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

Modelling Fruit Quality 73
Pruning and thinning were quite severe (40% of replacement canes were kept,
aberrant shaped and lateral flower buds removed). The number of seeds per fruit
was dramatically decreased in B1 compared to A and the reduction of the number
of flowers, which was stressed by thinning, was not sufficient to compensate the
deficit of fruit growth. On the contrary, the resulting small number of fruits was a
critical point. Yield was poor (15 tonnes/ha) as was the number of fruits in the
best grade: about two times less than for A though these fruits represented a high
percentage of the yield (Table 2). Accordingly, the yield value was weak (2400
/ha).
Situation B2 consisted in testing a less severe pruning option than in B1, i.e.
keeping 70% of replacement canes. Because of a higher number of fruits on vines,
fruit growth was repressed compared to B1. Accordingly, the proportion of fruits
of the best grade was lower (Table 2), but it remained high (76% of the number
corresponding to case A). Total yield (26.7 tonnes/ha) was better than in A, but
its value (4100 /ha) lower.
These results show that according to the model, changes in pruning and thinning
cannot modify the effect of unfavourable planting options in the simulated example.
In conclusion, SIMTECK focuses on fruit size variability by considering different
levels both from a biological and technical point of view. Technical operations are
incorporated in the processes to reflect the level at which they are reasoned. The
resulting model allows choosing a technical operation in order to reach a given
production in terms of fruit size distribution and total yield. In a next step, the
sequence of technical operations will have to be compared using economic criteria.
6. THE QUALITY FROM THE ECOLOGIST’S POINT OF VIEW
From the ecological angle, fruit quality can be considered in two ways. First, the
quality of wild fruits plays a major role in seed dissemination by animals and is a
key factor in the plant population dynamics. Indeed, many traits of fleshy fruits have
been interpreted as co-adapted traits of plants that govern the choice of a fruit species
by animals (Janzen, 1983). They include mass, palatability and nutrient content of
edible tissues (Gautier-Hion et al., 1985). Second, the fruit quality depends on the
effect of ecological factors on the state of the plant which bears them. This plant
can be subjected to diseases and be attacked by animals, mainly insects with negative
consequences on fruit quality. We are now in the framework of disease epidemiology
and predator-prey relationships which have been largely studied and modelled
(Gillman and Hails, 2000). This relationship between ecology and fruit quality is
of particular interest in the framework of Integrated Fruit Production (IFP), which
was the innovation of European horticulture in the 1980s (Sansavini, 1997). IFP
includes all the field management techniques intended to produce crops that meet
both commercial and consumer demands, especially with regard to edible quality,
while preserving the environment. IFP calls for adaptating agricultural practices,
thus challenging researchers with their capacity to producing data and tools to
accompany it. As regards biotechnical models applied to IFP, a lot remains to do
as very few of them take into account all the following essential aspects: