The Study Of Asa Soaking Seeds To Improve The Drought Resistance Of Wanma No.1 And The Development Of Drought-resistant Seed Coating Agent

Due to global warming,persistently low precipitation,or constrained water supply systems,the phenomenon of drought stress on crops is becoming more and more serious.Industrial hemp（Cannabis sativa L.）is one of the significant fiber crops in China.Low or no seedling emergence occurs as a result of its vulnerability to drought stress during seed germination and seedling emergence.Enhancing the drought resistance of industrial hemp throughout the seed germination and seedling emergence stages is crucial.To encourage seed germination and increase seedling resistance to ensure normal crop growth,seed soaking and seed coating are two regularly used seed treatment methods.Wanma No.1（W1）was the experimental material used in this research.In the first experiment,ascorbic acid was screened from four exogenous compounds,which could improve the drought resistance of Wanma No.1 seed during germination.By combining physiological and biochemical indices,transcriptome data,the potential mechanism of ascorbic acid soaking to increase the drought resistance of Wanma No.1 was investigated.In the second experiment,the drought-resistant seed coating agent of Wanma No.1 was created by using two exogenous compounds（ascorbic acid and gibberellin）as active ingredients to coat the seeds of Wanma No.1.With the use of a pot experiment in conjunction with agronomic traits,physiological and photosynthetic indices,the effects of seed coating on the seedling growth of Wanma No.1 under drought stress were investigated.The following are the main findings:1.800 mg/L ascorbic acid soaking significantly improved stress resistance under 15%PEG stress on the germination stage of Wanma No.1.The germination potential and germination rate of Wanma were much higher after soaking in ascorbic acid under 15%PEG stress compared to water soaking,increasing by 225%and 88%,respectively.This encouraged the growth of seedling roots and young buds and enhanced root dry weight.Besides,ascorbic acid soaking also significantly increased the antioxidant enzyme（SOD、POD）activity of Wanma seedlings under 15%PGE stress,decreased the content of ROS（H₂O₂、O₂^-）,increased the content of osmotic adjustment substances（SS、Pro）in seedlings,and maintained cell osmotic balance.According to transcriptome analysis,under 15%PEG stress,2352 differentially expressed genes were found in water soaking and exogenous ascorbic acid soaking treatments.Furthermore,the results from GO analysis showed that the activities of antioxidant the activities of antioxidant enzymes,hydrogen peroxide catabolism,and cellular oxidant detoxification were considerably enriched in the differentially expressed genes.KEGG analysis revealed that the majority of the differentially expressed genes were enriched in the MAPK signaling pathway,glutathione metabolism,and phenylpropionic acid production.2.Under drought stress,seed soaking with 800 mg/L ascorbic acid increased drought resistance of Wanma No.1.Ascorbic acid soaking significantly improved the agronomic traits of Wanma under drought stress,plant height grew by 34%,underground fresh weight increased by 66%,underground dry weight increased by 60%,and leaf area increased by67%.Contrary to water soaking,ascorbic acid soaking under drought stress boosted the activity of the antioxidant enzyme（SOD）,decreased the content of reactive oxygen species（H₂O₂、O₂^-）,and lessened the oxidative damage brought on by the drought.3.Create Wanma No.1 seed drought-resistant coating agent.The suitable film-forming agent and active ingredients were screened based on the germination and seedling growth of Wanma seeds under 15%PEG stress,and the formula of Wanma No.1 drought-resistant seed coating agent was obtained:15 g/L sodium carboxymethyl cellulose,0.3%sodium dodecyl sulfonate,0.05%tributyl phosphate,0.1%carmine,8000 mg/L ascorbic acid and2000 mg/L gibberellin.Wanma seeds were coated,and under 15%PEG stress,the germination potential and germination rate were greatly increased by 161%and 73%,respectively,and the radicle length also dramatically increased by 43%.Further in-pot experiments revealed that seed coating could considerably enhance the agronomic traits of Wanma seedlings under drought stress.The plant height was significantly increased by 24%,and the total surface area and average diameter of root system were significantly increased by 38%and 38%,respectively.According to the physiological and biochemical indexes showed that the coating may greatly boost the chlorophyll b content and net photosynthetic rate under drought stress.While the Pro content increased dramatically by 16%,the contents of O₂^-and ROS in leaves were significantly reduced by 28%and 27%,respectively.In conclusion,Wanma No.1 may more effectively germinate when exposed to drought stress due to the two treatments of 800 mg/L exogenous ascorbic acid soaking and particular seed coating,which can also help seedlings grow and develop.Through the antioxidant enzyme system,active oxygen scavenging,osmotic control,and photosynthesis,the two treatments increase the drought resistance of Wanma No.1 and provide both practical and theoretical support for enhancing drought resistance of industry hemp at the germination and seedling stages.