Abstract

Grain mold poses a significant constraint to sorghum production worldwide, including Ethiopia. The presence of mycotoxigenic molds also raises health concerns. This current study was aimed to assess the distribution of grain mold fungi, moisture content, temperature, and equilibrium relative humidity in freshly harvested and stored sorghum grain in eastern Ethiopia. A total of 720 sorghum grain samples were collected across eight districts (Awbare, Gorogutu, Haramaya, Jigjiga, Kersa, Kombolcha, Mieso, and Tulo) in three survey rounds during the main cropping seasons of 2016 and 2017. Fungal genera and species were isolated through direct plating on culture media in the laboratory and identified based on their macroscopic and microscopic features. The results showed that the average (12.9 to 13.5%) moisture content of fresh samples exceeded that of the moisture content (10.2 to 12%) of stored grain samples, with the highest moisture recorded in freshly harvested sorghum. Ideal conditions for grain mold growth significantly affected sorghum quality. A total of eighteen major fungal genera, including Alternaria, Aspergillus, Fusarium, and Penicillium, were isolated. Freshly harvested samples showed 99% contamination by Fusarium, followed by Alternaria (84%) and others. Stored samples had Aspergillus and Penicillium species. Overall, 76% of the sorghum grain collected in 2016 and 63% in 2017 were contaminated. Freshly harvested grain samples from Gorogutu district had a higher (76%) mold incidence than that of samples from Jigjiga (68%), Kersa (65%), and Awbare (64%) districts. Mold incidence was lower in six-month stored grains (64%) than the incidence in three-month stored (73%) and freshly harvested (71%) grain, showing reduced field fungi during storage. Further research is needed to generate additional information and develop efficient and sustainable managerial options against these sorghum grain mold fungi.

Key words: Alternaria, Aspergillus, contamination, Fusarium, health risk, incidence, moisture, Penicillium, temperature.