5 - Fruit morphology, anatomy, and physiology

Abstract

This chapter gives a synoptic view of the morphology, anatomy, and physiology of citrus fruits. The fruit is a modified berry or a specialized form of berry (hesperidium) resulting from a single ovary with 8–16 segments. The shape is also variable: oblate in grapefruit, mandarins, and tangerines; globose to oval (spherical or nearly so) in sweet oranges; oblong in lemons; and spherical in limes. The rind or peel is leathery—more so when it loses some moisture. It is fragile and breaks on folding when turgid. Seed size and shape also vary greatly among different species like mandarin, sweet orange, lemon, acid lime, grapefruit, and pummelo. Fruit anatomy and physiology are discussed. Transverse and longitudinal sections of the fruit are described, showing various anatomical parts, vascular bundles, and fruitlets. As citrus fruit develops, several physiological changes occur. There is a relationship between various functions of different organelles, tissues, organs, and the system as a whole. With growing age, changes occur in the functioning of tissues and systems. Biochemical changes occurring with growth and important physiological aspects with respect to postharvest life are discussed.