Comparative study with fluorescence microscopy revealed that the polle
n tubes of the self-pollinated rice variety BR-9 reached the ovary wit
hin 75 min after pollination. In P. coarctata it took 150 min. In the
cross between P. coarctata and BR-9, pollen tubes reached the ovary in
165 min but seed setting was not observed. In the cross between BR-9
and P. coarctata, small and deformed pollen tubes were formed and they
failed to grow through the stylodium.