Abstract:

Objective: This paper aims to study the improvement effect of adding shell powder soil conditioner in acidified soil with Malus hupehensis var. mengshanensis seedlings as material. Method: The orchard acidified soil (pH value is 5.45) was dug out and mixed with conditioner,which was applied to potted M. hupehensis var. mengshanensis seedlings. The three conditioner treatments were:large grain shell powder (DLB),medium grain shell powder (ZLB) and small particle shell powder (XLB),and the pH value of soil,plant height and relative chlorophyll content were measured. After 6 months of treatment,soil samples were collected 5 cm away from the seedlings. Genomic DNA was extracted and amplified to establish a library. The abundance,diversity and community structure of soil bacterial 16S rRNA gene V3+V4 region and fungi ITS1 + ITS2 region were detected. Result: The three kinds of shell powder conditioner were able to significantly improve the soil pH value to 6.5-7.2,which was 19.26% to 28.44% higher than the initial pH value. Both DLB and ZLB treatments could significantly increase plant height and relative chlorophyll content in leaves. According to the results of high throughput sequencing,a total of 736 515 effective bacterial tags and 782 991 effective fungal tags were obtained from 12 soil samples. The proportion of effective sequences was more than 72%. There were 1914 bacterial OTU and 446 fungal OTU in the three treatment groups and the control group. According to the analysis of community abundance index (Ace index and Chao index) and diversity index (Simpson index and Shannon index),three kinds of shell powder treatments significantly improved the abundance and diversity of soil bacterial community. Among them,ZLB treatment had the most significant effect. Ace,Chao and Shannon index increased by 53.84%,49.85% and 14.21%,respectively. Simpson index decreased by 54.76%. Three kinds of shell powder treatments had no significant effect on the abundance of fungal communities,but all of them reduced the diversity of fungal communities. Among them,DLB treatment had the most significant effect,with Shannon index reduced by 44.02%,Simpson index increased by 11.5 times compared with CK treatment. According to the analysis of Beta diversity of each treatment community,the soil microorganisms changed significantly after adding three kinds of shell powder to acidified soil. According to the analysis of the relative abundance composition of flora,at the level of family classification,all three kinds of shell powder treatments significantly increased the abundance of inferior bacteria (ABS-19 and Xanthomonadales),also increased the abundance of inferior fungi (Chaetomiaceae,Microascaceae,Lasiosphaeriaceae,and Ascobolaceae). All three kinds of shell powder treatments significantly decreased the abundance of dominant bacteria of Acidobacteriaceae and Solibacteraceae,and decreased the abundance of dominant fungi of Nectriaceae,Mortierellaceae,Pleosporaceae,and Cladosporiaceae. Conclusion: The application of three kinds of shell powder soil conditioners can increase the soil pH value and improve the growth of M. hupehensis var. mengshanensis,also change the abundance and diversity of bacteria and the diversity of fungi in acidified soils. As a new type of green biological conditioner,shell powder has great application potential.

Key words: shell powder, acidified soil, high throughput sequencing, soil bacteria, soil fungi