2019 ASA Southern Regional Branch

February 03 - 05, 2019

Peanut (Arachis hypogaea L.) productivity decreases when plants experience drought stress periods, mainly at the reproductive stage. Development of peanut cultivars with improved ability to overcome drought periods without compromising yield is of great relevance. Identification of metabolic traits associated with drought tolerance in peanut plants could potentially contribute to developing peanut cultivars with enhanced drought tolerance. The objective of this study was to verify the contribution of metabolic traits on drought tolerance of peanut genotypes. Therefore, ten runner-type peanut genotypes were planted under field conditions at Gibbs Farms, University of Georgia, Tifton Campus in 2017. The genotypes included commercially-available cultivars and lines from USDA-ARS. Irrigation treatments consisted of a well-watered control and drought stress imposed at the reproductive stage [30-70 days after planting (DAP)]. Drought stressed plots were covered with a rainout shelter to prevent rain/irrigation on stressed plants. Leaf samples were collected and immediately frozen for further analysis of activity of the antioxidant enzymes superoxide dismutase, catalase, and ascorbate peroxidase, and hydrogen peroxide as indicative of ROS. Leaves were also sampled for comprehensive fluorescence analysis. Leaves were dark adapted for at least 12 hours and OJIP fluorescence transient was assessed using a portable fluorometer (OS5p+) with full OJIP capabilities. Chloroplast pigments of chlorophylls a and b and carotenoids were quantified in leaves. Principal component analysis and cluster analysis were performed using JMP Pro 13.