Response Of Mineral Element Content And Yield Quality Of Apple Leaves And Fruit To Water And Nitrogen Supply

Mineral nutrition is the material basis of apple growth,yield and fruit quality.At present,there are many studies on the influence of water and fertilizer supply on apple yield and quality,but few studies on the change of mineral element content and its ratio.Therefore,in this study,the method of drip irrigation and fertilization was adopted to carry out the two-factor complete combination design experiment of water and nitrogen consumption at luochuan apple test station of northwest agriculture and forestry university from 2018 to 2019.The irrigation amount was set at two levels,namely 60-90%?W1?and50-80%?W2?.Four levels of nitrogen application were set,namely 0 kg ha^-1?N1?,120 kg ha^-1?N2?,240 kg ha^-1?N3?and 360 kg ha^-1?N4?.Research under different water and nitrogen dosage in apple leaf nitrogen?N?,phosphorus?P?,potassium?K?,calcium?Ca?,magnesium?Mg?content along with the growth period of dynamic change,the mineral elements content in fruit and the ratio and fruit quality and yield response to N fertigation water dosage,in order to provide the basis for apple efficient water management.The main results are as follows:?1?from the flowering stage to the maturity stage,the contents of N and P in the leaves of apple trees tended to decrease,the contents of K did not change significantly,and the contents of Ca and Mg tended to increase.Nitrogen:under the two water treatment conditions,the content of N element in the leaves at the N3 level showed a long-term crest at the new tip stop,and the content of N was significantly higher than that under other treatments.P:P content was the highest at the N2 level under two water levels,before the new shoot stopped for a long time.At the same phenological stage and under the same moisture condition,P content of leaves at the four nitrogen fertilizer levels was higher in the upper canopy than in the lower canopy.Potassium:at the W1 level,the first wave peak appeared in the new shoot resting period,and K content in N3 treated leaves was the highest;at the W2 level,the first wave peak appeared in the new shoot growing period,and potassium content in N2 treated leaves was the highest.In the lower part of the canopy,there were significant differences in nitrogen application under different water conditions,and W1N2 and W2N3 reached the maximum.Calcium:in the upper part of the canopy,the content of Ca in the leaves showed a trend of continuous growth throughout the growth period,and the growth rate was higher in the later growth period.In the lower canopy,the Ca content in the leaves of apple trees showed a trend of increasing,decreasing and increasing between the flowering period in April and the harvest period in September.During the young fruit growth period,Ca content in leaves treated with W1N2 and W2N3reached the maximum value.In each growth period,the content of Ca element treated by W2N3 was always the highest.Magnesium:the content of Mg elements increased rapidly from flowering period to the growing period of new shoots,and the treatment of W1N2 and W2N3 also reached the maximum value.The biggest increase was the treatment of W1N2and W2N2,which increased by 80%and 67%respectively.Under the condition of this experiment,the irrigation amount has no significant effect on the content of mineral elements in the leaves.Nitrogen application at N2 and N3 levels was beneficial to the accumulation of mineral elements in apple leaves.?2?the total content of mineral elements in apple fruits was K>Mg?Ca>N>P.There was no significant difference in the effect of nitrogen application on N and K content,and the effect on P,Ca and Mg content reached an extremely significant level.Nitrogen:the N element content of W2N2 treatment was always the highest,while the N element content of high water treatment was higher than that of low water treatment.Phosphorus:the content of P in the fruit was expressed as N2>N3>N4>N1.The content of P in the fruit at the N2 level was significantly higher than that of the other three treatments.Potassium:K content is highest in fruits treated with high water and low fertilizer and low water and high fertilizer.Calcium:with the exception of W1N4,the content of Ca in fruits increased significantly with the increase of nitrogen application,and the content of Ca in fruits under the treatment of W1N3 and W2N4 was the highest?39.29%and 38%,respectively?.Except for N4 treatment,the Ca content of other apple fruits treated with nitrogen showed high water ratio and high water content.Magnesium:with the increase of nitrogen application,the content of Mg in fruit increased obviously with the treatment of N1,N2 and N3,among which the content of Mg under the treatment of W1N3 was the highest,which was 50.80%.?3?the effect of nitrogen application on soluble sugar and Vc was significant.With the increase of nitrogen application,the soluble sugar content increased,the Vc content first increased and then decreased,and the Vc content of N2 treatment was the highest.It is effective to increase the yield of apple to increase the amount of nitrogen fertilizer.The highest yield of apples under W1N3 treatment was up to 34 277 kg ha^-1.?4?under the same water treatment condition,the ratios of K/Ca,K/Mg,?K+Mg?/Ca,K/?Ca+Mg?and K/?Ca+Mg?under N4 nitrogen application amount were the largest.The Ca leaves/Ca fruit were the largest at the W2N1 treatment level.?5?there was a significant positive or negative correlation between the mineral elements and the ratio in the fruit and the fruit quality and yield,and there was a correlation between the mineral elements in the leaves in the swelling stage and the fruit quality.