Effects of Brassinosteroid, Naphthalene Acetic Acid and Gibberellic Acid on In vitro Pollen Germination of Bisexual and Functional Male Flowers of Pomegranate Cultivars

The two types of flowers (bisexual and functional male) on a pomegranate tree produce their own pollen. Having these different sources for pollen can enable growers or breeders to have an option for crossing purposes. With this point of view, pollen collected from both type of flowers of three cultivars, ‘Antalya–14', ‘Aşınar' and ‘Çekirdeksiz', were tested for their ability to germinate in vitro on a medium (1% agar and 20% sucrose) containing three different group of hormones, gibberelic acid (GA3), naphthalene acetic acid (NAA) and 24–epibrassinolide (EBR). After 24 hours of incubation, pollens were evaluated and germination ratios were determined. Germination ability of pollen from different flowers greatly differed depending on the cultivars. Bisexual flowers from ‘Antalya–14' and ‘Çekirdeksiz' had significantly lower ratio, but not in cv. ‘Aşınar'. Effects of the hormones were mostly dependent on pollen source, type and concentration and also cultivar. GA3 reduced the ratio in bisexual flowers but the effect on functional males was not in the same manner. NAA caused a decrease in all pollen germination. EBR on the other hand, generally increased it while this influence was mainly related with the flower type and cultivar. A deduction can be made as cultivars with high germination ability in their male flowers could ensure adequate pollination and/or can be used as pollinators for other cultivars.