Document Type

Thesis - Open Access

Award Date

1981

Degree Name

Master of Science (MS)

Department

Plant Science

First Advisor

W.E. Arnold

Abstract

Each year over 1,250,000 acres in South Dakota are fallowed. Weeds are controlled mechanically or chemically to conserve moisture for the succeeding crop. Chemical fallow utilizes triazine herbicides to control weeds during the fallow season. Advantages of chemical fallow include increased moisture conservation, decreased erosion problems, and lower energy costs when compared to mechanical methods. Atrazine is a residual herbicide registered for use in chemical fallow. Atrazine carryover is unpredictable in arid regions and may result in injury to the succeeding crop. Development of atrazine resistance in wheat would reduce the carryover threat, and allow higher rates of atrazine for better weed control. The purpose of this study was to evaluate genotypes of wheat for resistance to atrazine. Reaction to atrazine was evaluated on 69 spring wheat cultivars and lines in 1978 at Brookings and Redfield, South Dakota. Atrazine dosage was selected based on Anderson's screening study. The herbicide was incorporated by double discing immediately following spray application. The wheat genotypes were hand-planted at a 2.5 cm depth in 3.0 m rows with a 0.3 m row spacing. Three replications were planted. The Brookings test was sprayed June 6 and planted June 7 on a Vienna Loam soil. Plant counts were made June 21, and at harvest. Rainfall totals for the first and second weeks after herbicide treatment were 0.28 and 0.66 cm. The Redfield test was sprayed and planted June 15 on a Great Bend Loam soil. Plant counts were made June 29 and at harvest. Rainfall totals for the first and second weeks after herbicide treatment were 0.28 cm and 0.66 cm. Spikes of surviving wheat plants from both locations were harvested at maturity. Seed was increased during the following winter in the greenhouse. The surviving wheat lines were evaluated in 1979 at Brookings and Redfield using the same procedure as previously described. The Brookings test was sprayed and planted May 24. Rainfall totals for the first and second weeks after herbicide treatment were 3.35 cm and 0.00 ern. Plant counts were made June 7 and at harvest. The Redfield test was sprayed and planted June 1. Rainfall totals for the first and second weeks after herbicide treatment were 0.05 cm and 0.74 cm. Plant counts were made June 7 and at harvest. The main objective of this study was to survey genotypes for resistance to atrazine and develop resistant genotypes by use of induced mutations.

Library of Congress Subject Headings

Herbicide resitance

Format

application/pdf

Number of Pages

42

Publisher

South Dakota State University

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