Intercropping with garlic alleviated continuous cropping obstacle of cucumber in plastic tunnel

Continuous cropping obstacle is prevalent for protected cultivated cucumber in China. Intercropping garlic may effectively relieve this obstacle due to its allelopathic and antimicrobial effects. A two-growing season investigation was carried out during autumn 2009 to spring 2010 in plastic tunnel to determine the effects of intercropped garlic and green garlic on the overall growth of cucumber and soil biological properties. Results showed that green garlic exhibited the inhibitory effect on the growth of cucumber in spring cultivation 2010. Garlic cucumber intercropping system increased yield of cucumber differently depending on garlic cultivars, with only cv. G005 showing significant increase (13.4%). Intercropping systems were evaluated as a greater net benefit system as compared to monoculture cultivation. Populations of soil bacteria and actinomyces were stimulated, while fungi were inhibited under intercropping system. Activities of soil invertase, urease, and alkaline phosphatase were encouraged under intercropping system in spring cultivation 2010 compared with monoculture. The promotion effect of intercropped garlic on urease and alkaline phosphatase maintained till garlic harvest. These results suggest that intercropping system can improve soil biology environment and alleviate continuous cropping obstacle of cucumber at different levels.