Buds and leaves in pomegranate (Punica granatum L.): Phenology in relation to structure and development

Phenological analysis provides a useful tool in the study of fruit trees in various aspects, and is mostly based only on morphological characters. In this two years study, morpho-anatomical analyses of vegetative organs were conducted using light and scanning electron microscopy during pomegranate annual cycle. Punica granatum L. cv. Rabbab-e-Neyriz was investigated at six ontogenetic stages. Two types of ecodormant scaly buds developed either only into vegetative shoots or went through vegetative and/or reproductive phase, with a predictable fate in winter. Bud dimorphism resulted in the appearance of four branch types in spring. Pomegranate is heterophyllous, with two types of leaves, already distinguishable in dormant buds on the basis of shape and especially the apex. Both leaf types revealed the same anatomical features, but differed in their developmental aspect leading to obcordate and lanceolate final shape. An accelerated rhythm of leaf growth was noticed and histodifferentiation initiated within the dormant buds. The functional significance and eventual consequences of heterophylly in pomegranate are discussed. (C) 2015 Elsevier GmbH. All rights reserved.