Optimum Time of Day for Maximum Flower Opening of Faba Bean1

Abstract

AbstractThe success of cross pollination by bees (Apis melliferaL. and Bombusssp.) depends on the number of flowers and the pattern of flower opening of a plant. Four cultivars of faba bean, Vicia fabaL. (‘Wierboon,’ ‘Minica,’ ‘Black Russian,’ and ‘Violetta di Policoro’) were studied for their patterns of flowering time and the implications on seed yield. Diurnal observations were made on 20 plants of three replications for each cultivar and for every 2 h from 0900 to 1700 h on 5 consecutive days. Time series models were used to fit the data, and the second‐order autoregressive model was found adequate. The fitted models indicated that Minica had a sharp daily flower‐opening peak compared with the other cultivars and that the peak flowering time was less regular in Wierboon than in other cultivars. These implied that Minica produced the most new flowers to display to bees but they were concentrated in a few hours; Wierboon tended to prolong its flowering peak when bees had decreased their visits to flowers. Although the flower patterns varied according to cultivars, the peaks of flowering time were similar. Usually, the number of flower openings increased from 0900 to 1500 h and then decreased. The number of new flowers opening peaked between 1500 and 1700 h.