Showing papers by "Christopher Walker published in 1985"
TL;DR: V Vesicular-arbuscular mycorrhizas of apple from 18 sites in the USA were examined, and there was no evidence that any location lacked adequate inoculum potential for apple.
Abstract: Summary
Vesicular-arbuscular mycorrhizas of apple (Malus domestica Borkh.) from 18 sites in the USA were examined. Species of Endogonaceae were identified from soil, and their relative abundance determined from spore extractions. There were no evident patterns in geographic distribution of fungi. A range of three to eight species was found among sites, Glomus being more common in number of species and spores than Gigaspora, Acaulospora, or Sclerocystis. Pot cultures made with soil from some sites yielded species not recovered by sieving. Colonizing ability of all fungi isolated was assessed with apple and sorghum. Colonization potential of soils was determined by dilution techniques with apple as the host. Roots from all sites were endomycorrhizal, but not ectomycorrhizal. Proportion and intensity of colonization were negatively correlated with soil Zn and, at most sites, P levels. Colonization of rootstock clones varied among, but not within sites. Soil colonization potential was highly correlated with degree of root colonization in the field, and there was no evidence that any location lacked adequate inoculum potential for apple.
56 citations
TL;DR: Six species of vesicular-arbuscular mycorrhizal fungi originally isolated from orchard soils were evaluated at low phosphorus and high phosphorus levels for root colonization and effects on growth of apple seedlings.
Abstract: Summary
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.
44 citations
TL;DR: Examination of soil samples from sand dunes of the eastern seaboard of the U.S.A. revealed three previously undescribed species of Gigaspora producing spores with roughened outer walls.
Abstract: Examination of soil samples from sand dunes of the eastern seaboard of the U.S.A. revealed three previously undescribed species of Gigaspora producing spores with roughened outer walls. Spores of G...
40 citations
TL;DR: A mycorrhizal association between Pinus contorta (lodgepole pine) and Endogone lactiflua is described.
Abstract: A mycorrhizal association between Pinus contorta (lodgepole pine) and Endogone lactiflua is described.
23 citations