Effect Of Nitrogen Application Period On Mineral Elements Content And Fruit Quality Of 'Pinot Noir' Grape

In this experiment,four-year-old pinot noir grape was used as the material in Hexi Corridor area,and nitrogen fertilizer was applied in one-off ditch in the germination period,inflorescence separation period,fruit expansion period,and fruit color conversion period,respectively.The effects of nitrogen application on nitrogen absorption,distribution and utilization in grape were studied by ¹⁵N tracer technique.By measuring the content of mineral nutrient elements in plant organs and comparing the dynamic change of mineral elements in each organ,the influence of nitrogen application period on grape mineral nutrition was determined.The effects of nitrogen application period on grape growth and fruit quality were analyzed by measuring the growth index and quality index of the plants.By using correlation analysis and path analysis,the relationship between mineral elements and fruit quality in root,leaf and fruit was discussed.The results show that:Firstly,the comprehensive analysis of ¹⁵N test results are as follows:The nitrogen accumulation of plants treated with ISS fertilization is the highest when the fruit matured,reaching 32.0 g/plant.For each fertilization treatment plant,the leaf nitrogen accumulation is the highest among different organs.The ¹⁵N absorption and requisition capacity of the new shoots,leaves and fruits of the plant showed the rule of BBS>BES>ISS>BVS among the four fertilization treatments.Under the fertilization treatment of BBS,ISS and BVS,plant leaves have the lowest capacity of ¹⁵N absorption and regulation,and the N_dff values are 7.73%,3.52%and 1.29%,respectively.There is a difference in the ¹⁵N distribution rate of each organ of the plant under different fertilization treatments.In ISS fertilization treatments,the ¹⁵N distribution rate is the highest in vegetative organs and the lowest in reproductive organs,with the values of72.3%and 6.4%respectively.In addition,plants with ISS fertilization have the highest¹⁵N utilization rate at fruit ripening,reaching 17.77%.Secondly,the element content of various organs of pinot noir grape changed regularly with the passage of time during the annual growth cycle when nitrogen was one-time applicated in different phenological periods.In ISS treatment mainly show as follows:With the phenological period,Phosphorus,copper and boron rose first and then fell in the roots and leaves,potassium decreased in the new shoots,fruits and leaves,calcium,manganese and zinc decreased first and then rose in the new shoots,magnesium increased in the new shoots and leaves,and iron gradually rose in the roots of the plants.The total accumulation of phosphorus,potassium,calcium,magnesium,copper,iron,manganese and zinc of the plants in each treatment period were the highest in the ISS,the lowest in the BBS,and the accumulation of boron was ISS=BES>BBS>BVS during fruit ripening.In addition,with the same treatment,the accumulation of elements in each organ of the plant was also different.Thirdly,when nitrogen was applied at different phenological stages at one time,the soluble solids contents in the mature fruit were the highest in the ISS and the lowest in the BVS,which were 26.02%and 22.49%respectively.The contents of fructose,glucose and reducing sugar among treatments were BES>ISS>BVS>BBS>CK,and the content of reducing sugar and glucose in each treatment was the highest and the lowest.The content of malic acid was the highest in the BVS and the lowest in the BBS,with a difference of 1.30 g/L.In addition,the content of gluconic acid and lactic acid among those treatments were BVS>BBS=CK>ISS>BES,and the content of total phenol and anthocyanin were the highest in the ISS treatment,with the content of 25.31 mg/g and32.97 mg/g,respectively.Fourthly,In the bud burst stage treatment,the correlation analysis showed that the total phenols in pinot noir grapes were mainly determined by the copper in the root which affected the copper and boron in the fruit,and the relationship was negative.During the inflorescence separation period treatment,the soluble protein in fruit was mainly determined by the nitrogen in the root by affecting the phosphorus in the fruit and has a negative correlation.The total phenols and anthocyanins were determined by the influence of manganese in root on copper element in fruit,and showed linear positive correlation and linear negative correlation respectively.Tannin was mainly determined by the effect of manganese in leaves and copper in roots on manganese,zinc and boron in fruits.During the fruit expansion stage treatment,the soluble solids in the fruit were mainly determined by the interaction of magnesium elements in leaves and potassium elements in roots by affecting calcium elements in fruit,and total phenol,tannin and anthocyanin were mainly determined by boron elements in leaves by affecting zinc elements in fruit.The anthocyanins in fruit were determined by the influence of calcium in root on iron in fruit during the fruit coloring stage treatment.The path analysis of the control group showed that the linear regression equations of total phenol and titrable acid were TP=23.972+0.010Mg-0.039Fe,TA=1.246-0.001Fe-?3.732E+5?Ca-?2.697E+5?K.The direct effect of magnesium on the total phenols in fruits was the greatest,and the direct diameter coefficient was 0.723.The direct effect of iron on titratable acid in fruit was the greatest.Analysis of each indirect path coefficient shows that magnesium has a greater indirect effect on the total phenol through iron,during which the connection path coefficient is 0.305.The indirect effect of calcium element on the titratable acid through potassium element is large,and the connection diameter coefficient is 0.517.