The role of seed in the determination of yield of grain crops

The seed is the harvested organ in grain crops and, consequently, the accumulation of dry matter by the seed is an important component of the yield production process. The growth of individual seeds, usually characterised by the rate and duration of growth, is, at least partially, controlled by the seed itself. It is this control that gives the seed a significant role in the yield production process. Genetic variation in seed growth rate, which is substantial, is not related to yield, but variation related to environmental conditions during seed filling often is. Genetic and environmental variation in seed-fill duration is usually directly related to yield. Much is now known about the regulation of seed growth and this knowledge, if applied, may help answer some of the important questions still facing crop scientists as they try to increase yields in the future.