The seed-coat of all white-flowered varieties of Vicia faba and segregants tested was free of tannin. In two field trials, the whole grain of white-flowered varieties was significantly higher in in vitro digestibility of the dry matter, on aveiage 4-7 % higher, than coloured-flowered varieties of similar seed size. In subsequent trials where the testa and cotyledon were examined separately, this difference was shown to be largely due to a mean D value (digestibility of the organic matter) of the testa in tannin-free varieties of 56-4% compared with 17-2% in tannin-containing varieties. Seed size was positively correlated with D value but not because of differing proportions of testa.Differences between varieties in acid-pepsin solubility and protein content of the testa were much smaller and not associated with presence of tannin. The testa colour of some tannin-free F% plants was a darker shade of grey than either parental population. An inbred line completely lacking in anthocyanin in flowers and stem but with the normal black wing spot had tannin in its testa.Grains of peas from the coloured-flowered variety, Minerva, reacted to a tannin test wheieas those from white-flowered varieties, Greenshaft and Flavanda, did not.The case for breeding further tannin-free varieties of Vicia faba is discussed.

Inbred lines and hybrids of English tick and horse beans and exotic stocks were studied with respect to pod set, floral structure and pollen production and germination to find out why most inbred lines set few or no seeds without tripping whereas most hybrids and some inbred lines set equally well with or without tripping. The most important outcome was new information on variation between genotypes in flower structure and pollen quantity and on how these two characters affect the mechanics of self-pollination. Though heterosis in terms of abundant pollen production could be a factor in the self-pollinating ability of hybrids, some of the inbred lines were capable of self pollination despite limited pollen production, because the structure of the flower permitted the pollen to reach the stigma via a short route. The floral features associated with the ability to self-pollinate in the inbred lines included a relatively short style bending at more or less a right angle, few and short stylar hairs and stigmatic papillae, and less pronounced ridges on the inside of the keel petals. The implications of these findings to the development of self-pollin ated varieties of field beans are briefly discussed. barrier to pollination, which is absent in the flowers of self-pollinating plants. 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 availaThe material studied (Table 1) comprised inbred bility and activity of bees. lines selfed for four or more generations and F t The ability of field-bean plants to set seeds with-hybrids, derived from stocks of English spring and out flower manipulation (tripping) is known as winter beans and exotic material from Sudan and autofertility and this varies with the genotype and India. The plants were grown, during the spring of level of inbreeding, hybrids being usually more 1975, singly in 18-cm pots filled with John Innes autofertile than inbred plants. Although in most No. 2 compost and placed on a capillary bench in a cases highly inbred plants set practically no seeds bee-proofed glasshouse, without flower manipulation, the existence of selfpollinating lines has been reported (Hayes & Pod set with and without tripping Hanna, 1968;Kambal, 1969; Toynbee-Clarke, Flowers were tripped by depressing the wing 1974).petals thus releasing the style and s...

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1. Diallel crosses between six inbred lines of winter beans, the selfed parent lines and two commercial varieties were grown in a field trial in two years and records made of yield, number of steins, podded nodes, pods, weight of seed, plant height and width and flowering date. From these data four quotients representing components of yield were obtained.