Relationship Between Fruit Quality And Seasonal Variation Of Nitrogen,Phosphorus And Potassium Of Soil And Leaves In ‘Changshou Shatian' Pomelo (Citrus Grandis[L.] Osbeck)

Pomelo(Citrus maxima(Burm.)Merr.cv.Shatian Yu.),one of the local fruits,has a long history of cultivation in Changshou Chongqing.The fruits are juicy and rich in multiple nutrition.It has been the main economic species of local farmers' planting.But there are some problems in the long-term production,such as variety degradation,smaller fruits,more seeds,lower yield,poor appearance,maturity concentration,and labor shortages.Therefore,finding out the relationship of soil nutrient-leaf nutrient-yield and quality of fruit for scientific guiding for fertilizing is the key technologies to promote the integration of Shatinyu quality and efficiency.In this study,the author analyzed the soil nutrient,leaf nutrient and fruit quality in different year-old orchards(young orchard,adult orchard and old orchard)in Lin Feng town,discussed seasonal changes(spring,summer and Autumn)soil nutrient content and the effect on fruit quality,providing a theoretical basis for orchard fertilization management and quality and efficiency.1.The average soil total nitrogen content in young orchard was significantly higher than the adult and old orchard.Young and old orchard soil total phosphorus content was significantly higher than the adult orchard;Soil available phosphorus content in old orchard was significantly higher than the young orchard.Soil total potassium content in young orchard was significantly higher than the old orchard,and the old orchard average soil potassium content was significantly higher than the adult orchard;young orchard soil available potassium content was significantly higher than the adult orchard,the soil available potassium content of young orchard changed with season,autumn > spring > summer,and autumn content was significantly higher than summer.2.Spring leaf average total phosphorus content of young trees and aged trees were significantly higher than the adult trees,spring leaf total phosphorus content of three orchards showed seasonal differences summer >autumn > spring,and spring and summer content was significantly higher than autumn,spring leaf total phosphorus content of aged trees changed more greatly.Spring leaf total potassium content of old trees and young trees was significantly higher than the adult trees,spring leaf total potassium content of aged trees showed difference: summer > autumn > spring,summer and autumn content were significantly higher than spring in aged trees,the young tree content changed more greatly.3.The soil total phosphorus content in fall was significantly higher than that in spring,the order of total phosphorus content in both spring and fall : young orchard > old orchard> adult orchard,and young orchard content was significantly higher than adult orchard in fall,while different orchards' total phosphorus content varies in spring;The effective phosphorus content of different orchards showed maximum change in spring.The soil total potassium content in summer and fall was significantly higher than that in spring,the order of the soil total potassium content showed :young orchard > old orchard > adult orchard,and young orchard soil total potassium content was significantly higher than adult orchard,and the total potassium content of different orchards changed greatly in fall;The average available potassium content in fall was significantly higher than in spring,the order of the soil available potassium content showed in both spring and fall :young orchard > old orchard > adult orchard,and young orchard soil available potassium content was significantly higher than adult and old orchards,and the available potassium content of different orchards changed greatly in fall.4.The total nitrogen content difference of varies orchards were not significant among three seasons,the spring leaf total nitrogen content change of different orchards in summer was relatively large.The total phosphorus content in spring and summer was significantly higher than that in autumn,the order of the spring leaf phosphorus content showed in both spring and summer: old orchard > young orchard > adult orchard;in fall: adult orchard > young orchard > old orchard,the total phosphorus content of aged orchard and young orchard was significantly higher than that of adult orchard,and the spring leaf total phosphorus content change of different orchards in spring was relatively large.The total potassium content in summer and fall was significantly higher than that in spring,the order of the spring leaf phosphorus content showed in both summer and fall :young orchard > old orchard > adult orchard;in spring: old orchard > young orchard > adult orchard,the total potassium content of young orchard in both summer and fall was significantly higher than that of adult orchard,and the spring leaf total phosphorus content change of different orchards in summer was relatively large.5.The difference between spring soil N-P-K content and spring leaf N-P-K content did not reach a significant level,except the negative correlation between alkaline nitrogen and leaf N-P-K,the rest mostly showed positive correlation.Summer soil total phosphorus(r=0.925**)and available potassium(r=0.820**)content were significantly positively correlated with the spring leaf potassium content,and the soil available potassium content was positively correlated with the total potassium content of leaves(r=0.820**).Autumn soil total nitrogen(r=0.822**),total phosphorus(r=0.801**)and total potassium(r=0.875**)content were significantly positively correlated with the spring leaf potassium content.6.Fruit quality analysis showed that adult orchard fruit weight was significantly higher than that of young and old orchard,the reducing sugar content of fruit in the old orchard was significantly higher than that in young and adult orchard,and fruit weight,seed number,titratable acid and Vc vary in a large range.7.Correlation analysis among spring orchard soil,leaf nutrient content and fruit quality,fruit weight(r=0.669*),soluble sugar and total phosphorus(r=0.713*)were significantly positively correlation;reducing sugar and soil available iron(r=-0.712*)was significant negative correlation and linear relationship;soluble sugar and leaf total potassium(r=0.790*)was significantly positively correlated.Correlation analysis of summer orchard soil,titratable acid and soil organic matter(r=0.754*)was positively correlation.Titratable acid was significantly positive correlated with soil total nitrogen(r=0.814**).Sucrose and leaf total phosphorus showed a negative correlation and a significant linear relationship(r=-0.825**).Correlation analysis of autumn spring orchard soil,fruit weight(r=0.847**)was positively correlated with leaf total phosphorus significantly,titratable acid and leaf total phosphorus significantly negative correlation(r=-0.683*).8.The suitable range of the content of large and medium elements in spring leaves of ‘Changshou shatian' Pomelo was preliminarily determined: N 2.22%,P 0.17%,K 1.16%,Ca 3.39%,Mg 0.27%,and the radio was 1?0.08?0.66?1.53?0.12.