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Terminal drought greatly enhanced Aspergillus flavus Link infection (AI) and aflatoxin contamination (AC) in peanut. Identification of new surrogate traits which have an association with AC may be effective to improve peanut varieties with reduced AI and AC. The objective of this work was to examine the relationships of nutrient uptake and N2-fixation (NF) with AC in peanut in a terminal drought condition. Five peanut varieties were tested in well-watered (WW) and terminal drought (TD) conditions (1/3 available water (AW) from R7 (7th reproductive growth stage; beginning of pod maturity stage)). Data were collected for nutrient uptake (nitrogen, phosphorus, potassium, calcium, magnesium), nodule dry weight (NDW), and NF. AI and AC were also examined. Nutrient uptake, NDW, and NF had negative and significant correlations with AI and AC in the TD condition. Negative and significant correlations of the drought tolerance index of nutrient uptake, NDW, and NF with AI and AC were also observed in the TD condition. The results showed that the ability to maintain nutrient uptake and NF in TD might be a mechanism of tolerance to AI and AC. Moreover, due to their negative impacts on AI and AC, nutrient uptake and NF could be used as selection traits for resistance to AI and AC in peanut in TD.

Information on physiological traits that can be potentially use as surrogate traits for drought tolerance is very important to minimized yield reduction under drought. This study investigated the correlations between root traits and nutrient uptake and N2 fixation (NF) in peanut under terminal drought condition. Five peanut genotypes-ICGV 98308, ICGV 98324, ICGV 98348, Tainan 9 and Tifton 8-were tested under well-watered and terminal drought conditions at beginning maturity (R7) growth stage until final harvest. A split-plot experiment in randomized complete block design with four replicates was used. The data were recorded for nutrient uptake, NF, nodule dry weight (NDW) and root traits. Root surface area was significantly correlated with uptake of N, P, K and Mg but it did not correlate with uptake of Ca under terminal drought. Strong correlations between root volume, root length density (RLD), % RLD and uptake of N, P, K and Mg were observed under terminal drought. However, root dry weight (RDW) did not correlate with nutrient uptake under both environments but correlated with uptake of Ca significantly under terminal drought. Despite the deep RLD of peanut genotypes under terminal drought, the plants could not take up and contribute sufficient Ca. Only large root systems at 0-50 cm (about fruiting zone) might be able to accumulate Ca. A deeper root system could help maintain nodule growth and NF even under severe terminal drought condition. Deep root systems favor nutrient uptake under terminal drought because of strong correlations between these traits. Moreover, drought avoidance by enhancing root surface area, root volume, RLD and % RLD are the main mechanisms that help peanut to maintain nodule growth and NF under terminal drought condition. [ABSTRACT FROM AUTHOR]

Terminal drought greatly enhanced Aspergillus flavus Link infection (AI) and aflatoxin contamination (AC) in peanut. Identification of new surrogate traits which have an association with AC may be effective to improve peanut varieties with reduced AI and AC. The objective of this work was to examine the relationships of nutrient uptake and N2-fixation (NF) with AC in peanut in a terminal drought condition. Five peanut varieties were tested in well-watered (WW) and terminal drought (TD) conditions (1/3 available water (AW) from R7 (7th reproductive growth stage; beginning of pod maturity stage)). Data were collected for nutrient uptake (nitrogen, phosphorus, potassium, calcium, magnesium), nodule dry weight (NDW), and NF. AI and AC were also examined. Nutrient uptake, NDW, and NF had negative and significant correlations with AI and AC in the TD condition. Negative and significant correlations of the drought tolerance index of nutrient uptake, NDW, and NF with AI and AC were also observed in the TD condition. The results showed that the ability to maintain nutrient uptake and NF in TD might be a mechanism of tolerance to AI and AC. Moreover, due to their negative impacts on AI and AC, nutrient uptake and NF could be used as selection traits for resistance to AI and AC in peanut in TD. [ABSTRACT FROM AUTHOR]