5株生防菌定殖能力、促生作用及其对木薯细菌性枯萎病生防潜力的研究

Colonization Ability and Growth-Promoting Effects of Five Biocontrol Bacteria,and the Biocontrol Potential Against Cassava Bacterial Blight

生物防治是防控木薯病害的有效手段之一。生防菌株的筛选、定殖能力直接关系到菌株抗性的稳定性及防治木薯细菌性枯萎病的效果。本研究在前期大田初步筛选菌株及大棚盆栽防效测定实验的基础上,根据综合赋值结果优选5株生防菌株,对其大田防效潜力进行测定;分析生防菌株对木薯各项生长指标的影响;筛选出防效和促生效果均表现较好的菌株,研究其在木薯不同部位的定殖能力及消长动态变化,旨在为筛选木薯细菌性枯萎病生防菌株提供数据参考,为后期生防菌剂的研发提供理论依据。结果表明:5株生防菌株中HWY-3-1防效最好,平均防效为61.35%,DBS-5最低,为5.02%,其余3株菌株HWS-4-3、HS-4-7、HNR-3-7的防效分别为45.02%、19.09%和24.08%;与对照相比,5株生防菌株对木薯均有不同程度的促生效果,其中HWY-3-1菌株处理的木薯在株高、最大薯块直径和单株薯块重等生理特性上显著高于其他生防菌处理,HWY-3-1和HWS-4-3菌株处理后木薯的基部茎粗和薯块数显著高于其他菌株处理;综合比较,生防菌株HWY-3-1、HWS-4-3和DBS-5的防效和促生效果较好。3株生防菌株接种在木薯3个部位后均能稳定定殖,HWY-3-1的定殖能力最强;在根表土的定殖量显著高于叶片,嫩茎中的定殖量最少;3株菌株定殖后活菌数量均呈先上升后下降最后趋于稳定的变化趋势。

Biocontrol is effective for cassava disease prevention and control.The screening and colonization ability of biocontrol strains are directly related to the stability of stain resistance and the effects of controlling cassava bacterial blight(CBB).Based on the preliminary screening of strains in the field and the determination experiment of control effects in greenhouse,five biocontrol strains were selected under comprehensive evaluation to probe into the biocontrol potential in the field.Moreover,bacteria’s effects on the growth indexes of cassava were analyzed.The strains with good control and growth-promoting effects were screened.Their colonization ability and dynamic changes in different parts of cassava were studied,thus to provide data reference for screening biocontrol bacteria for CBB control and offer theoretical support for the future R&D of biocontrol agents.The results showed that HWY-3-1 topped the five biocontrol strains for control effect,with an average control effect of 61.35%.DBS-5 was the lowest,with a 5.02%control effect.The control effect of the other three strains HWS-4-3,HS-4-7 and HNR-3-7 was 45.02%,19.09%and 24.08%,respectively.Compared with the control group,the five strains showed different growth-promoting effects on cassava.Physiological characteristics,such as height,maximum tuber diameter and tuber weight per plant,of cassava treated with HWY-3-1 strain were significantly higher than those treated with other strains.The basal stem diameter and tuber number of cassava treated with HWY-3-1 and HWS-4-3 strains were significantly larger than those treated with other strains.Comprehensive comparison revealed that HWY-3-1,HWS-4-3 and DBS-5 stains had better control and growth-promoting effects.The three strains could colonize stably after inoculation in three parts of cassava,with HWY-3-1 having the strongest colonization ability.The amount of colonized bacteria in root topsoil was significantly higher than that in leaves,and that in young stems was the least.The number of living bacteria after colonization first grew,then fell,and finally plateaued out.