Fruit quality prediction on cider apple: effect of annual fruit load, soil and climate
Résumé
Monitoring during 12 years, a network of about twenty plots in commercial orchards was used to analyse the respective influence of soil, climate and trees load, on fruit quality at harvest for two important varieties of cider apples: Douce Coëtligné and Douce Moën. A first analysis was conducted to compare the quality results of the two cultivars, to define the load levels and soil types able to explain some of the fruit variability, and to propose a first prediction of the quality at harvest according to growing conditions defined as combinations of variety x load x soil. It was shown that fruit load effect was often predominant. In a second step, PLS method with cross-validation has been used to predict the remaining variability of fruit quality around the previous defined reference value (depending on load and soil). At this stage, annual characteristics of climate from bud break to fruit ripening, were supposed to be the main factors able to modulate the reference value. Promising results were obtained with the variety Douce Moën to estimate fruit weight, density and acidity of juice with a quite good quality of estimation.