Effects of N supply, water stress and the water and nitrogen interaction on assimilate partitioning in <I>Populus</I> 'Balsam Spire' hybrid (<I>Populus balsamefera var</I>. <I>Muchuxii </I>(Henery) X <I>Populus trichocarpa </I>var. <I>Hastata </I>(Dode) Farwell.) were studied through three greenhouse experiments. The seedlings in the first experiment received either 1 or 3 or 9 mol N m<sup>-3</sup> over almost a whole growing season. Growth of the different parts of trees increased markedly by N supply. N supply increased whole tree photosynthesis through increasing total leaf area and decreased photosynthetic nitrogen use efficiency. Total respiration also increased with increasing N supply as a result of increasing leaf respiration and below-ground respiration. Below-ground respiration as a proportion of total respiration, however, decreased with increasing N supply. Nitrogen and carbon content and concentrations in different tree components and in the whole tree increased with increasing N supply. Partitioning of nitrogen into different parts of tree, however, showed no response to N supply. The proportion of carbon allocated to the leaves increased while that allocated to the roots decreased as a result of increasing N supply through increasing the concentrations of structural carbon compounds at the expense of those of non-structural carbon compounds. The ratio of total non-structural to total structural carbon compounds, therefore, increased with increasing N supply. In the second experiment, three treatments were applied to trees in the second half of their growing season by withholding irrigation either suddenly or gradually.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:336453 |
| Date | January 1995 |
| Creators | Ibrahim, Loutfy |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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