The length of pollen tubes on PEG media was measured after
24 hours under a light microscope. The effect of PEG on pollen
germination and tube growth varied according to concentration
and time. Pollen grains from genotype Pdp 4 had the highest germination
percentage on all media (Fig. 3A-B and 4). The highest
germination percentage (96%) was obtained in a media with 20%
PEG for genotype Pdp 4 (Fig. 3B). The germination percentage
steadily improved with increasing PEG concentration for all genotype.
The greatest influence of increased PEG concentrations was
observed for genotype PdP1, where in comparison there was a very
low germination rate for the control (1%). Overall in comparison to
the control there was a 15 times greater germination potential for
germination on 20% PEG (15%). Genotype Pdp4 had a greater germination
percentage on PEG free medium than other three genotypes
on the best medim with 20% PEG (Fig. 4).
Genotype Pdp4 had 6.4 times greater germination on medium
with 20% PEG compared to genotype Pdp1. Also, genotype Pdp4 had
2.13 times greater germination compared to genotype Pdp2 and
1.48 times in relation to genotype Pdp3 on same medium (Fig. 4).
The influence of genotype and PEG was observed for longer
pollen tubes, therefore pollen tube growth linearly increased from
gen Pdp1 to gen Pdp4. A similar trend exists at higher PEG concentration.
The highest pollen tube length (822 m) of genotype Pdp4
was obtained in medium containing 20% PEG (Fig. 4B; Fig. 5).