Effects Of Nitrogen-potassium Ratios And Fertilization Methods On Growth And Fruit Quality Of Fig Fruits At The Expansion Stage

Nitrogen and potassium are the basic elements of fruit growth and development,they are indispensable in the process of fig growth,development and quality formation,nitrogen and potassium combined application has a significant role in promoting plant growth and fruit development,and there are few studies on the application of nitrogen and potassium fertilizers on fig.In this experiment,taking the four-year-‘Boji hong’fig as the test material,under the cultivation conditions of plastic greenhouse,7 different nitrogen and potassium ratios and 2 application methods of soil application and foliar spraying were set up,a total of 14 treatments combinations,and the effects of different nitrogen and potassium ratios and fertilization methods on the growth,development and quality of fig fruits at the expansion stage were studied,in order to provide theoretical guidance and scientific basis for the rational fertilization of figs.The main findings are as follows:Soil application of appropriate proportion of nitrogen and potassium fertilizer can promote the growth of fig trees,increase the content of P and Mg in leaves,promote the color of fruit peel turn red,and facilitate the accumulation of soluble sugar and Vitamin C in fruit.Compared with the control,the nitrogen content of soil application is 13.04 kg·667m^-2,the content of potassium sulfate is 11.11 kg·667m^-2（T5）,the fig plant height,new shoot length and diameter thickness increased most significantly,and the increases were 23.9%,17.8%and 34.4%in the control group,respectively;the content of K in leaves reached the maximum;the content of anthocyanin in the peel was the highest,the color of fruit peel was the best,and the content of glucose,fructose,sucrose and Vitamin C in the fruit were the highest.Foliar spraying of appropriate proportion of nitrogen and potassium fertilizer can effectively improve the photosynthesis of fig leaves,promote the content of N,Ca,Mg in leaves and N,P,Ca and Mg in fruits,increase the weight of single fruit,promote the increase of fruit transverse and longitudinal diameter,increase the content of soluble solids and soluble proteins,and reduce titrable acid.Compared to the control,the nitrogen content of foliar sprays is 4.35 g·L^-1and content of potassium sulphate is 3.7 g·L^-1,fig leaves have the strongest net photosynthetic rate,transpiration,stomatal conductivity,the lowest intercellular CO₂concentration,and the highest photosynthetic efficiency.Fig fruits have reached the maximum single fruit weight,and the content of soluble solids is the highest in fig fruits,the lowest content of titratable acid,and the largest content of soluble protein.In combination,foliar spraying and soil application of different proportions of nitrogen and potassium fertilizer have made the quality of fig improve to varying degrees in all aspects.Considering the effects of various treatments on fig,foliar spraying can be preferred in fertilization and the content of nitrogen is 4.35 g·L^-1and potassium sulphate is3.7 g·L^-1.