2.3 Assessment of male gametophyte fertility
Viability of the male gametophyte was determined by microscopic
observation of pollen grains stained with Alexander’s stain
(Alexander, 1967) using Nikon Eclipse 90i
microscope with attached Nikon DS-Ri1 camera for all opened flowers from
time of suspension of watering to anthesis of the last bud after
rewatering. Pollen stained red were considered viable. Pollen viability
was calculated using the formula: