Production Practices and Quality Assessment of Food Crops. Vol. 1

62 M. Génard and F. Lescourret
Figure 5. CaShoo data versus experimental data in the ‘Suncrest’ peach cultivar and several shootto-fruit
ratios (S/F): variation of shoot and fruit growth (mean ± sd) according to degree-days either
observed (circles and full lines) or simulated (squares and dotted lines).
sum of squares divided by the total sum of squares, was examined. The three main
effects were significant and explained most of the variation of the simulated fruit
size at harvest (Table 1).
The contribution of the initial size of leafy shoots, which strongly influences
the development of leaf area, was of the same order of magnitude in late and early
cultivars. The contribution of the light environment was greater in the late cultivar,
whereas the contribution of the initial fruit size was greater in the early cultivar. The
higher sensitivity of early maturing cultivars to initial fruit size is probably due to
a stronger sink activity of the fruit resulting from a shorter growing season.
To conclude, the structure of ‘CaShoo’ allows complex behaviours to emerge
from interactions between sources and sinks, such as photosynthetic regulation
with fruit load changes. The flux of carbohydrates into a sink, which is a significant
determinant of fruit quality, was partly controlled by the sink (for instance actual
mass) and partly by the source (for instance leaf area).