10种农业化学品对柑橘内生菌枯草芽孢杆菌L1-21的影响

Effect of ten agrochemicals on the indigenous endophyte Bacillus subtilis L1-21 in citrus leaves

【目的】明确农业化学品对柑橘内生菌的影响,指导柑橘合理用药。【方法】采用平板菌落计数法,测定了6种杀虫剂、3种杀菌剂和微肥EDTA-Cu对生防菌株枯草芽孢杆菌L1-21的相容性及对柑橘植株内生菌的抑制作用。【结果】56.00 mg·L^(-1)吡虫啉、121.80 mg·L^(-1)虫螨腈、4.00 mg·L^(-1)甲氨基阿维菌素、50.00 mg·L^(-1)噻虫嗪、45.60 mg·L^(-1)氟氯氰菊酯、800.00 mg·L^(-1)辛硫磷、402.00 mg·L^(-1)喹啉铜、3728.00 mg·L^(-1)硫磺、620.60 mg·L^(-1)氧化亚铜和321.00 mg·L^(-1)EDTA-Cu在平板上对L1-21的抑制率均达100.00%。2倍剂量处理离体叶片24 h后,除8.00 mg·L^(-1)甲氨基阿维菌素的抑制率(16.84%)显著低于其他5种杀虫剂外,其他5种杀虫剂对L1-21的抑制率均无显著差异。2倍剂量处理柑橘活体叶片24 h后,8.00 mg·L^(-1)甲氨基阿维菌素对柑橘叶片内的L1-21抑制作用(4.23%)不明显,显著低于其他5种杀虫剂和3种杀菌剂与微肥EDTACu;对内生菌总量的抑制率以8.00 mg·L^(-1)甲氨基阿维菌素(6.78%)最低,其他制品达46.90%~70.06%,且差异未达显著水平。【结论】10种农业化学品在平板上均可抑制L1-21,抑制率的大小与其浓度有关。2倍田间登记使用量处理时,10种农业化学品均可影响L1-21在柑橘叶片上的定殖及降低柑橘内生细菌总量。因此,田间施用化学品对柑橘内生菌的负面影响不可忽视。

【Aim】The present study assessed the effects of agrochemicals on indigenous citrus endophytes.【Method】The compatibility of six pesticides,three bactericides,and one micro-element fertilizer with the endophytic strain Bacillus subtilis L1-21 was tested.【Result】Citrus endophyte suppression ability was monitored through population dynamics on plates and after spraying on citrus leaves.The results suggested that 56.00 mg·L^(-1) imidacloprid,121.80 mg·L^(-1) chlorfenapyr,4.00 mg·L^(-1) methylaminoabamectin,50.00 mg·L^(-1) thiamethoxam,45.60 mg·L^(-1) cyfluthrim,800.00 mg·L^(-1) phoxim,402.00 mg·L^(-1) oxine-copper,3728.00 mg·L^(-1) sulphur,620.60 mg·L^(-1)cuprous oxide,and 321.00 mg·L^(-1) EDTA-Cu completely suppressed the endophyte L1-21 growth on plates.The 2-fold treatment on detached leaves after 24 h suggested an inhibition rate of methylaminoabamectin 8.00 mg·L^(-1)(16.84%)that was significantly lower than the five pesticides tested.However,no significant difference was found in the inhibition rate by these five pesticides on endophyte L1-21.In vivo results showed that the inhibition rate caused by 8.00 mg·L^(-1) of methylaminoabamectin on L1-21 inside citrus leaves(4.23%)was not serious,and lower than the ones caused by the five pesticides,three bactericides and micro-element EDTA-Cu.The lowest inhibition rate on citrus endophytes was recorded for 8.00 mg·L^(-1) methylamino-abamectin(6.78%),and it was 46.90%-70.06%for other agrochemicals with no significant difference among them.【Conclusion】The ten examined agrochemicals can inhibit endophyte L1-21 on plates in a concentration-dependent manner.In addition,these agrochemicals directly affect endophyte L1-21 in citrus leaves,resulting in a reduced number of endophytes,and the adverse effect of these agrochemicals on citrus endophytes cannot be neglected.