Effects of temperature and photoperiod on flowering and yield components of lupin genotypes in the field

Abstract

The effects of photoperiod and temperature and/or insolation on flowering and yield components were measured for 24 genotypes of five Lupinus species in the field. Environmental factors were varied by sowing on three dates (April 2, May 17, and July 1) and by extending natural photoperiod with artificial light. Lack of vernalizing temperature (<10¦C) following early April sowing retarded flower initiation substantially in the midseason to late genotypes of Lupinus angustifolius and L. pilosus and to a lesser degree other species. Genotypes with no vernalization requirement flowered fastest following April sowing. Flowering of all genotypes was accelerated considerably by 24-hour photoperiod, L. luteus being the most responsive species. Number of flowers per primary inflorescence was reduced, and percentage of flowers setting pods increased, by treatments that led to earlier flowering. Number of seeds per pod and 20-seed weight were not affected by the treatments, except that higher temperatures increased 20-seed weight significantly in L. luteus and L. cosentini. Number of flowers, percentage flower set, and 20-seed weight were found to be the most important yield components in the primary inflorescences of lupins.