Autonomous self-pollination provides reproductive assurance, whereas insect pollination enhances yield in sesame under tropical field conditions

Abstract

Sesame (Sesamum indicum L.) exhibits a mixed mating system, in which both self- and cross-pollination can occur. In tropical environments, the contribution of pollinators may enhance fertilization efficiency and increase crop yield. This study aimed to evaluate the role of pollinators in sesame production and its degree of pollinator dependence. Two experiments were carried out in Cruz das Almas, Bahia, Brazil. In the first, open-pollinated plants were compared with pollinator-excluded plants (cages) to assess grain yield, yield components and seed quality. In the second, pollination requirements were investigated using five treatments: open pollination, pollinator exclusion (paper bags), wind-mediated pollination (cages), geitonogamous pollination and hand cross-pollination. Open-pollinated plants produced a greater number of fruits and seeds per fruit, resulting in greater grain yield. In contrast, seed mass, number of branches and physiological seed quality were not affected by pollination treatments. Seedling dry biomass was greater in the presence of pollinators. Overall, grain yield was 28.6% greater under open pollination, corresponding to a pollinator dependence of 22%. Controlled pollination treatments showed that self-pollination provides reproductive assurance under pollinator limitation, whereas insect pollination enhances reproductive performance. Sesame exhibited a mixed mating system, with self-pollination and insect-mediated pollination acting complementarily. This balance helps ensure stable production, while pollinators play an important role in maximizing yield under tropical agricultural conditions.