Submitted to: Tropical and Subtropical Agroecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2009
Publication Date: 7/22/2009
Citation: Prom, L.K., Erpelding, J.E. 2009. New sources of grain mold resistance among accessions from Sudan. Tropical and Subtropical Agroecosystems. 10:457-463. Interpretive Summary: Worldwide, grain mold is the most important disease of sorghum, especially in areas with frequent rains late in the growing season. Seeds infected with grain mold have lower yield and quality. In this study, 59 sorghum lines collected from Sudan were screened in Isabela, Puerto Rico for resistance against Fusarium thapsinum, one of the fungal agents that can cause grain mold. Forty-two out of the 59 accessions tested were either highly susceptible or susceptible to grain mold. However, sorghum lines PI570011, PI570027, PI569992, PI569882, PI571312, PI570759, and PI267548 showed high levels of resistance to the fungus and also had the highest germination rates. This suggests that these seven lines may be useful in breeding programs to develop grain mold resistance lines which will increase productivity and profitability of sorghum.
Technical Abstract: Fifty-nine sorghum accessions from Sudan were evaluated in replicated plots at Isabela, Puerto Rico, for resistance against Fusarium thapsinum, one of the causal agents of grain mold. The environmental conditions during this study, especially at and after physiological maturity were optimal for grain mold development. Highly significant negative correlations between grain mold severity ratings in the field and on threshed grains with germination rate and seed weight were recorded, indicating that germination and seed weight were adversely affected when challenged with F. thapsinum. Temperature showed a significant negative correlated with grain mold severity and a significant positive correlated with germination rate. However, no significant correlation was observed between rainfall and grain mold severity or germination rate. Accessions PI570011, PI570027, PI569992, PI569882, PI571312, PI570759, and PI267548 exhibited the lowest grain mold severities and among the highest germination rates, indicating that these accessions may possess genetic resistance to grain mold and might be useful in sorghum enhancement programs. Four of these accessions had significantly higher germination rates than the resistant control genotypes with PI267548 having the highest germination rate. PI267548 was the only white seeded accessions showing significantly better grain mold resistance than the control genotypes.