Fruit set and yield of apple trees cv. Gala treated with seaweed extract of ascophyllum nodosum and thidiazuron

Abstract

Abstract The low effective fruiting is one of the biggest problems of apples’ production in Brazil and its main cause involves the process of pollination. The objective was to evaluate the fruit set and production of apple trees cv. Gala treated with extract of seaweed Ascophyllum nodosum and thidiazuron. The experiment was carried out during two cycles (2015/2016 and 2016/2017) in Porto Amazonas, State of Paraná, Brazil, with apple trees cv. Gala. The following treatments were applied at full bloom: thidiazuron at 10 and 15 mg L-1, Ascophyllum nodosum seaweed extract (Algamare®) at concentrations of 0.1, 0.2, 0.3, 0.4 and 0.6%. No treated plants were used as control. It was evaluated: fruit set, number of fruits, fruit weight, yield per plant, number of seeds per fruit, length and diameter of fruit, length/diameter ratio (L/D), titratable acidity, soluble solids, firmness and growth of shoots. The algae extract presented similar effects of thidiazuron in apple trees, promoting, in at least one of the cycles, the increase in fruit set, number of fruits, weight and length of fruits without changing their maturation. The application of Algamare® at 0.3% was the most effective treatment for yield improvement in ‘Gala’ apples.