Study of pollen-pistil interactions on crosses between 'Rocha' pear and potential pollinators.

摘要

Currently, 'Rocha' pear production relies mainly on spraying with growth regulators, as this cultivar can set fruit parthenocarpically. The identification of suitable pollinators and cross pollination is of the most important for the development of alternatives, which are safer to consumers and to the environment. Observations of pollen-pistil interactions between the cv. Rocha and potential pollinators were carried out through fluorescence microscopy. Crosses with 'Aurora' and 'Limonera' and selected 'Rocha' clones, Clone 1, Clone 2, Clone 4c, Clone Z and Clone T behaved as incompatible. But, 'Beurre Precoce Morettini', 'Doyenne du Comice', 'Passe Crassane', 'Clapp's Favourite', 'General Leclerc', 'Beurre d'Avril', 'Coscia', 'Tosca', 'Carapinheira', 'Amendoa' and 'Agua' showed themselves to be compatible with 'Rocha'. The percentage of styles with pollen tubes at the base of the style varied between 0 and 4% in the incompatible crosses and between 61 and 96% in the compatible crosses. The number of pollen tubes registered per flower varied between 0-0.04, in the first case, and 4.1-8.9 in the latter. These results analysed in combination with the S genotypes for these cultivars showed that crosses between cultivars either sharing a common allele or with two different alleles were indistinguishable in terms of pollen tube growth in the style and presumably this can explain why other authors have not found differences in fruit set. These results also confirm previous work conducted by other groups on the molecular identification of the S-alleles coding for the S-RNases involved in the self-incompatibility mechanism.