Glomus-wetland rice mycorrhizas influenced by nursery inoculation techniques under high fertility soil conditions

We investigated the effect of nursery inoculation techniques on mycorrhizal colonization and sporulation, growth responses, and nutrient (N and P) uptake to determine the suitable nursery inoculation method of wetland rice (Oryza sativa L.) under high-fertility soil conditions. Seedlings were produced in dry-nursery (DN, watered to 60% of -0.03 MPa) and wet-nursery (WN, 3-5 cm water from the soil surface) conditions with or without arbuscular mycorrihizal fungal (Glomus spp.) inoculation. Soil was gamma-ray sterilized before use in this experiment. Mycorrizal fungal colonization was 56% in DN and 23% in WN plants at 6 weeks of growth. The arbuscular mycorrhizal fungal colonization was significantly higher in plants of DN origin than in WN plants after transplantation to the pots, irrespective of growing stages. Mycorrhizal colonization was significantly decreased to 28% in DN plants and to 25% in WN plants at harvest. The grain yield was significantly influenced by nursery conditions. N and P acqusition of wetland rice plants inoculated with Glomus spp. was significantly greater than that of non- inoculated plants at maturity, especially in those originating from DN conditions. P translocation from shoots to grain was accelerated by mycorrhizas.