Development of a simulation model for potential production of sweet cherry: its usefulness to analyse planting density

Abstract

A simulation model for potential production of sweet cherry (Prunus avium L.) was developed using information from literature. Parameterisation was done using values from literature and experimental measurements. An experiment with four different densities (2051, 2564, 3419 and 5128 trees ha-1) in two cultivars (Karina and Regina) was evaluated to (1) obtain the values of some parameters and (2) to (partially) test the model. The main objectives of the research were: 1) To understand and explain yield differences between combinations of densities and cultivars from an ecophysiological point of view. 2) To find out if a mechanistic model for sweet cherry can explain yield differences due to planting densities. 3) To study if light interception is the main parameter explaining yield differences. 4) To estimate which is the optimum LAI (and light interception) to maximise fruit production. In the experiment, both LAI and fruit production did not differ between treatments, suggesting that intra-specific competition compensated the effect of differences in planting density. In both the experiment and in the simulations in the conditions of the experiment, no reduction of fresh weight of individual fruits was observed under any yield value. This situation would indicate that potential sweet cherry production is generally limited by reproductive sink strength, therefore being more sensitive to flower bud differentiation and fruit-set rather than to light interception. The model was suitable to explain the main mechanisms of fruit production, even considering that prediction of absolute values could not be properly tested. A LAI-value between 4 and 5 and about 40 fruits per m2 of leaf area seem to be good targets to optimise fruit production without detrimental effects in fresh weight of individual fruits.