Hormonal balance during floral development in Coffea arabica

Abstract

In Coffea arabica, phenological stages are influenced by climatic conditions. Factors such as photoperiod, rain, and temperature affect the hormone concentration in coffee plants, which can induce the transition of plants from the vegetative to the reproductive stages. During the period from flowering induction to bud formation, different hormones play specific roles in regulating flowering and subsequent fruit production. It is believed that hormones such as gibberellins (GA), abscisic acid (ABA), salicylic acid (SA), and ethylene, may be involved modulating the expression of genes involved in flowering induction and development. Therefore, this study aimed to investigate the hormonal regulation during the reproductive period of coffee plants. To better understand hormonal regulation, leaf and flower bud samples were collected monthly from March (induction of flowering) to September (after anthesis), and the endogenous concentrations of GA1, GA3, ABA, and AS were quantified. These variations in hormone levels were compared to environmental conditions recorded during the reproductive period. The following year, plant growth regulators corresponding to these hormones were applied in the field, specifically in March. Samples were collected pre- and post-application, and hormone concentrations were quantified to determine whether the applied dosage modulated endogenous levels. This study revealed that hormonal balance is contingent on environmental factors and tissue specificity throughout each developmental stage. Furthermore, this research proposes specific dosages for future studies involving the application of plant growth regulators in Coffea arabica. Finally, this study demonstrates how the regulation of these plant hormones occurs during the reproductive stage of coffee, enabling the development of strategies for applying growth regulators in the field to modulate reproductive development.