, and soluble sugar, IAA, GA3 and ZR in the leaves reach their maximum values under mild drought stress. The SOD, POD, catalase (CAT) activities and soluble protein content reach their maximum values under moderate stress. The contents of malondialdehyde, ABA, and carbon nitrogen ratio all significantly elevated along with the increasing degree of drought stress. The above physiological indexes showed that the flowering rate of branches increased significantly under drought stress, of which the effect of the moderate stress was the most obvious. The results indicated that the plant cell damage could be alleviated by increasing ABA content and antioxidant enzyme activity, and the flower bud differentiation and flower formation rate of branches were promoted under moderate drought stress.

Key words: Erythrina sykesii, drought stress, flower bud differentiation, physiological characteristics

摘要： 为了研究干旱胁迫诱导刺桐Erythrina sykesii花芽分化的生理特性，以8年生刺桐为材料，测定干旱胁迫下刺桐叶片光合色素、可溶性糖、丙二醛、内源激素含量和超氧化物歧化酶、过氧化物酶活性等生理指标，分析刺桐对干旱胁迫的生理响应及其成花诱导特性。结果表明，随着干旱胁迫程度增加，刺桐的光合色素、抗氧化酶活性和内源激素含量均呈先增后降的变化趋势；轻度干旱胁迫时刺桐叶片叶绿素和类胡萝卜素、淀粉、可溶性糖、IAA、GA3和ZR含量达到最大值；中度干旱胁迫时SOD、POD和CAT活性，可溶性蛋白含量达到最大值；丙二醛、ABA含量和碳氮比均随着干旱胁迫程度增加而显著增加。以上生理指标变化表明，干旱胁迫下刺桐枝条成花率显著提高，其中中度胁迫效果最明显。刺桐在中度干旱胁迫下通过提高ABA含量和抗氧化酶活性，缓解植株的细胞损伤；同时通过提高可溶性蛋白合成和碳氮比，促进植株花芽分化，提高枝条成花率。

关键词: 刺桐, 干旱胁迫, 花芽分化, 生理特性