Symbiont effectof rhizobiumbacteria and vesicular arbuscular mycorrhizal fungi onPisum sativumin recultivated mine spoils

Abstract

The frequency (F%) of spontaneous endomycorrhizal fungal infection (AMF) and the root nodulation of Pisum sativum L. was studied after 8 and 15 years of recultivation in 4 soils (andesitic tuff, yellow sand, yellow clay, and grey clay) disturbed by mining activities. The effects of Rhizobium inoculation and the interaction of both microsymbionts with plant production were also examined, along with humus content and the humus stability coefficient, in the following variations: control, NPK fertilizer, NPK + lignite, NPK + straw, and sewage sludge. Dump spoils originating from deep geological layers were poor in organic materials. After 12 years of recultivation, the humus content increased significantly. No such increase was noted in grey clay and the natural, brown forest soil used as an undisturbed (control) sample. The degradation of soils by mining brings about a decrease in the rhizobial and mycorrhizal population, so the number of spontaneous Rhizobium nodules is relatively low and does not influence the yield of peas. Inoculation with a selected, effective strain of Rhizobium leguminosarum bv. viceae, however, enhanced dry matter production in these microbiologically degraded soils. Although the frequency of AMF infection was also higher after rhizobial inoculation, no positive correlation was found between dry matter production of peas and the F% of AMF. Spoils treated with lignite, straw, and sewage sludge had an especially high level of spontaneous mycorrhizal populations, indicating that organic materials had a favorable effect on the recultivation processes and fertility of mine spoils.