Anatomical and physiological characteristics of sink cells

Much of the plant material we eat originates from reproductive and storage sinks. Crop yield is the ultimate product of the whole plant’s net photosynthesis and the relative partitioning of dry matter to the organ of agricultural significance. The photosynthetic activity of the sources determines the potential amount of assimilates that can be transported to the sinks. The question is whether assimilate distribution to the sinks is controlled by the source (a feed-forward effect) or by the sink (a feedback effect). Many investigators have suggested that the overall physiological and metabolical processes taking place in the sink tissues are the main factors determining assimilate partitioning (see Krapp et al. 1993). However, a recent discussion of the question of sink strength and the extent of its importance in source-sink relationships (Farrar 1993) emphasized the range of contradictory views.