Effect Of Storage Nutrition On Cold Resistance,next Year Growth And Nitrogen Absorption And Utilization Of Blueberry

Storage nutrients are the nutrients accumulated in the roots,trunk and branches before the tree overwinters,mainly including nitrogen storage nutrients and carbon storage nutrients.The level of storage nutrients plays an important role in the cold resistance of fruit trees,the growth and development of the following spring and the uptake of nitrogen.In this experiment,five-year-old"Northland"blueberry plants were used as test material,using the isotope ¹⁵N tracer technique.The experiment was conducted to investigate the effect of nutrient storage on cold resistance,next year’s growth and nitrogen uptake and utilisation of blueberries through autumn basal fertilisation,late autumn foliar N application,leaf removal and branch N application.The aim was to enhance the resistance of blueberry trees,improve their spring development and provide a theoretical basis for spring nitrogen uptake and utilisation.The experimental treatments were as follows:late autumn foliar application of 1%,3%and 5%concentrations of urea,labelled A1,A2 and A3respectively,B1 treatment was no leaf removal+branch application of nitrogen,B2 treatment was leaf removal+branch application without nitrogen,B3 treatment was leaf removal+branch application of nitrogen,C treatment was autumn application of basal fertiliser and CK was the control.The main results were as follows:1.Effect of different treatments on blueberry storage nutrient levels:starch,soluble sugar and soluble protein are important indicators of tree storage nutrients.Leaf removal reduced nutrient return,so that the starch,soluble sugar and soluble protein contents of annual branches in leaf removal+branch without nitrogen application treatment（B2）were lower than the control by 6.92%,9.67%and 6.53%,respectively.Also its root system contained 7.93%,9.10%,and 6.68%less starch,soluble sugar,and soluble protein,respectively,than the control.Leaf removal+branch nitrogen application treatment（B3）resulted in supplementation of starch,soluble sugars and soluble protein with insignificant changes compared to CK.Autumn basal fertilizer,foliar nitrogen application at 1%N and 3%N concentrations significantly increased tree nutrient storage,with foliar nitrogen application at 3%concentration（A2）being the best.Starch,soluble sugar and soluble protein contents of roots were higher in the autumn basal fertilizer treatment（C）,while starch,soluble sugar and soluble protein contents of branches were higher in the 3%N concentration treatment（A2）.2.Effect of different treatments on cold resistance of blueberry:Studies on cold resistance of blueberry with different treatments showed that autumn basal fertilizer（C）,foliar application of 3%N concentration（A2）and no leaf removal+branch and trunk application of N（B1）treatments were more effective in cold resistance of trees.Compared with the control,autumn application of basal fertilizer（C）,foliar application of nitrogen（A1,A2 and A3）and branch and trunk application of nitrogen（B1）effectively promoted soluble protein,soluble sugar and starch contents as well as increased SOD and POD activities in branches,and reduced branch conductivity values and malondialdehyde contents.3.Effects of different treatments on blueberry growth in the following spring:autumn application of basal fertilizer（C）,foliar application of nitrogen（A1,A2,A3）and branch application of nitrogen（B1）could effectively enhance the root and leaf development of blueberry in the following year;the fruit had the best index in C treatment,which also promoted the development of fruit appearance and morphology,soluble protein,soluble sugar and anthocyanin were higher than the control by 18.13%,100.10%and Soluble protein,soluble sugar and anthocyanin were higher than the control by 18.13%,100.10%and 19.23%,respectively,while titratable acid was lower than the control by 41.63%.4.Effect of different treatments on blueberry N in the following spring:15N was applied to the soil in the following spring and ¹⁵N was preferentially allocated to the root system in all treatments,before being transferred to the above-ground.The results of the experiment showed that the highest Ndff values were found in the root system,followed by the above-ground neonatal organs,and the lowest in the central stem and perennial branches.The autumn basal fertiliser（C）had the highest N utilisation rate,64.25%higher than the control,followed by foliar and branch application of 3%N concentration（A2,B1）,53.07%and 42.43%higher than the control respectively.B2 treatment was significantly lower than the control,with only 7.73%N utilisation rate,19.96%lower than the control.