Control of lupin flower initiation by vernalization, photoperiod and temperature under controlled environment

Controlled environment studies of the effects of vernalization, photoperiod, and growing period temperatures were carried out on selected cultivars of four annual Lupinus species. All responded to both vernalization and photoperiod to varying degrees, and in at least two there were indications of an additional effect of growing period temperatures specifically on flower initiation. Flower initiation in L. angustifolius was found to be controlled mainly by its vernalization requirement, with subsidiary control by photoperiod. In L. cosentini vernalization, photoperiod, and an acceleration of initiation by high temperatures all appeared to play important roles, with critical control by photoperiod under short days. L. luteus responded strongly to both vernalization and photoperiod, but long days were able to substitute for vernalization to a marked degree. The results are discussed in the context of the ecology of lupins and the breeding of new crop cultivars.