© 1996 Heron Publishing—Victoria, Canada
Modeling the response of peach fruit growth to water stress
M. Génard and J. G. Huguet
Unité de Recherche en Ecophysiologie et Horticulture, Institut National de la Recherche Agronomique, Domaine Saint-Paul, Site
Agroparc, 84914 Avignon Cedex 9, France / Received February 14, 1995
Summary
We applied a semi-mechanistic model of fresh matter accumulation to peach fruit during the stage of rapid mesocarp development.
The model, which is based on simple hypotheses of fluid flows into and out of the fruit, assumes that solution flow into the
fruit increases with fruit weight and transpiration per unit weight, and decreases with the maximum daily shrinkage of the
trunk, which was used as an indicator of water stress. Fruit transpiration was assumed to increase with fruit size and with
radiation. Fruit respiration was considered to be related to fruit growth and to temperature. The model simulates variability
in growth among fruits according to climatic conditions, degree of water stress and weight of the fruit at the beginning of
the simulation. We used data obtained from well-watered and water-stressed trees grown in containers to estimate model parameters
and to test the model. There was close agreement between the simulated and measured values. A sensitivity analysis showed
that initial fruit weight partly determined the variation in growth among fruits. The analysis also indicated that there was
an optimal irradiance for fruit growth and that the effect of high global radiation on growth varied according to the stage
of fruit development. Water stress, which was the most important factor influencing fruit growth, rapidly depressed growth,
particularly when applied late in the season.
Keywords:
Prunus persica, solar radiation, solution flow, transpiration, trunk shrinkage, water balance.
