2，4-表芸苔素内酯对干旱胁迫下紫花苜蓿生理特性的影响

doi:10.11686/cyxb2025365

摘要/Abstract

摘要：

随着全球气候变暖，干旱胁迫已成为制约作物生长和产量的主要环境因素。紫花苜蓿作为重要的牧草作物，其生长及生产性能在干旱条件下受到显著影响。2，4-表芸苔素内酯（EBR）是一种人工合成植物激素，可提高植物抗逆性，但其对紫花苜蓿抗旱性的影响及浓度效应尚不明确。本研究以紫花苜蓿‘中苜1号’为材料，通过叶面喷施不同浓度EBR（0、0.02、0.03、0.05、0.10、0.20 mg·L^-1），结合干旱胁迫处理，探讨EBR对紫花苜蓿幼苗生长、光合色素含量、抗氧化酶活性及活性氧（ROS）代谢的影响。结果显示，干旱胁迫使紫花苜蓿株高、茎粗、叶面积、地上部鲜重和相对含水量分别下降36.7%、35.4%、43.6%、66.5%和40.7%，叶绿素a、叶绿素b、总叶绿素和类胡萝卜素含量分别下降65.6%、73.4%、67.7%和78.0%，丙二醛（MDA）含量和相对电导率分别升高45.1%和65.5%，超氧阴离子（O₂^-·）产生速率和过氧化氢（H₂O₂）含量分别增加100.0%和79.4%，脯氨酸（Pro）含量增加931.8%。外源EBR处理，尤其是0.05 mg·L^-1浓度，显著缓解了干旱胁迫的不利影响：株高、茎粗、叶面积、地上部鲜重和相对含水量分别较干旱组提升31.3%、19.9%、62.6%、128.6%和47.5%；叶绿素a、叶绿素b、总叶绿素及类胡萝卜素含量分别提升120.2%、183.8%、134.3%和221.6%；MDA含量和相对电导率分别降低28.8%和26.0%；O₂^-·产生速率和H?O?含量分别降低43.9%和41.9%；超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）和抗坏血酸过氧化物酶（APX）活性分别提高62.3%、74.6%、83.8%和150.5%；Pro含量则显著降低64.5%。高浓度EBR（0.20 mg·L^-1）缓解效果减弱，表现出明显的浓度依赖性。综上，适宜浓度EBR（0.05 mg·L^-1）可通过激活抗氧化防御系统以降低ROS积累和膜损伤，从而提高紫花苜蓿幼苗的耐旱性。本研究为EBR在紫花苜蓿抗旱生产中的应用提供了理论依据。

关键词: 2，4-表芸苔素内酯, 紫花苜蓿, 干旱胁迫, 抗氧化酶系统

Abstract:

With global climate warming， drought stress has become a major environmental factor restricting crop growth and yield. Alfalfa （Medicago sativa） is an important forage crop significantly impacted by drought， and shows reduced growth and yield under drought conditions. 2，4-epibrassinolide （EBR） is a synthetic plant hormone that can enhance the stress resistance of plants， but its effects on the drought tolerance of alfalfa and the concentration dependence of such effects remain unclear. In this study， seedlings of alfalfa ‘Zhongmu No.1’ were treated with EBR （0， 0.02， 0.03， 0.05， 0.10， 0.20 mg·L^-1） by foliar spraying and then subjected to a drought stress treatment. The effects of EBR on seedling growth， photosynthetic pigment content， antioxidant enzyme activities， and reactive oxygen species （ROS） metabolism under drought conditions were evaluated. The results show that the drought treatment negatively affected plant height， stem diameter， leaf area， aboveground fresh weight， and relative water content， with these parameters being 36.7%， 35.4%， 43.6%， 66.5%， and 40.7% lower， respectively， in the drought-treated plants than in the control plants. The contents of chlorophyll a， chlorophyll b， total chlorophyll， and carotenoids were 65.6%， 73.4%， 67.7%， and 78.0% lower， respectively， in the drought-treated plants than in the control plants. The malondialdehyde （MDA） content and relative electrical conductivity were 45.1% and 65.5% higher， respectively， in the drought-treated plants than in the control plants. The superoxide anion （O₂^-·） production rate and hydrogen peroxide （H₂O₂） content were increased by 100.0% and 79.4%， respectively， and the proline （Pro） content was increased by 931.8% in the drought-treated plants compared with the control plants. Treatment with EBR， especially at 0.05 mg·L^-1， significantly alleviated the adverse effects of drought stress. Under drought stress， compared with the controls， the seedlings treated with EBR at 0.05 mg·L^-1 showed increased plant height， stem diameter， leaf area， aboveground fresh weight， and relative water content （by 31.3%， 19.9%， 62.6%， 128.6%， and 47.5%， respectively）； increased contents of chlorophyll a， chlorophyll b， total chlorophyll， and carotenoids （by 120.2%， 183.8%， 134.3%， and 221.6%， respectively）； decreased MDA content and relative electrical conductivity （by 28.8% and 26.0%， respectively）； decreased O₂^-· production rate and H₂O₂ content （by 43.9% and 41.9%， respectively）， increased activities of superoxide dismutase， catalase， peroxidase， and ascorbate peroxidase （by 62.3%， 74.6%， 83.8%， and 150.5%， respectively）； and a significant decrease of 64.5% in Pro content. The drought alleviation effect of EBR at the highest concentration （0.20 mg·L^-1） was lower than that at lower concentrations， showing a clear concentration dependence. In conclusion， treatment with EBR at a concentration （0.05 mg·L^-1） enhanced the drought tolerance of alfalfa seedlings by activating the antioxidant defense system to reduce ROS accumulation and ameliorate membrane damage. The findings of this study provide guidelines for the application of EBR in alfalfa production under drought conditions.

Key words: 2，4-epibrassinolide, alfalfa, drought stress, antioxidant enzyme system

余冬雯, 王晓彤, 马永龙, 吴轩, 杨金辉, 童玉花, 李淑霞. 2，4-表芸苔素内酯对干旱胁迫下紫花苜蓿生理特性的影响[J]. 草业学报, 2026, 35(9): 63-74.

Dong-wen YU, Xiao-tong WANG, Yong-long MA, Xuan WU, Jin-hui YANG, Yu-hua TONG, Shu-xia LI. Effects of 2，4-epibrassinolide on the physiological characteristics of alfalfa under drought stress[J]. Acta Prataculturae Sinica, 2026, 35(9): 63-74.

图/表 8

图1 外源2，4-表芸苔素内酯对干旱胁迫下紫花苜蓿幼苗表型，株高，茎粗和叶面积的影响CK：对照组Control group； D：干旱胁迫组Drought stress group； D+EBR0.02， D+EBR0.03， D+EBR0.05， D+EBR0.10， D+EBR0.20：干旱胁迫+不同浓度2，4-表芸苔素内酯溶液Drought stress+different concentrations of 2，4-epibrassinolide solution （0.02， 0.03， 0.05， 0.10， 0.20 mg·L-1）. 不同字母表示各处理在P<0.05水平存在显著差异，相同字母代表无显著差异。下同。Different letters mean significant differences among treatments at P<0.05 level， and same letters mean no significant difference. The same below.

Fig.1 The effects of exogenous 2，4-epibrassinolide （EBR） on the phenotype， plant height， stem diameter and leaf area of alfalfa seedlings under drought stress

图2 外源2，4-表芸苔素内酯对干旱胁迫下紫花苜蓿幼苗地上部鲜重和相对含水量的影响

Fig.2 The effects of exogenous EBR on the aboveground fresh weight and relative water content of alfalfa seedlings under drought stress

图3 外源2，4-表芸苔素内酯对干旱胁迫下紫花苜蓿幼苗叶片光合色素含量的影响FW：新鲜重量Fresh weight. 下同The same below.

Fig.3 The effects of exogenous EBR on photosynthetic pigment content in leaves of alfalfa seedlings under drought stress

图4 外源2，4-表芸苔素内酯对干旱胁迫下紫花苜蓿幼苗叶片丙二醛含量和相对电导率的影响

Fig.4 The effect of exogenous EBR on the malondialdehyde （MDA） content and relative conductivity in leaves of alfalfa seedlings under drought stress

图5 外源2，4-表芸苔素内酯对干旱胁迫下紫花苜蓿幼苗叶片超氧阴离子产生速率和过氧化氢含量的影响

Fig.5 The effects of exogenous EBR on superoxide anion production rate and hydrogen peroxide content in leaves of alfalfa seedlings under drought stress

图6 外源2，4-表芸苔素内酯对干旱胁迫下紫花苜蓿幼苗叶片抗氧化酶活性的影响

Fig.6 The effects of exogenous EBR on the antioxidant enzyme activity in leaves of alfalfa seedlings under drought stress

图7 外源2，4-表芸苔素内酯对干旱胁迫下紫花苜蓿幼苗叶片中脯氨酸含量的影响

Fig.7 The effects of exogenous EBR on proline content in leaves of alfalfa seedlings under drought stress

图8 主要生理指标间的相关性分析色块颜色从红色（正相关）到蓝色（负相关），相关系数为-1~1。*和**分别表示相关性在P≤0.05和P≤0.01水平上显著。Color patches range from red （positive correlation） to blue （negative correlation） with correlation coefficients ranging from -1 to 1. * and ** indicate significant correlation at P≤0.05 and P≤0.01， respectively.

Fig.8 Correlation analysis between the main physiological indexes

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