During this time the grain loses water at a constant rate. The embryo and aleurone enter a state of
dormancy around the time of grain maximum fresh weight. This stage is known as Harvest Ripe.
The colour of the grain changes from golden to light brown but there is a wide degree of variability in the
timing of this process both between different grains in the ear and different ears in the crop. In practise this
stage of crop growth is closely monitored by the farmer. The moisture content of the grain is carefully
watched so that the crop is harvested at the optimum time.
Often the harvested grain is air dried after combining to precisely control its moisture content during storage. Without this controlled process of desiccation, the internal biological processes of pre-germination and germination may start and the grain can be ruined. Pre-harvest sprouting is a major agronomic problem. Weak dormancy induction and a short period of after-ripening can have detrimental consequences for malting quality. The understanding of these complex processes, at the genetic level, is essential to prevent grain spoilage.
More information on dormancy induction, late embryogenesis-abundant (LEA) proteins, the role of abscisic acid (ABA) is available here.