Study On Nutrition And Water Absorption And Root-zone Restriction In Citrus

In order to improve the traditional cultivation mode,reduce fertilizer use,bring down environmental load,improve the yield and quality of citrus,provide theoretical basis for water management of citrus,5-year-old red tangerine?Citrus tangerina Hort.ex Tanaka?was selected as materials.Fruit quality,tree growth and nutritions,fertilizer and water absorption of different growth stages of citrus were analysed under different concentration nutrient solutions(N 180 mg·L^-1,N 240 mg·L^-1,N 300mg·L^-1).To explore the application of root-zone restriction cultivation techniques in citrus,5-year-old Satsuma mandarin?Citrus unshiu Marc.cv.unbergii Nakai?was selected as materials,and fruit quality,tree nutritions and soil nutrients,microorganisms,enzymatic activity of different depth of soil were analysed under different root-zone volume?50L,100L,150L?and land cultivation?control?.The results showed:1.Vegetative growth?basal diameter,shoot length and diameter?of citrus of N 240 mg·L^-1 and N 300 mg·L^-1 treatments were better than N180 mg·L^-1 treatment,but the fruity weight,yield,edible rate,soluble solid content and soluble solids/acidity ratio of N 180 mg·L^-1 treatment were all better than others.So the fertilizer and water absorption of N 180 mg·L^-1treatment was used as the standard.Under the experimental system,water absorption of citrus was 131.60 cubic meters per 666.7 m² during the whole developmental stages.N absorption was 24.15 Kg,P absorption was3.92 Kg,K absorption was 27.00 Kg,Ca absorption was 17.31 Kg,Mg absorption was 5.16 Kg per 666.7 m².2.The leaf photosynthesis were significantly suppressed under root restriction,but the content of soil organic matter and nitrate nitrogen was obviously increased of citrus.100L root-zone treatment had higher available soil potassium content and N,P leaf contents than control,while the other two treatments decreased these contents.N,P,K contents of the fruits were all significantly declined under the root restriction.In addition to the Catalase activity reduced,rhizosphere soil enzyme activity of 150L and 100L root-zone volume were significantly enhanced.With the reduction of the root-zone volume,soil microorganisms quantities were gradually decreased.Fruit quality was improved under root restriction and the effect was more obvious under 150L and 100L root-zone volume,Root-zone restriction can obviously improve soil enzyme activity,content of soil organic matter,and fruit quality.100L and 150L root-zone volume improve the performance most obviously with have less influence on soil microorganisms.