High dilutions of zinc sulfate on management of thrips and yield of onion in an organic production system

Resumo

The cost of onion cultivation in conventional systems in Santa Catarina (SC), Brazil, is high due to the use of agrochemicals, which pose risks to the farmers’ health and contaminate the environment. The aim of the present study was to evaluate the effect of high dilutions (HD) of zinc sulfate on the incidence of and damage by thrips, physiological maturation and yield of onion in an organic production system. The study was conducted over three years from 2011to 2013 at Ituporanga Experimental Station, Epagri, SC. Treatments consisted in zinc sulfate HD administered in foliar sprays in dilutions 6cH, 12cH and 30cH and untreated control. The experiment was performed in randomized blocks and four replications. The incidence of and damage by thrips, chlorophyll index and yield were not affected by the treatments. The postharvest storage of onion bulbs with HD of zinc sulfate was fit to the following model in 2011: y= 0.014.x³ -0.626.x² +5.894.x +56.21 (R²= 0.56,p= 0.02).