Effects of straw biological reactor on the soil microenvironment and plant growth of grapes cultivated in greenhouse

The soil around the root (rhizosphere) is a critical interface for the exchange of resources between plants and the soil microenvironment. This study aims to explore the effects of straw biological reactor on the soil microenvironment and plant rhizosphere of grape growth in the greenhouse. Four experimental treatments of internal straw bioreactor were set, according to the material compositions: (maize straw 2.4×104 kg/hm2 + fermentation strain ratio 2‰), (maize straw 3.6×104 kg/hm2+ fermentation strain ratio 2‰), (maize straw 2.4×104 kg/hm2 + fermentation strain ratio 3‰) and (maize straw 3.6×104 kg/hm2 + fermentation strain ratio 3‰). The conventional cultivation of grapes in the greenhouse was used as control. The results showed that the soil temperature significantly increased in the year when the straw bioreactor was conducted between the rows of the grape plant. There was a higher ratio of fermentation strains in the biological reactor, while the faster straw rotted in the early stage, as the soil temperature varied greatly. But there was a very weak effect of straw biological reactor on the soil temperature in the next year. The treatments of straw bioreactors between the rows of grape plants were effectively improved the numbers of bacteria and fungi in the rhizosphere soil. Specifically, the number of soil bacteria in the treatment with the higher straw application amount (3.6×104 kg/hm2) was significantly different from that with the lower straw application amount (2.4×104 kg/hm2). However, there was a relatively weak effect of straw bioreactor on the soil actinomycetes. The soil urease activity increased significantly in the year with straw biorereactor treatment, increased by 38.5%-68.4% compared to the control group, but remained relatively stable in the next year. The activity of soil sucrase showed a continuously increasing trend under the condition of the same application amount of straw in the reactor, whereas, there was no significant difference of soil sucrase activity between the treatments with the fermentation strain ratio of 2‰ and 3‰. Consequently, the straw bioreactor between the rows of grape plants can be expected to effectively improve the root activity of grape, as well as the content of photosynthetic pigments chlorophyll a and chlorophyll b in leaves, particularly for a higher yield. In conclusion, the soil temperature, nutrients, and microbial environment were significantly improved after the straw bioreactor between the rows of grape plants, indicating a positive effect on the plant growth and yield of grapes. The finding can also provide a strong reference for grape production in cold areas.