INHERITANCE OF SEED DORMANCY IN LISIANTHUS (EUSTOMA-GRANDIFLORUM)

The genetics of chill-related seed dormancy, exhibited by a lisianthus (Eustoma grandiflorum) genotype native to North America, was investig ated. Less than 1 % of the seeds germinated by direct hydration at 20 degrees C, while full germination (98 %) was attained by chilling imbi bed seeds, for at least 11 days, at 3 degrees C, before transferring t hem to 20 degrees C. The inheritance of seed dormancy was analysed in F-1, BC1 and F-2 populations, derived from mating between a normal non -chill-requiring genotype (P-1) and the above chill-requiring genotype (P-2). F-1 seeds, of both reciprocals, and BC1 (P-1) seeds were all n on-dormant. The proportion of seed dormancy in F-2 and BC1 (P-2) was 0 .06 and 0.68, respectively. The inheritance model proposed includes si x diallelic loci with cumulative effects, in which the presence of at least nine 'dormancy-conferring' alleles is necessary for inducing phe notypic seed dormancy. Possible implications of inherent seed dormancy on the utilization of native lisianthus germplasm for breeding are di scussed.