11.2.1 Time-course

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Figure 11.2 Peach growth is biphasic, showing a double sigmoidal pattern in terms of both fresh mass and dry mass. Pericarp cell division is especially active during early stages of phase 1, while enlargement of an existing population of cells is largely responsible for growth during phase 2.

(Based on Chalmers and van den Ende 1975)

Fruit can increase in mass or volume by 100-fold or more from fertilisation to maturity, and such changes commonly follow a sigmoid curve (Figure 11.2 for peach; see Harris et al. 1968 for grape). Interpretation of such growth curves is complex because a single variable (mass, length, volume) is commonly applied to an object which contains several organs and different tissue types, each developing at their own rate and in accordance with their own program. Moreover, at a cellular level, comparative levels of division and expansion change with ontogeny, while shifts in airspace percentage also play a part in volume increases. Added to this, changes in storage products (oil, starch and sugar) and structural carbohydrate (endocarp thickening) influence dry matter content. Representative cases are covered later.