钾对外生菌根真菌的分泌作用及氮、磷、钾含量的影响

Effects of potassium on the secretion of proton and oxalate by ectomycorrhizal fungi and the concentrations of nitrogen,phosphorus and potassium in their hyphae

用无钾、低钾、中钾和高钾的液体培养基培养外生菌根真菌 1 4～ 2 1 d,随着钾离子浓度的降低 ,外生菌根真菌分泌H+和草酸的速率提高。由于 H+能取代 2∶ 1型粘粒矿物晶层和晶格内的钾 ,草酸能络合矿物中的 Fe、Al离子 ,促进 Al-O八面体风化 ,推测菌根真菌和菌根活化土壤无效钾的能力在低钾时较强 ,在高钾时较弱。在外生菌根真菌分泌的 H+中 ,草酸电离可能不是它们的主要来源 ,而是一些目前尚未知道的有机酸。此外 ,液体培养基中的钾离子不同程度地影响外生菌根真菌体内的氮、磷、钾含量 ,看来环境中的钾离子供应影响了真菌菌丝对养分的吸收。

Ectomycorrhizal fungi were grown in the liquid culture medium for 14 to 21 days.The efflux rates of H\++ and oxalate by the fungi were increased as the concentration of potassium decreased in the medium.Taking into account of potassium replacement in the interlayer of 2∶1 clay minerals by H\++ and the weathering of Al\|O lattices by oxalate,the higher ability of potassium mobilization by ectomycorrhizal fungi could occur in insufficient potassium systems than that in sufficient ones.Moreover,H\++ in the liquid culture medium at harvest was not mainly from oxalate but from some unknown matters such as organic acids.The concentrations of nitrogen,phosphorus and potassium in the fungi were influenced variedly by the potassium in the culture medium.It suggests that their absorption by the hyphae could be affected by the external supply of potassium.