Effects of 1-Naphthaleneacetic Acid on the Panicle and Fruit Characteristics of ‘Irwin’ Mango Trees

Excessive vegetative growth of mangoes inhibits reproductive growth during greenhouse cultivation, resulting in a loss of fruit production. To investigate the effect of a 1-naphthaleneacetic acid (NAA) treatment, two concentrations (30 and 70 mg·L-1) were applied to the shoot apices of ‘Irwin’ mango cultivars. With changes in greenhouse temperatures, the characteristics of the reproductive organs were determined at BBCH (Biologische, Bundesanstalt, Bundessortenamt, and Chemische Industrie) scales of 615 and 809. During flower bud initiation, the maximum temperature reached 35°C, and the minimum temperature dropped to 5°C; the daily difference ranged from 1.3 to 23.9°C. The NAA treatment induced increased panicle emergence rates and reduced panicle malformation. In the flowering pattern, the flowering time was reduced, especially with 70 mg·L-1 NAA. The relative panicle quality index indicated that trees treated with 30 mg·L-1 NAA had the highest value, followed by the control and those treated with 70 mg·L-1 NAA. Additionally, the NAA treatment significantly increased fruit diameters and weights compared to the control. However, firmness decreased after the NAA treatment. Overall, this study highlights the potential of a NAA treatment as a tool for improving the yield and quality of mango crops, particularly under challenging environmental conditions.