Arbuscular mycorrhizal fungal growth on citrus roots and its correlations with soil available phosphorus content and phosphatase activity
通过观测田间国庆1号温州密柑/枳和国庆4号温州密柑/枳根系菌根侵染率、孢子密度、根际有效磷和磷酸酶活性的年变化,探讨丛枝菌根真菌生长与根际有效磷和磷酸酶活性的相关性.结果表明，2种柑橘菌根侵染率和孢子密度的年变化均呈 “Λ”形，2月和12月较低，4月和10月居中，6月和8月较高；有效磷和中性磷酸酶年变化呈“V”形.2种柑橘的菌根侵染率都与孢子密度呈极显著正相关，与有效磷呈极显著负相关，说明较高的孢子密度和较低的有效磷对菌根侵染率有促进作用；2种柑橘的孢子密度均与有效磷呈极显著负相关，与中性磷酸酶和总磷酸酶呈极显著正相关，表明中性磷酸酶和总磷酸酶对孢子密度有刺激作用，而有效磷对其有抑制作用.柑橘树下有机磷矿化主要以中性磷酸酶为主.
In 2004,a field investigation was made on the mycorrhizal infection rate,spore density,soil available phosphorus content,and soil phosphatase activity in the Guoqing No.1 (Citrus unshiu)/trifoliate orange (Poncirus trifoliata) and Guoqing No.4 (C.unshiu)/trifoliate orange (P.trifoliata) plantations,aimed to approach the correlations between the arbuscular mycorrhizal fungal growth on citrus roots and the available phosphorus content and phosphatase activity in rhizosphere soil.The results showed that the annual variation of mycorrhizal infection rate and spore density in the test plantations was in “Λ” shape,while that of soil available phosphorus content and neutral phosphatase activity was in “V” shape.The mycorrhizal infection rate was significantly positively correlated with spore density (P<0.01),and negatively correlated with soil available phosphorus content (P<0.01),indicating that higher spore density and lower soil available phosphorus content could accelerate the mycorrhizai infection on citrus roots.The pore density was significantly negatively correlated with soil available phosphorus content (P<0.01) while positively correlated with soil total and neutral phosphatase activity (P<0.01),suggesting that soil available phosphorus could inhibit the increase of spore density,while soil total and neutral phosphatase activity could stimulate it.The mineralization of soil organic phosphorus in citrus plantations was mainly depended on soil neutral phosphatase activity.
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