Pomegranate fruit development and maturation

Summary

The development of pomegranate fruit was studied under continental (Bet Shean Valley) and moderate maritime (coastal plain) climatic conditions. Fertile flowers were vase-shaped and developed into fruits. Bell-shaped flowers with few egg cells were sterile and did not produce fruits. Gibberellic acid induced the sterile flowers to develop into small fruits; however, these were devoid of juicy seeds. The growth curve of pomegranate fruits from both climatic regions showed a single sigmoid pattern. The seeds accounted for about half of the fruit weight. The edible juicy tissue of the seeds grew continuously from June to October whereas the internal stone tissue stopped growing and hardened by the end of June. Juice, total soluble solids (TSS) and anthocyanin content increased continuously during maturation while acidity decreased. Fruit of cv Mule’s Head ripens early and has a low acid content, whereas fruit of the late-ripening cv Wonderful has high juice contents, TSS, acids and anthocyanins, and is therefore suitable for processing. In the hot Bet Shean Valley fruits matured more rapidly than in the coastal plain, but acidity and anthocyanin contents were lower. C0₂ evolution from the fruits was low and no climacteric peak or measurable ethylene were detected during fruit maturation, thus suggesting that the pomegranate is a non-climacteric fruit.