The Effect of Component Frequency and Plant Density on Yields of Cultivar Mixtures in Spring Faba Beans

The effect of plant density and component frequency was examined in mixtures of two spring faba bean ( Vicia faba L.) cultivars Donas and Minden grown in a replacement series experiment in the field. There were two densities, 44 and 25 plants m⁻².
At low density mixtures yielded significantly more (+ 22.5 %) than the mean of the components grown in monoculture. The advantage was considerably reduced (+ 7.8 %) at high density. A frequency dependent advantage was observed when the proportion of the components in mixtures was varied. At high density and when averaged over the two densities, the greatest yield advantages were obtained when Danas , the high yielding component represented 75 % of the mixture, whilst at low density the greatest advantage was achieved at 50 : 50 mixture. Such gains were either due to component co-operation or complementation type interactions.
Mixtures produced greater total dry weights and more podded nodes per plant than the mean of the components. The remaining characters had values which were more or less similar for monocultures and mixtures.