Résumé
Oil palm (
Elaeis guineensis
Jacq.) produces bunches throughout the year, following annual cycles marked by a peak season, with genetic diversity regarding the regularity of the annual profile of bunch production. The aim of this study was to understand this diversity among a set of oil palm crosses. We hypothesized that this diversity originated from differential responses to water balance and bunch load. Seven crosses with different production cycles were studied during 6 years in Benin, where dry seasons are marked. Phenological stages of phytomer development were recorded from leaf appearance to bunch harvest. Inequality in the distribution over the months of the year of phytomers at each stage was quantified using the Gini coefficient. We found that annual variations in the rate of early abortions, sex ratio, time between leaf opening and appearance of female inflorescence (AFI) and time between AFI and flowering strongly contributed to the diversity in production profile among crosses. To a lesser extent, annual variations in the time of bunch maturation also generated diversity in the production profile. Sex ratio was positively correlated with water balance and negatively with bunch load when leaves were around axil number -25 (approximately 29 months before harvest). Early abortions were positively correlated with bunch load when leaves were at axil number 10 (approximately 9 months before harvest). Correlations varied among crosses, indicating differential responses of crosses to variations in water balance and bunch load, which eventually created significant diversity among crosses regarding the regularity of bunch production profiles.