Strategies for Increasing the Apple Epidermis Red Colored with Physiogrow® Color

Aims: Evaluate different dosages and number of applications of the commercial product Physiogrow® Color on the percentage of red coloration of the epidermis, productivity and fruit quality in 'Royal Gala' apple trees, in the Midwest region of the state of Santa Catarina, Brazil.

Study Design: The experiment was arranged in a randomized block design with five replications. Place and Duration of Study: The experiment was carried out in the municipality of Fraiburgo-SC, Brazil (latitude 27º01'S, longitude 50º77’ W, altitude 950 meters), during the growing seasons of 2017/2018 and 2018/2019.

Methodology: The treatments were: Control (No application), Physiogrow® color (4, 8 and 12 L ha-1) 7 days before harvest (DBH), Physiogrow® Color 2 L ha-1 (30 DAC) + 2 L ha-17 DBH, Physiogrow® Color 4 L ha-1 (30 DBH) + 4 L ha-17 DBH, and Physiogrow® Color 6 L ha-1 (30 DBH) + 6 L ha-1 7 DBH. The variables evaluated were: Production (kg plant-1 and fruits plant-1), average fresh fruit mass (g), classification of fruits by percentage of red coloration of the epidermis (<50%, 50-80% and > 80%), firmness of the pulp (lb in-2) and soluble solids (°Brix). The harvest was carried out on January 25, 2018 and February 16, 2019, first and second year, respectively. Plant production, as well as pulp firmness of fruits, were not affected by treatments, in both years. Physiogrow® Color promoted better distribution of fruits in categories of greater red coloration of the epidermis and reduction of the percentage of fruits in the category with coloration inferior to 50%, although a different behavior among the harvests was observed. The application of Physiogrow® Color 8 L ha-1 7 DBH contributes to the improvement of the coloration of ‘Royal Gala’ apples.