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Title: Effects of nitrogen supply, water stress, and the interaction between water and nitrogen on assimilate partitioning in poplar
Author: Ibrahim, Loutfy
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1995
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Effects of N supply, water stress and the water and nitrogen interaction on assimilate partitioning in Populus 'Balsam Spire' hybrid (Populus balsamefera var. Muchuxii (Henery) X Populus trichocarpa var. Hastata (Dode) Farwell.) were studied through three greenhouse experiments. The seedlings in the first experiment received either 1 or 3 or 9 mol N m-3 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.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Forestry & agroforestry & sustainable forestry Forests and forestry