Effects Of Nitrogen And Iron Synergistic Application On The Physiology And Quality Of Wine Grapes

The high soil pH in the eastern foothills of Helan,low availability of mineral nutrients,especially low effective iron content,coupled with unreasonable fertilization methods,lead to an urgent need for theoretical innovation and applied research on the regulation of grape nutrition in the production area.Using 9-year-old "Cabernet Sauvignon" as the test material,using a split-plot design,and use foliar spray to study the synergistic effects of different types of nitrogen and iron,the synergistic application of nitrogen and iron with different dosages,and the synergy of nitrogen and iron at different times on the physiological indicators,berry quality of wine grapes and metabolites in peel,and master the reasonable synergistic fertilization methods of nitrogen and iron fertilizers,to provide technical and theoretical support for the improvement of grape quality.The main findings are as follows:(1)Both nitrogen and iron can effectively regulate the physiology of wine grapes,increasing the content of chlorophyll and increasing the content of nitrogen and iron in leaves and petioles.Phenylalanine combined with chelated iron can significantly improve the leaves photosynthetic rate,stomatal conductance,leaf transpiration rate increased,and berry tannin.Urea combined with chelated iron can significantly improve the intercellular CO2 concentration and water use efficiency of grape leaves,increased the grape ratio of sugar and acid.The combined application of Urea and Ferric citrate can significantly increase the chlorophyll content of leaves.The principal component analysis of the leaf physiological characteristics,plant nitrogen,iron content and grape fruit quality and yield of wine grape plants showed that the combined application of Phenylalanine and Ferric citrate had a better effect,and the principal component analysis of the wine grape quality index showed that the combined application of Urea and Ferric citrate had the highest comprehensive score.In conclusion,the synergistic application of Urea and Ferric citrate can help improve the quality of grape berries.(2)The study found that the amount of nitrogen fertilizer in the vegetative growth period of grapes was significantly negatively correlated with chlorophyll b,and the amount of nitrogen fertilizer in the reproductive period of grapes was positively correlated with the soluble solids,sugar-acid ratio and 100-grain weight of berries.Fertilizer dosage was significantly positively correlated with leaf iron content and grape yield.The principal component analysis showed that the synergistic application of 1.5‰ Urea and 1.0‰ Chelated iron could not only significantly adjust the physiological growth index and chlorophyll content of wine grape leaves,but also significantly increase the nitrogen and iron content in leaf petioles,among which total chlorophyll was more than the rest,the treatments increased by 5.32%-86.79%.The synergistic application of 2.5‰ Urea and 1.5‰ Chelated iron was beneficial to improve the morphological indexes of wine grape berries,and the spike length and 100-grain weight increased by 5.11%-47.27%and 0.61%-27.68%.2.0‰ Urea and 1.5‰ Chelated iron had a significant effect on the quality improvement of wine grape berries.The comprehensive analysis showed that the synergistic application of 2.0‰ concentration Urea and 1.5‰ concentration Chelated iron was helpful to improve the quality of grape berries.(3)The photosynthetic rate,stomatal conductance,and leaf transpiration rate of grape leaves reached 14.20 μmol·m-2·s-1,124.50 mmol·m-2·s-1,and 3.73 μmol·m-2·s-1 respectively after nitrogen and iron fertilizers were applied simultaneously the early stage of expansion,and the physiological adjustment effect was significant.The chlorophyll content of grape leaves increased by 5.73%-144.12%after the application of nitrogen in the early stage of expansion to the later stage of grape veraison and iron application the early stage of expansion,and the chlorophyll content increased significantly.The tannin and total phenolic contents of berries were significantly increased after nitrogen application from the early stage of expansion to the later stage of grape veraison and after iron application in the later stage of grape veraison,which increased by 1.58%-20.22%and 1.48%-60.64%respectively compared with the other treatments.Nitrogen application in the later stage of grape veraison and iron application in the early stage of expansion on the intercellular CO2 concentration of grape leaves,water use efficiency,soluble solids in grape berries,sugar-acid ratio,spike length,100-grain weight,yield and essential amino acids in grape peel.The synergistic application of urea in the later stage of grape veraison and chelated iron from the early stage of expansion to the later stage of grape veraison can significantly increase the content of metabolites in grape peel,especially the flavonoids,compared with the application of urea in the early stage of expansion and the application of chelated iron in the early stage of expansion,there were 4 high metabolite expressions.The synergistic application of urea and chelated iron application the early stage of expansion had the best effect on improving grape yield,berry quality and essential amino acid content.The application of nitrogen and iron in the vineyards at the eastern foothills of Helan Mountain in Ningxia is beneficial to improve the quality of wine grapes.Urea and Ferric citrate were applied synergistically;The optimal concentration of synergistic application was 2.0‰ Urea and 1.5‰ Chelated iron;The best application period was the application of urea in the later stage of grape veraison and the application of chelated iron in the early stage of expansion.