铺地木蓝对肇庆地区柑橘园土壤养分及细菌群落的影响

【目的】探究铺地木蓝在柑橘果园种植 1 年后对杂草、0~20 cm 土层土壤养分含量和土壤细菌多样性的影响。【方法】设置自然生草（CK1）、土壤覆盖遮草布（PD1）、土壤覆盖银黑地膜 + 种植铺地木蓝（PD2）、种植铺地木蓝（PD3）4 个处理，1 年后调查杂草种类、测定土壤理化性质（pH、有机质、全氮、碱解氮、全磷、速效磷、全钾和速效钾）和土壤细菌群落情况。【结果】 PD2 处理土壤全氮（0.86 mg/g）、全磷（0.78 g/kg）、速效磷（23.84 mg/kg ）、全钾（11.91 g/kg）、有机质（34.82 g/kg）含量最高；PD2 处理土壤全氮和碱解氮含量比 PD1处理的分别增加了 0.37、27.43 mg/kg，PD1 处理土壤全磷含量最低（0.41 g/kg），PD3 处理速效磷（10.67 mg/kg）和有机质（25.99 g/kg）含量最低；PD1~PD3 处理的土壤全钾含量均大于 CK1 处理，速效钾含量则相反；杂草调查结果表明 PD1、PD2 处理均可很好地抑制杂草的生长。与 CK1 相比，PD1~PD3 处理均可降低土壤细菌群落多样性，但不影响细菌群落分布均匀性。PD2 和 PD3 处理的土壤细菌群落结构和丰度较相似，表现为变形菌门（Proteobacteria）相对丰度降低，绿弯菌门（Chloroflexi）、酸杆菌门（Acidobacteria）、浮霉菌门（Planctomycetes）、罗库菌门（Rokubacteria）、芽单胞菌门（Gemmatimonadetes）等有益细菌的相对丰度增加；其中 PD2 处理的优势菌属为 MND1（3.47%）、Sh765B-TzT-35（4.37%），PD3 处理的优势菌属为 MND1（4.29%）。从 PD1 处理土壤中检测到视为土壤环境恶化的标志类群异常球菌 - 栖热菌门（5.10%）。【结论】柑橘果园行间道覆盖地膜后再种植铺地木蓝的综合表现最好，可以增加土壤养分和土壤中有益细菌群落的相对丰度。

Effects of Indigofera spicata on Soil Nutrients and Bacterial Communities of Citrus Orchards in Zhaoqing Area

【Objective】The study aims to explore the effects of Indigofera spicata on weeds, soil nutrient content and soil diversity in 0~20 cm soil layer after planting in citrus orchards for one year.【Method】Four different treatments were set up: naturally growing grass (CK1), soil covered with grass repellent cloth (PD1), soil covered with silver-black plastic film + planting Indigofera spicata (PD2), and planting the Indigofera spicata (PD3). After one year of planting, weed species were investigated, soil physicochemical properties (pH, organic matter, total nitrogen, alkali-hydrolytic nitrogen, total phosphorus, available phosphorus, total potassium and available potassium) and soil bacterial community were determined.【Result】The contents of total nitrogen (0.86 mg/g), total phosphorus (0.78 g/kg), available phosphorus (23.84 mg/kg), total potassium (11.91 g/kg) and organic matter (34.82 g/kg) in soil treated with PD2 were the highest. Compared with PD1 treatment, the total nitrogen content and alkali-hydrolyzable nitrogen content of PD2 treatment increased by 0.37 mg/g and 27.43 mg/kg, respectively. The content of total phosphorus in soil treated with PD1 was the lowest (0.41 g/kg), and the contents of available phosphorus (10.67 mg/kg) and organic matter (25.99 g/kg) were the lowest in the PD3 treatment. The soil total potassium content of PD1-PD3 treatments was greater than that of CK1 treatment, while the available potassium content showed the opposite result. The weed survey results showed that both PD1 and PD2 treatments could well inhibit the growth of weeds. Compared with CK1, treatments PD1-PD3 could reduce the diversity of bacterial communities, but do not affected the uniformity of bacterial community distribution. The soil bacterial community structure and abundance of PD2 and PD3 treatments were similar, which showed that the relative abundance of Proteobacteria decreased; the relative abundance of beneficial bacteria such as Chloroflexi,Acidobacteria,Planctomycetes, Rokubacteria and Gemmatimonadetes increased; among them, the dominant bacterial genera treated with PD2 were MND1 (3.47%), Sh765B-TzT-35 (4.37%), and the dominant bacterial genus treated with PD3 was MND1 (4.29%). Deinococcus-Thermus (5.10%) regarded as a marker of soil environmental deterioration was detected in PD1-treated soil.【Conclusion】Citrus orchard pavement covered with plastic film and then planted with the Indigofera spicata shows the best comprehensive performance, which can increase soil nutrients and the relative abundance of beneficial bacteria communities.