Response to Drought Stress in a Subset of the U.S. Peanut Mini-core Evaluated in Oklahoma, Texas, and Virginia

In many parts of the world, limited water and climate change are significant challenges to the future of peanut production, and much work remains in developing heat- and drought-tolerant cultivars. To this end, we evaluated 21 accessions of the U.S. peanut mini-core under water-limited conditions in 2018 and 2019 in Oklahoma, Texas, and Virginia. These accessions were identified as potentially exhibiting phenotypic extremes for ten drought stress traits, and therefore may be useful for identifying genetic markers associated with drought tolerance. Results indicated that plant wilting and paraheliotropism (leaf folding) were less affected by genotype by environment interactions than SCMR (SPAD chlorophyll meter readings), flower counts, yield, TSMK (total sound mature kernels), and seed weight. No differences among genotypes were observed with canopy temperature, canopy temperature depression, or NDVI (normalized difference vegetation index). Paraheliotropism was moderately correlated (|r| = 0.40 to 0.52, P < 0.01) with SCMR and flower counts in the Southwest; SCMR was also correlated with yield and TSMK (r = 0.48, P < 0.01). Despite environmental differences between subhumid Virginia and the semiarid Southwest, the locations shared genotypes at the extremes for most traits. This information may be useful for future studies by highlighting traits associated with drought tolerance that may be more stable in different production environments, as well as divergent genotypes for those traits.