Influence of Shade on the Growth and Sink Activity of Young Flower Heads and Peduncles of White Clover (Trifolium repens L.)

The influence of shade on the growth and sink activity of young flower heads and peduncles of white clover (Trifolium repens L.) plants was measured in controlled environments. Measurement of the peduncle elongation rate using a linear voltage displacement transducer showed that when the inflorescence alone was shaded, peduncle elongation was higher than in the light. Translocation studies using 11C-labelling techniques showed that shading the inflorescence alone had little effect on translocation of assimilates into the inflorescence but induced a major change in partitioning of assimilates within it. Peduncle elongation induced by shade accompanied an increase in partitioning of photoassimilates to the peduncle, at the expense of the flower head.