不同磷浓度对丛枝菌根真菌吸收同化外源氮能力的影响

摘要

Arbuscular mycorrohizal ( AM) fungus ( Glomous intraradices) was innoculated to kaoliang ( Sorghum bi-color) as a host plant and grown in a tri-chamber-isolated culture container to study the influence of arbuscular mycor-rohizal on the ability to assimilate exogenous nitrogen ( EN) by adding different phosphorus concentration ( PC) and nitrogen of NH4 NO3 , glutamine ( Gln) onto the hyphal chambers. The result showed that AM fungus infected the root system of sorghum, but the mycorrhizal infection rate differences was not significant;and the number of spores in the one with high PC (P120) was significantly higher than in those with low PC;the content of the exo-rhizo-hyphal dry weight inside the chamber in low PC was the highest, and the one with Gln as EN was higher than those without adding nitrogen source and NH4NO3;low PC (P30) significantly promoted the increment of dry weight of leaves and stems on the ground and underground mycorrhizal of sorghum. However, chlorophyll content had no significant differ-ences on different treatments. Total nitrogen content of stems and leaves was the highest when NH4 NO3 was used as EN, total nitrogen content under different PC was in the order of P30>P120>P0>P60, the content of arginine in mycorrhizal was higher when using Gln as EN than those using other EN sources. Moreover, it was the highest under low PC. The study indicated that the ability of AM fungus to assimilate EN was related to PC difference, under low PC it was more advantageous to AM fungus on EN assimilation, and the ability to assimilate NH4+ form nitrogen source was the strongest.%以高粱( Sorghum bicolor)为宿主植物,丛枝菌根( arbuscular mycrohiza,AM)真菌根内球囊霉( Glomous intraradices)为接种菌剂,三室隔离培养盒为培养容器,通过在菌丝室添加不同浓度梯度磷素及外源氮NH4 NO3、Gln,研究磷浓度对AM真菌同化吸收不同外源氮能力的影响。实验结果显示：AM真菌能够侵染于高粱植物根系,但菌根侵染率差异不显著；在高磷浓度下孢子数量显著高于低磷浓度下孢子数量；菌丝室内根外菌丝( ERM)干重在低磷浓度下含量最高,且以Gln为外源氮时含量比不加氮源和NH4 NO3为氮源时高；低磷浓度促使高粱地上茎叶和地下菌根干重显著提高,叶绿素含量在不同处理下没有显著差异。茎叶总氮含量均在以NH4 NO3为外源氮时最高,不同磷浓度下其总氮含量为P30>P120>P0>P60,菌根精氨酸含量在Gln为外源氮时含量比其他氮源下高,且在低磷(P30)浓度下含量最高。研究表明AM真菌对于吸收同化外源氮的能力与其生长环境中磷浓度高低有关,在低磷浓度下更利于AM真菌根外菌丝同化吸收外源氮,且对NH4+形式氮源吸收能力最强。