A Study on the Characteristics of Buds and Flowers in Pomegranate: Differences among Cultivars

Abstract

The growing cultivation of pomegranate and the interest of consumers in the nutraceutical properties of the fruit have not yet spurred similar increases in the knowledge base of some important botanical and physiological aspects of this species, such as bud differentiation. The aim of this research was to study the bud morphology of four pomegranate cultivars (‘Comune S. Giorgio’, ‘Wonderful’, ‘Ki-Zakuro’, and ‘Haku Botan’) to better clarify the bud differentiation process. In all four cultivars, the number and the position of the buds were variable, from a typical two buds per node to a single bud or more (3). Two types of buds were observed: small and thin on the twigs (short, medium, and long) and large and round on the spurs; large buds were also observed on twigs but in a reduced number. Flowers showed differences among the cultivars, with a larger number of petals in ‘ornamental’ cultivars because of the petaloidy. Hermaphrodite flowers were larger and longer than the staminate flowers and also more abundant. Moreover, flowers developing from a flower bud were longer than flowers developing from mixed buds. The presence of an undifferentiated meristem, starch grains in the protective scales, and two small transition leaves were observed in all the types of buds from summer to the end of endodormancy in all cultivars. However, a dome-shaped meristem was observed in a few flower buds. Our observations indicate pomegranate behaves as a species for warm, sub-tropical, and tropical areas more than for temperate ones.

Keywords

• flower bud
• mixed bud
• bud differentiation
• microscopic observations
• µCT
• starch grains