The Effects of Glomus Etunicatus and Soil Phosphorus on Phytophthora Root Rot of Soybean
Whatley, Thomas Lamar
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/70581
Description
Title
The Effects of Glomus Etunicatus and Soil Phosphorus on Phytophthora Root Rot of Soybean
Author(s)
Whatley, Thomas Lamar
Issue Date
1982
Department of Study
Plant Pathology
Discipline
Plant Pathology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Plant Pathology
Abstract
Microplot and large plot studies indicated the cultivars 'Harosoy' and 'Williams' inoculated with Glomus etunicatus (GE) were susceptible to Phytophthora root rot caused by Phytophthora megasperma var. sojae (PMS); however, at soil phosphorus (P) levels equal to a Bray P1 of 19 or 75 kg/ha plant heights and yields were greater and significantly greater for final height and yield with a soil P1 of 75 kg/ha with application of both GE and PMS rather than PMS alone. Tolerance of PMS due to GE at Bray P1 levels of 75 kg/ha or less may be caused by improved P nutrition but no tolerance existed at higher P levels.
Root dry weight of soybeans grown in 150 cc tubes increased to an optimum level of P and decreased with additional P, exclusive of PMS. In a large plot experiment leaflet P increased with increasing soil P; however, without PMS dry matter and yield increased to the 444 kg/ha level of added P and decreased insignificantly at the 888 kg/ha P level. However, at 0, 444, 888 kg/ha added P Phytophthora root rot reduced dry matter 10, 54 and 51%, stand 19, 53 and 51%, yield 13, 39 and 39%, respectively. In plots with reduced plant populations due to high P and PMS the remaining stressed plants were unable to compensate for the yield of the missing plants.
In greenhouse susceptibility studies resistance to PMS race 1 contained in 'Harosoy 63' was not sufficient to prevent root dry weight losses due to PMS race 1 at high P levels. Reductions in root dry weight caused by PMS and high P were additive. When both root halves of a split root experiment were infested with PMS the low P side had a significantly greater root weight than the high P side. Under disease stress low P may permit greater root growth than high P. In the field losses associated with PMS may not be aleviated by resistant cultivars.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
