Stover yield, morphological fractions and nutrient composition of five stay-green sorghum (Sorghum biochar L.) varieties at the physiological maturity stage.

Abstract

Stay-green sorghum varieties are known for their drought resistance and ability to retain green biomass during grain filling, making them crucial for sustainable agriculture in arid regions. However, there is limited information on their stover yield (SY) and nutritional quality when both grain and forage are harvested. This study assessed five stay-green sorghum varieties at the Bako Agricultural Research Centre using a randomized complete block design with three replications in 2020, 2021, and 2022. The research evaluated SY, morphological traits, and nutrient composition. Results indicated that the Chemeda and Gemedi varieties produced the highest SY, digestible dry matter, and organic matter yield, with greater plant height and stem dry matter yield. These varieties are better suited for and could be targeted toward smallholder farmers who require large quantities of fodder for dry-season feeding when feed shortages are prevalent. In contrast, Asosa1 yielded the highest leaf biomass and leaf-to-stem ratio, followed by Adukara, suggesting that stover produced by such varieties would contribute to higher-quality forage that supports livestock productivity. SY varied significantly (P < 0.001) across seasons, with the highest in year 1, followed by year 3, and the lowest in year 2. Ash, neutral detergent fiber, acid detergent fiber, and cellulose concentrations showed no significant difference (P > 0.05) among varieties, though some quality traits differed (P < 0.05). Crude protein ranged from 5.44 % (Chemeda) to 3.18 % (Marara). These levels were below the threshold required for optimal rumen microbial activity, highlighting the need for supplementation with high-quality feed to support effective animal performance. Most traits, except for the leaf-to-stem ratio, showed strong positive correlations. Overall, Asosa1 and Adukara provided less stover with higher nutritional quality, while Chemeda and Gemedi offered greater quantities of lower-quality stover. The choice of variety should be based on the livestock production purpose of the end users. Future research should focus on assessing the performance of ruminant animals fed stover from the recommended varieties.