Ammonium thiosulfate as blossom thinner in 'Maxi Gala' apple trees

Abstract: The objective of this work was to evaluate the feasibility of using ammonium thiosulfate as a chemical blossom thinner in 'Maxi Gala' apple (Malus domestica) trees and its effects on fruit quality. The experiment was carried out in an experimental orchard in the Southern Brazil, in a randomized complete block design, with five replicates. Ammonium thiosulfate was sprayed on the apple trees at the full bloom stage, at 0, 1.5, 2.5, and 3.5%. Evaluations were performed for the effects on crop load, fruit set, yield efficiency, and fruit quality parameters such as weight, shape, total soluble solids, seed number, flesh firmness, color, and russeting occurrence. Ammonium thiosulfate at 2.5% is effective to reduce crop load and to improve fruit quality. The thinning effect of ammonium thiosulfate is not dependent on the weather conditions during the crop season. The rate of 3.5% of ammonium thiosulfate causes overthinning and does not result in the improvement of fruit quality.

摘要：本研究旨在评估硫代硫酸铵(ammonium thiosulfate)作为‘Maxi Gala’苹果（Malus domestica）化学疏花剂的可行性，及其对果实品质的影响。试验于巴西南部一处试验果园开展，采用随机完全区组设计，设置5次重复。于盛花期对苹果树喷施浓度分别为0、1.5%、2.5%及3.5%的硫代硫酸铵溶液。本研究针对硫代硫酸铵对挂果量、坐果率、产量效率以及单果重、果形、总可溶性固形物含量、种子数量、果肉硬度、果皮色泽和果锈发生情况等果实品质指标的影响进行了评价。结果表明，2.5%浓度的硫代硫酸铵可有效降低挂果量并改善果实品质；其疏果效果不受作物生长季天气条件的影响；3.5%浓度的硫代硫酸铵会造成过度疏果，且无法提升果实品质。