Influence of Storage Temperature on Viability and In Vitro Germination Capacity of Pear (Pyrus spp.) Pollen

Pollen viability and germination capability in three pear cultivars viz. Pathernakh, Punjab Beauty and Shinseiki were investigated up to 12 weeks (3 months) stored at different temperatures i.e. room temperature, refrigerator (40oC), freezer (-20oC) and liquid N (-120oC). Viability was tested in 2 per cent acetocarmine solution whereas, for in Vitro pollen germination pollen grains were germinated in 10 percent sucrose solution at weekly intervals. The pollen viability and in Vitro germination percentages of the genotypes were significantly affected by storage temperatures. The pooled data for a period of two years revealed that average viability varied from 40.68% (Shinseiki) to 48.75% (Patharnakh) whereas, germination percentage varied from 34.93% (Shinseiki) to 42.81% (Patharnakh) among the cultivars under study. Pollen stored at low temperature (-120oC and -20oC) showed better viability and germination percentage as compared to pollen stored at room temperature and 4 oC. The cultivar Patharnakh had maximum viability and germination percentage when pollen were stored at -20 (67.40% and 59.62%, rsespectively) and -196? (68.06% and 61.83%, respectively), followed by Punjab Beauty and Shinseiki. The results indicate that pollen collected and stored at sub-zero temperatures from early blooming pear varieties can be stored for very long period without any appreciable loss of viability and germination and can be used along the whole blooming season for hybridization programmes by fruit breeders even at distant places for the development of new strains so as to widen the genetic base and create variability in pear.