Effects Of Combined Application Of Nitrogen And Phosphorus On Plant,Soil Nutrient Utilization And Flower Bud Quality Of Grey Jujube

In this experiment,the four-year gray jujube in the 13th Regiment of the First Division of the Corps was used as the research material,and a two-factor three-level randomized block design was adopted.The annual pure nutrient application rates of nitrogen fertilizer（urea）are:N1（202.5 kg/hm²）,N2（405 kg/hm²）and N3（607.5 kg/hm²）;the annual pure nutrient application rates of phosphate fertilizer（diammonium phosphate）are:P1（210 kg/hm²）,P2（375 kg/hm²）and P3（540 kg/hm²）;the combined treatments are:T1（N1P1）,T2（N1P2）,T3（N1P3）,T4（N2P1）,T5（N2P2）,T6（N2P3）,T7（N3P1）,T8（N3P2）,T9（N3P3）,all treatments have the same amount of potassium fertilizer,and neither nitrogen nor phosphate fertilizer was applied as a blank control（CK）.The effect of different nitrogen and phosphorus ratios on tree growth,physiological indicators,soil nutrients,pH,and electrical conductivity was studied;the effect of various fertilization treatments on the quality,yield and quality of jujube flower buds was analyzed.The best fertilization plan suitable for this experimental area was obtained,which provided reference for rational fertilization,cost-saving and efficiency-saving for jujube.The main test results are as follows:1.From the bud stage to the final flowering stage of the jujube tree,the length,diameters and number of leaves on the fruiting branches all show a trend of"rapid growth-slow growth-rapid growth-slow growth"with the passage of growth time;The vegetative growth promotion of T2 treatment is the best;the net photosynthetic rate of leaves is the highest under T3 treatment;the leaf area index of T5 treatment is higher than other treatments;the SPAD value of leaves is the highest under T9 treatment.2.The total nitrogen content of the leaves of jujubes with perennial branches is higher than that of the leaves with new branches,but the total phosphorus content is just the opposite.The nutrient content of jujube leaves is higher under T6（N2P3）treatment.The pH of the soil in each treatment was significantly lower than the background value,while the EC was much higher than the background value.Correlation analysis found that there is a significant negative correlation between soil pH and EC.The increase in the amount of nitrogen fertilizer applied alleviated the damage of soil alkalinity to a certain extent,but at the same time it also increased the risk of soil damage by salt.According to comprehensive analysis T1 and T2treatments can effectively improve soil acidity,alkalinity and salinity.3.The flowering phenology of jujube trees was 2 to 3 days earlier than the control under different fertilization treatments,each fertilization treatment had a certain positive effect on the pollen quality and fruit setting rate of jujube trees.The fruit setting rate of T3 treatment was the highest as 2.89%,and the fruit setting rate is 0.24～1.37%higher for fertilizer treatments than that of the control.T2 treatment had the best effect on promoting the growth of secondary branches and jujube hanging in the same year.According to comprehensive analysis,T2 and T3 treatments have significant effects on improving the quality of flower buds.4.Fertilization can improve the yield and quality of jujube fruit,and the yield of T3 is the highest as10227.16 kg/hm2,the yield of different treatments increased by 4.81～63.33%than that of the control;Among them,the vitamin C content of fresh dates（T9）and hanging dried dates（T2）were 29.07%and197.95%higher than those of the control respectively.Except for the T8 and T9 treatments,the vitamin C content of the hanging dried dates in the T2 treatment was significantly higher than the other treatments.Through comprehensive analysis of the effects of fertilization on soil nutrients and jujube growth physiological indicators,fruit yield and quality,T2（N:202.5 kg/hm²+P₂O₅:375 kg/hm²）treatment was finally screened as the best fertilization plan for this area,which provide reference for the production of grey jujube.