Study on variability and associations involving protein content, amino acids and grain yield in sorghum

Quantitative estimations of total protein and five amino acids in 50 varieties of grain sorghum revealed significant variability for protein content (5.1–11.4%) and amino acids: lysine (0.30–2.75%), histidine (0.82–2.95%), arginine (1.70–7.61%), phenylalanine (1.88–6.14%), and isoleucine (4.43–11.85%). Five high protein (> 10.0%) lines were selected, but all were poor yielders. Correlation analysis revealed significant negative relationship of protein content with grain yield and the levels of four amino acids in their proteins. However, absence of significant negative relationship between protein content and lysine suggests the possibility of combining high protein and high lysine traits in sorghum grain. Amino acid content in the whole grain (flour), on the other hand, correlated positively with grain protein percent.