幼苗期梭梭对干旱胁迫的响应及耐旱阈值分析OACHSSCD

Determining the drought tolerance and drought threshold of plant seedlings is a key scientific and technical issue in the cultivation of artificial vegetation in arid desert areas.However,the method for determining the growth drought threshold based on multiple indicators such as plant growth and physiological activity is still immature,which limits the water management in the construction of artificial vegetation in desert areas.In this study,we took Haloxylon ammodendron,an important constructive species in the desert ecosystem of northern China,as the research object,a hydroponic experiment was conducted to simulate 6 drought gradients(from 0MPa to-1.5MPa).The changes in growth,physiological and biochemical indicators of H.ammodendron seedlings were monitored,the multi-indicator synergistic responses of H.ammodendron to drought stress were analyzed,and the method combining principal component analysis and Logistic model was used to clarify its growth drought threshold.The results showed that:(1)With the intensification of drought stress(water potential≤-0.7MPa),the plant height and root length of the seedlings decreased significantly,the root-shoot ratio increased,the biomass was allocated to the root system,the osmotic adjustment substances accumulated,and the antioxidant enzymes were significantly activated.This indicated that under severe drought conditions,H.ammodendron seedlings would adjust their growth strategies,transferring more resources to the root system to enhance water absorption capacity,while accumulating osmotic substances to maintain cell turgor and activating antioxidant enzymes to scavenge reactive oxygen species,thereby reducing the damage caused by drought stress.(2)H.ammodendron seedlings showed synergistic responses of multiple physiological indicators when coping with drought,which was manifested in the synergistic effect of superoxide dismutase,catalase and peroxidase,and the simultaneous increase of proline and soluble sugar under drought stress.(3)Based on the principal component factors of multiple physiological indicators,the Logistic model of the response of H.ammodendron physiological indicators to the water potential gradient showed that its growth drought threshold was-0.73MPa,that is,the habitat with water potential lower than this value would affect the growth and activity of H.ammodendron seedlings.In conclusion,this study quantified the growth drought threshold of H.ammodendron at the seedling stage.It can help managers formulate scientific irrigation strategies,ensure that the water potential in the growth environment of H.ammodendron seedlings is maintained above the drought threshold,and improve the survival rate and growth quality of artificial vegetation.At the same time,it can also provide a theoretical basis for the screening and breeding of H.ammodendron varieties with stronger drought resistance,which is of great significance for promoting the sustainable development of artificial vegetation construction in arid desert areas.