Genetics of Seed Dormancy and its Association with Other Traits in Safflower¹

Abstract

Two selections of wild safflower ( Carthamns palaestinus Eig.) possessing short‐term seed dormancy and three cultivars of domestic safflower ( C. tinctorius L.) were used in crosses to study the genetics of seed (achene) dormancy and its association with other traits. Seeds from the parents of each cross differed significantly in all germination periods (24, 48, and 72 hours after 2 and 24 weeks of storage). Seed of all populations stored for 24 weeks had higher germination percentage than that stored for 2 weeks, which indicated that seed dormancy was lessened by long‐term storage. Variability of the F 2 generation was of genetic origin, except in a few cases. Heritability in the broad sense ranged from 0 to 99% for 2 and 24 weeks of storage. Heritability estimates in the narrow sense were 55, 46, and 33% for 24, 48, and 72 hours of germination, respectively, for 2 weeks of storage. Except for one case, gene action was nonadditive. Seed germination characteristics were quantitatively inherited. The expectation of genetic advance for 48 hours of seed germination was higher than that of 24 and 72 hours of germination for 2 weeks of storage. Thus, selection for 48 hours of a 2 week storage period should be most desirable. Germination of seeds from plants with striped hulls and green midveins of cotyledons was higher than germination of those with nonstriped hulls and purple midveins. Correlation coefficients for all germination periods with seed weight and pappus were low. Correlation coefficients for seed weight with pappus were also low. Thus, these traits are not important in breeding for seed dormancy.