The present work was accomplished to evaluate the effects of storage on the viability of pollen grains from Natal, Pêra and Valência cultivars of sweet oranges. The grains were stored at 3 temperatures: -10ºC (freezer), 4ºC (refrigerator), and room temperature; 2 environments (with or without desiccator) and in the presence or absence of silica-gel. The germination was evaluated every 7 days, during 9 weeks. To evaluate the germination, a medium consisting of 1% and sucrose 10%, 800 mg L-1 calcium nitrate (Ca(NO3)2 4H2O), 200 mg L-1 boric acid (H3BO3) and pH 6,5 was used. The pollen was incubated at 25 ± 2ºC temperature for 12 hours. The evaluation was performed using the percentage of pollen grains germinated. It was observed that pollen grains viability diminished as the storage time increased; the storage in freezer temperature (-10ºC) was much more efficient than in refrigerator (4ºC) and in room temperature. The best results were reached when freezer and desiccator were used. Valência cultivar was superior when compared whit the others, in all treatments.
Citrus sinensis; Palinology; tissue culture; improvement varieties
