Duration of the Phenological Stages of Peach Trees at Tropics

This study aims to evaluate the duration of the phenological stages and determine the adaptability and stability of reproductive and vegetative phases of peach trees under tropics with the purpose of optimizing the production system. The experiment was set up in a randomized plot design with 23 cultivars (‘Aurora-1’, ‘Biuti’, ‘Bonão’, ‘Centenário’, ‘Charme’, ‘Delicioso Precoce’, ‘Diamante’, ‘Douçura-2’, ‘Douradão’, ‘Dourado-2’, ‘Eldorado’, ‘Flordaprince’, ‘Jóia-3’, ‘Kampai’, ‘Libra’, ‘Maciel’, ‘Maravilha’, ‘Marli’, ‘Okinawa’, ‘Ouromel-4’, ‘Premier’, ‘Régis’, and ‘Tropical’) in 2014-2016. The average duration (in days) for the three years, between pruning day and each phenological stage (OS - sprouted buds had opened, onset of flowering – OF, full bloom – FB, end of flowering – EF, beginning of fruit harvest - BH, and end of harvest - EH) in each plot, was evaluated through visual observations including the chill hours accumulation(CA) of each cultivar for accumulated number of hours with temperatures (≤7.2°C), (≤12°C) and (≥25℃), the thermal demand, expressed in degree-days of development (GDD) and the adaptability and stability of OS and EH. ‘Eldorado’ was the latest-ripening cultivar and the precocious cultivars were earliest ripening ‘Aurora-1’, ‘Centenário’, ‘Flordaprince’, ‘Kampai’ when considering OS, OF, FB and EF. The cultivar ‘Eldorado’ was sooner considering BH and EH, but it has a high standard deviation; that is, high variation among the years. The latest, when considering BH and EH, was the cultivar ‘Biuti’. Overall, 2016 was the year with the highest CA (≤7.2 ℃ and ≤12 ℃) and with more hours under warm temperatures (≥25 ℃) for OS, OF and FB. Regarding GDD until OS, OF and FB the cultivar with the highest GDD was ‘Eldorado’ and the lowest were ‘Aurora-1’, ‘Centenário’, ‘Flordaprince’, ‘Jóia-3’, ‘Kampai’, ‘Okinawa’, ‘Régis’ and ‘Tropical’. ‘Biuti’ had the highest GDD for BH while the lowest was ‘Eldorado’. ‘Douçura-2’ had general adaptability for OS and EH. The most precocious cultivars, with the greatest adaptability for sprouting and flowering in the tropics, were ‘Aurora-1’, ‘Joía-3’, ‘Kampai’, and ‘Tropical’.