Enhancing Flowering and Nut Development of Tacunan Dwarf Coconut (Cocos nucifera L.) through Plant Growth Regulators

Abstract

Coconut production in Central Visayas, Philippines, is increasingly constrained by climate variability, recurrent drought, and alkaline soils that disrupt the reproductive cycle and limit yield by reducing spathe emergence, flower development, flowering time, and nut retention. This study evaluated plant growth regulators (PGRs) for enhancing reproductive performance in the Tacunan dwarf coconut (Cocos nucifera L.). Using a randomized complete block design, four treatments were applied to 10-year-old palms: control, auxin (100 ppm), ethylene (100 ppm), and combined auxin–ethylene (50 ppm each). Treatments produced distinct responses. Auxin accelerated spathe emergence by 16 days and raised female flower production to 90.50 per palm by week 8, yielding earlier and more prolific flowering. Ethylene reduced flower number to 58.16, but shortened time to flowering to 88.75 days and improved nut retention to 70.50 nuts per month, versus 46.33 in the control. The combination treatment gave intermediate results, indicating responses constrained by dosage or hormonal antagonism. Button shedding and delayed flowering, typically induced by alkaline soil (pH 7.98) and drought, were partially mitigated by auxin and ethylene, leading to enhanced cell enlargement and regulation of pollination. Although the four-month duration was insufficient to assess effects on nut size and weight, the results provide novel empirical evidence that PGR interventions improve coconut reproductive performance and establish a baseline for long-term strategies to stabilize coconut yields under stress-prone conditions.