Effects of maize grain size, shape and hardness on drying rate and the occurrence of stress cracks

The effects of maize (Zea mays L) grain hardness, morphological factors (grain size and shape), drying rate and the development of stress cracking over time were investigated for four hybrids (Hmv565 − 3 × E1386, CF06, CF05 and Furio). The re‐parametrised Morgan–Mercer–Flodin (MMF) model successfully predicted the rate (κ) and maximum value (α) of percentage checked stress cracking (checking) in various sizes, shapes and hardnesses of grains with time after drying. The maximum percentage checking (α) was significantly correlated with grain length (r = −0.707), thickness (r = 0.620), roundness (r = 0.703) and the shortest diffusion pathway (r = 0.627). The rate (κ) of percentage checking with time after drying was significantly correlated with grain bulk density (r = −0.564), hardness ratio (r = −0.611) and drying rate (r = 0.551) and, to a lesser extent, with grain size parameters including hundred‐grain weight, grain length and width. Removing small and round grains could reduce checked stress cracking by up to 50% in some dent maize hybrids.