A progress report… citrus response to removed terminal buds and leaves

IT HAS BEEN KNOWN for many years that the apical buds inhibit the growth and development of lateral buds. This inhibition is largely due to growth regulators produced by the apical shoot and leaves. Other researchers have reported that buds are also inhibited by the presence of growing leaves—and that in several herbaceous species, the expanded leaves partially inhibited their axillary buds. Long after the removal of the terminal buds, the leaves delayed axillary bud growth. Defoliation has been shown to significantly accelerate bud growth of Poncirus trijoliata. However, length of time to bud growth varied with the season. The addition of 1 per cent NAA in lanolin paste to the leaf scars of defoliated plants inhibited bud growth. This auxin produced by the leaves may be responsible for inhibition of bud growth, as is auxin produced by the apical bud.