Resumen de Mechanical mandarin thinning related to fruitlet developing stage
Angelo Romano, Antonio Torregrosa, Sebastià Balasch, Coral Ortiz
Mandarin thinning is done by hand, increasing labor cost and raising total crop production costs. Mechanical thinning has been tested in peaches and other fruits. To achieve the maximum efficiency thinning requires to be applied at a specific stage of vegetative development. In this research study the mechanical thinning of mandarin branches during the different fruit developing stages has been assessed using a vibratory laboratory device (amplitudes 0.015 m and 0.030 mm and frequencies 34.8 Hz and 37.8 Hz). Branches with flower buds, flowers, small green fruits and medium green fruits were tested during 12 weeks and two different seasons. It was possible to detach mechanically flower buds, flowers and green fruits using different combinations of amplitudes and frequencies. Removal percentage decreased when increasing retention traction force, according to a logarithmic regression model. During fruit setting (weeks 5, 6 and 7) removal percentage was higher, when the retention force is very low. The first weeks just after the natural thinning could be consider the adequate time for a mechanical thinning operation.
