Effects of Different Defoliants on Defoliation and Nutrient Reflux of'Dongzao'Jujube
The research systematically studied the effects of different types and concentrations of chemical defoliants on the defoliation and nutrient reflux of 5-year-old'Dongzao'jujube in greenhouse via foliar spraying.The results showed that:(1)0.20％ethephon treatment had the best defoliation effect on jujube trees,with a high defoliation rate of 75.75％on 7 days after treatment;(2)The nitrogen,phosphorus,and potassium reflux caused by natural fallen leaves of jujube trees were 4.14,0.27,and 3.18 g·kg-1,respectively;(3)Leaf nitrogen reflux occurred under all chemical defoliant treatments and 4％urea,8％urea,10％urea,0.5％zinc sulfate,and 1.0％zinc sulfate treatments significantly increased leaf nitrogen reflux.Leaves phosphorus reflux can be found under 4％urea,8％urea,10％urea,0.5％zinc sulfate,1.0％zinc sulfate,2.0％zinc sulfate,0.05％ethephon and 0.10％ethephon treatments.Potassium backflow can be detected in leaves treated with 4％urea,8％urea,10％urea,0.5％zinc sulfate,0.05％ethephon,and 0.20％ethephon.However,only 8％and 10％urea treatments significantly increased leaf nitrogen,phosphorus and potassium reflux.In conclusion,0.20％ethephon is the best treatment for rapid defoliation in production.The best treatment for the purpose of shedding leaves at a specific period without leaf nutrient waste is 8％or 10％urea,which significantly improves the backflow of nitrogen,phosphorus,and potassium.
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