Nutrient uptakes and their contributions to yield in peanut genotypes with different levels of terminal drought resistance

Different peanut yields under terminal drought might be due to the different nutrient uptakes among peanut genotypes. Nutrient uptake was presumed to be a drought-resistant trait and might involve drought tolerance mechanisms. The aims of this study, therefore, were to characterize the effect of terminal drought on peanut nutrient uptake and to investigate the genotypic variability of nutrient uptake and its interactions with terminal drought. Field experiments were conducted at the Field Crop Research Station of Khon Kaen University, Khon Kaen, Thailand, from October 2010 to January 2011 and October 2011 to January 2012. Six peanut genotypes were tested under well-watered and terminal drought conditions. Data were recorded for N, P, K, Ca, and Mg uptake and biomass (BM) and pod yield (PY); the ratio of nutrient uptake under stress condition was calculated. Terminal drought significantly reduced nutrient uptake in both years, and peanut genotypes differed considerably with respect to nutrient uptakes under well-watered and terminal drought conditions. ICGV 98324 and ICGV 98348 were the best genotypes for nutrient uptake under terminal drought. Tainan 9 and Tifton 8 had low nutrient uptake under both conditions. ICGV 98308 and Tifton 8 had medium uptake and Tainan 9 had the lowest. Significant correlations between nutrient uptakes and BM and PY were mostly observed under well-watered and drought conditions. Based on nutrient uptake, ICGV 98324 and ICGV 98348 were identified as drought-tolerant lines. These genotypes could maintain high nutrient uptakes across water regimes; consequently, these traits can also be used as efficient tools for selecting peanut genotypes with terminal drought tolerance.