氯化钾抑制玉米茎腐病发生与土壤微生物关系初探

十二年的钾肥长期定位试验表明,氯化钾能够显著降低玉米茎腐病的发生率。为了探讨其机理,通过室内培养试验,研究了PDA培养基中添加氯化钾和土壤浸提液对禾谷镰刀菌(Fusarium.graminearum)生长速度的影响,分析了长期施用氯化钾条件下玉米各生育期根际真菌、细菌和放线菌数目的变化。结果发现,一定浓度的氯化钾不能直接抑制禾谷镰刀菌的生长;与不施氯化钾处理相比,施氯化钾处理的土壤浸提液对禾谷镰刀菌生长具有明显的抑制效果,表明土壤浸提液在病原菌与玉米互作中发挥一定作用。长期施氯化钾显著影响玉米生育前期根际土壤真菌和放线菌数目,对根际土壤细菌数目影响不明显,而且真菌数目与茎腐病的发生率呈显著负相关。各处理根际土壤真菌与放线菌数目差异显著时期正处于病原菌的主要浸染时期,因此,施氯化钾引起的玉米根际土壤微生物区系(尤其是真菌数目)的变化是抑制玉米茎腐病发生的机制之一。

Preliminary study on the relation between potassium chloride suppressing corn stalk rot and soil microorganism characteristics

It has been observed from a 12-year fixed site field trial in Jilin Province that potassium chloride(KCl) application has a significant positive influence on corn stalk rot incidence.Incubation experiment was conducted to study the effects of KCl and soil extracts on the growth of Fusarium graminearum,the most common stalk rot fungi in this area and population changes in rhizosphere fungi,bacteria and actinomyces at the different growth stages of corn.The results showed that KCl addition to the PDA medium could not directly suppress Fusarium graminearum development.Soil extracts from soil samples which taken from the field plots with and without KCl application affected Fusarium graminearum development,with soil extracts with KCl treatments suppressed Fusarium graminearum development more significantly,compared with that from no KCl supply.These results indicated that soil extracts played a role in the interaction between corn and Fusarium graminearum.Long-term KCl application increased the populations of rhizosphere fungi and actinomyces in the early growth stages,nevertheless there was no significant difference existed in rhizosphere bacteria number among the treatments.And the populations of rhizosphere fungi were correlated negatively with stalk rot incidence in the early grown stages of corn.The sensitive infection stages of pathogen to corn were consisted with the stages when the significant difference in rhizosphere fungi and actinomyces populations was found.Consequently,the change in rhizosphere microbe population(especially fungi) is one of the mechanisms of potassium chloride suppressing corn stalk rot.