The Effect of High Nutrient Addition Upon Seasonal Patterns of Mycorrhizal Development, Host Growth, and Root Phosphorus and Carbohydrate Content in Fraxinus Pennsylvanica Marsh

SUMMARY The 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 simitaly 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.