干旱胁迫与复水对福建青冈幼苗生长和生理特性的影响OA

This study investigates the growth regulation strategies and physiological and biochemical response mechanisms of Cyclobalanopsis chungii under different drought stress gradients and during rehydration,providing a scientific basis for selecting C.chungii as a precious timber species for ecological restoration and afforestation and for evaluating its drought resistance and stress tolerance.Using one-year-old container seedlings of C.chungii,a set of pot-based water control experiments were conducted to examine the effects of different drought stress intensities(control CK,mild T1,moderate T2,severe T3)and rehydration on the growth and physiological characteristics of C.chungii seedlings.The results showed that:(1)Under T2 and T3 drought stress treatments,the growth indices of C.chungii differed significantly from that of CK,while no significant difference between T1 and CK treatments.Specifically,the seedling height,ground diameter,total biomass,and root architecture indices of C.chungii in the stress treatments were generally lower than those of CK treatment,whereas the root-to-shoot ratios were significantly higher.(2)The contents of chlorophyll a,chlorophyll b,total chlorophyll,and carotenoid in C.chungii under drought stress all showed a decreasing trend with prolonged drought stress duration.After rehydration,chlorophyll parameters increased compared with those at 40 days of stress,but remained significantly lower than that of in CK.(3)During drought stress,the contents of soluble sugar,soluble protein,free proline,and malondialdehyde(MDA),as well as the activities of superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)in C.chungii,were higher than those in CK treatment at each stress duration.After rehydration,the levels of osmoregulatory substances and antioxidant enzyme activities decreased,but soluble protein content and peroxidase(POD)activity remained significantly higher than those in the CK treatment,while MDA,soluble sugar,and free proline showed no significant difference compared with the CK treatment.Those findings indicate that C.chungii seedlings exhibit a certain tolerance to mild and moderate drought stress,primarily responding through the regulation of osmoregulatory substances and antioxidant enzyme activities to mitigate stress damage,thereby,demonstrating strong ecological adaptability.The C.chungii can be considered as a candidate species for valuable timber tree species in plantations and ecological restoration afforestation in southern China.