BARRIERS PREVENTING HYBRIDIZATION OF LATHYRUS-ODORATUS WITH L-CHLORANTHUS AND LATHYRUS-CHRYSANTHUS

Interspecific hybridisation of the sweet pea, Lathyrus odoratus L., wi th two yellow flowered relatives, Lathyrus chloranthus Boiss. and L. c hrysanthus Boiss., was undertaken with the aim of transferring yellow flower colour into the sweet pea. Initial reciprocal cross pollination s of L odoratus 'Original', with the two species, produced no viable s eed, suggesting the presence of interspecific hybridisation barriers. Observation of events following further reciprocal cross pollinations confirmed the presence of hybridisation barriers which prevented the f ormation of hybrid embryos in all cross combinations except L chlorant hus x L odoratus. Post-fertilisation hybridisation barriers subsequent ly prevented die maturation of such hybrid embryos. Further crosses us ing a range of sweet pea cultivars indicated varying degrees of impedi ment to hybridisation depending on the cultivar used. Pre-fertilisatio n hybridisation barriers which prevented the growth of foreign pollen tubes to the bases of styles were observed in L odoratus x L chloranth us crosses and reciprocal L odoratus x L chrysanthus crosses involving long-styled L odoratus cultivars.