Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/26/2006
Publication Date: 5/31/2007
Citation: Sullivan, D.G., Holbrook Jr, C.C. 2007. Using ground-based reflectance measurements as selection criterion for drought and aflatoxin resistant peanut genotypes. Crop Science. 47:423-432. Interpretive Summary: Preharvest aflatoxin contamination impacts edible peanut yield, reduces profitability, and remains a serious challenge to the United States peanut industry. Because the fungus that causes aflatoxin contamination is ubiquitous in soils, development of high yielding-aflatoxin resistant peanut cultivars is a promising alternative to controlling preharvest contamination. Yet, laboratory screening for aflatoxin yields highly variable results, can be cost-prohibitive and is oftentimes poorly correlated with field measurements. In order to maximize breeding potential, field characterization for aflatoxin resistance necessitates a quantitative index sufficient to differentiate among moderately resistant genotypes with potentially higher expected yields. Ground based remote sensing in the visible and near-infrared regions of the light spectrum was evaluated as a new tool to facilitate the identification of drought and aflatoxin resistant peanut varieties. Results showed the remotely sensed indices provide more accurate and quantitative results compared to the standard visual rating technique. These data will provide the foundation for a remote sensing methodology that can be used to accelerate breeding progress in developing peanut cultivars with resistance to drought and aflatoxin contamination.
Technical Abstract: Drought stress and aflatoxin contamination continue to challenge peanut (Arachis hypogaea L.) producers across the U.S. Thus, the continued development of drought and aflatoxin resistant peanut cultivars is essential to maintain productivity under less than ideal growing conditions. Remote sensing of canopy reflectance is a well-established method of evaluating crop condition, and shows promise as a tool for rapid selection of drought and aflatoxin resistant peanut genotypes. The objective of this study was to evaluate ground based reflectance measurements to more accurately quantify differences in genotype response to drought conditions. In April 2004 and 2005 several small plots (4 m x 2 m) were established at the Gibbs Farm research facilities in Tifton, GA. Treatments consisted of five peanut genotypes encompassing a range of drought tolerance and yield characteristics. Drought conditions were simulated beginning 90 days after planting and maintained through harvest. Once drought conditions were established, a handheld radiometer was used to acquire twice weekly reflectance measurements in the visible and near infrared. Benchmark indices were developed based on the change in remotely sensed vegetation indices to measure the change in crop response between non-stressed and drought stressed conditions. Significant treatment differences in benchmark indices were observed between drought tolerant, moderately drought tolerant and drought intolerant varieties. The indices were also highly correlated with yield (r = -0.50 - -0.75, alpha = 0.05) and aflatoxin contamination (r = 0.45 – 0.75, alpha = 0.05). These indices could aid plant breeders in more accurately assessing genetic differences, which would accelerate breeding progress in developing peanut cultivars with resistance to drought and aflatoxin contamination.