The photoperiodic sensitivity of some spring wheats with special reference to the variety thatcher

Abstract

Earlier studies of the processes leading to flowering in spring wheats have been extended to embrace a genetic analysis of photoperiodic sensitivity in several spring varieties. The American variety Thatcher proved particularly sensitive to the short days experienced in the greenhouse during the winter months. Compared with Selkirk, Thatcher is later under short days, and this lateness appears to be conditioned by a second minor gene over and above that already recognized in Selkirk. The backcrossing procedure has been used to establish two new recombinant genotypes intermediate in behaviour between the parental varieties Triple Dirk and Thatcher. Abnormalities in ear development of sensitive varieties like Thatcher were consistently produced when plants raised under short days were transferred to long days soon after the estimated time of initiation of floral primordia.