Correlation between relative growth rate and specific leaf area requires associations of specific leaf area with nitrogen absorption rate of roots
Article first published online: 28 JUN 2008
© The Authors (2008). Journal compilation © New Phytologist (2008)
Volume 179, Issue 2, pages 417–427, July 2008
How to Cite
Osone, Y., Ishida, A. and Tateno, M. (2008), Correlation between relative growth rate and specific leaf area requires associations of specific leaf area with nitrogen absorption rate of roots. New Phytologist, 179: 417–427. doi: 10.1111/j.1469-8137.2008.02476.x
- Issue published online: 28 JUN 2008
- Article first published online: 28 JUN 2008
- Received: 1 February 2008; Accepted: 15 March 2008
- balanced growth hypothesis;
- nitrogen absorption rate;
- relative growth rate;
- specific leaf area
- • Close correlations between specific leaf area (SLA) and relative growth rate (RGR) have been reported in many studies. However, theoretically, SLA by itself has small net positive effect on RGR because any increase in SLA inevitably causes a decrease in area-based leaf nitrogen concentration (LNCa), another RGR component. It was hypothesized that, for a correlation between SLA and RGR, SLA needs to be associated with specific nitrogen absorption rate of roots (SAR), which counteracts the negative effect of SLA on LNCa.
- • Five trees and six herbs were grown under optimal conditions and relationships between SAR and RGR components were analyzed using a model based on balanced growth hypothesis.
- • SLA varied 1.9-fold between species. Simulations predicted that, if SAR is not associated with SLA, this variation in SLA would cause a 47% decrease in LNCa along the SLA gradient, leading to a marginal net positive effect on RGR. In reality, SAR was positively related to SLA, showing a 3.9-fold variation, which largely compensated for the negative effect of SLA on LNCa. Consequently, LNCa values were almost constant across species and a positive SLA–RGR relationship was achieved.
- • These results highlight the importance of leaf–root interactions in understanding interspecific differences in RGR.