Arbuscular Mycorrhizal Fungal Diversity In Jujube Orchard Under Facility Cultivation

Facility cultivation mode is an efficient industrial mode of economic forest fruit trees and an important way to adjust industrial layout and increase farmers ’ income.Under the condition of facility cultivation,due to the relatively closed space and special microclimate environment,as well as the use of a large number of chemical fertilizers and high-intensity artificial cultivation,soil microbial community imbalance will affect the normal growth of trees,resulting in a decline in yield and quality.Arbuscular mycorrhizal fungi(AMF)are a kind of endophytic fungi that can symbiosis with most terrestrial plant roots.Mycorrhizal symbiosis improves the nutrition and water absorption of host plants,thereby promoting plant growth and improving plant resistance.Ziziphus jujuba is a typical mycorrhizal tree species,previous studies have shown that mycorrhizal symbiosis can significantly improve the growth and stress resistance of jujube.In this study,the soil characteristics and distribution of Ziziphus jujuba ‘Dongzao’ orchard and the mycorrhizal status of ‘Dongzao’ root were analyzed,the diversity of AMF community was analyzed by high-throughput sequencing.Further analysis of the driving effect of environment and cultivation mode on AMF community diversity and community assembly mechanism,and to provide theoretical guidance for health management of winter jujube orchard under facility conditions,the main results were as follows :(1)During the fruit color change period of ‘Dongzao’,19 greenhouses and 13 rain shelters were randomly selected to collect roots and rhizosphere soil in Dali county,Shaanxi province.The analysis of soil physical and chemical properties showed that the greenhouse soil was strong alkaline(p H 8.73),the soil was slightly salted,the contents of available potassium and available phosphorus were rich,the soil organic carbon content was extremely low,and the total nitrogen content was lack.The rain shelter was alkaline(p H 8.16),and the soil was moderately salted.Available potassium content is rich,available phosphorus content is above average,soil organic carbon,total nitrogen content is lack.Compared with the greenhouse,the activity of sucrase in rain shelter increased by 77.44 %,and there was no difference in urease and alkaline phosphatase,easily extracted glomalin content increased by234.63%,total glomalin,infection rate and spore density had no difference.(2)High throughput sequencing of AMF r DNA SSU region,primer selected AMDGR/AMV4.5NF,at 97% similarity threshold,identified 225 OTUs,of which 165 OTUs were identified as genus,belonging to 6 families,4 orders.Among them,Glomus,Paraglomus and Claroideoglomus were common genera in greenhouse and rain shelter,and Scutellospora,Ambispora and Diversispora were unique genus in rain shelter.The relative abundance of Glomus,Paraglomus and Scutellospora in different types of protected cultivation was significantly different.Relative abundance and extractable glomus content of Glomus and Paraglomus in community.(3)The OTU richness of AMF in rain shelter was 56.6,which was significantly higher than that in warm shed(37.88).Correlation analysis showed that p H was negatively correlated with richness index and Faith ’ s PD evolutionary diversity index,showing a single peak model.Ammonia nitrogen was positively correlated with Faith ’ s PD index,showing a single peak model.Ammonia nitrogen,invertase and richness index showed a significant positive correlation,showing a linear model.There was a significant positive correlation between invertase and Faith ’ s PD index,showing a linear model relationship.(4)PCo A analysis based on bray-curtis distance algorithm shows that there are significant differences in AMF composition between greenhouses and rain shelters.Adonis multivariate analysis of variance showed that p H,available potassium,available phosphorus,ammonia nitrogen and cultivation types had extremely significant or significant effects on the community structure of AMF.The overall contribution rate of soil environmental factors to community composition was higher than that of protected cultivation types.The β-nearest neighbor classification index showed that the random diffusion process was the dominant factor to promote the assembly of AMF community.Sidak test showed that 16 species could be used as indicator species for inter-group differences,including 4 in greenhouse and 12 in rain shelter.