Monosomic Analysis of Photoperiod Response in Wheat¹

Abstract

Identification of specific chromosomes containing the genes for photoperiod response in common wheat ( Tritlcure aestivum L. era. Thell.) was undertaken. F 1 and F 2 progenies from crosses of a photoperiod insensitive spring wheat (‘Sonora 64’) with 21 diferent monosomic lines of a sensitive winter wheat (‘Cheyenne’) were grown with the parental cultlvars under a 10‐hour photoperlod. A disomic F 2 population was used to measure the standard segregation pattern. The vernalized winter parent was still in the vegetative state after 152 days under a 10‐hour photoperiod. The spring parent headed, on an average, 54 days after planting. The F 1 population headed, on an average, 66 days after planting. Disomlc F 2 population segregation under a 10‐hour photoperiod indicated that three gene pairs, with dominant epistasis for earliness of one of the factors, controlled this character. Heading response of the F 2 progenies of the monosomic line for chromosome 2D showed that this chromosome is the carrier of the Ppd 1 gene with the dominant epistatic effect. Two of the four chromosomes 2B, 4B, 3D, and 6D are possible carriers of the other two genes.