Alternative products in the budbreak of ‘eva rubi’ apple trees under subtropical climate conditions

Abstract

The apple tree requires chilling accumulation for budbreak. In locals where the chill accumalition is insufficient, chemical promoters are used to induce uniform budburst.  However, alternatives that minimize damage to the environment and applicator have been sought. Thus, the aim of this work was to evaluate the efficiency of hydrogen peroxide, pau-d'alho hydrolate, lime sulphur and neem oil in inducing budbreak of ‘Eva Rubi’ apple tree in agroecological cultivation. Different concentrations (0%, 5%, 10%, 15% and 20%) of pau-d'alho hydrolate and hydrogen peroxide were tested in Palmas and Pato Branco. Three additionals treatments were added in the Lapa region, where mineral oil 3%, Dormex 0.5%, and Dormex 0.5% + 3% mineral oil were applied. In 2023, a new experiment was carried out only in Pato Branco, repeating the same concentrations of pau d'alho hydrolate and including new treatments with lime sulphur (1, 2, 3 and 4%) associated with 3% Neem oil. Percentage of budbreak, fruit set, productivity, and fruit mass were evaluated. The treatments showed no difference in the analyzed variables for Pato Branco and Palmas. In Lapa, there was an improvement in the percentage of budbreak in the plants treated with 15% ‘pau d'alho’ hydrolate, but still insufficient to state that this product can be used as budbreak inducer, however it suggests potential use, requiring, for that, the continuity of research in other species and experimental conditions. No phytotoxic effect was observed for hydrogen peroxide and ‘Pau d’alho’ hydrolate at the studied dosages.