Effects Of Different Vegetable Rotation On Microbial Diversity Of Tomato Continuous Cropping Substrate And Tomato Growth In Greenhouse

The effects of cabbage,bean and celery rotation on the physical and chemical properties of the substrate,the enzyme activity of the substrate and the growth,physiology and quality of tomato in greenhouse were studied.The microbial community structure and diversity in the substrate after rotation were evaluated by using Illumina miseq high-throughput sequencing platform.The purpose of this study was to explore the effect of different vegetable rotation on improving the microbial flora and physical and chemical properties of tomato continuous cropping substrate,and to provide theoretical and technical basis for overcoming the obstacles of continuous cropping and sustainable development of substrate cultivation.The main results are as follows:1.The EC,organic matter,total potassium and available phosphorus of tomato continuous cropping increased by 31.20%,7.40%,10.99%,13.65%and 3.38%,16.75%,26.42%and 8.91%respectively.The pH value and total nitrogen content of celery grown-substrate increased by 4.59%and 5.60%respectively.Through RDA analysis,most of the fungi are positively related to organic matter and available phosphorus,and negatively related to pH.Most of the beneficial bacteria,such as actinomycetes,blastomyces and rhizobia,are positively related to the content of available phosphorus,EC,available potassium,total phosphorus,total potassium and organic matter,and negatively related to pH.2.In the organic substrate of continuous cropping tomato,rotation celery treatment can significantly improve the diversity and richness of fungi in the culture substrate,while the diversity of rotation cabbage treatment and rotation bean treatment is significantly lower than that of tomato continuous cropping treatment.Further PCoA analysis showed that the fungal community structure of three rotation treatments was different from that of tomato continuous cropping.The relative abundances of several harmful fungi（such as Pseudomonas,Gibberella and Pyrenochaeta）in continuous cropping were significantly higher than those in three rotation treatments,and the decreased abundances of harmful fungi in rotation celery were more obvious.3.In the organic substrate of continuous cropping tomato,the observed species,Chao 1index and Shannon index of rotation treatment of cabbage,bean and celery were higher than that of continuous cropping treatment,indicating that the bacterial richness and diversity of rotation treatment were higher than that of continuous cropping treatment.The hierarchical cluster analysis and PCoA analysis of bacterial community showed that the bacterial community of rotation and continuous cropping were obviously separated.The dominant bacteria in each rotation were azotobacter,actinomycete and anaerobe4.The plant height,stem diameter and leaf area of tomato under different rotation were higher than those under continuous cropping.The plant height and leaf area of treated with cabbage were the largest at the peak and end of fruit bearing period.During the whole growth period,there was no significant difference in the stem diameter of each rotation treatment,but the total stem diameter of cabbage treatment was larger.5.The results showed that celery rotation could significantly increase the intercellular CO₂ concentration（Ci）,transpiration rate（Tr）,stomatal conductance（Gs）and net photosynthetic rate（Pn）of tomato leaves,with the increase of 38.15%,62.99%,65.06%and48.46%,respectively.Compared with continuous cropping,the Tr and Gs of tomato leaves were significantly increased by 69.12%,58.86%and 50.85%,62.81%respectively.Compared with continuous cropping,qP of tomato leaves was significantly increased by 4.00%in soybean rotation and 91.67%in celery rotation.The activities of SOD and POD in rotation celery were higher than that in tomato continuous cropping,and the activities of SOD and PODin rotation celery were significantly higher than that in tomato continuous cropping,increased by 15.70%and 53.16%,respectively.The content of MDA and Pro in continuous cropping was significantly higher than that in rotation,and the degree of membrane lipid peroxidation in rotation celery was the lowest,with a decrease of 31.97%and 47.02%,respectively.6.Different vegetable rotation had a great influence on the quality of tomato.Celery rotation,cabbage rotation and bean rotation significantly increased the soluble sugar content of tomato fruit,which were 54.18%,42.34%and 39.74%higher than that of continuous cropping,and celery rotation significantly increased the soluble protein content and ascorbic acid content of tomato fruit,which were 75.56%and 0.30%higher than that of continuous cropping.The content of organic acid and nitrate in tomato fruit of continuous cropping was significantly higher than that of each rotation.In conclusion,from the perspective of physical and chemical properties of substrate,microflora changes and the growth and development effect of tomato after rotation,the microbial community diversity of celery rotation is the highest,and the effect of improving the quality of tomato after rotation is the best,followed by cabbage rotation,while continuous cropping seriously reduces the microbial diversity and richness in the culture substrate,and affects the subsequent crop growth physiology and quality of tomato.Therefore,rotation of celery in the organic substrate of continuous cropping of tomato can overcome the obstacle of continuous cropping of organic substrate,so as to realize efficient and sustainable production of tomato organic substrate in facility.