LAUSR

Abstract. Flowering time is a vulnerable stage of plant development and is therefore a significant determinant of adaptation and grain yield in faba bean (Vicia faba L.). It is largely controlled by genotype, environmental factors of temperature and photoperiod, and genotype-by-environment interactions. The aim of this study was to evaluate variation in flowering time and the responses of flowering time to ambient temperature and photoperiod in Australian faba bean. Time of sowing experiments were carried out to assess variation among lines for flowering time (measured in days to flowering, thermal time to flowering and node of first flower) and to determine plant sensitivities to ambient temperature and photoperiod by regression analysis in the field, while four controlled environment experiments of differing temperature and photoperiod were undertaken to further analyse the variation in responses. Results showed significant variation in responses to both ambient temperature and photoperiod. Photoperiod was the main factor influencing variation in flowering time, with lines grouped as sensitive, intermediate or insensitive. The responses to ambient temperature were more complex. Most lines fit the traditional linear model, but with possible variation in optimal temperature and/or vernalisation response, while some lines showed temperature insensitivity.