Viabilidade do pólen de citrus em diferentes condições de armazenamento

Abstract

The conventional plant breeding programs look for the quick and easy identification procedures to keep the pollen grains viable for long periods of time in order to give more flexibility to the plant breeding workers. This present work was made trying to evaluate the viability of the storaged pollen grain from citric varieties 'Natal', 'Pêra' and 'Valência'. The floral buds were picked up in the ‘balloon’ stage. The anthers were separated from the floral structures and kept under temperatures of 28°C ± 1°C by 48 hours until the antese’s occurrence. The pollen was stored in glass jars and kept under 3 storage temperatures: -10ºC (freezer), 4ºC (refrigerator), and room temperature; 2 environment (with and without desiccator) and in sílica-gel presence and absence. The germination index evaluation was made with fresh pollen every 7 days during 9 weeks. To evaluate the germination was used Petri dishes with agar 1% and sucrose 10%, 800mgL-1 calcium nitrate (Ca(NO3)2 4H2O), 200mgL-1 boric acid (H3BO3) and pH 6,5. The pollen was spread over the culture medium surface and incubated at 25 ± 2°C temperature for 12 hours. The evaluation was made using thepercentage of pollen grains germinated, it was looked under light optical microscope with 4 repetitions. It was then observed that the pollen grains reduce their viability was the storage time increases; the storage in freezer temperature (-10ºC) was much more efficient than in refrigerator (4ºC) and to room temperature. The better results were reached when were used freezer and desiccator. 'Valência' variety showed superior when it was compared to the others, in all treatments.