Seed Mycoflora for Grain Mold from Natural Infection in Sorghum Germplasm Grown at Isabela, Puerto Rico and their Association with Kernel Weight and Germination

John Erpelding and Louis Prom

Seed mycoflora, kernel weight and seed germination were evaluated for 20 sorghum germplasm lines naturally infected with grain mold during the 2002 and 2003 growing seasons in Isabela, Puerto Rico. Mycoflora analysis of the kernels revealed Fusarium semitectum as the most frequently recovered fungal species. Fusarium verticillioides, F. thapsinum, other Fusarium species, Curvularia lunata, Bipolaris spp., Alternaria spp., Colletotrichum graminicola and several unknown fungal species were also isolated from mold infected grain. Bipolaris spp., Alternaria spp. and C. graminicola were isolated at the lowest frequencies from infected grain. Variation was observed in the frequency of fungal species isolated between years and between germplasm lines. Seed germination was positively correlated with kernel weight and negatively correlated with the incidence of F. semitectum, C. lunata and Bipolaris spp. Non-significant negative associations between germination with Fusarium spp. and between kernel weight with F. semitectum, F. thapsinum and C. lunata were also observed. Significant negative associations occurred between the incidence of F. semitectum with the frequency of C. lunata and F. thapsinum. The incidence of grain mold did not reduce seed germination for several sorghum lines, suggesting potential sources of tolerance for sorghum improvement.

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