EFFECTS OF MOISTURE, STARCH, AND MICROSTRUCTURE ON THE MECHANICAL PROPERTIES OF MAIZE KERNELS DURING MECHANICAL HARVEST AFTER PHYSIOLOGICAL MATURITY

This study addressed the issue of high grain breakage rates during mechanical maize harvesting, which significantly compromise grain quality and subsequent storage performance. A comparison was conducted between maize subjected to natural dehydration (CK) and maize treated with a desiccant (SY). The research analysed the moisture content of various plant organs, grain starch composition, and puncture resistance characteristics across three kernel regions during maturation. The results revealed a strong positive correlation between the grain dehydration rate and moisture loss in both the stalk and cob. Desiccant application accelerated grain dehydration and promoted the conversion of branched-chain starch. In both treatments, decreasing kernel moisture content led to the development of a thicker and denser internal cuticle layer, which increased the yield load and elastic modulus in the lateral and apical kernel regions. When kernel moisture content dropped below 25%, the SY group exhibited significantly higher yield load and elastic modulus than the CK group. These findings provide a theoretical foundation for improving kernel impact resistance and reducing grain breakage during mechanical harvesting.