title: Response of onion plants to arbuscular mycorrhizae : 2. Effects of nitrogen fertilization on biomass and bulb firmness.
abstract: The effects of N fertilization on growth and root colonization of preinoculated onion (Allium cepa L. cv. Improved Autumn Spice) were studied. Onion transplants, inoculated with either Glomus intraradices, G. versiforme or nothing at sowing, were grown under three levels of N in soils which had either been irradiated, irradiated and amended with nonmycorrhizal 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 bulbs 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.
authors.affiliation: DREPA, 555 boulevard Roland-Therrien, Longueuil, Québec, J4H 3Y9 Canada , Canada.
authors.forename: G
authors.initials: G
authors.lastname: Charron
authors.affiliation: Agriculture and Agri-Food Canada, ECORC - K.W. Neatby 2057, Central Experimental Farm, Ottawa, Ontario, K1A 0C6 Canada, Canada.
authors.forename: V
authors.initials: V
authors.lastname: Furlan
authors.affiliation: Natural Resources Canada, 1055 rue du P.E.P.S., C.P. 3800, Sainte-Foy, Québec, G1V 4C7 Canada, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Bernier-Cardou
authors.affiliation: Food Research and Development Centre, 3600 boulevard Casavant Ouest, Saint-Hyacinthe, Québec, J2S 8E3 Canada, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Doyon