Effects of inoculated mycorrhizal fungi and non-mycorrhizal beneficial micro-organisms on plant traits, nutrient uptake and root-associated fungal community composition of the Cymbidium hybridum in greenhouse.

Abstract

The aim of this study was to assess the effects of beneficial micro-organisms on the growth, nutrient accumulation and root-associated fungal species composition of pot orchids grown in the greenhouse. A greenhouse pot experiment was conducted to investigate the beneficial effects of a mycorrhizal fungus, Epulorhiza repens isolate ML01, an endophytic fungus, Umbelopsis nana isolate ZH3A-3 and a mixed commercial inoculum Rem, alone or in combination. Nested PCR assays showed that both isolates ML01 and ZH3A-3 can successfully establish in inoculated soil. All the inoculants significantly increased the plant total dry weight of Cymbidium hybridum 'Golden Boy', whereas only co-inoculation with the endophytic fungus ZH3A-3 and the Rem enhanced the fresh weight and height of host plants. The mycorrhizal fungus positively affected P, K, Ca, Mg content in shoots and Zn content in roots, while the endophytic fungus improved N, P, Ca accumulation in shoots and roots. Co-inoculation with the Rem and ML01 improved root to shoot translocation of Fe and Zn. In addition, inoculation with ZH3A-3, ML01+Rem and ZH3A-3+Rem decreased the relative frequency of Fusarium sp. on orchid roots. Trichoderma sp. were isolated from the roots treated with ML01, ML01+Rem and ZH3A-3+Rem. Both mycorrhizal and endophytic fungi had the potential to create favourable microflora in the orchid roots and stimulate the growth of transplanted plantlets under greenhouse condition. The newly isolated endophytic strain ZH3A-3 showed significant application value in orchid production.