碳酸钙和根际作用对酸性红壤解磷微生物丰度的影响

选用玉米品种郑单958为试验材料,设置不添加碳酸钙(CK)、每千克土添加0.3g碳酸钙(Ca-0.3)和0.5g碳酸钙(Ca-0.5)3个碳酸钙处理,以相应处理未种植物土壤为非根际对照土壤,研究了碳酸钙和根际作用对酸性红壤磷酸酶活性及解磷微生物相关功能基因phoC和phoD丰度的影响。结果表明:碳酸钙添加能有效改善玉米生长,促进地上部氮、磷、钾和钙的吸收。土壤酸性磷酸酶(ACP)活性显著高于碱性磷酸酶(ALP)活性,表明酸性土壤中ACP在矿化有机磷方面占主导地位。根际土壤ACP、ALP活性和phoD基因拷贝数均显著高于非根际,而仅Ca-0.5处理ALP活性和phoD基因拷贝数显著高于CK,说明根际效应强于碳酸钙处理。phoC基因拷贝数与土壤铵态氮、硝态氮含量存在显著相关性,ALP活性和phoD基因拷贝数与土壤pH及铵态氮、硝态氮、有效磷、交换性钙含量均存在显著相关性。可见,碳酸钙和根际作用均影响酸性土壤解磷微生物功能和丰度,但根际效应更加明显,这些作用与土壤理化因子的改变密切相关。

Effects of Calcium Carbonate and Rhizosphere on Abundance of Phosphate-Solubilizing Microorganisms in Acidic Red Soil

Phosphorus (P) deficiency is one of the main characteristics of acidic soils. Increasing P availability is the primary way to improve crop productivity in acidic soil. In view of the important role of phosphate-solubilizing microorganisms (PSM) in soil P conversion and availability, maize variety, Zhengdan 958 was used as experiment material, soils were treated with calcium carbonate (CaCO3) at rates of 0, 0.3, 0.5g per kg soil. The present study investigated the effects of CaCO3 and rhizosphere on phosphatase activity and the abundance of PSM associated functional genes phoC and phoD in acidic red soil. Results showed that CaCO3 addition could effectively improve the growth of maize and promote the absorption of nitrogen, phosphorus, potassium and calcium in shoots. Soil acid phosphatase (ACP) activity was significantly higher than alkaline phosphatase (ALP) activity, indicating that the dominated effect of ACP in mineralizing organic P in acidic soils. The ACP, ALP activity and phoD gene copy number in rhizosphere soil were significantly higher than that of non-rhizosphere, while ALP activity and phoD gene copy number under Ca-0.5 treatment were significantly higher than CK, indicating that rhizosphere effect was stronger than CaCO3 treatment. phoC gene copy number were closely related to ammonium nitrogen and nitrate nitrogen, while both ALP activity and phoD gene copy number were closely related to soil pH, ammonium nitrogen, nitrate nitrogen, available phosphorus and exchangeable calcium. It can be seen that both CaCO3 and rhizosphere affected the function and abundance of PSM in acid soil, but the rhizosphere effect of crops was more obvious, which was closed related to the changes of soil physicochemical properties.