Production regularity of ‘Ponkan’ mandarin trees submitted to chemical thinning

Resumo

Alternate bearing is a problem that has influenced the productivity and fruits quality of ‘Ponkan’ mandarin trees. The aim of this research was to evaluate the effect of chemical thinning on alternate bearing and productivity of ‘Ponkan’ mandarin tree. Ten-year-old plants grafted on ‘Rangpur’ lime (Citrus limonia Osbeck) were evaluated in a commercial orchard from December 2006 to July 2008. Five Ethephon concentrations were applied: 0, 150, 300, 450 and 600 mg L-1 in two fruit development stages (30 mm and 40 mm of transverse diameter). The experiment was set in a 5×2 factorial scheme, in randomized blocks with four replications. In the first year after chemical thinning with Ethephon the productivity was evaluated in plants of different treatments. In the second year the alternate bearing and the productivity were evaluated. The chemical thinning promotes yield regularity in ‘Ponkan’ mandarin trees, with the application of Ethephon at concentrations between 300 mg L-1 to 600 mg L-1. Plants sprayed with 600 mg L-1 of Ethephon produced fruit higher amounts in following year to thinning.