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Research article2007Peer reviewedOpen access

Testing the growth-differentiation balance hypothesis: dynamic responses of willows to nutrient availability

Glynn C, Herms DA, Orians CM, Hansen RC, Larsson S

Abstract

Here, the growth-differentiation balance hypothesis (GDBH) was tested by quantifying temporal variation in the relative growth rate (RGR), net assimilation rate (NAR), and phenylpropanoid concentrations of two willow species (Salix sericea and Salix eriocephala) across five fertility levels. Initially, RGR increased and total phenylpropanoids declined (although every individual phenolic did not) as fertility increased, but NAR was unaffected. Subsequently, NAR and phenylpropanoids declined in the low fertility treatment, generating a quadratic response of secondary metabolism across the nutrient gradient. As above- and below-ground growth rates equilibrated, NAR and phenylpropanoids increased in the low fertility treatment, re-establishing a negative linear effect of fertility on secondary metabolism. A transient quadratic response of secondary metabolism is predicted when GDBH is integrated with models of optimal phenotypic plasticity, occurring when low NAR imposes carbon constraints on secondary metabolism in low nutrient environments. Once plants acclimate to nutrient limitation, the equilibrium allocation state is predicted to be a negative correlation between growth and secondary metabolism. Although both willow species generally responded according to GDBH, the complexity observed suggests that prediction of the effects of nutrient availability on secondary metabolism (and other plastic responses) in specific cases requires a priori knowledge of the physiological status of the plant and soil nutrient availability

Keywords

condensed tannins; growth-differentiation balance hypothesis; optimality theory; phenolic glycosides; phenotypic plasticity; secondary metabolism; Salix eriocephala; Salix sericea

Published in

New Phytologist
2007, Volume: 176, number: 3, pages: 623-634
Publisher: BLACKWELL PUBLISHING

      SLU Authors

      • UKÄ Subject classification

      Forest Science
      Environmental Sciences related to Agriculture and Land-use

      Publication identifier

      DOI: https://doi.org/10.1111/j.1469-8137.2007.02203.x

      Permanent link to this page (URI)

      https://res.slu.se/id/publ/16294