| Continuous cropping obstacle became serious in cucumber production in greenhouse, which resulted in soil micro ecological environment deterioration and land persistence utilization decrease, and affected cucmber yield and quality and diseases. Crop rotation and intercropping are often used to improve soil micro ecological environment, relieve soil-borne disease, and increase crop yield to avoid continuous cropping obstacle. The study was divided into two parts containing crop rotation and intercropping, and cucumber was taken as tested material. On the base of our intercropping experiment, onion-cucumber and garlic-cucumber were applied as intercropping treatments to investigate effects of intercropping treatments on cucumber production in the next year and the continous effectiveness. Wheat-cucumber and hairy vetch-cucumber were designed as crop rotationtreatments to study effects on cucumber yield, diseases and micro ecological environment.Results including several conclusions as follow.(1) Both of crop rotation and intercropping could inhibit cucumber diseases, and the inhibition of cucumber downy mildew was the most obvious. The inhibition of wheat-cucumber on downy mildew was significant, while garlic-cucumber inhibited downy mildew in late period of growth of the third planting.(2) Crop rotation and intercropping conduced to cucumber yield increase, especially in the early stage, cucumber yield increased significantly. The yield of wheat-cucumber increased most significantly (p<0.01), and the yield of hairy vetch-cucumber increased significantly (p<0.05), while the total yield of onion-cucumber increased significantly too (p<0.05).(3) Crop rotation and intercropping were benefit to increase soil immediate nutrition. Hairy vetch-cucumber and garlic-cucumber were beneficial for resolving continuous cropping obstacles.(4) Crop rotation and intercropping increased the enzyme activity and improved micro-ecological environment efficiently. The enzyme activity of PPO(polyphenol oxidase), CAT(catalase) and convertase of wheat-cucumber were overall higher, and the enzyme activity of urease increased most significantly, compared to control. Intercropping increased the enzyme activity of PPO in the first and second cucumber crop and the enzyme activity of urease all the time most significantly (p<0.01). The effect of onion-cucumber was the most significantly, and continous effect was the the most obvious.(5) Crop rotation and intercropping played an important role in soil microbial quantity and community construction. The soil fungi quantity of wheat-cucumber decreased and the soil bacteria and fungi quantity of hairy vetch-cucumber increased, which was opposite to actinomyces, and cucumber Fusarium oxysporum in the soil was significantly inhibited in the early stage of cucumber growth (p<0.05). Garlic-cucumber increased soil fungi and actinomyces quantity in the early growth period, and soil bacteria quantity for the first crop, but inhibited Fusarium oxysporum in the soil.(6) Crop rotation and intercropping increased soil bacteria specials and richness. Effect of rotation on soil bacterial community construction was comparatively obvious, especially for hairy vetch-cucumber, which decreased cucumber rhizosphere soil fungi specials. Distinction of cucumber rhizosphere soil bacterial community construction existed between the third crop and the first and second crops. Onion-cucumber increased cucumber rhizosphere soil bacterial communities in the harvest time of the third crop, while little effect on soil fungi. Effect of intercropping on cucumber rhizosphere soil fungal community construction was different between the first crop and others.Therefore, Crop rotation and intercropping were beneficial for resolving continuous cropping obstacles, increasing cucumber yield significantly, and inhibiting deseases, and increased soil fertilizer and bioactivity, and changed soil microbial community construction, which was favored to improve the soil micro ecological environment. |
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