Nitrogen forms affect root structure and water uptake in the hybrid poplar |
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| Authors: | Susy Domenicano Lluís Coll Christian Messier Frank Berninger |
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| Institution: | 1.Département des Sciences Biologiques,Université du Québec à Montréal,Montréal,Canada;2.Centre Tecnològic Forestal de Catalunya (CTFC),Solsona,Spain;3.Department of Forest Sciences, PL27,University of Helsinki,Helsinki,Finland |
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| Abstract: | The study analyses the effects of two different forms of nitrogen fertilisation (nitrate and ammonium) on root structure and
water uptake of two hybrid poplar (Populus maximowiczii x P. balsamifera) clones in a field experiment. Water uptake was studied using sap flow gauges on individual proximal roots and coarse root
structure was examined by excavating 18 whole-root systems. Finer roots were scanned and analyzed for architecture. Nitrogen
forms did not affect coarse-root system development, but had a significant effect on fine-root development. Nitrate-treated
trees presented higher fine:coarse root ratios and higher specific root lengths than control or ammonium treated trees. These
allocation differences affected the water uptake capacity of the plants as reflected by the higher sapflow rate in the nitrate
treatment. The diameter of proximal roots at the tree base predicted well the total root biomass and length. The diameter
of smaller lateral roots also predicted the lateral root mass, length, surface area and the number of tips. The effect of
nitrogen fertilisation on the fine root structure translated into an effect on the functioning of the fine roots forming a
link between form (architecture) and function (water uptake). |
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