Genetic variation and trait associations of yield, protein and grain micronutrients for identification of promising sorghum varieties

Sorghum is, globally, the fifth most important cereal after maize, rice, wheat and barley. The crop is tolerant to semi-arid and arid climatic conditions. Twenty-five sorghum varieties grown in South Africa were evaluated in the field at two locations with the objective of identifying high yielding, micronutrient dense genotypes. Two clusters were formed based on measured traits. Tx430 (G13), CIMMYT entry 49 (G12), E35-1 (G16), Framida (G19), IS1934 (G7) and IS14380 (G14) formed cluster A. The rest of the sorghum entries formed cluster B. Wide variation was exhibited for grain yield, ranging from 1.12 t ha−1 to 3.96 t ha−1 with a mean grain yield of 2.83 tha−1. Analysis of variance also revealed significant differences among the varieties for protein, total starch, amylose and mineral content. Two varieties, Tx430 and AR-3048 exhibited very high protein content. Fe content ranged from 43.7 mg kg−1 (Kuyuma) to 61.2 mg kg−1 (IS14380) with an average of 50.5 mg kg−1. Zn content ranged from 13.7 mg kg−1 (Macia) to 23.4 mg kg−1 (Tx430) with a mean of 17.4 mg kg−1. Grain yield was significantly positively correlated with plant height, panicle weight and thousand kernel weight. Significant positive correlations were observed between Fe content and Zn, Cu, Mn and P. This data indicated that simultaneous genetic improvement of sorghum varieties for Fe and other important minerals, and starch content in the same genetic background was possible, without a penalty to grain yield