Phenotyping Peanut Genotypes for Drought Tolerance

Abstract

Drought and heat stress can result in aflatoxin contamination of peanuts especially when this occurs during the last three to six wk of the growing season. Identifying drought-tolerant genotypes may aid in development of peanuts that are less susceptible to aflatoxin contamination. Research was conducted to phenotype seven peanut genotypes based on their response to drought stress. Six peanut genotypes that have exhibited lower aflatoxin and/or drought tolerance in previous researches (Tifguard, Tifrunner, Florida-07, PI 158839, NC 3033, C76-16) were compared to an aflatoxin-susceptible genotype, A72. The phenotyping methods included visual ratings, chlorophyll fluorescence (PI ABS , Q EO , and F v /F m ), SPAD chlorophyll meter reading (SCMR), normalized difference vegetation index (NDVI), canopy temperature (CT), canopy temperature depression (CTD), and pod yield. Based on these traits, Tifguard and Tifrunner exhibited greater drought tolerance mechanisms than the other genotypes and may be good candidates to be incorporated in future drought tolerance studies. After the aflatoxin content of the different genotypes was measured, aflatoxin contamination showed high correlations with visual ratings (0.85), CTD (0.81), NDVI (0.79), and CT (0.73), and moderate correlations with F v /F m (0.62) and SCMR (0.57) (P $ 0.05). These easily measurable, rapid and cost-effective phenotyping methods may be used as alternative to more tedious and costly methods of identifying genotypes that are less susceptible to aflatoxin contamination. Using a combination of these methods is beneficial but not always practical. The combined use of visual ratings, CTD and NDVI is advised for initial evaluation of drought tolerance in peanut genotypes.

Genome-Wide Detection of SNP Markers Associated with Four Physiological Traits in Groundnut (Arachis hypogaea L.) Mini Core Collection

“…Nageswara Rao et al [7] also reported similar specific leaf area between peanut genotypes. These physiological traits (LAI, CT, SCMR, and NDVI) are important in improving productivity and are used as indirect indices for improving drought tolerance in peanut [8]. Traits such as SCMR and NDVI determine the photosynthetic potential of plants and have been reported to be highly associated with yield and can be effective as in-season predictors of yield [33,34].…”

“…Chlorophyll content and fluorescence parameters determine the integrity of the internal apparatus for photosynthesis and provide a precise platform for detection and quantification of plant tolerance to drought stress [6] and were speculated as a useful indicator for photosynthetic capacity in groundnut [7]. Canopy temperature (CT) was reported to be a marker for drought tolerance through its negative correlation with transpiration cooling and carbon dioxide exchange rate [8]. Genotypes that maintain cooler canopies under stress conditions possess a high potential for water stress tolerance and high yield [8].…”

“…Canopy temperature (CT) was reported to be a marker for drought tolerance through its negative correlation with transpiration cooling and carbon dioxide exchange rate [8]. Genotypes that maintain cooler canopies under stress conditions possess a high potential for water stress tolerance and high yield [8]. Healthy vegetation measured by normalized difference vegetative index (NDVI) under drought conditions correlates to high photosynthetic potential and yield of groundnut [8].…”

“…Genotypes that maintain cooler canopies under stress conditions possess a high potential for water stress tolerance and high yield [8]. Healthy vegetation measured by normalized difference vegetative index (NDVI) under drought conditions correlates to high photosynthetic potential and yield of groundnut [8]. Drought reduces leaf area by constraining mitosis, cell proliferation, leaf expansion and carbohydrate supply [9] and genotypes with wider leaf areas under water stress have the capacity for high photosynthesis.…”

“…Drought reduces leaf area by constraining mitosis, cell proliferation, leaf expansion and carbohydrate supply [9] and genotypes with wider leaf areas under water stress have the capacity for high photosynthesis. These drought surrogate traits are adaptation mechanisms used by groundnut (and other crops) to survive drought conditions [8].…”