不同配方落叶剂对榕树冬季集中落叶的效应

Effects of different defoliant formulations on concentrated deciduous leaves of Ficus microcarpa L. f. in winter

【目的】探讨不同配方落叶剂对榕树冬季集中落叶的效应及对其生理变化的影响,为有效防治榕树叶部病虫害提供参考依据。【方法】以5年生榕树为试验材料,采用经正交试验筛选获得的5种由不同浓度乙烯利、碘化钾和尿素配成的落叶剂,对榕树进行叶面喷施处理(T1～T5),以喷施清水为对照(CK),统计分析各处理的落叶率、萌发率和病情指数,并测定若干生理指标。【结果】T1～T5处理榕树的落叶率均显著高于CK(P<0.05),叶片病情指数极显著低于CK(P<0.01),其中,喷药后第14 d T5处理的落叶率最高,为90.33%,其次为T4处理,为84.67%,T3处理的落叶率为72.67%。各落叶剂处理榕树叶片的叶绿素和可溶性蛋白含量呈先下降后上升的变化趋势,相对电导率和丙二醛(MDA)含量呈先上升后下降的变化趋势。落叶剂处理7 d后,榕树树体均恢复生长,其中T5处理对榕树树体的胁迫较小,对榕树后期发芽影响较小,萌发率达72.36%。【结论】以0.8%乙烯利+0.2%碘化钾+2.0%尿素配成的落叶剂对榕树的落叶效果最佳且生理胁迫小,对其后期叶片萌发影响小,是最佳的榕树落叶剂配方。

【Objective】The effects of different formulations of defoliant agents on the concentration of deciduous leaves in winter and their physiological changes were discussed in order to provide reference for the effective control of leaf diseases and insect pests of Ficus microcarpa L.f.【Method】Five kinds of defoliant agents composed of different concentrations of ethephon,potassium iodide and urea were used to spray the leaf surface of the 5-year-old F.microcarpa(T1-T5).Control(CK)was sprayed by clear water.The defoliation rate,germination rate and disease index of each treatment were analyzed statistically,and physiological indexes were determined.【Result】The defoliation rates in T1-T5 were significantly higher than that of CK(P<0.05),and the disease index of leaf was significantly lower than that of CK(P<0.01).Among them,T5 treatment had the highest defoliation rate(90.33%)on day 14 after spraying,followed by T4(84.67%)and T3(72.67%).The content of chlorophyll and soluble protein in leaves of F.microcarpa treated with defoliant agent decreased first and then increased,and the relative electrical conductivity and malondialdehyde(MDA)content increased first and then decreased.Tree growth resumed in all defoliant treatment groups 7 d after spraying.T5 treatment had little stress on tree and had slight effects on germination later,and the germination rate was 72.36%.【Conclusion】The defoliant with 0.8%ethephon,0.2%potassium iodide and 2.0%urea has the best effect on the leaves of F.microcarpa,and has little effects on the leaf germination in the later stage,so it is the best formula of defoliant for F.microcarpa.