Morphophysiological Responses of Black Pepper to GA3: Growth, Photosynthesis, Carbohydrates and Flowering

Black pepper (Piper nigrum L.) faces challenges related to irregular flowering, which compromises crop productivity. Gibberellic acid (GA3) is a plant growth regulator known for its role in inducing reproductive processes, although its effects on this species are not yet fully understood. This study aimed to evaluate the influence of different GA3 doses on flowering and vegetative growth in black pepper plants. The experiment was conducted with black pepper seedlings of the Bragantina cultivar in a randomized block design, with four doses of GA3 (0, 10, 20, and 30 mg L−1) and six replications, using eight-month-old plants grown in pots under full sun. GA3 applications were performed in two floral induction cycles. Variables related to flowering, chlorophyll a fluorescence, vegetative growth, biomass allocation, and carbohydrate distribution were evaluated. The data were subjected to analysis of variance, regression analysis, mean grouping tests, and principal component analysis. The results showed that intermediate doses (10 and 20 mg L−1) significantly stimulated flowering at early developmental stages, whereas the 30 mg L−1 dose enhanced vegetative growth while reducing floral induction. Additionally, GA3 affected physiological parameters by increasing photosynthetic efficiency and altering carbohydrate balance, with higher accumulation of soluble sugars in leaves and reduced starch content in roots. It is concluded that GA3 application is a promising strategy to modulate reproductive transition in black pepper, with 10 to 20 mg L−1 doses recommended to promote flowering without compromising plant development.