THE EFFECT OF HIGH NUTRIENT ADDITION UPON SEASONAL PATTERNS OF MYCORRHIZAL DEVELOPMENT, HOST GROWTH, AND ROOT PHOSPHORUS AND CARBOHYDRATE CONTENT IN FRAXINUS PENNSYLVANICA MARSH

Abstract

SUMMARYThe effects of Glomus macrocarpum and a high rate of nutrient addition upon growth, root carbohydrate and P content, and mycorrhizal development in green ash {Fraxinus pennsylvanica) seedlings were studied over two growing seasons. Mycorrhizal and simila -ly growing non-mycorrhizal seedlings had similar seasonal patterns in growth and in root carbohydrate and P content. No clear difference in mycorrhizal development as as result of nutrient treatment occurred until the middle of the second growing season when the percent root infection of seedlings that received low nutrient increased and that of seedlings that received high nutrient decreased. A seasonal cycle with two phases in the interaction of the VA mycorrhiza and host growth, root .shoot ratios, root infection, root content of soluble sugars, starch and P, arbuscule and vesicle numbers, and spore population is proposed.

Mycorrhization of micropropagated mature wild cherry (Prunus avium L.) and common ash (Fraxinus excelsior L.)

“…In the current experiments, however, we achieved beneficial mycorrhizal effects using a substratum with a high level (60%) of inert or low density materials which are not normally conducive to mycorrhiza formation (Ravolanirina 1990, Wood 1991). Our results using relatively high P fertilisation, equivalent to at least 360 kg P ha -1 , are similar to those of Douds and Chaney (1986) and Le Tacon and Bouchard (1988), who also showed mycorrhizal effects with Fraxinus spp. in the presence of high soil P.…”

“…(Clark 1969, Douds and Chaney 1986, Ponder 1984. The latter studies used substrata containing at least one-third soil and no peat.…”

“…Such fungi have beneficial effects on plant development, especially through improved phosphorus (P) nutrition, increased resistance to pathogens and better root development . The absence of symbiosis may account for the poor development of ash plants, even in heavily fertilised soils (Douds andChaney 1986, Le Tacon andBouchard 1988).…”

Influence of growth stage on the association between some tropical legumes and two variant species ofGlomusin an andosol

“…This is because the rate of growth, plant demand for nutrients as well as mineral nutrient allocation, and other benefits attributed to VAM fungi can vary considerably depending on the stage of growth of the plant (Douds and Chaney 1986;Dunne and Fitter 1989). For example, Fitter (1986) and Dunne and Fitter (1989) observed that phosphorus concentrations of plants among various inoculation treatments may vary only during part of the growth cycle.…”

The role of arbuscular mycorrhizal fungi in prairie wetlands

“…Often, an inverse relationship exists between the level of AMF colonization and the amount of available phosphate in the soil (Douds and Chaney, 1986;. AMF have decreased the biomass of some plant species in high nutrient soils compared to plants without AMF, suggesting that AMF can act as pathogenic parasites Koide, 1985).…”