Effect of low temperatures during flowering on floral cycle and pollen tube growth in nine avocado cultivars

The floral response of the type A avocado cultivars ‘Reed’, ‘Wurtz’, ‘Rincon’ and ‘Jalna’, and the type B cultivars ‘Bacon’, ‘Ryan’, ‘Edranol’, ‘Sharwil’ and ‘Hazzard’ was tested under growth-cabinet conditions of 17° C day, 12° C night, with a 12-h photoperiod and photon flux density of 400 μE m^?2 s^?1 (400–700 nm). Most of the flowers of all type A cultivars and the type B cultivar ‘Bacon’ had both a female and a male stage. None of the flowers of the other type B cultivars had a female stage but opened in the male stage only. Hand pollination resulted in some ovule penetration in the cultivars with female stage flowers. In those with only male-stage flowers, the pollen tubes grew no further than the style. Maintenance of fertility under low-temperature conditions during flowering appeared to be partly, but not entirely, linked to the type A flowering cycle.