Comparing the effects of grain weathering and presence of fungal communities on waxy and non‐waxy sorghum hybrids grown across Texas

Grain weathering in grain sorghum [Sorghum bicolor (L.) Moench] is a persistent concern for producers in warm and humid climates. Further, grain sorghum genotypes are known to vary in their response to grain weathering; in some cases, this response is associated with a specific grain trait. For example, waxy endosperm sorghum is perceived to be more susceptible to grain weathering. This study herein compared waxy, heterozygous waxy, and non-waxy sorghum hybrids grown in multiple environments for grain weathering susceptibility and characterization of the fungal communities on the grain. The traits used to evaluate grain weathering included first grain weathering rating (FGWR), area under the disease progress curve (AUDPC), initial germination (IG), and reduction in germination (RIG). Grain weathering intensity varied among the tested environments; increased weathering occurred with wetter conditions. In combined analyses, the environment accounted for more variation (70.2, 38.2, 39.9, and 81.1%) than did genotype (9.0, 26.9, 15.8, and 5.0%) for FGWR, AUDPC, IG, and RIG, respectively. In only one of the four environments were the waxy and heterozygous waxy hybrids statistically different from the non-waxy genotypes. Ultimately, variation was more associated with genotypes than endosperm classes. Overall, Alternaria spp., Bipolaris spp., Fusarium semitectum, Curvularia spp., and Aspergillus niger were the most frequently observed pathogens across environments. Within an environment, the percent of different fungal pathogens remained relatively constant, but varied across environments. There was no clear distinction between either the level of grain weathering or the presence of a particular pathogen and endosperm type. The results indicate that grain sorghums with waxy endosperm are no more susceptible to grain weathering than those with normal, non-waxy endosperm.