Investigation of biological characteristics of fruit development and physiological disorders of Musang King durian ( <i>Durio zibethinus</i> Murr.)

Abstract This study investigates the biological characteristics of fruit development and physiological disorders in the Musang King durian ( Durio zibethinus Murr.). The experiment was conducted on 20 7-year-old trees cultivated in Nhon Nghia commune, Phong Dien district, Can Tho City, from October 2023 to July 2024. The results revealed a 7-day flowering period post-first bloom, with peak blooming observed between the second and fourth days. Flower opening commenced at 16:00–17:00 h, achieving a fruit set rate of 93%. Fruit development spanned 90 days after fruit set (DAFS) and was characterized by three distinct growth phases: slow growth (0–28 DAFS), rapid growth (28–70 DAFS), and ripening (70–90 DAFS). Immature fruit drop primarily occurred within the first 14 days (35.0%). The fruit’s flesh began to form at 42 DAFS, reaching its maximum growth rate by 56 DAFS. At harvest, fruits averaged 2161.8 ± 74.7 g, with an edible portion constituting 24.8% of total weight. Physiological disorders, including hardened flesh and discoloration, were first observed at 70 DAFS (16.7%), increasing to 30.0, 6.7, and 13.3% at harvest for hardened flesh, aril tip burn, and flesh discoloration, respectively. These disorders significantly impacted commercial fruit quality.