Analysis on the barriers of interspecific hybridization in beardless irises

ObjectiveIn order to study the crossbreeding barriers and time of ovary abortion in beardless irises, five Iris sibirica varieties were crossed respectively with Iris pseudacorus and Iris halophila var. sogdiana.

MethodGrowing of pollen and ovaries after common pollination were observed and showed by figures. Rate of seed setting and germination were counted finally.

ResultOvary abortion was found in 9-16 days after pollination. There were four reasons, pollen difficult adherence, low rate of pollen germination, pollen tube elongation disorders and embryo abortion for post-zygotic barrier. Post-zygotic and pro-zygotic barrier were the main reasons for the cross incompatibility between I.pseudacorus and five I. sibirica varieties. Post-zygotic was the main reason for cross incompatibility between I. halophila var. sogdiana and five I. sibirica varieties; I. halophila var. sogdiana was higher than I. pseudacorus in cross compatibitily.

ConclusionThe results suggested that pollen germination can be the barrier test index before distant hybridization; appropriate measures could be done after observing pollen germination to increase seed setting rate; cross compatibility was different in varied species and there was no significant difference between diploid and tetraploid in the inter-species distant hybridization with different number of chromosomes; there were different types of crossbreeding barriers in reciprocal cross. The rate of cross compatibility can be improved in irises inter-species by reciprocal cross to get more rich offsprings.