Effects Of Zinc Oxide Nano-priming On Seed Germination Of Alfalfa And Salt Resistance Of Seedlings

The growth of alfalfa seedlings(Medicago sativa L.)was limited by saline-alkali stress during cultivation.However,priming the seeds with nano metal elements can promote seed germination and improve the survival rate of seedlings and crop yield.In this study,we investigated the effects of different concentrations and durations of nano-zinc oxide priming treatment on the germination characteristics of alfalfa seeds under salt stress.We also analyzed the physiological and biochemical changes in the photosynthetic,antioxidant,and osmotic systems of alfalfa seedlings after nano-zinc oxide priming.1.Different priming times and concentrations of nano-zinc oxide significantly improved the germination potential,germination rate,germination index,and vigor index of alfalfa seeds under salt stress(P < 0.05).The optimal priming time was 12 hours,and the optimal priming concentration was 100 mg/L,respectively,which significantly enhanced amylase activity(P < 0.05).2.Compared to the control group,the chlorophyll content of alfalfa seedlings treated with nano-zinc oxide increased significantly.The trend was upward as the concentration of nano-zinc oxide increased to 100 mg/L,and it slightly decreased when it reached 150 mg/L.Under no-salt stress,the optimal concentration of nano-zinc oxide for promoting chlorophyll content was 100 mg/L with a priming time of 12 hours.Under salt stress,the optimal priming time and concentration to increase the content of chlorophyll was 6 hours and 50mg/L of nano-zinc oxide,respectively.3.Salt stress caused a decrease in the values of photosynthetic parameters of alfalfa seedlings treated with nano-zinc oxide.The opening and closing of stomata in the leaves also decreased,indicating that salt stress can inhibit photosynthesis of alfalfa seedlings and damage the stomatal morphology.However,the defense ability of the photosynthetic system of alfalfa seedlings induced by 12-hour priming with 100 mg/L and 150 mg/L of nano-zinc oxide under salt stress was significantly better than that induced by other priming times and concentrations of nano-zinc oxide.4.This study investigated the effects of nano-zinc oxide on the growth and physiological indicators of alfalfa under salt stress.The results showed that different priming times(6 h,12 h,18 h)and concentrations of nano-zinc oxide can enhance the tolerance of alfalfa seedlings to salt stress,significantly increasing antioxidant enzymes,leaf penetration parameters,total soluble sugar,total soluble protein,and proline indicators,while reducing antioxidant damage indicators such as malondialdehyde and superoxide ions.The optimal concentration of nano-zinc oxide for priming these effects was 150 mg/L with a priming time of 12 hours.This study demonstrates that nano-zinc oxide can effectively improve the germination characteristics of alfalfa seeds under salt stress by increasing the water absorption rate of seeds and enhancing amylase activity.Furthermore,it can continuously improve the photosynthetic characteristics and stress resistance during subsequent growth,effectively improving the cultivation and establishment of alfalfa and the survival status of seedlings.The optimal priming concentration of nano-zinc oxide was found to be 100-150 mg/L.These findings provide a reference and basis for the enrichment theory of nano-metal elements and the theory of plant seed germination and growth processes.Moreover,they have implications for the promotion and application of alfalfa in agricultural practices.