Fruit Growth Patterns of Four Apple Cultivars Using Nonlinear Growth Models

Fruit diameter increase was monitored in four apple cultivars during three consecutive years (2006-2008) from t-stage until harvest. Individual fruit diameter increase was described using a negative exponential equation. Fruit growth curves of early ('Gala Brookfield'), mid-season ('Golden Delicious Reinders') and late ripening apple cultivars ('Braeburn Hillwell', 'Fuji Kiku 8') were denoted with an appropriate nonlinear model and each model parameter was evaluated separately. Apple fruit analyzed in the present study exhibited a similar growth curve for all analyzed cultivars i.e. a linear increase in fruit diameter in the beginning of fruit growth, followed by a slow curvilinear enlargement towards the asymptote in the final stages of fruit growth a few weeks before technological maturity. Asymptote was significantly dependent on cultivar, exhibiting higher correlation between predicted final fruit diameter and measured fruit diameter at harvest for late ripening cultivars. Similar growth rates have been calculated for 'Gala Brookfield', 'Golden Delicious Reinders' and 'Fuji Kiku 8' and a slower growth rate was characteristic for 'Braeburn Hillwell' cultivar.