Carbon nutrition root branching and elongation : can the present state of knowledge allow a predective approach at a whole-plant level?

International audienceSome of the experimental elements which are necessary for modelling the effects of plant carbon nutrition on the geometrical characteristics of root systems are reviewed. Reductions in intercepted irradiance or in the concentration of atmospheric CO2 decrease the total root biomass and length. In addition to these global effects, carbon supply affects parameters which determine the architecture of the root system, such as the number of primary roots, their rate of branching, the individual elongation rates of different orders of branching and the elongation rates of branches which appear on apical vs basal parts of the supporting axis. Priorities in carbon allocation to different parts of the root system could be accounted for by simple models of source/sink relations. Through such effects, considerable changes in characteristics of the root system are possible, such as rooting depth or root density in different soil layers. However, progress in modelling is hampered by the relative inadequacy of current knowledge on the effect of carbon supply to the root system, which is still too general and too qualitative to allow predictive simulations of the resulting systems

Emergence and hypocotyl growth in sunflower (Helianthus annuus L.) hybrids of different plant height

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