The Development of Wheat Grain in Relation to Endogenous Growth Substances

Abstract

Changes in the endogenous gibberellins and abscisic acid of the developing grains of Triticum aestivum L. have been studied in relation to growth of the grain. The maximum grain volume is inversely related to temperature and is reached while the dry weight is still small. This stage is associated with a sharp increase in gibberellins. Starch formation is the principal feature of the next stage of development and this ceases shortly after the beginning of a period of rapid water loss. This water loss is preceded by an increase in the abscisic acid content. Changes in the endosperm are associated with changes in the biochemical and physical attributes of the pericarp; these also have been correlated with changes in growth substances. The results are related to the ripening process and the final dry weight of the grain.