Effects Of Different Exogenous Choline Fatty Acids On Growth,Yield And Quality Of Maize

Exogenous choline compounds are widely used in improving crop growth and stress resistance.In order to explore its application in regulating crop growth,the effects of exogenous choline fatty acids on maize seed germination,seedling growth,maize yield and quality were investigated,and the molecular mechanism of exogenous choline fatty acids affecting crop growth was preliminarily discussed.The main results are as follows:（1）Four kinds of choline fatty acids,choline glutaric acid,choline adipic acid,choline heptylic acid and choline octanedioic acid,were synthesized by one-step neutralization method,and their effects on maize seed germination were investigated.The results showed that the four kinds of choline fatty acids could promote the growth of roots and buds of maize seeds in different degrees under normal environment and PEG simulated drought stress.Moreover,under drought stress,different choline fatty acid treatments are helpful to improve antioxidant enzyme activity in buds,reduce MDA content in young roots and stems,and effectively alleviate oxidative damage caused by drought stress.（2）At low concentration(20 mg L^-1),choline fatty acids such as choline glutaric acid and choline adipic acid can promote the root length,plant height,fresh root weight and fresh stem weight of maize hydroponic seedlings in different degrees.Among them,the fresh weight of stems and roots of maize seedlings treated with choline glutaric acid,choline adipic acid and choline octanedioic acid increased significantly,and the fresh weight of stems increased significantly by 18.3%,19.3%and 22.8%compared with the control.The fresh weight of young roots increased significantly by 22.9%,10.5%and 15.2%.Chlorophyll content in leaves increased significantly under choline fatty acid treatment.（3）The differential gene analysis of maize leaf transcriptome under choline chloride,choline glutaric acid and control treatment showed that compared with the control treatment,the gene expression of key enzymes in photosynthesis,carbon and nitrogen metabolism in maize leaves under the two exogenous choline treatments changed significantly,which significantly promoted the synthesis of photosystem-related proteins,zeatin and the expression of carbon and nitrogen accumulation.Compared with choline chloride,choline glutaric acid significantly upregulated the expression of nitrite reductase,amylase and other genes.The nitrate reductase activity of leaves treated with choline glutaric acid was significantly higher than that of choline chloride and control treatment,which showed that choline glutaric acid might be better than choline chloride in promoting gene expression of metabolic pathways such as carbon and nitrogen in hydroponic maize.（4）The field experiments in 2021 and 2022 showed that spraying exogenous choline fatty acid at the early stage of grain filling was helpful to increase plant biomass and grain weight per ear,and the total nitrogen content and starch content of maize stalk showed an increasing trend.Compared with CK,choline octanedioic acid,choline adipic acid and choline glutaric acid treatments increased the total nitrogen content of stems by 35%,19%and 29%respectively,and the starch content of stems increased by 4.3%,0.6%and 5.9%respectively.