Growth analysis of the tomato fruit, Lycopersicon esculentum Mill

The growth of organs, organisms and populations is generally expressed in the form of sigmoid curves on cartesian ordinates. This growth curve has been observed for stems (Greulach, 1973), leaves (Maksymowych, 1973; Williams, 1975) and for many fruits, although e.g. drupaceous fruits show a double sigmoid curve due to a growth interruption during the development of embryo tissues (Bollard, 1970). Sigmoid curves, however, are quite insensitive, especially at the start of the growing period where, owing to scale limitation, 'they conceal more than they reveal' (Williams, 1975). Because growth is rather multiplicative than additive in character, logarithmic transformations as advocated by Williams (1975) allow a better analysis of the early stages of growth. For leaves, an illuminating method turned out to be the calculation of the relative growth rate (RGR), originally proposed by Blackman (1919) as the 'efficiency index' :