M. Black

The photocontrol of growth in higher plants depends on the participation of cell
enlargement, as revealed by measurements of cell length, diameter or volume. Although
many studies of the photocontrol of growth omit an examination at cellular level, it is
nevertheless necessary to include them, sometimes making assumptions about the
contribution of cell extension to the overall growth pattern. It is clear, furthermore, that the
role of cell division must be considered where necessary. Emphasis in this chapter will be
on the growth of selected organs and possible mechanisms of the photocontrol of cell
growth. Little or no attention will be given to growth substance/light interactions, effects of
light on stem sections, root growth, tropistic movements and seed germination, most of which
are covered elsewhere in this and other volumes of this Encyclopedia.