室内模拟旱直播稻田环境下齐整小核菌Sclerotium rolfsii菌株SC64致病力的影响因子及除草效果的研究

本文通过温室盆栽试验,以鳢肠Eclipta prostrata为例,研究杂草叶龄、不同含菌丝体基质接种量以及温度、土壤湿度、保湿期时间等环境因子对菌株SC64侵染鳢肠的影响。在此基础上,温室条件下模拟旱直播水稻田环境下菌株SC64防治节节菜Rotala indica、异型莎草Cyperus difformis、鸭舌草Monochoria vaginalis和耳叶水苋Ammannia arenaria的试验。结果表明,鳢肠幼苗在5叶期以下,接种含菌丝体固体基质剂量在100g m 2以上,温度范围27～33℃,土壤相对饱水90%左右,并且接菌后湿度保持至少24 h,是菌株SC64达到理想除草效果的必需条件。温室模拟试验结果显示,接种含菌丝体固体基质剂量在120 g m 2时,28 d可引起节节菜和鸭舌草81%和74%的植株死亡率及83.8%和82.5%的鲜重抑制率;对异型莎草和耳叶水苋的防效稍差,仅能引起约50%的植株死亡率及60%～65%的鲜重抑制率。这表明菌株SC64可有效控制阔叶杂草,具有开发作为生物除草剂的潜力。

Factors Affecting Pathogenicity of Sclerotium rolfsii Isolate SC64 to Broadleaf Weeds under Simulated Dry-seeded Rice Condition

The fungus Sclerotium rolfsii is presently under development as a bioherbicide for broadleaf weed species by using fungus-infested solid substrates as application material in this laboratory.We examined the effect of host-plant growth stage,dosage of inoculum,soil moisture condition,temperature,and damp soil duration on plant mortality and fresh weight inhibition of eclipta（Eclipta prostrata） caused by isolate SC64 in pot experiments under greenhouse conditions.Perfect control efficacy was recorded following application before 5 leaf stage,with over 100 g m 2fungus-infested substrates（rice husk/bran substrate,2：1,v/v）,and exposure of weeds to 27 33 ℃,soil of 90% water holding capacity and at least 24 h damp soil duration.A simulation experiment of dry-seeded rice was carried out to examine the performance of S.rolfsii SC64 to broadleaf weeds under greenhouse conditions.Results showed that isolate SC64（120 g m 2） caused 81% and 74% plant mortality,83.8% and 82.5% fresh weight reduction for Rotala indica and Monochoria vaginalis,respectively.Plant mortality and fresh weight reduction for Cyperus difformis and Ammannia arenaria were relatively lower,which were approximately 50% and 60% 65%,respectively.It was indicated that this fungus could be a good candidate for further study and a promising biocontrol agent against broadleaf weeds under specific environmental conditions.