Fifty years of semi-dwarf spring wheat breeding at CIMMYT: Grain yield progress in optimum, drought and heat stress environments

•Continuous breeding progress in grain yield from 1965–2014 in optimum, drought and heat environments.•Drip irrigation system in high yielding environments can improve yield potential.•A graphical LASSO estimation model expands the understanding of complex relationship between grain yield and other traits.•Highest yielding varieties have employed different trait strategies to attain grain yield.