ARS | Publication request: Photosynthesis and carbon partitioning/source-sink relationships

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: October 10, 2011
Publication Date: December 14, 2012
Citation: Pettigrew, W.T. 2012. Photosynthesis and carbon partitioning/source-sink relationships. In D.M. Oosterhuis J. Tom Cothern (ed.) Cotton Flowering and Fruiting. The Cotton Foundation. Cordova, TN. p. 25-34.

Interpretive Summary: Photosynthesis is a two step process whereby plants convert the sunlight intercepted by the leaves into chemical energy and in turn use that chemical energy to produce sugars for growth from carbon dioxide absorbed out of the air and water absorbed through the roots. This is a process that underpins much of plant growth and development. Because photosynthesis is a process operating at the most basic level, there is a clear, though sometimes indirect, connection between photosynthesis, flowering, and yield production. The scope of this review chapter is to examine the interplay between the photosynthesizing, sugar producing tissue and the reproductive growth (fruiting buds, flowers, and bolls). The importance to yield production of an appropriate partitioning of the sugars produced by photosynthesis into reproductive growth rather stem, branch or leaf growth is discussed. We also discuss a theoretical pathway to yield improvements by improving the synchronicity between peak canopy production of photosynthetic sugars and the peak demand for these sugars by the growing reproductive structures. This chapter will be utilized by physiologists, agronomists, geneticists, extension specialists, and consultants to formulate future research plans and directions

Technical Abstract: Photosynthesis is one of the principle biochemical process underpinning plant growth and development. Crop photosynthesis can be thought of as being broken down into 3 components: 1) leaf area development, 2) photosynthetic rate per unit leaf area, and 3) partitioning the assimilates between vegetative and reproductive growth, or source-to-sink relationships. The production of chemical energy from sunlight and the subsequent use of that energy to fix CO2 into photoassimilates constitute the source side of the equation. The fruiting buds, flowers, and fruit development constitute the reproductive sink side of the yield equation. Other vegetative growing points can operate as secondary sinks at the same time as the reproductive growth is occurring. This interplay between the vegetative source and the reproductive sink can influence crop photosynthesis because the capacity for carbon assimilation can be somewhat regulated by the utilization of those photoassimilates.