外源CaCl2对复合盐碱胁迫下无芒雀麦幼苗生长及生理稳态的影响OA

As a forage species widely cultivated in Northwest China,Bromus inermis exhibits promi-nent application potential in the ecological restoration and amelioration of salinized soils.To explore the mitigating effect and physiological regulatory mechanism of exogenous calcium chloride(CaCl2)on the growth of Bromus inermis under combined saline-alkali stress,this study focused on Bromus inermis'Xinque No.3'to investigate the regulatory effects of exogenous CaCl2 on seedling growth and physiologi-cal homeostasis under 200 mmol/L combined saline-alkali stress.The results showed that mixed saline-alkali stress significantly inhibited the growth of Bromus inermis(P<0.05),resulting in decreased photo-synthetic efficiency and reactive oxygen species accumulation.Exogenous CaCl2 exhibited a regulatory pat-tern of low-concentration promotion and high-concentration inhibition.Among all treatments,10 mmol/L CaCl2(SAT2)presented the optimal ameliorative effect:seedling plant height,leaf area and chlorophyll con-tent were significantly increased compared with the stressed group(P<0.05),and the net photosynthetic rate was enhanced by 33.68%.Antioxidant enzyme activities were significantly elevated(P<0.05),while malondialdehyde content and relative electrical conductivity were reduced by 31.39%and 53.58%,respec-tively.Leaf Na+content was decreased by 35.74%,K+content was increased by 197.26%,and the Na+/K+ratio decreased by 78.11%.In conclusion,exogenous CaCl2 at an appropriate concentration alleviates mixed saline-alkali stress damage in Bromus inermis mainly by activating the antioxidant defense system,maintaining photosynthetic homeostasis,promoting K+uptake,and inhibiting Na+accumulation,whereas high concentrations exert inhibitory effects.This study clarifies the physiological response characteristics of CaCl2 in alleviating mixed saline-alkali injury,and provides a theoretical support and technical reference for forage cultivation in saline-alkali soils.