不同施磷水平下AM真菌发育及其对玉米氮磷吸收的影响

Development of arbuscular mycorrhizal(AM) fungi and their influences on the absorption of N and P of maize at different soil phosphorus application levels

【目的】不同丛枝菌根(abuscular mycorrhizal,AM)真菌菌种(株)因其分离地点及宿主的不同,其生理发育与生态功能差异显著,尤其是土壤养分状况对其影响更明显。研究不同土壤磷水平对AM真菌侵染宿主及生长发育繁殖的影响,以及不同AM真菌对玉米生长及氮磷吸收的影响,可以深化了解AM真菌与土壤磷的关系。【方法】采用盆栽试验,以玉米为宿主植物,土壤灭菌后分别添加0、50、200、500 mg/kg 4个水平的磷营养(P0、P50、P200、P500),并分别接种6种AM真菌,以不接种为对照。测定了AM真菌侵染率、丛枝丰度、孢子数、菌丝密度、玉米植株氮磷比(N/P)生态化学计量特征,讨论了不同土壤磷水平与AM真菌生长发育间的关系,以及AM真菌对玉米吸收利用氮、磷的影响。【结果】在P50条件下,AM真菌的侵染率、根内丛枝结构、根外生物量(孢子数、菌丝密度)显著高于不加磷P0和P200和P500处理,而且AM真菌侵染及生长发育指标在高磷水平时,显著下降。不同磷水平处理下,不同AM真菌对玉米的侵染能力及生物量存在明显差异。在P0和P50条件下,接种G.m处理侵染率达到75%,菌丝密度达240 m/g,显著高于其他五个AM真菌。AM真菌C.c、R.a、C.et的菌根侵染状况及生物量次之,D.s、D.eb最差。在高磷P200和P500条件下,仅有F.m真菌处理的侵染状况及生物量最高。在P0、P50水平下,接种F.m、R.a、D.eb显著降低了植株氮含量;在不加磷(P0)水平下,接种处理均显著促进了玉米植株中磷含量的提高,在P50水平下,F.m植株磷含量显著高于不接种对照;在P0、P50、P200水平下,接种AM真菌处理降低了玉米植株中N/P比,且不同菌种间存在差异,接种真菌F.m处理的N/P比明显最低。【结论】土壤添加低量磷(50 mg/kg)更适合AM真菌的侵染及生长发育,也利于菌根效应的发挥。侵染能力及效应以耐高磷菌种F.m最好,然后依次为C.c、R.a、C.et。在适量磷条件下,接种AM真菌能够调节植株体N/P比达到平衡,改善植物营养状况,促进玉米生长。

[ Objectives ] Exploring the infection and reproduction of AM fungi and the effects of different AM fungi on the growth, the absorption of N and P of maize at different phosphorus （P） levels will help toscreen efficient and resistant to high phosphorus AM fungi. [ Methods ] A pot experiment was conducted using maize as test materials. A completely randomized block design with a two factors of AM fungi strains x phosphoruslevels of treatments was established. There were six AM fungi strains and four phosphorus applied levels （0, 50, 200, 500 mg/kg） in total, using no-mycorrhizae addition as controls. The growth and nutrient uptake of maize, and the infection rate, spore number, mycelium density of AM fungi were investigated. [ Results ] At P50 level, the infection rate, the arbuscular structure in root, the spore number, mycelia density of AM fungi were significantly higher than that of the treatment without P and P200 and P500 levels of P, and infection ability and growth of AM fungi was significantly decreased at high P level. AM fungal Funneliformis mosseae had the higher infection rate reached 75% and the higher mycelium density being 240 m/g than that of the other five AM fungi. The mycorrhizal infection of AM fungi C.c, R.a and G.et was the second, followed by D.s and C.eb. At P200 and P500 levels of P, F. mosseae had only the highest infection and fungi biomass. Inoculation with F.m, R.a and D.eb significantly reduced the N concentration of maize at the P0 and P50 levels. At P0 level, the inoculation with AM fungi significantly promoted the P concentration of maize plants, that ofF. mosseae only at P50 level. At P0, P50 and P200 levels, the inoculation with AM fungi decreased the N/P ratio of maize. The N/P ratio of fungi inoculated with F. mosseae was significantly lower than that of other treatments. [ Conclusions ] Relatively low P concentration of 50 mg/kg in soilis more suitable for infection and growth of AM fungi. F.m, a strain resisted the higher P level in soil, shows the highest infection ability, following are C.c, R.a, C.et in turn. The inoculation of AM fungi is able to adjust the N and P balance in the plant roots, improve the plant nutrition status and promote the growth of maize.