Abstract: Pot experiment was conducted to investigate the effect and physiological mechanism of alleviating watermelon wilt disease occurred in continuous cropping soil by intercropped with aerobically growing rice. The results showed that in mono-cropping system, 66.7% of watermelon was infected with wilt disease and 44.4% died after 40 days of transplanting, by contrast, watermelon grew normally in intercropping system. Intercropping significantly reduce occurrence of wilt disease and death rate of watermelon, with the results of lower malondialdehyd (MDA) in roots and leaves, higher soluble protein, lower activities of catalases (CAT), peroxidases (POD), polyphenoloxides (PPO) in roots and leaves and phenylalantine ammonia lyases (PAL) in leaves of watermelon, in comparison with monocropping. The number of Fusarium oxysporum in the rhizosphere soil of watermelon intercropped with aerobically growing rice was decreased by 91%, compared with those in monocropping. Intercropping changed microbiodiversity in rhizosphere soil by phospholipid fatty acids (PLFA), having more bacteria and actinomyces and less fungi compared to monocropping. This finding suggests that intercropping system decreased infection of watermelon wilt disease by restraining pathogen (Fusarium oxysporum) growth and regulating microbiodiversity in rhizosphere soil.

Key words: watermelon, intercropping, wilt disease, Fusarium Oxysporum