Influence of cucumber-celery intercropping on growth and fusarium wilt of cucumber

Cucumber wilt is a soil disease that is very prevalent in the production and cultivation of cucumber. The disease is highly difficult to prevent and cure. A number of studies have shown that crops intercropping was one of the most effective methods of reducing the occurrence of plant soil disease. Also celery (Apium graveolens L.) has been proved to be a plant with high allelopathy. To explore application of allelopathic effect of celery for cucumber fusarium wilt control, we conducted an experiment of celery and cucumber (Cucumis sativus L.) intercropping. In the experiment, three planting patterns were set, which were cucumber-celery intercropping, celery monoculture and cucumber monoculture. The vegetative and reproductive growths of cucumber were investigated. The allelopathic effect of soil extracts of different planting patterns on cucumber fusarium wilt were analyzed through measurement of colony diameter of Fusaium oxysporum f. sp. cucumerinum cultivated on PDA medium. Meantime, the effect of allelopathy on cucumber wilt and the disease prevention of cucumber-celery intercropping in field was studied through field inoculation of F. oxysporum. The results showed that intercropping enhanced vegetative growth of cucumber, lowered node of the first female flower bud and increased the number of female flowers blooming within the node range from one to thirty, which laid a good foundation for high yield of cucumber. The colony diameter of F. oxysporum in PAD medium with soil extracts under cucumber-celery intercropping was smallest, which was significantly different from that under monoculture of celery or cucumber (P < 0.05). There was a certain degree of inhibiting effect of ethanol, acetone, and aqueous extracts of soils under cucumber-celery intercropping on cucumber wilt. Moreover, allelopathy-inhibiting effect was 38.11%-75.90% of soil extracts under cucumber-celery intercropping. For three extract agents, colony diameter of ethanol extract was smallest, which reached a very significant level when compared respectively with acetone and distilled water (P < 0.01). Soils of different planting patterns were used to plant cucumber, cucumber fusarium wilt was inoculated during the first true leaf stage. The results showed that in soil of cucumber-celery intercropping, disease index of cucumber wilt reduced with control efficiency reaching 57.03%-72.15%. Therefore, allelopathy-inhibiting effect of cucumber-celery intercropping on cucumber wilt was obvious, which provided theoretical basis for the prevention and control of cucumber soil-borne diseases through intercropping with celery.