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适生区外‘丰彩’花椒根际土壤胞外酶活性与微生物群落结构特征研究
Differences in Extracellular Enzyme Activities and Microbial Community Structure Between Rhizosphere and Non-rhizosphere Soils of Zanthoxylum bungeanum. ‘Fengcai’ in Marginal Habitats
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摘要: 为明确‘丰彩’花椒在适生区外的土壤生态适应性,以海拔1 000 m栽植的‘丰彩’花椒幼树根际(0~30cm)土壤为研究对象,非根际为对照,系统分析了土壤养分含量、胞外酶活性及微生物群落结构差异。采用高通量测序技术和荧光法测定土壤养分含量、胞外酶活性及细菌16S rRNA和真菌18S rRNA基因的丰度和群落组成,并通过相关性分析探究土壤微生物多样性、胞外酶活性与环境因子的相关关系。结果表明:根际土壤有机碳、全氮、C:N及N:P均高于非根际,而全磷和C:P较低,但差异未达显著水平;根际土壤BG、CBH、NAG、LAP、ACP、EC:P、EC:P以及EN:P均高于非根际,VL值为0.73~0.81,非根际土壤较根际低4.43%,VA为54.28°~58.98°,根际与非根际土壤均存在磷限制,且根际土壤磷限制程度更高;土壤微生物群落以细菌为主,优势类群为Actinobacteriota和Chloroflexota,真菌中Mucoromycota丰度升高,根际细菌多样性显著高于非根际,而真菌多样性则相反;相关性分析显示,细菌Chao指数及物种数与N:P呈显著正相关,而真菌的Chao指数及物种数与N:P呈显著负相关;NAG、LAP、ACP与土壤TN呈显著正相关;LAP、ACP与C:P呈显著负相关。Abstract: To clarify the soil ecological adaptability of Zanthoxylum bungeanum. 'Fengcai' in non-suitable areas, we investigated rhizosphere and non-rhizosphere (0~30 cm) soils of Zanthoxylum bungeanum. 'Fengcai' seedlings cultivated at an altitude of
1000 m, and systematically analyzed differences in soil nutrient content, extracellular enzyme activities, and microbial community structures.Soil nutrient content, extracellular enzyme activities, and the abundance and community composition of bacterial 16S rRNA and fungal 18S rRNA genes were determined using high-throughput sequencing and fluorescence methods. Correlation analyses were further performed to explore the relationships among soil microbial diversity, extracellular enzyme activities, and environmental factors(1) Rhizosphere soils had higher levels of organic carbon, total nitrogen, C:N, and N:P ratios, and lower total phosphorus and C:P ratios compared to non-rhizosphere soils, though differences were not statistically significant ; (2) Enzyme activities of BG, CBH, NAG, LAP, ACP, as well as EC:P and EN:P ratios, were higher in rhizosphere soils, yet not significant. VL ranged from 0.73 to 0.81, with non-rhizosphere soil values 4.43% lower than rhizosphere, indicating slightly higher carbon limitation in the rhizosphere. VA ranged from 54.28° to 58.98°, suggesting phosphorus limitation in both soil types, with slightly higher limitation in the rhizosphere; (3) Bacterial abundance greatly exceeded fungal abundance. Rhizosphere soils showed increased relative abundances of Actinobacteriota and Chloroflexota, and higher levels of Mucoromycota among fungi. Bacterial diversity was significantly higher in rhizosphere soils, whereas fungal diversity was higher in non-rhizosphere soils; (4) Correlation analysis revealed that bacterial Chao1 index and observed species were positively correlated with N:P (P<0.05), while fungal Chao1 and observed species were negatively correlated with N:P (P<0.05). NAG, LAP, and ACP were significantly positively correlated with soil (P<0.05); while LAP and ACP were significantly negatively correlated with C:P (P<0.05). This study revealed the rhizosphere microenvironmental regulation characteristics of Zanthoxylum bungeanum. 'Fengcai' in non-suitable areas and elucidated the interrelationships among soil nutrients, microbial communities, and extracellular enzyme activities. These findings not only provide a scientific basis for precision fertilization and cultivation management of Zanthoxylum bungeanum. 'Fengcai', but also offer theoretical support for understanding the soil ecological mechanisms and sustainable expansion strategies of economic tree species beyond their suitable habitats.
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