Effect Of Foliar Spraying Of DES On Wheat Growth And Nitrogen Fertilizer Utilization Of Basal

The application of nitrogen fertilizer contributes up to 30%to 50%to grain yield increase and is the most effective way to increase grain production.China is the world’s largest consumer of nitrogen fertilizer.However,the utilization rate of nitrogen fertilizer is only 41.3%,far lower than the 60%of developed countries in Europe and America.How to scientifically solve the problem of low utilization rate of nitrogen fertilizer in China is a very important research topic in China at this stage.Above-ground growth control of crops is an important way to promote crop root absorption of nutrients and improve the utilization rate of nitrogen fertilizer.Foliar spraying of plant growth regulators,biostimulants,organic acids,sugars and nutrients can make up for the lack of nutrient absorption by the roots,increase crop yield,improve crop quality and increase nutrient utilization,and reduce the amount of fertilizer,and has been fully utilized by countries all over the world,but there are shortcomings in our foliar fertilizer products such as low technical content,poor quality and unqualified nutrient content.Deep eutectic solvents（DES）is a green solvent with unique physical properties,which has been widely studied in many research fields because it shows outstanding characteristics such as strong thermal and chemical stability,non-volatile,low price and simple preparation.However,it is not clear whether foliar spraying of DES can improve nitrogen fertilizer utilization.In this study,DES were prepared from choline chloride,ethylene glycol,glucose and citric acid,and commercially available foliar fertilizers containing amino acids and alginate were selected for comparison.There were arranged as:（1）control without nitrogen fertilizer（CK）,（2）conventional N application+water spraying（W）,（3）conventional N application+foliar fertilizer containing amino acid spraying（Y1）,（4）conventional N application+foliar fertilizer containing alginate spraying（Y2）,and（5）conventional N application+DES spraying（D）.Winter wheat（Jimai 22）was used as the test crop,To investigate the effects of foliar sprays of low eutectic solvents on root morphology,root active,nutrient uptake and field wheat seed yield in winter wheat at the seedling stage;The ¹⁵N tracer technique was also used to analysis the change pattern of N utilization and its destination of base-applied fertilizers,with a view to providing a scientific basis for the green upgrading and application of traditional liquid foliar fertilizers.The main findings of the study are as follows:（1）Foliar application of DES significantly increased the above-ground and root dry matter mass of wheat seedlings by 22.63%and 31.03%respectively compared to the water application treatment.The foliar fertilizer treatments all optimized the root morphology of wheat seedlings,with the foliar DES treatment significantly increasing the total root length,root surface area and root volume of wheat seedlings compared to the other treatments.All foliar fertilizer treatments significantly increased the total root absorption area of wheat seedlings,but only the foliar DES treatment significantly increased the active root absorption area and root activity.（2）The foliar application treatments all significantly increased the uptake of N,P and K by the above-ground and root systems of wheat,with the foliar application of a DES treatment being the best,significantly increasing the total uptake of N,P and K by 38.84%,23.64%and10.31%compared to the water application treatment.Correlation analysis showed that the dry matter mass and total N uptake of wheat were significantly and positively correlated with total root length and root surface area and total uptake area.（3）Foliar fertilizer treatments significantly increased the SPAD of flag leaf of wheat by17.14%～32.24%,delayed the senescence of flag leaf of wheat and enhanced the photosynthesis of wheat at the late stage of filling compared to water spraying treatment,with the best effect of foliar spraying with DES.The foliar fertilizer treatment significantly increased the above-ground biomass of wheat by 14.77%to 19.56%compared to the water spray treatment,and significantly increased the wheat grain yield by 17.48%to 21.11%by increasing the number of wheat spike,and the foliar spray treatment with DES had the best yield increase.（4）Foliar spraying of DES treatment significantly increased fertilizer N uptake in wheat seeds by 9.43%compared to water spraying treatment;foliar spraying of DES treatment significantly increased soil N uptake in seeds by 35.71%compared to water spraying treatment;foliar spraying of DES treatment significantly increased apparent N fertilizer utilization by14.53 percentage points compared to water spraying treatment;N fertilizer agronomic efficiency significantly increased by 31.09%～41.20%;fertilizer N utilization rate significantly increased by 4.65 percentage points;fertilizer N residue rate significantly increased by 7.94 and 8.95percentage points and fertilizer N loss rate significantly reduced by 12.13 and 10.73 percentage points in the foliar spraying of DES treatment compared to the foliar spraying of foliar fertilizer containing amino acid and foliar fertilizer containing alginate treatment.In summary,the foliar application of DES can significantly increase the chlorophyll content of wheat and enhance photosynthesis.It can also optimize the root morphology of wheat and enhance root active and root absorption area,thus enhancing the uptake and utilization of nitrogen nutrients by wheat,ultimately achieving increased wheat yields and improving the utilization of nitrogen from base-applied fertilizers.