Su Lihe, Huang Rongzheng, Fu Dongqing, Chen Yongcheng, Zhang Xudong, Chen Ying, Liu Chaorong, Hu Tianyu, Ma Chunhui
College of Animal Science and Technology, Shihezi University, Shihezi 832000, China.
Plants (Basel). 2025 Aug 10;14(16):2479. doi: 10.3390/plants14162479.
Climate change due to global warming increases the susceptibility of plants to multiple combined stresses. Soil salinization and high temperature stresses that co-occur in arid/semiarid regions severely restrict the growth and development of plants. Although alfalfa ( L.) is an important forage grass, the physiological mechanisms driving its responses to combined salt and heat stress are not yet clear. This study aimed to reveal the physiological and biochemical response mechanisms of six alfalfa cultivars to different stresses by comparing plant morphology, agronomic traits, photosynthetic characteristics, and physiological and biochemical responses under control conditions, salt stress (200 mM NaCl), heat stress (38 °C), and combined salt and heat stress. Compared with single stresses, combined stress significantly inhibited the growth and biomass accumulation of alfalfa. Under combined stress, the cultivars presented decreases in plant height and total fresh biomass of 11.87-26.49% and 28.22-39.97%, respectively, compared with those of the control plants. Heat stress promoted alfalfa photosynthesis by increasing stomatal conductance, net photosynthetic rate, and transpiration rate, while salt stress and combined stress significantly suppressed these effects. Combined stress significantly increased the concentration of Na but decreased that of K and the relative water content in alfalfa leaves. Compared with the control and single stress treatments, combined stress significantly increased the level of membrane lipid peroxidation and accumulation of reactive oxygen species. The proline contents in the leaves of the different alfalfa cultivars were 2.79-11.26 times greater under combined stress than in the control. Combined stress causes alfalfa to redistribute energy from growth and development to stress defense pathways, ultimately leading to a reduction in biomass. Our study provides theoretical guidance for analyzing the mechanisms of grass resistance to combined salt and heat stress.
全球变暖导致的气候变化增加了植物对多种复合胁迫的敏感性。干旱/半干旱地区同时出现的土壤盐渍化和高温胁迫严重限制了植物的生长发育。虽然紫花苜蓿是一种重要的牧草，但其对盐和热复合胁迫响应的生理机制尚不清楚。本研究旨在通过比较对照条件、盐胁迫（200 mM NaCl）、热胁迫（38℃）以及盐和热复合胁迫下的植物形态、农艺性状、光合特性以及生理生化响应，揭示6个紫花苜蓿品种对不同胁迫的生理生化响应机制。与单一胁迫相比，复合胁迫显著抑制了紫花苜蓿的生长和生物量积累。在复合胁迫下，与对照植株相比，各品种的株高和总鲜生物量分别降低了11.87 - 26.49%和28.22 - 39.97%。热胁迫通过增加气孔导度、净光合速率和蒸腾速率促进紫花苜蓿光合作用，而盐胁迫和复合胁迫显著抑制了这些作用。复合胁迫显著增加了紫花苜蓿叶片中Na的浓度，但降低了K的浓度和相对含水量。与对照和单一胁迫处理相比，复合胁迫显著提高了膜脂过氧化水平和活性氧的积累。在复合胁迫下，不同紫花苜蓿品种叶片中的脯氨酸含量是对照的2.79 - 11.26倍。复合胁迫导致紫花苜蓿将能量从生长发育重新分配到胁迫防御途径，最终导致生物量减少。我们的研究为分析牧草对盐和热复合胁迫的抗性机制提供了理论指导。
