Effect of N fertilizer on formation of Vam Fungi, growth and mineral concentration of Onion

Abstract

The effects on N fertilization on growth and root colonization of preinoculated onion (Allium cepa) were studied. Onion transplants, inoculated with either Glomus intraradices, Glomus versiforme or nothing at sowing, were grown under three levels of N in soils which had either been irradiated, Irradiated and amended with non-mycorrhizal microflora, or not irradiated. Interactions between inoculation and soil treatment had a significant effect on dry biomass and final bulb diameter. Control plants cultivated in non-irradiated natural soil grew normally because of the presence of indigenous arbuscular mycorrhizae, but control plants in irradiated soils were stunted. There was no such difference among inoculated plants. In non-irradiated natural soil, bulbs of onions inoculated with G. intraradices or G. versiforme were significantly firmer than bulb of control plants. Bulb firmness decreased as N fertilization level increased. In non-irradiated natural soil, tissue P concentration of onion plants preinoculated with either fungus was significantly higher than that of control plants. In all soil types,- N, P, and Zn concentrations were higher in onion plants colonized by G. versiforme than in those colonized by G. intraradices. The opposite was true of Mn tissue concentration