In vitro pollen germination of Betula utilis, a typical tree line species in Himalayas

Abstract

The study was conducted to determine the optimum medium for in vitro pollen germination for B. utilis based on germination percentages and length of the pollen tube. Studies about pollen germination and tube growth of B. utilis are limited. Therefore, this study aimed to investigate the effects of sucrose (1, 3, 5, 10 and 15%), boric acid (25, 50, 100 and 200 ppm), calcium nitrate (50, 100, 200, 300 and 400 ppm), magnesium sulfate (50, 100, 200 and 300 ppm) and potassium nitrate (50, 100 and 200 ppm) and time of incubation on pollen germination and tube growth. Pollen germination rates and tube growth were recorded periodically at 2, 4, 6, and 10 h. The length varied significantly with different concentrations and incubation time. The germination rate and pollen tube length varied significantly with different concentrations and incubation time. Pollen germination was maximal (98 ± 6.1%) when the germination medium contained 10% sucrose solution supplemented with 100 ppm H3BO3, 300 ppm Ca(NO3)2, 200 ppm MgSO4 and 100 ppm KNO3, after 6 h of incubation. In addition, results revealed that pollen grains collected immediately after anther dehiscence showed the best germination ability but gradually decreased with time.