Path models for the abscission of reproductive structures in three contrasting cultivars of faba bean (Vicia faba)

Abstract

We hypothesized that the differences in the amount of abscission of reproductive structures in three physiological types of faba bean (Vicia faba L.) were due to different physiological responses to an internal competition for resources in the plant. Vicia faba 'Aguadulce' has an indeterminate growth habit and a dichotomous system of vascularization in its inflorescences. Vicia faba 'D83146-123' has a determinate growth habit and a dichotomous system of vascularization in its inflorescences. Vicia faba 'B 87.151' has an indeterminate growth habit and an independent vascular system in its inflorescences. Flower and pod abscission were related to growth and developmental attributes using multiple regressions as well as path analysis. The path models showed that abscission in the determinate growth cultivar was positively related to plant height and branch number, suggesting that competition for vegetative growth is still responsible for abscission in this cultivar. Future breeding should focus on reducing branch number in this cultivar. Results suggest that competition between reproductive structures has been attenuated in the independent vascular system cultivar even if flowers and pods continue to abscind. Further selection should be concentrated on a reduction of height and an independent vascular system within the stem to reduce competition between inflorescences. Key words: faba bean, flower abscission, pod abscission, path analysis, Vicia faba.