Submitted to: American Peanut Research and Education Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2008
Publication Date: 1/15/2009
Citation: Girdthai, T., Jogloy, S., Vorasoot, N., Akkasaeng, C., Patanothai, A., Wongkaew, S., Holbrook Jr, C.C. 2008. Association between surrogate traits of drought tolerance and aflatoxin contamination in peanut cultivars under terminal drought. In: Proceedings of American Peanut Research and Education Society, July 15-18, 2008, Oklahoma City, Oklahoma. p. 29-30. Interpretive Summary: not required
Technical Abstract: Terminal drought induces pre-harvest aflatoxin contamination (PAC). Drought resistance traits are promising as indirect selection tools for improving resistance to PAC. The objectives of this study were to determine the effects of terminal drought on Aspergillus invasion and aflatoxin contamination and to investigate the association between surrogate traits of drought tolerance and aflatoxin contamination. Field tests under rainout shelters were conducted in the dry seasons 2004/05 and 2005/06. A split-plot design with four replications was used. Two water regimes (field capacity (FC) and 1/3 available soil water at 80 day after emergence to harvest (AW)) were assigned in main plots, and eleven peanut genotypes were assigned in subplots. Data were recorded for relative water content (RWC), chlorophyll density, specific leaf area (SLA), pod yield, drought tolerance index (DTI), A. flavus infection and aflatoxin contamination. Traits related to drought resistance were associated well with those related to aflatoxin contamination under drought conditions but not under well-watered conditions. Negative and significant associations between DTI and aflatoxin contamination and between DTI and A. flavus infection indicated that increasing drought tolerance resulted in reduced aflatoxin contamination. High and positive correlations between SLA and aflatoxin contamination indicated that greater leaf thickness was associated with reduced PAC. Although weakly significant, there were negative correlations between chlorophyll density and aflatoxin contamination. The relationships were rather consistent across seasons. Multiple correlation coefficients between drought tolerance traits and aflatoxin contamination were much stronger than correlations for individual traits, and A. flavus infection alone accounted for the majority of the correlation coefficients, indicating synergistic contribution of the traits to aflatoxin contamination. Breeding peanut for resistance to PAC is very difficult, and progress has been slow. Breeding for drought tolerance using these traits as selection criteria may help to accelerate progress in developing resistance to PAC. Tifton-8 was identified as the genotype with low A. flavus infection and aflatoxin contamination.