Date of Graduation

5-2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Crop, Soil & Environmental Sciences (PhD)

Degree Level

Graduate

Department

Crop, Soil & Environmental Sciences

Advisor

Derrick M. Oosterhuis

Committee Member

Fred M. Bourland

Second Committee Member

Curt R. Rom

Third Committee Member

Richard J. Norman

Fourth Committee Member

Bobbie L. McMichael

Abstract

High temperature stress is among the most difficult to control abiotic factors affecting crop yields in the Southern United States due to its wide regional influence. Cotton (Gossypium hirsutum L.) though a tropical plant in origin, it is sensitive to the effects of high temperature. This is of particular concern when the warmest temperatures coincide with the most sensitive developmental stage of flowering. Thus, the capacity to improve cotton’s ability to tolerate heat stress has been a significant focus for many decades. Therefore, this research was composed of several different components all designed to investigate heat stress effects. Using a combination of environmental growth chamber, field, and exploratory data modeling studies it appears that high temperatures affect cotton fruit production ubiquitously. This conclusion, based upon the results of several novel experiments of identifying heat stress effects were summarized under the following objectives:

1) Identify historic regional effects of high temperature for both irrigated and non-irrigated fields in the Mississippi Delta

2) Determine the impact heat has on the carbohydrate status of the flower and subtending leaf the days surrounding anthesis

3) Characterize acclimation potential to repeated periods of heat stress that emphasizes that the timing of analytical collections is an important under-reported factor in plant development

4) Investigate well-irrigated cotton and its response to heat stress to ascertain if irrigation could provide protection from increased temperatures

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