寡雄腐霉发酵液对番茄生长的影响及对灰霉病的防治作用

为了研发对番茄灰霉病高效、稳定、安全的生物农药,试验利用自主分离获得的寡雄腐霉菌株制备发酵液,采用盆栽试验研究寡雄腐霉发酵液对番茄生长的影响和对灰霉病的防治效果及机制,并在大田生产中验证其生防效果。结果表明,盆栽试验中,寡雄腐霉发酵液促进健康番茄植株生长,植株总生物量和根系生物量分别增加9.5%和15.4%,提高了植株叶绿素含量、根系活力及氮、磷、钾吸收量,并使带病番茄植株的发病率和病情指数分别降低57.2%和60.3%,相对防治效果达60.3%,施用寡雄腐霉发酵液对番茄叶片细胞膜具有保护性,降低丙二醛含量,提高病原性相关酶""超氧化物歧化酶、多酚氧化酶和苯丙氨酸解氨酶活性。后续田间试验中寡雄腐霉发酵液对番茄灰霉病的防治效果达71.2%。说明寡雄腐霉发酵液能有效防治番茄灰霉病,还具有促进番茄生长的作用,并且可诱导番茄植株对病原菌的防御作用,应用前景广泛。

Influence of the fermentation broth of Pythium oligandrum on the growth and botrytis control of tomato seedlings

Grey mold (Botrytis cinerea Pers.) is a pathogenic fungus of tomato botrytis, which occurs seriously in continuous cropping soil and causes heavily economic losses in tomato production. Farmers have to grow tomato annually in the same soil since lack of soil resources in China. Chemicals such as carbendazim, thiophanate-methyl and benlate have been used to control tomato botrytis for decades and a large amount of these chemicals have thus remained in both tomato fruits and soils, which is harmful to both human being and the environment. On the other hand, the pathogenic Botrytis cinerea has also developed resistance to these chemicals. As a result, an increasing attention has been paid to develop safe, effective, and stable bio-agents to control tomato botrytis in recent years. Studies have reported that Pythium oligandrum could inhibit or kill plant pathogenic fungi, including Botrytis cinerea, Phytophthora nicotiana and Pythium aphanidermatum. The oospores of P. oligandrum have been hence used to control black shank disease of tobacco, grey mold of tomato, and root rot of cucumber. However, the bio-control effect of the oospore agent is unstable and unsatisfactory because their germination and hyphal growth are significantly influenced by temperature, humidity, sun light, soil types, rainfall, and agricultural measurements. To address the importance of metabolites produced by P. oligandrum in bio-controlling of plant fungal diseases, in both greenhouse and field experiments we tested the hypothesis that P. oligandrum fermentation broth could influence the growth and botrytis control of tomato. For the greenhouse pot experiment, four treatments had been examined: plants inoculated or not inoculated with pathogen plus culture solution or plus fermentation broth. Meanwhile, tomato seedlings were respectively sprayed with water (control), fermentation broth or culture solution, before the occurrence of botrytis in the field. In the greenhouse pot experiment, the fermentation broth promoted the growth of tomato seedlings and total plant biomass production by 9.5% and root biomass by 15.4% compared to the control (pathogen inoculation plus culture solution). Chlorophyll concentrations in the leaves, root activities, and nutrient absorption (nitrogen, phosphorus, and potassium) in the field seedlings were also increased by spraying the fermentation broth. Meanwhile, the disease incidence was reduced by 57.2% and disease index by 60.3% with the fermentation broth supply under pathogen inoculation, leading to 60.3% of the relative control efficacy. Further results showed that the fermentation broth could protect the cell membrane of leaves against the pathogen damage, since less malondialdehyde, one of the oxidative products of cell lipids, was detected. In addition, the fermentation broth stimulated enzyme activities related to plant disease resistance such as superoxide dismutase, polyphenol oxidase, and phenylalanine ammonialyase in the leaves of tomato seedlings. The relative control efficacy of the fermentation broth reached 71.2% in the filed tomato seedlings. In summary, the fermentation broth of P. oligandrum have multiple functions, including the induction of the resistance to grey mold, the decrease in botrytis occurrence, and the promotion of plant growth, which are different from other bio-control agents that can control diseases only. Our research showed the potential of the metabolites produced by P. oligandrum as an effective, stable and safe bio-control agent. Further investigations are needed to clarify the effectiveness of metabolites from P. oligandrum in disease control.