Pollen-pistil interaction in ‘Manzanillo’ olive (Olea europaea L.) under self-, free- And cross-pollination

Manzanillo’ olive (Olea europaea L.) cultivar suffers from pollination deficits that make it difficult for growers to achieve high productivity. This variety has been designated as completely self-incompatible by some authors, while others label it as partially self-incompatible. The aim of this study was to determine the degree of self-incompatibility and identify obstacles to self-fertilization in ‘Manzanillo’. For this, in a multivarietal orchard in El Ejido-Almería, Spain (36° 50’ NL, 2° 24’‘WL), a completely randomized experiment was established with four pollination treatments (self-pollination, free-pollination, and cross-pollination with pollen from ‘Picual’ and ‘Sevillano’). Pollen adhesion and germination, pollen tube growth and fertilization every three days after pollination were evaluated. Analyses showed no differences among treatments in pollen adhesion. The effect of pollination on pollen germination was erratic, because although free-pollination showed more germination than self-pollination at the beginning, the differences disappeared at nine days after anthesis. The clearest self-incompatibility reaction was detected in the growth of the pollen tube, with little and late growth of the pollen tube under self-pollination. The lowest fertilization rate was observed with self-pollination, and the highest with free-pollination.