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Source-sink interactions

source-sinkNew research investigates how plant growth is controlled by the supply of carbon from photosynthesis (source strength) verses the demand for carbon in growing tissues (sink strength). This control has important implications for how trees and crops respond to the continuing increase in atmospheric CO2.

We have developed a theoretical approach to integrate current perspectives on plant source-sink interactions, reconciling past work on source activity, allocation and sink development. As atmospheric CO2 continues to rise, this has important implications for forest carbon sequestration, savanna woody plant encroachment and crop production.

Rising CO2 stimulates photosynthesis, but carbon storage in forests only increases over long timescales if trees are able to use this carbon in wood growth. Since the world’s forests currently absorb about a quarter of human CO2 emissions, the control of growth by sources and sinks has major implications for climate change.

CO2-fertilisation is also important in savannas, where rapid growth enables trees to escape fire and reach maturity. Through this mechanism, rising CO2 is thought to be causing rapid encroachment of trees into savannas, which causes problems for local people because trees limit grass production for grazing, and deplete groundwater.

Finally, rising CO2 has the potential to fertilise crop production. Our research has investigated how the grain yield of crop wild relatives was fertilised by CO2 15,000 years ago. We have also looked at how CO2-fertilisation of growth in a domesticated crop is limited by sink development. Future work will investigate how crop domestication and improvement have changed source-sink interactions and limited the CO2-fertilization response of crops.

We collaborate with Alistair Rogers from Brookhaven National Lab and Mark Rees on this work.

Selected recent publications in this area

White, A., Rogers, A., Rees, M., Osborne, C.P. (2016) How can we make plants grow faster? A source-sink perspective on growth rate. Journal of Experimental Botany, 67, 31-45.

Burnett, A.C., Rogers, A., Rees, M., Osborne, C.P. (2016) Carbon source-sink limitations differ in two species with contrasting growth strategies. Plant, Cell and Environment, 39, 2460-2472.

Cunniff, J., Jones, G., Charles, M., Osborne, C.P. (2017) Yield responses of wild C3 and C4 crop progenitors to sub-ambient CO2: a test for the role of CO2 limitation in the origin of agriculture. Global Change Biology, 23, 380-393.

Cunniff, J., Charles, M., Jones, G., Osborne, C.P. (2016) Reduced plant water status under sub-ambient pCO2 limits plant productivity in the wild progenitors of C3 and C4 cereals. Annals of Botany, 118, 1163-1173.