Determination of Potential Pollinizer Grafted Pear Hybrids (Pyrus communis × Pyrus pyrifolia) for Subtropical Regions in Brazil

The pear tree is originally a temperate-climate fruit tree. The cross Pyrus communis × Pyrus pyrifolia generated hybrid cultivars adapted to subtropical regions. However, the low effective fruiting is a limiting factor for the expansion of pear tree crops in subtropical regions and no pollinizer plants have been identified for these cultivars in subtropical regions. This work aimed to identify possible pollinizer pear tree cultivars in subtropical regions by evaluating the stigmatic receptivity, the germination percentage, and the number of pollen grains. Seven hybrid pear cultivars were used. Flowers of each cultivar at each floral stage were collected (E, E2, F, F2, and G). The stigmatic receptivity was evaluated by immersing the material in 3% hydrogen peroxide. Flowers were collected for the quantification of anthers, pollen grains per anther and per flower, and pollen grain germination. Stigmas were 100% receptive for all cultivars at the F2 and G stages. Cultivar Cascatense showed a large number of anthers and pollen grains per anther and per flower. The highest pollen grain germination percentage was detected for Cascatense (72.75%). Cultivars Seleta and Triunfo have high stigmatic receptivity for a longer period during the flowering stage, proven to be a potential female parent. Cascatense has a higher germination percentage and a larger number of anthers per flower, pollen grains per anther, and pollen grains per flower. Cascatense has a high potential to be used as a pollinizer, both in pear tree breeding programs and commercial orchards.