Glucose performs better than fructose, sucrose, and diluted nectar for germination of banana pollen

Abstract

Poor stigma receptivity is one of the limitations to seed set in East African Highland Bananas (EAHBs) that constrains their improvement through conventional breeding. This study aimed at identifying a suitable pollen germination media (PGM) for faster germination of banana pollen both in vitro and in vivo. PGM was prepared by dissolving 0.01 g H3BO3, 0.25 g MgSO4.7H2O, 0.25 g KNO3 and 0.4 g Ca(NO3)2 in 1 L along with different sugars. Sucrose, glucose, fructose, glucose + fructose, and glucose + fructose + sucrose at six concentration levels of 10, 30, 50, 100, 150 and 200 g L-1 were tested. Pollen from Calcutta 4 and TMB2x8075-7 diploid bananas was dusted on a cover slip and slowly lowered over four drops of PGM on a glass slide. The set up was incubated in a humid chamber for 3 h and germinated pollen counted using a light microscope at X40 magnification. Results revealed that glucose at 10 and 30 g L-1 concentration performed best with the latter having the higher pollen germination percentage. Results from comparison of 30 g L-1 glucose PGM with diluted banana nectar from Tereza and TMB2x8075-7 showed that 30 g L-1 glucose PGM generated highest pollen germination. It is suggested that glucose being a monosaccharide is a more readily available energy source for pollen. When 30 g L-1 glucose PGM was applied on stigmas after pollination, stigma receptivity was enhanced.