Branching, flowering and pod-set patterns in snap-bean (Phaseolus vulgaris L.) as affected by temperature

Abstract

The effect of temperature on branching, flowering and pod-set patterns of determinate snap-bean (Phaseolus vulgaris L.) cultivars has not been well documented. In this work, well-defined rigid gradients of branching and flowering were found in determinate snap-bean. However, in spite of the great developmental stability of these gradients, pod production and distribution along the main axis of the bean plant was highly plastic in its response to environmental conditions. Under controlled conditions, high temperature (32/27 °C) drastically reduced pod production even though branching and flowering were greatly increased. Under lower temperatures most (>50%) mature pods were produced by branches of the first and second trifoliolate leaves. Low night temperature (12 °C) increased branching and relative pod production by more basal nodes, mainly by primary leaves branches. Large shifts in the relative contribution to mature pod production by main inflorescence and branches at different nodal positions along the main shoot were observed also in the field. It appears that in determinate cultivars of snap-bean the rigid gradients in branching and flowering do not limit pod production because of compensatory rapid developmental adaptation to transient environmental stresses. Key words: Snap-bean, Phaseolus vulgaris L., branching, pod-set, temperature