The effect of pollen donors and pollen viability on fruitlet drop in Macadamia integrifolia (Maiden & Betche)

Abstract

Fruitlet drop in 'Beaumont' macadamia [Macadamia integrifolia (Maiden & Betche)] is marked and rapid immediately after fruit set but slows steadily as the fruits mature. To assess the effect of pollen donors on fruitlet drop, both pollen viability, based on pollen germination, and fruitlet viability, after hand-pollination, were analysed. Pollen viability of nine cultivars, namely 'Bond 23', Ikalka', 'Kakea', 'Keauhou', 'Yonik', '14/14', '764', 'Cate', and 'Beaumont', was assessed during two years by germination on artificial medium. 'lkalka' had the highest pollen viability with 84%, and 'Cate' the poorest with 45%. Hand-pollination of 'Beaumont' with nine cultivars as pollen donor was carried out during two years. Fruitlet survival was determined a few weeks after pollination. 'Keauhou' had the highest number of fruitlets cm-1 of inflorescence five weeks after pollination, while '764' had the lowest number of fruitlets.