ABSTRACT
In general developing fruits and seeds are rich sources of plant growth substances. Often there are sequential, ontogenetic changes in the maximal concentrations of the different groups of hormones during seed development and also the case for developing cereal grains. This chapter considers only certain aspects of hormonal status and responsiveness of developing cereal grains. The fluctuation in the amounts of extractable gibberellins in developing cereal grains is more complex than for the other groups of hormones. Cytokinin content has been related to grain size in barley but the close relationship between grain size and cell number in wheat endosperm has not been examined in terms of differences in endogenous cytokinins. As with auxin, the abscisic acid (ABA) content of developing cereal grains follows the pattern of accumulation of dry matter and a proportion is co-transported from leaves with assimilates.
