Prediction of flowering occurrence in faba bean (Vicia faba L.)

Quantitative information about response of phenological development to temperature and photoperiod in faba bean is limited. This study was undertaken to examine phenological development of four faba bean cultivars (conducted Barakat, Saraziri, Eraghi, Gavi) under 11 sowing dates. The experiment was conducted in Gorgan during 2005-2006. Various response functions were evaluated for quantifying response flowering rate to temperature and photoperiod. Results indicated that response of faba bean flowering rate is described by beta- segmented (Barakat, Saraziri, Eraghi) and beta- quadratic (Gavi). Using these functions, cardinal temperatures (base, optimum, and ceiling) for flowering and critical photoperiod (the photoperiod below which flowering rate begins to decrease) and photoperiod sensitivity coefficient (slope of the function in response to photoperiod) for flowering rate were determined. Barakat, Saraziri and Eraghi Cultivars showed a qualitative long-day plant (LDP) response to photoperiod and progress towards flowering stopped when photoperiod decreased about 10 h per day. But Gavi cultivar showed a quantitative long-day plant (LDP) response to photoperiod. Critical photoperiod estimated by beta-segmented function for Barakat, Saraziri, Eraghi Cultivars were between 14.5 to 16.1 h and by beta- quadratic function for Gavi Cultivar was 15.3.