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Document Type

Thesis - University Access Only

Award Date

1989

Degree Name

Master of Science (MS)

Department / School

Agronomy

First Advisor

Fred A. Cholick

Abstract

Significant increases in spring wheat (Triticum aestivum L.) yields have occurred in the Northern Great Plains due to the effects of chloride on root and foliar diseases. However, yield increases due to chloride fertilizers have also occurred in the absence of disease. The response mechanism to chloride is not yet clearly understood. A field experiment was conducted to determine the effects of chloride on reproductive spike development and the effects of chloride on plant water relations in spring wheat. Marshall and Guard were planted in a split-split plot RCB design with six replications. A fungicide Tilt was applied to one half of the main plot. Sampling for evaluation of development was conducted only from fungicide treated plots. Two levels of KCl were used; o kg ha-1 and 135 kg ha-1. Spike differentiation was evaluated using a combination scale system by George and Kirby. Chloride significantly increased the stage of reproductive development. This response was varietal specific. Chloride increased reproductive development in Marshall more than in Guard. A chloride source study in a RCB design containing cacl2, KCl, KN03, arid a check was used to separate the effects of K+ from cl-. Chloride and not potassium was found to decrease the time to heading based on relative peduncle lengths. A study to determine the effect of time of application of chloride fertilizers from a similar RCB design, indicated that peduncle lengths at grain fill in chloride treated plots were significantly longer only when application of KCl was made prior to the double ridge stage. The plant water relationships of Marshall, Guard and Butte were evaluated from the same study. Relative water content (RWC), solute potential (SP), solute potential corrected for full turgor, and stomatal conductance (SC) were measured weekly from flag leaf emergence through grain fill. Across varieties Marshall had significantly higher RWC and frequently had solute potentials 2 bars lower than Guard and Butte. There were no significant interactions within varieties in response to KCl. Stomatal conductance was monitored over an 11-hour period. Marshall had significantly higher stomatal conductance values than Guard reaching peak differences approximately midday. There was also a significant chloride by variety interaction. Guard in treated plots had greater stomatal conductance values than control plots but there was no such effect for Marshall.

Library of Congress Subject Headings

Wheat -- Genetics

Wheat -- Development

Wheat -- Breeding

Format

application/pdf

Number of Pages

109

Publisher

South Dakota State University

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