Flowering response of Vanilla planifolia and a Vanilla planifolia x Vanilla pompona hybrid to apex decapitation, in intensive crop management system

In this work, we monitored the flowering phenology of two vanilla varieties (Ordinary V. planifolia and a V. planifolia X V. pompona hybrid) cultivated under intensive cultivation conditions. Thirty-three vine and stem development parameters were monitored during the first three flowering cycles. Data analyses at the plot, plant and stem scales, shed light on the vanilla development parameters influencing flowering probability and intensity. Thus, the effectiveness of manual decapitation to promote flowering, a practice commonly adopted empirically by vanilla growers, was formally confirmed. Flowering was hastened by one year (~46% increase in plant flowering probability in the cycle 2 for both varieties), and the quantity of inflorescences increased by 5 to 178% at plot scale, fluctuating notably with the flowering year and stem rot prevalence caused by a fungus of the genus Fusarium. The high beneficial impact of apex decapitation on flowering intensity the year following the decapitation was highlighted, with decapitated stems aged 16-20 months showing the greatest flowering rates compared to decapitated stems aged 4-8 months or 28-32 months. According to our results, practicing manual decapitation starting from the second year after planting should be recommended, as it reduces the time to first flowering and increases the number of inflorescences. However, given the complex interactions observed between the parameters studied, further research is needed to evaluate the long term effects of apex decapitation in different environmental and agronomic conditions.