Micronutrient content and geometrical features of grain sorghum subjected to water stress

Sorghum bicolor L. Moench is a cereal producing reasonable yield in dry and semi-dry, hot and saline regions, where the production of other crops is limited. Sorghum grain is a rich source of minerals including magnesium (Mg), iron (Fe), zinc (Zn), Manganese (Mn), and calcium (Ca). However, the quantity of minerals can be dependent on the different agricultural and climatic conditions. Therefore, the objective of this study was to investigate the effect of water stress on the micronutrients (Ca, Fe, Mg, Mn, and Zn) and geometrical features of ten sorghum genotypes. There were different patterns observed in terms of grain micronutrients produced under normal and deficit irrigation depending on the genotype. A high concentration of Ca (878.9 ppm), Fe (335.8 ppm), and Mn (22.8 ppm) under normal irrigation and a value of Mg (1435.36-1783.21 and 1410.81-1890.95 ppm) and Zn (1.65-20.34 and 4.04-15.13 ppm) in the normal and water stress condition, respectively, was observed in the genotypes. Water stress had more influence on Ca, Fe, and Zn concentrations in comparison to Mg and Mn. The discrimination models based on the selected geometrical features of the sorghum grains produced under normal and deficit irrigation indicated a relatively low classification accuracy (40-67%). Therefore, an integrated approach using geometric and textural features is suggested to improve classification accuracy.