Potassium nitrate as apple cv. golden delicious (Malus domestica) dormancy-breaking agent

Abstract

Two experiments were carried out simultaneously in Fraiburgo and Rio das Antas-SC, with the objective of breaking dormancy on apple cv. Golden Delicious (Malus domestica, Borkh), where the effect of KNO₃ alone and in combination with the usual treatment-Triona B-5% + DNOC-0,12% was studied. The occurrence of many cold hour (temperature about 7.2°C or lower) caused a decrease in flowering response to the applied dormancy-breaking chemicals. Mineral oil +DNOC advanced flowering, bud-break and shortened the bloom period in Fraiburgo, but the effect of KNO₃ seemed to be more pronounced in Rio das Antas. Mineral oil + DNOC enhanced flower bud-break but this response was not reached with KNO₃. KNO₃ did not show significant effect during the flowering and production period while mineral oil + DNOC had pronounced influence in the third year of application.