Carbon source-sink limitations differ between two species with contrasting growth strategies: Source-sink limitations vary with growth strategy

• Published in: Plant, cell and environment Vol. 39; no. 11
• Main Authors: Burnett, Angela C., Rogers, A., Rees, M., Osborne, Colin P.
• Format: Journal Article
• Language: English
• Published: United States Wiley 22.09.2016
• Subjects: ENVIRONMENTAL SCIENCES
• ISSN: 0140-7791; 1365-3040

When we understand how carbon source and sink strengths limit plant growth we realized how critical the knowledge gap is in hindering efforts to maximize crop yield. Here, we investigated how differences in growth rate arise from source–sink limitations, using a model system comparing a fast-growing domesticated annual barley (Hordeum vulgare cv. NFC Tipple) with a slow-growing wild perennial relative (Hordeum bulbosum). Source strength was manipulated by growing plants at sub-ambient and elevated CO2 concentrations ([CO2]). Limitations on vegetative growth imposed by source and sink were diagnosed by measuring relative growth rate, developmental plasticity, photosynthesis and major carbon and nitrogen metabolite pools. Growth was sink limited in the annual but source limited in the perennial. RGR and carbon acquisition were higher in the annual, but photosynthesis responded weakly to elevated [CO2] indicating that source strength was near maximal at current [CO2]. In contrast, photosynthetic rate and sink development responded strongly to elevated [CO2] in the perennial, indicating significant source limitation. Sink limitation was avoided in the perennial by high sink plasticity: a marked increase in tillering and root:shoot ratio at elevated [CO2], and lower non-structural carbohydrate accumulation. Finally, by alleviating sink limitation during vegetative development could be important for maximizing growth of elite cereals under future elevated [CO2].