THE POLLINATION REQUIREMENT OF THE FIELD BEAN (VICIA FABA)

Abstract

Many of the flowers on field bean plants fail to produce pods even when fully pollinated. When insect pollination is prevented pod production on the lowest inflorescences, which normally produce most pods, is reduced but a compensatory increase on the upper ones ensures a moderate yield. This change in the distribution of pods may be a useful indication of insufficient pollination.Areas in which crops requiring pollination are grown usually contain some pollinating insects, such as honey-bees kept by local beekeepers, solitary bees and bumble bees. It is desirable that growers should be able to judge when additional bees are needed. Information useful for this purpose has now been obtained for the field bean. The investigation was undertaken because doubts had been expressed as to whether this crop was being adequately pollinated at Rothamsted. EXPERIMENTS (a) The capacity of the plant to produce mature pods when adequately pollinatedIn 1956, zoo fully open bean flowers were marked. After a fortnight about 50% had produced pods but later many of these fell off and very few remained until harvest. Thus more flowers were pollinated than produced mature pods. However, the further conclusion that pollination had been more than adequate depended on the assumption that the pods which fell off were in positions where mature pods could be produced under suitable circumstances. Pods mostly fell from the upper inflorescences and the upper flowers of the lower ones and it seemed possible that only imperfect pods could occur in these positions.This possibility was investigated in 1957. Plants chosen at random w q e divided into three groups, each of which was given a distinguishing mark. Only the main stems were used for the experiment but the side shoots were not removed, The lowest four inflorescences on the stems were removed in one group and the lowest three flowers on each inflorescence in another. The third group was left untreated. At the end of the season the pods and beans on each inflorescence were counted ( Table I). Removal of flowers from the positions where mature pods are normally produced resulted in compensatory increases in production on the other parts of the plants. The removal of these flowers from a few plants in the crop could not have caused the pollinating insects to give increased attention to the remaining flowers. The increased yield of the latter shows that pollination was not the factor

A study on the pollination mechanism in field beans (Vicia faba L.)

“…The present investigation Field beans are intermediate in breeding be-was undertaken with the objective of throwing haviour between completely cross-pollinated and some light on the nature of this barrier and how completely self-pollinated crops (Fyfe & Bailey, hybrids and self-pollinating lines overcome it. Such 1951) and their seed set is markedly reduced in the knowledge is of interest both intrinsically and as an absence of pollinating bees (Riedel & Wort, 1960; aid in the development of self-pollinated varieties Scriven, Cooper & Allen, 1961;Free, 1966). Devel-of field beans, opment of completely self-pollinated varieties is being sought (Lawes, 1973) to eliminate dependence MATERIALS AND METHODS on bees for pollination, thereby avoiding fluctuations in yield caused by variations in the availa-The material studied (Table 1) comprised inbred bility and activity of bees.…”

Pollination, Fertilization and Floral Traits Co-Segregating with Autofertility in Faba Bean

“…An increased fertilization frequency at the upper flowering nodes of the AS plants was also observed (data not shown). The change in the distribution of pods was considered to be a useful indication of insufficient pollination (Reidel and Wort 1960). Setting pods at the upper flowering nodes was considered to be a good reproductive strategy that compensates the insufficient pollination, which ensures that some seeds are produced on a plant (Rowland et al 1983).…”

Estimates of the frequency of fertilization in field beans (Vicia faba L.)

“…Even in less severe conditions only about 24% of the ovules develop into mature seeds (Rowlands, 1960). Riedel & Wort (1960) concluded that pollination was not a factor limiting production and the observation that removing the apex of the plant at the right stage can increase the proportion of flowers developing pods also suggests that more flowers are fertilized than pods are set (Chapman, Guest & Peat, 1978). Furthermore, flower abortion has been considered a post-fertilization phenomenon caused by embryo abortion (Rowlands, 1960;Chapman, Fagg & Peat, 1979), usually after the 8-to 12-day stage of embryo development (Rowlands, 1964).…”