关键词: 苹果, 果园, 覆盖模式, 高通量测序, 荧光定量PCR, 土壤细菌, 苦瓜, 一代杂种, 品种

Abstract: Four types of mulching techniques（cornstalk mulch，sawdust mulch，forest soil mulch，control）in the dryland apple orchards of Weibei were tested in this study. Based on the determination of soil basic physical and chemical indicators and enzyme activity，the quantitative analysis of soil bacterial community structure and diversity under different coverage measures were carried out by using real-time PCR（q-PCR）and Illumina HiSeq high-throughput sequencing technology. The results showed that different mulching treatments significantly increased water content，organic matter and total nitrogen of 0–20 cm soil layer and reduced soil pH value. At the same time，soil urease，sucrase and catalase activities were remarkably improved. The results of real-time PCR indicated that the 16S rRNA copy number of soil bacteria under each covering treatment was observably higher than that of clear tillage. Illumina HiSeq high-throughput sequencing revealed that Proteobacteria，Acidophilus and Actinomycetes were dominant bacteria populations at phylum level whose relative abundances ranged from 57.12% to 74.72%；α-proteobacteria，subgroup_6，β-proteobacteria and δ-deformation were dominant at class level，and the relative abundances ranged from 33.39% to 43.15%. The α diversity analysis showed that different mulching treatments could increase the abundances and diversity indices of soil bacterial communities. The analysis of β diversity manifested that there were considerable differences in the phylogenetic compositions of each bacterial treatment compared to the control bacterial community. The results of RDA analysis showed that there were correlations between relative soil bacterial community abundances and soil nutrient and enzyme activities in the condition of different mulching treatments. These three mulching treatments had positive effects on 100-fruit weight and sugar content，among which cornstalk mulch was the best.

Key words: apple, orchard, mulching practice, high-throughput sequencing, q-PCR, soil bacteria, bitter gourd, hybrid, cultivar