Studies on the morphology of stamens and pollen grains in some cultivars of Spanish chestnut (Castanea sativa Mill.)

Sweet chestnut (Castanea sativa Mill.) is a multi-purpose species cultivated for timber and nuts. However, recent years have seen a reduction in chestnut production. There are several reasons for this including abandonment of traditional cultivation practices, plant diseases, and problems during pollen differentiation. It appears that reduction in chestnut yield, recorded over recent decades, is associated with a decrease in the trees with longistaminate catkins, which are low yielding, but are fundamental for efficient pollination and the successive fertilization. Present study has been undertaken to provide new insights into the stamen and pollen morphology of four Andalusian chestnut cultivars (‘Helechal’, ‘Temprana’, ‘Vázquez’,‘Ancha de Alàjar’). It was observed that catkins in these cultivars are brachistaminate, and poor fertilization capability. The cultivar ‘Vázquez’ showed the longest stamens, and also the highest percentage of normal pollen and therefore, show highest fertilization capacity. On the other hand, shortest stamens and the lowest percentage of normal pollen grains, were recorded in cultivar ‘Ancha de Alàjar’ which cannot be considered a good pollinator.