生防菌Alternaria amaranthi-3对反枝苋的防治效果

反枝苋Amaranthus retroflexus是一种世界性恶性杂草。为了确定微生物除草剂候选菌Alternaria amaranthi-3防除反枝苋的潜力,通过盆栽试验研究了接种浓度、露期和水乳剂型对A.ama-ranthi-3菌株致病力的影响。结果显示,接种浓度显著影响菌株的致病力,在48h露期条件下,接种孢子浓度为105个/mL时,菌株水剂对反枝苋幼苗生长抑制率为35.55%;浓度为107个/mL时,生长抑制率达到75.25%。露期对该菌株的致病力也有较大影响,在不保湿条件下,菌株水剂对反枝苋的生长抑制率为26.43%,而保湿48h处理的生长抑制率达到77.96%。Span80∶Tween80=1∶3的复配乳化剂和大豆油制备的水乳剂可显著降低露期对菌株防效的影响和提高菌株的致病力,无露期时,菌株水乳剂对反枝苋的生长抑制率达到88.35%,显著高于水剂;48h露期条件下,菌株水乳剂处理的生长抑制率为90.59%,而菌株水剂处理为77.96%。表明通过剂型的改进菌株Alternaria amaranthi-3能有效防除反枝苋。

Biocontrol efficiency of Alternaria amaranthi-3 to Amaranthus retroflexus

Redroot pigweed, Amaranthus retroflexus, is a notorious weed worldwide. To evaluate the potential of Alternaria amaranthi-3 as a mycoherbicide for redroot pigweed control. The effect of inoculum potential, dew period and formulation of emulsions in water (EW) on the pathogenicity of A.amaranthi-3 was studied using pot experiment. The result showed that the inoculum potential significantly affected the pathogenic efficiency. When the redroot pigweed was inoculated with 1×10⁵ spore/mL, the strain spore in aqueous formulations inhibited the growth of redroot pigweed at 35.55%. The inhibition of the aqueous formulation against redroot pigweed growth arrived 75.25% at 1×10⁷ spore/mL concentration. The pathogenicity of the strain was dependent on the dew period. Without a dew period, aqueous formulation of strain provided the inhibition rate of 26.43%. In 48h dew period, the aqueous formulation of strain can provide the inhibition rate of 77.96%. The EW significantly enhanced the pathogenicity of the strain and reduced the requirement of dew period for maximum weed control. In the absence of dew, the biocontrol potential of the EW formulation is better than that of aqueous formulation, the inhibition rate was 88.35% and 26.43% respectively. In 48h dew period, EW formulation and aqueous formulation inhibited the growth of redroot pigweed at 90.59% and 77.96% respectively. These results indicated that when A.amaranthi-3 was properly formulated, A.amaranthi-3 can be effective for controlling redroot pigweed.