Temperature and gibberellin effects on growth and anthocyanin pigmentation in Photinia leaves

The effects of temperature and gibberellic acid (GA(3)) on the growth characteristics and anthocyanin leaf pigmentation in Photinia x fuaseri cv. Red Robin were examined. Shoot growth intensity increased and red leaf pigmentation decreased with rise in temperature. A close correlation was observed between pigmentation and growth cycles, anthocyanin concentration in young leaves being the greatest during the periods of active growth. GA3 treatment caused a substantial increase in the length of the growth cycle, yielding longer stems with red pigmentation, for a much longer period. No changes in internode length, leaf size or shape were induced by this treatment. These phenomena were observed at different temperatures, even though the growth cycle length varied substantially.