Characteristic Comparison of bmr and Conventional Sorghum as Promising Forage Grown on Ultisol Soil Applied Different Levels of Organic Fertilizer

Abstract

As promising cereal plant for forage sources, sorghum was grown easily on most of Indonesian soils and produce high number of biomass. Sorghum utilization for ruminant feed purpose still using conventional sorghum, it’s not designed specify for forage source and it’s have limiting factor about high lignin content which can reduce fiber digestibility. Mutation breeding techniques produced promising sorghum mutant line for forage with low lignin content and high nutrition forage quality. Brown Midrib (bmr) sorghum was obtained by gamma ray irradiation at 250 Gy for producing sorghum mutant lines containing low lignin, which is possible to be used for forage sources in animal livestock feed. A serial research was conducted to compare the bmr lines sorghum (PATIR 3.2 and 3.5) and conventional sweet sorghum varieties (Numbu and CTY-33) on marginal Ultisol soil applied with different levels (0, 10, 20, and 40 ton ha^-1) of organic fertilizer. The research parameters were Viability, Pest Disturbance Intensity (PDI), Stem Diameter, Stem Height, Stem °brix, and forage Crude Protein Content. Research result showed that bmr line sorghum have similar average of Viability (91.90 vs. 93.30%), and forage Crude Protein Content (7.49 vs. 7.45%) Generally, bmr sorghum lines have bigger on stem diameter but shorter on stem height. The superiority of bmr lines were lower on PDI (13.84 vs. 31.33%) and higher on Stem °brix content (12.77 vs. 12.30°brix) compare with conventional ones. Based on the characteristics, bmr lines sorghum (PATIR 3.2 and 3.5) could be considered its utilization for forage source in marginal soil to replace conventional sorghum varieties which not design for feed source purpose.