Forage Quality Characterization of a Chemically Induced Brown‐Midrib Mutant in Pearl Millet

Based on the negative relationship between lignin and digestibility, one of the most effective means of increasing forage digestibility is by reducing lignin content. Our objective was to chemically induce a brown‐midrib (bmr) mutation in pearl millet, Pennisetum americanum (L.) Leeke, and evaluate the resulting mutants for lignin content and similarity to existing bmr mutants in other species. Seeds from two inbred pearl millet lines derived from Tift 23D2B1/2 ✕ PI 185642 were treated with either ethyl methyl sulfonate or diethyl sulfate, planted, and selfed in 1984. In 1985 a single plant in one head row exhibited a brown‐midrib phenotype, and was selfed. The bmr pearl millet was compared to selfed normal plants from the same head row along with bmr and normal sorghum, Sorghum bicolor (L.) Moench., and maize, Zea mays L., in 1986 at two locations. Plants were harvested at anthesis and analyzed for apparent in vitro dry matter digestibility (IVDMD), permanganate lignin, alkali‐labile phenolics, and other quality parameters. Lignin concentration in bmr pearl millet was 40 g kg−1 compared to 50 g kg−1 for its normal counterpart, and IVDMD was 726 g kg−1 for the bmr genotype compared to 659 g kg−1 for the normal genotype. The differences in phenolic monomer concentrations between normal and bmr pearl millet were more like those in sorghum than maize. Based on IVDMD, lignin and phenolic monomer analyses, we concluded that bmr pearl millet was similar phenotypically to bmr mutants in sorghum. This trait has excellent potential for improving the quality of forage pearl millet.