不同落叶剂对冬枣落叶效果及养分回流的影响

Effects of Different Defoliants on Defoliation and Nutrient Reflux of‘Dongzao’Jujube

为了探究不同种类不同浓度化学落叶剂对5年生‘冬枣’落叶效果及养分回流的影响,以设施‘冬枣’为研究对象,叶面喷施落叶剂,测定叶片内氮磷钾元素含量及统计落叶率等指标。结果发现:(1)0.20%乙烯利处理枣树的落叶最好,处理后7 d落叶率高达75.75%;(2)枣树自然落叶可发生养分回流现象,其中氮、磷、钾养分回流量分别为4.14、0.27和3.18 g·kg^(-1);(3)所有化学落叶剂处理下叶片氮均发生养分回流,其中4%尿素、8%尿素、10%尿素、0.5%硫酸锌、1.0%硫酸锌处理显著提高叶片氮养分回流量;4%尿素、8%尿素、10%尿素、0.5%硫酸锌、1.0%硫酸锌、2.0%硫酸锌、0.05%乙烯利和0.10%乙烯利处理的叶片磷可发生养分回流;4%尿素、8%尿素、10%尿素、0.5%硫酸锌、0.05%乙烯利和0.20%乙烯利处理的叶片钾可发生养分回流,但仅8%和10%尿素处理同时显著提高叶片氮、磷、钾养分回流量。综上,生产上以快速落叶为目的的最好处理为0.20%乙烯利;以特定时期落叶且不浪费叶片养分为目的的最好处理为尿素(8%或10%均可),可显著提高氮、磷、钾的养分回流量。

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.