Effects Of Nitrogen Fertilizer On Carbon And Nitrogen Metabolism And Tree Nutrition Level Of Jackfruit

In this paper,the effects of nitrogen fertilizer on the carbon and nitrogen metabolites,chlorophyll and nutrient contents of N,P and K in the leaves of jackfruit plants were studied by leaf urea application.The main results were as follows:1.Urea treatment had certain effects on nitrate nitrogen in the leaves of jackfruit plants.The effect of fertilization concentration on nitrate nitrogen was greater than the effect of fertilization times.After 30 days of fertilization,the nitrate content of N3 treatment(0.5% urea)increased.After fertilization 10,the ammonium content of leaves in N2 treatment(0.3%)was higher than that of control group N0(not fertilized),clear water group NH,N1.(0.1%),N3(0.5%),and N0(no fertilization),N1(0.1%)were significantly different.The number of sprays did not significantly affect nitrate nitrogen or ammonium nitrogen.The effect of urea concentration on the ammonium nitrogen and nitrate nitrogen content was not significant.On the whole,N3T2(0.5% concentration,spraying twice)can significantly increase the content of nitrate nitrogen and ammonium in the leaves.2.The change of SPAD value was the highest at 20 d-30 d after urea application,but the chlorophyll a,chlorophyll b and chlorophyll a+b of the leaves changed significantly only after 10 d of fertilization.The concentration of urea application was significantly positively correlated with each measurement index,and the effect of N3 treatment(0.5%)was the most significant.T2(spraying 2 times)and T3(spraying 3 times)have the greatest influence on the SPAD value of the leaves.The combined treatment of N3T3(0.5% concentration,spray 3 times)had the most significant effect on the four indicators related to chlorophyll.3.The content of soluble total sugar and sucrose increased with the increase of urea concentration,and the content of N3 treatment(0.5%)was the highest.Soluble sugar and glucose content were highest under T3(spray 3 times)treatment.The concentration of urea treatment was positively correlated with the starch content,N3(0.5%)treatment > N2(0.3%)treatment > N1(0.1%)treatment,but the number of sprays did not cause significant effects.Under the interaction of concentration and frequency,the combination of three spraying times under N3(0.5%)treatment had the greatest influence on soluble total sugar content.10d-20 d after treatment,N1T2(0.1% concentration,spraying 2 times),N1T3(0.1% concentration,spraying 3 times)and N3T1(0.5% concentration,spraying once)treated with the highest sucrose content;After 30 days,N3T3(0.5% concentration,spray 3 times)treated the highest content.After 10 days of treatment,the fertilization treatment significantly reduced the glucose content;20 days after treatment,the glucose content of N3(0.5%)increased.20 days after treatment,N3T2(0.5% concentration,spray 2 times)combined treatment of the highest content of fructose.The starch content of N3(0.5%)treatment was the highest.4.The interaction of urea concentration and frequency can reduce the amino acid content.After 20-30 days of fertilization treatment,the amino acid content of 0.1% spraying(N1T3)is at the highest level.The effect of nitrogen application on protein content was not obvious.At 30 days after treatment,the protein content of N1(0.1%)treatment was the highest,and the combination treatment of N3T3(0.5% concentration,spray 3 times)was significantly higher than that of the other groups at 40 days.5.The content of N element in leaves was different from that in the control under different concentrations of nitrogen fertilizer,but there was no obvious rule.The N content of N1(0.1%)treatment was the highest.The content of P element was the highest after 10-20 d after N3(0.5%)treatment.10-20 d after fertilization treatment,the order of K element content was N1(0.1%)>N2(0.3%)>N3(0.5%),and 30-40 d after fertilization treatment,the order of K element content was N3(0.5%)> N2(0.3%)> N1(0.1%).Under the interaction of concentration and frequency,10-30 d after treatment,N1T1(0.1% concentration,spraying once),N1T2(0.1% concentration,spraying 2 times)and N3T1(0.5% concentration,spraying once)The content of N elements in the leaves was the highest under the treatment of the group.The content of leaf P was highest after treatment for 10-20 d,N3T2(0.5% concentration,spraying twice);30d-40 d after fertilization treatment.There was little difference between each treatment and the control.The content of K element in each treatment was basically the same as that of the control,showing a decreasing-rising-decreasing trend.6.The SPAD value,chlorophyll a and chlorophyll b were significantly correlated with the urea treatment concentration.The chlorophyll a content and chlorophyll b content were significantly correlated with the treatment concentration.Starch was significantly correlated with urea treatment concentration.The content of N element and P element was significantly correlated with the urea treatment concentration.The four indicators related to chlorophyll were significantly correlated with nitrate content,and both were significantly or significantly correlated with P content.