INHIBITION OF EAR-EMERGENCE TIME AND SENSITIVITY TO DAY-LENGTH DETERMINED BY THE GROUP-6 CHROMOSOMES OF WHEAT

Increased dosage of the group 6 chromosomes of Chinese Spring wheat de lays ear-emergence. Reduced dosage of the same chromosomes has the con verse effect and accelerates emergence. Both effects are removed by ve rnalization. It is proposed that genes on these chromosomes produce a flowering inhibitor, sensitive to vernalization. It is suggested that this inhibitor may be affected by the major Vrn genes for vernalizatio n requirement on the group 5 chromosomes through their production of a flowering promoter which either suppresses the group 6 genes or compl exes with the inhibitor, thereby accelerating ear-emergence. A gene (o r genes) for sensitivity to day-length was detected on the long-arm of chromosome 6B which, in its absence, delayed ear-emergence under shor t days. The genes for inhibition of emergence were also probably locat ed on the long-arms of the group 6 chromosomes, but were separate from the gene(s) for day-length sensitivity.