Study On Cucumber Rhizosphere Bacteria Diversity And Yield Of Vegetable Crops Rotation

It is the pick of the basket that crop rotation of plants. It had been recognized that continuous cropping was harmful and crop rotation was favourable. But the mechanism was not very clearly. The structure of soil microorganism could show that whether the soil ecological environment is good or bad. The reseached object was cucumber which had very serious problems when continuous cropped. It investigated the effect about seven crop rotation modes on cucumber root soil bacterial community diversity by PCR-DGGE. And the results were checked by cucumber desease happening and yield. The purpose was to discover the mechanism which decrease cucumber deseases and increase yield. And it was to provide theory principle for cultivation of cucumber and improving ecological environment of cucumber root.This results including several conclusions as flowing:1. Rotation of different vegetables impacts on soil bacterial community. In the rotation modes which were researched in this research, kidney bean-celery-cucumber rotation, tomato-celery-cucumber rotation and tomato-kidney bean-cucumber rotation modes can promote soil bacterial community diversity and evenness. These rotation modes are better rotation modes for cucumber planting.2. .Rotation of different vegetables impacts on cucumber desease happening. Rotation decrease cucumber desease happening. In the rotation modes which were researched in this research, kidney bean-celery-cucumber rotation mode can decrease three cucumber deseases happening, so it is a better rotation mode. Tomato-celery-cucumber rotation and tomato- kidney bean-cucumber rotation modes decrease cucumber downy mildew and angular leaf spot deseases respectively, so they are another two better rotation modes.3. Rotation of different vegetables impacts on soil nutrinent. Rotation equilibrate soil nutrinent In the rotation modes which were researched in this research, tomato- kidney bean-cucumber rotation mode could cut down nitrogen content and salinity in soil significantly, it increased organic matterand in soil. kidney bean-celery-cucumber rotation mode could increased organic matter in soil and cut down salinity in soil.4. Rotation of different vegetables impacts on cucumber yield. The yield of rotation planting is significantly more than that of continuous cropping. The sequence is kidney bean-celery-cucumber rotation >tomato-celery-cucumber rotation >tomato-kidney bean-cucumber rotation >cucumber- celery-cucumber rotation >kidney bean-tomato-cucumber rotation >cucumber-tomato-cucumber rotation >cucumber-kidney bean-cucumber rotation.5. There is a relationship between soil bacterial community diversity index and cucumber disease index. The diversity index is very significantly negative correlate with cucumber downy mildew disease index, and it significantly negative correlate with cucumber powdery mildew and angular leaf spot disease index. There is another relationship between soil bacterial community evenness index and cucumber disease index. The evenness index is significantly negative correlate with cucumber powdery mildew and angular leaf spot. disease index.In summary, crop rotation could increase soil bacteria diversity, decrease cucumber disease and balance soil nutrient. In the rotation modes which were researched in this research, kidney bean-celery-cucumber rotation, tomato-celery-cucumber rotation and tomato-kidney bean-cucumber rotation could create better ecological environment for cucumber grough。...