|LUIS, J - University Of Georgia|
|OZIAS-AKINS, P - University Of Georgia|
|Holbrook, Carl - Corley|
|KEMERAIT JR, R - University Of Georgia|
|SNIDER, J - University Of Georgia|
|LIAKOS, V - University Of Georgia|
Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2015
Publication Date: 1/15/2016
Citation: Luis, J.M., Ozias-Akins, P., Holbrook Jr, C.C., Kemerait Jr, R.C., Snider, J.L., Liakos, V. 2016. Phenotyping peanut genotypes for drought tolerance. Peanut Science. 43:36-48.
Interpretive Summary: Aspergillus fungi can colonize seed of several agricultural crops including peanut, and this can result in the contamination of the edible yield from these crops with the toxic chemical, aflatoxin. Breeding efforts are ongoing to attempt to develop peanut varieties which resist aflatoxin contamination, however, aflatoxin contamination is difficult and expensive to measure. Drought resistance traits are promising as indirect selection tools for improving resistance to preharvest aflatoxin contamination (PAC). The objectives of this study were to determine the effect of terminal drought on PAC and to investigate the associations between surrogate traits for drought tolerance and PAC. Traits related to drought resistance were associated well with those related to PAC under drought conditions. These easily measurable, rapid and cost-effective screening methods may be used as alternatives to more tedious and costly methods of identifying genotypes that are less susceptible to aflatoxin contamination. Breeding for drought tolerance using these traits as selection criteria may help to accelerate progress in developing resistance to PAC.
Technical Abstract: Drought and heat stress can result in aflatoxin contamination of peanuts especially when this occurs during the last three to six weeks of the growing season. Identifying drought-tolerant genotypes may aid in development of peanuts that are less susceptible to aflatoxin contamination. This study was conducted to phenotype seven peanut genotypes (Tifguard, Tifrunner, Florida-07, PI 158839, NC 3033, C76-16, and A72) based on their response to drought stress. The phenotyping methods included visual ratings, chlorophyll fluorescence (CF), 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 showed better drought-coping 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 CF (0.62) and SCMR (0.57). These easily measurable, rapid and cost-effective phenotyping methods may be used as alternatives to more tedious and costly methods of identifying genotypes that are less susceptible to aflatoxin contamination. Each method evaluates a particular drought-coping mechanism of the plant, thus, using a combination of methods would be more powerful than using a method alone.