| In the middle and lower reaches of the Yangtze River,rice-wheat rotation is one of the main cropping pattern.In this pattern,wheat seeds are susceptible to low temperature,waterlogging and other adversity stresses after sowing,resulting in lower seed germination and emergence rates and lower quality of wheat seedlings,which directly affect the growth and development of wheat,reduce yield and quality,and seriously hinder the development of wheat production in the region.It is important to study how to improve the resistance of wheat seeds to low temperature and waterlogging to enhance the yield,quality and economic efficiency of wheat in this region.In this study,we investigated the effects of eight priming treatments on seed germination and seedling growth under waterlogging stress,low temperature stress and compound stress of low temperature and waterlogging,and on this basis,we selected two priming treatments with good effects.To elucidate the physiological mechanism of priming treatment to improve seeds’ tolerance to low temperature and waterlogging by measuring α-amylase activity,soluble sugar content,soluble protein content,malondialdehyde content and respiration rate during wheat seed germination.The results of the study are as follows:(1)Waterlogging stress,low temperature stress and compound stress of low temperature and waterlogging environment inhibited wheat seed germination and seedling growth,reducing wheat seed germination potential,germination percentage and germination index by 2.3%-10.0%,13.6%-100.0% and 25.0%-100.0%,respectively.Waterlogging stress,low temperature stress and compound stress of low temperature and waterlogging reduced wheat seed vigor index and root length shoot length of wheat seedlings by 0.6%-20.9%,72.4%-96.9% and 72.0%-97.9%,respectively.The inhibition of wheat seed germination and seedling growth by low temperature stress and compound stress of low temperature and waterlogging were not significantly different,but both were significantly higher than the waterlogging stress treatment.(2)Priming treatment of wheat seeds significantly alleviates the effects of waterlogging stress,low temperature stress and compound stress of low temperature and waterlogging on seed germination and seedling growth.Under the three stress environments of waterlogging stress,low temperature stress and compound stress of low temperature and waterlogging,wheat seed germination potential increased by 3.1%-3.2%after SA and Na Cl priming treatments,germination percentage and germination index 2023increased by 34.1%-34.8% and 25.4%-28.2% after SA and sodium selenite priming treatments,respectively,and wheat vigor index,root length at day 7 and shoot length at day 14 increased by 60.2%-65.7%,25.6%-67.8% and 40.0%-146.1% after PEG and GA-initiated treatments,respectively.Under these three stress environments,SA and sodium selenite priming were the most effective in promoting seed germination,and PEG and GA priming were the most effective in promoting seedling growth.(3)SA,which is more effective for seed germination,and PEG,which is more effective for seedling growth,were selected for seed priming treatment,respectively.Analysis of the main physiological indicators of seed germination under waterlogging stress,low temperature stress and compound stress of low temperature and waterlogging revealed that SA priming treatment increased α-amylase activity,soluble sugar,soluble protein content and respiration rate of seeds on day 4 by 7.5%-218.0%,1.2%-23.0%,4.9%-27.5%,3.5%-33.8%,respectively,and increased malondialdehyde content in seeds decreased by 15.0%-41.6%,PEG priming treatment increased α-amylase activity,soluble sugar,soluble protein content and respiration rate of seeds on day 4 by 15.0%-222.4%,1.8%-34.5%,1.4%-18.9%,1.6%-37.0%,respectively,and increased malondialdehyde content in seeds decreased by 25.0%-38.5%.This alleviates the damage caused by adversity stress to the seeds and helps to enhance seed resistance.In summary,SA and PEG priming treatment perform optimally between different seed treatments.Priming treatment can significantly promote the early onset and seedling growth of wheat under waterlogging stress,low temperature stress and compound stress of low temperature and waterlogging,and its regulatory effect of alleviating the damage of wheat seeds under stress stress is achieved by increasing α-amylase activity,soluble sugar,soluble protein content and respiration rate,and reducing malondialdehyde content. |
