Growth and abscission dynamics of ‘Cox’s Orange Pippin’ and ‘Golden Delicious’ apple fruits

Abstract

SummaryThe dynamics of growth and abscission of individual apple fruits were investigated in ‘Cox’s Orange Pippin’ and ‘Golden Delicious’ over a five-year period. Fruits originating from flower buds tagged in winter were observed regularly and measured diametrically from full bloom until harvest. Results show that the drop of an individual apple fruit can be forecast seven to fourteen days before it actually happens. Also, the growth of individual fruits may be described more accurately by a double sigmoid curve. Fruit development is divided into three distinct stages, because a period of severe slowing down of growth (stage 2) appears between two periods of more rapid growth. “June drop” is not directly connected with the intensity of this growth rate reduction.