Temperature and light effects on stem elongation

Diurnal temperature fluctuation interacts with light quality find photoperiod to affect plant stem elongation. Stem cell elongation but not division increases as day temperature increases relative to night temperature and as day length increases for many species. The effect of diurnal temperature fluctuation and photoperiod on stem elongation are mediated via phytochrome where stem elongation increases as %P(fr) decreases. The basis for diurnal temperature and photoperiod effects on stem elongation is associated with temperature fluctuation when stimuli occur during the period of most rapid stem elongation during a 24-hour cycle, i.e., the end of the scotoperiod and beginning of the photoperiod. The basis for thigmotropic inhibition of stem elongation is associated with endogenous stimulation of ethylene synthesis. Application of this information to commercial plant production and potential future research directions will be discussed.