EFFECT OF POLLINATION OF ONION SEEDS UNDER ISOLATION BY THE RED MASON BEE (Osmia rufa L.) (Apoidea, Megachilidae) ON THE SETTING AND QUALITY OF OBTAINED SEEDS Zdzis³aw W ilkaniec, K arol G iejdasz, Grzegorz P rószyñski

Summary The aim of the experiment was to assess the results of the pollination of seed onion by the red mason bee Osmia rufa L. in isolated conditions in comparison with self-pollination and free pollination. The results allowed the authors to conclude that Osmia rufa is an effective onion pollinator. Even though the mean number of fruits in the inflorescence set as a result of onion flower pollination by Osmia rufa, was lower than that resulting from free pollination, the percentage of pollinated flowers, which set seeds in the total number of flowers in the inflorescence was very similar in both systems of pollination. In addition, the total seed yield as well as the weight of 1,000 seed did not differ in the case of the pollination by the solitary bee and free pollination. Seeds set as a result of the pollination by the solitary bee and free pollination were characterized by the best germination capacity and energy. Self-pollinated onion inflorescences produced the lowest seed yields, which were, in addition, characterized by low germination capacity and energy.