Pollen Quantity, Viability and in vitro Pollen Germination of Longan (Dimocarpus longan Lour.)‏.

Abstract

Dimocarpus longan Lour. is an evergreen fruit tree species of Sapindaceae family grown in subtropical region. Short flowering period coupled with narrow genetic base are the major constraints in longan genetic improvement. Pollens are known to directly influence reproductive success and genetic structure of the plant population. In this study, we compared the pollen quantity, viability and in vitro pollen germination of M1 and M2 type flowers of nine longan genotypes. Acetocarmine, 2, 3, 5-triphenyl tetrazolium chloride, 2, 5-diphenyl monotetrazolium bromide and aniline blue-lectophenol staining methods were used for pollen viability assessment while different concentrations of sucrose, boric acid (H3BO3) and agar were used for in vitro pollen germination test through hanging drop technique. Pollen tube growth was evaluated by incubating the media containing pollen at different temperature and duration. Highest pollen quantity per anther (5278) was observed in M2 flower of Lgc-06. Acetocarmine (2.0 %) showed best results for pollen viability (94.37 %) in M2 pollen of Lgc-06. Germination media containing 15 % sucrose + 100 ppm Boric acid + 0.5 % agar showed promising results for pollen germination (80.33 %). Highest germination rate (83.66 %) and maximum pollen tube growth was observed at 30oC for 24 hours. Overall, pollen from M2 flower had significantly higher pollen quantity, viability and in vitro pollen germination percentage compared to pollen from M1 flower.