Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: August 3, 1997
Publication Date: N/A
Technical Abstract: Enhancement of antioxidant metabolism has been suggested as a means for improving plant performance under conditions of water and temperature stress. Modifications of antioxidant metabolism intended to reduce stress damage have shown variable results. As transgenic plants are developed with enhanced antioxidant metabolism, it is important to know when and to what extent their activity should be increased in order to maximize their protective abilities. Changes in the total amount and the ratio of reduced/ oxidized glutathione have been reported in response to water and tempera- ture stress. The goal of this study was to determine the levels and temporal patterns of glutathione in cotton grown in the field under different irrigation regimes. Cotton (gossypium hirsutum) was grown in the field in Lubbock, Texas during the summer of 1996. Two levels of soil moisture were established 1) rainfed which received only natural rainfall (301 mm total) and 2) irrigated which was irrigated on a 3-day interval with 2 cm/event interval by surface drip irrigation (637 mm total). The fourth fully-expended leaf was harvested from plants of both treatments at a 2-week interval over the growing season. The amount of glutathione, oxidized, reduced, and total was determined in the sampled leaves. The total glutathione pool varied over the course of the growing season from a high of 200 ng/gfw to a low value of 70 ng/gfw. In general the levels of glutathione were lower in fully irrigated cotton than in rainfed though no variation in response to individual irrigation or rainfall events were evident. The ratio of oxidized to reduced glutathione was calculated and compared between treatments over the season.