The effect of nitrogen supply on root growth and development in sycamore and Sitka spruce trees |
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Authors: | MACKIE-DAWSON L A; MILLARD P; PROE M F |
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Institution: | Plants Division, The Macaulay Land Use Research Institute Craigiebuckler, Aberdeen, AB9 2QJ, Scotland |
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Abstract: | Sycamore (Acer pseudoplatanus L.) and Sitka spruce (Picea sitchensis(Bong.) Carr.) were grown in sand culture in glasshouses withtwo levels of N supplied with irrigation 1.0 (deficient) and6.0 (sufficient) molNm3, all as NH4NO3. Providing trees with a sufficient N supply increased both theirabove ground growth and N content compared with the N deficientplants. Provision of the generous N supply also altered thedistribution of growth between leaves and roots, with the N-deficientplants having a higher root:leaf or root:needle ratio than thewell fertilized trees. Provision of a generous N supply stimulatedroot growth, especially at the later harvests, which was reflectedmainly in growth of the tap root in sycamore. There was an increasein both root mass and root diameter with N supply. When thegrowth of white roots was monitored using a borescope, it wasshown that there were significantly more new roots producedby the well-fertilized trees. The borescope data also showeddetail of the bimodal seasonal pattern of root growth underhigh N in Sitka spruce which related to trends in nitrogen uptake. |
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