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 F2 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.

Genetic Analysis of Salt Tolerance in Safflower (Carthamus tinctorius L.)

“…Golkar et al [23] reported a high value for broad-sense heritability of seeds/capsule (99%) that was different to our results. Kotecha and Zimmerman [25] reported high broad-sense heritability (86%) for 100-seed weight in normal condition that was different to our result. This difference could be compromised from epistasis effect of additive × additive in genetic control of 1000-seed weight in salt stress.…”

“…Generation mean analysis fitted different genetic models for studied traits of safflower under salt stress. In this study, genetic control of plant height was under the control of additive, dominance and additive× additive epistasis, that is quiet different to previous reports [23]; Shahbazi and Saeidi [24] and Kotecha and Zimmerman [25] but similar with the results of Golkar [7] for seedling plant height in salt stress. It is the first report that implied on the importance of dominance and [i] epistasis.…”

“…The importance of additive gene action and additive× additive interaction in genetic control of 1000-seed weight was previously reported by Golkar et al [23] and Shahbazi and Saeidi [24] in normal condition, that is similar to our results. Kotecha and Zimmerman [25] reported the partial or over dominance gene action for genetic control of seed weight in different crosses of safflower. The efficiency of any selection program is mainly dependent on additive genetic variance which is due to the breeding value of the genotype [30].…”

Introgression potential between safflower (Carthamus tinctorius) and wild relatives of the genus Carthamus

“…Several weedy relatives of C. tinctorius have been studied and hybrids between these relatives and safflower have been used to study the inheritance of a number of domestication traits [ 32 , 33 ]. The wild and weedy species C. oxyacanthus, C. persicus and C. palaestinus were shown to have seeds that are released by shattering, although in our study C. palaestinus was non-shattering.…”

Biology of Safflower (Carthamus tinctorius)

“…Low levels of dormancy have been observed in safflower, with some variation between cultivars; however, this low level of dormancy was lost during storage. For example, dormancy was lost after 24 weeks of storage at room temperature (Kotecha and Zimmerman, 1978).…”