COLONIZATION AND EFFICACY OF DIFFERENT ENDOMYCORRHIZAL FUNGI WITH APPLE SEEDLINGS AT TWO PHOSPHORUS LEVELS

Abstract

Six species of vesicular‐arbuscular mycorrhizal fungi originally isolated from orchard soils were evaluated at low phosphorus (approx. 30 mg kg−1) and high phosphorus (approx. 180 mg kg−1) levels for root colonization and effects on growth of apple (Malus domestica Borkh.) seedlings. Fungi tested were Gigaspora calospora (Nicol. & Gerd.) Gerd. & Trappe, Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, Glomus maculosum sp. ined., Glomus manihotis Howeler, Sieverding & Schenck, Glomus bitunicatum sp. ined., and two isolates of Glomus occultum Walker. Trees grew larger and had higher leaf P concentrations at high soil P than at low soil P regardless of mycorrhizas. At low P, fungal species differed in percentage root length colonized, intensity of colonization, types of mycorrhizal structures formed, and number of spores produced. Fungal species also differed in effects on plant growth. At harvest, five treatments were taller than the non‐mycorrhizal control trees, and two were not. Stem diameter and total dry weight were increased by only three treatments. At high P, no treatment resulted in greater than 5 % of root length colonized, and endogonaceous fungi had little influence on plant growth. Copyright © 1985, Wiley Blackwell. All rights reserved