Vernalization responses in narrow-leafed lupin (Lupinus angustifolius) genotypes

Abstract

Three experiments were conducted to characterize vernalization response in 13 diverse narrowleafed lupin (Lupinus angustifolius) genotypes, and to identify the genetic basis of differences in vernalization response. The aim was to better understand how flowering time may be manipulated in lupin breeding. The genotypes consisted of breeding lines with parents of wild origin, plus selected commercial varieties. Treatments included response to different periods of vernalization and response to different sowing dates. Most of the genotypes required vernalization for flowering. There were three types of response to vernalization observed; an absolute requirement, a reduced response, in which vernalization did not appear to be essential for flowering, and no response in lines carrying the natural mutant gene Ku (Gladstones and Hill 1969). In genotypes with an absolute requirement for vernalization, the period of vernalization at 5¦C required to ensure flowering varied between 2 and 4 weeks, and flowering was hastened by increasing periods of vernalization. When vernalization was marginally inadequate, abnormal inflorescences formed. An apparent thermosensitive response, in which vernalization hastened flowering but did not appear to be essential, occurred in cv. Wandoo, which carries the gene æeflÆ. This response could also possibly be explained not by the lack of an essential requirement for vernalization, but by an ability of the cultivar to respond to vernalization at fairly high temperatures, around 16¦C. Crossing studies identified a major gene the same as or allelic to æeflÆ in one genotype, but no other single genes with major effect on vernalization response were detected in genotypes of wild origin.