Budburst and flowering intensity by the spraying of dormancy-breaking products in ‘Eva’ apple trees

Abstract

Spraying of dormancy-breaking chemicals is a mandatory procedure to produce temperate fruits in low-chill regions. Although hydrogen cyanamide (HC) + mineral oil (MO) show efficiency enhancing budburst, the usage of HC is restricted in some countries due to its toxicity. Therefore, this research aimed to evaluate the efficiency of spraying different dormancy-breaking agents on ‘Eva’ apple tree buds, under the conditions of the Depressão Central of Rio Grande do Sul, Brazil. Different doses of Erger® (0, 2, 3, 4, 5%) + 3% Ca(NO3)2 were tested and compared with MO (4%) or MO (4%) + HC (0.6%). Budburst rate of apical and axillary buds, physiological alterations in buds, return bloom, yield and fruit weight were evaluated. Erger® treatments efficiently enhanced budburst, with a result equivalent to HC + MO treatment. The budburst rate increased as the Erger® dose increased, also causing the increment of the return bloom in the following year. However, doses of 4 and 5% caused the death of shoots. The activity of the peroxidases and the content of H2O2 in the buds were affected by the treatments. Yield and fruit mass were different in response to treatments, although the effect varied between years. Erger® + Ca(NO3)2 spraying increase budburst in apical and axillary buds of ‘Eva’ apple tree in low-chill conditions and doses up to 3% of the commercial product do not cause toxicity.

Advancing Sustainability in Tree Crop Pest Management: Refining Spray Application Rate with a Laser-guided Variable-rate Sprayer in Apple Orchards

“…As a consequence, growers traditionally applied pesticides lib-erally, spraying to the point of runoff to ensure sufficient control of pests that have the potential to devastate crops, including those pests for which a small amount of damage can result in significant economic losses. This practice is still common despite some modern pesticide labels recommending lower spray volume application rates (Darde et al, 2019;Lordan et al, 2019;Walklate et al, 2003). Moreover, in crops where there are dense canopies or multirow production blocks, such as orchards and nurseries, large volumes of spray solution are applied by airassisted sprayers to ensure adequate spray deposition in the interior of the canopy, regardless of whether the tree is positioned in an exterior or interior row (Zhu et al, 2017).…”

Effect of Hydrogen Cyanamide on Bud Break, Fruit Yield and Quality of Highbush Blueberry in Greenhouse Production

“…Campoy et al ( 2011) observed advanced blooming and harvest times for 'Early Maycrest' peach plants when they were treated with HC in combination with mineral oil [34]. Similarly, the application of 0.6% HC in combination with 4% mineral oil to 'Eva' apple trees can also effectively promote earlier vegetative and reproductive bud break [6]. In our study, application of HC alone or in combination with GA 3 , mineral oil, and KNO 3 , as well as ethephon promoted budbreak and fruit ripening in highbush blueberry (Table 2), and there is no clear difference in the effect on advancing budbreak and fruit ripening among different treatments.…”

“…Some chemical products, such as gibberellins (GA) [4], cytokinins [5], mineral oil (MO) [6], and potassium nitrate (KNO 3 ) [7] have been shown to exert a positive effect on the release of dormancy and thus on bud break when applied at the right concentration to the buds of many fruit crops. Hydrogen cyanamide (HC) is the most effective of a range of chemicals used to advance and synchronize bud break, promote early ripening, and increase fruit productivity in deciduous fruit trees [8][9][10].…”

“…Hydrogen cyanamide (HC) is the most effective of a range of chemicals used to advance and synchronize bud break, promote early ripening, and increase fruit productivity in deciduous fruit trees [8][9][10]. Hydrogen cyanamide can also be used in combination with mineral oil [6], abscisic acid [11], gibberellins [12], and garlic extracts [13].…”

“…The application concentration of the dormancy breaking agents is the key to successful dormancy breaking. It has been confirmed in many practical applications of fruits that low-concentration dormancy breaking agents cannot release plants from dormancy, and high-concentration can cause serious phytotoxicity to plants [6]. The optimal concentration range varies with treatment time, plant species, tree vigor and production system, and the appropriate concentration under specific conditions needs to be determined through experiments.…”