Sorghum seed fungal community and their association with grain mold severity, seed weight, and germination rate

Authors: Prom, Louis; ISAKEIT, THOMAS - Texas A&M University; Cuevas, Hugo; ERATTAIMUTHU, SARADHA - Texas A&M University; JACOBSEN, ROXANNE - Texas A&M University

Submitted to: Journal of Agriculture and Crops
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2020
Publication Date: 12/1/2020
Citation: Prom, L.K., Isakeit, T., Cuevas, H.E., Erattaimuthu, S., Jacobsen, R. 2020. Sorghum seed fungal community and their association with grain mold severity, seed weight, and germination rate. Journal of Agriculture and Crops. 7(1):14-19. https://doi.org/10.32861/jac.71.14.19.
DOI: https://doi.org/10.32861/jac.71.14.19

Interpretive Summary: Worldwide, grain mold is the most important disease of sorghum and due to the many fungi associated with it, controlling the disease can be difficult. Losses in grain yield on highly susceptible sorghum lines can reach 100%. Sorghum samples collected from Texas, Georgia, and Florida showed that most of the lines were moderately susceptible to grain mold, and that Alternaria spp. in South Texas, Florida and Georgia, and Fusarium incarnatum, F. acuminatum, F. equiseti, and F. semitectum complex were the most frequently isolated fungal species. This work is significant because sorghum lines in these areas could be evaluated for their response to these grain mold fungi to identify resistant sources which in turn can be used by breeders to develop new grain mold resistant sorghum lines and hybrids.

Technical Abstract: Grain mold, considered the most important disease of sorghum, is associated with several fungal genera. The disease reduces both yield and quality. In this study, over 300 sorghum seed samples collected from Texas, Florida, and Georgia were evaluated for grain mold severity, seed weight, germination rate, and seed fungal community. Grain mold severity of the seed samples, except for those collected from Cameron, Texas, were rated 3 or higher, indicating that these sorghum lines were moderately susceptible under naturally-infected field conditions during the 2016 and 2017 growing seasons. Seed weight across surveyed locations ranged from 1.1g to 4.0g for samples collected in Texas during the same period. Percent germination rates for samples collected in Texas ranged from 59.6% to 86.7%. Sorghum samples collected from Florida and Georgia exhibited moderately susceptible response to grain mold infection. Mean seed weight was 1.9g for samples collected from Florida, while in Georgia, mean seed weight was 2.3g. Germination rate was low for samples collected from Florida and Georgia. Mycological analysis of sorghum seed samples collected from farmers' fields in Central and South Texas during the 2016 and 2017 growing seasons showed Alternaria species as the most frequently isolated fungal genus, accounting for 40% and 42% in 2016 and 2017, followed by Fusarium incarnatum, F. acuminatum, F. equiseti, and F. semitectum Complex. In Florida and Georgia, Fusarium incarnatum, F. acuminatum, F. equiseti, and F. semitectum Complex was the most frequently recovered fungal species, accounting for 77% and 72% of the total.