Phenotypic plasticity of fine root growth increases plant productivity in pine seedlings.
BACKGROUND
The plastic response of fine roots to a changing environment is suggested to affect the growth and form of a plant. Here we show that the plasticity of fine root growth may increase plant productivity based on an experiment using young seedlings (14-week old) of loblolly pine. We use two contrasting pine ecotypes, "mesic" and "xeric", to investigate the adaptive significance of such a plastic response.


RESULTS
The partitioning of biomass to fine roots is observed to reduce with increased nutrient availability. For the "mesic" ecotype, increased stem biomass as a consequence of more nutrients may be primarily due to reduced fine-root biomass partitioning. For the "xeric" ecotype, the favorable influence of the plasticity of fine root growth on stem growth results from increased allocation of biomass to foliage and decreased allocation to fine roots. An evolutionary genetic analysis indicates that the plasticity of fine root growth is inducible, whereas the plasticity of foliage is constitutive.


CONCLUSIONS
Results promise to enhance a fundamental understanding of evolutionary changes of tree architecture under domestication and to design sound silvicultural and breeding measures for improving plant productivity.
Wu
Rongling
R
School of Life Sciences, Zhejiang Forestry University, Lin'an, Zhejiang 311300, People's Republic of China. Rwu@stat.ufl.edu
Grissom
James E
JE
McKeand
Steven E
SE
O'Malley
David M
DM
D000222:Adaptation, Physiological / Q000235:genetics / Q000502:physiology*; D018533:Biomass; D004777:Environment; D005308:Fertilizers; D010641:Phenotype; D041603:Pinus taeda / Q000145:classification / Q000235:genetics / Q000254:growth & development*; D018517:Plant Roots / Q000254:growth & development*; D018547:Plant Stems / Q000254:growth & development; D011897:Random Allocation; D014867:Water
D005308:Fertilizers; D014867:Water