Degree Type


Date of Award


Degree Name

Doctor of Philosophy




Five selected clones of Alnus glutinosa were evaluated for nurse and tree crop potential. The clones were compared using net photosynthesis rates, respiration rates, acetylene reduction rates, height-growth rates and dry weights (root, shoot, and nodule) when grown under three levels of moisture stress (-0.2, -2.2, and -4.4 bars of moisture tension). The water potential for moisture levels was controlled using unpurified polyethylene glycol (P.E.G.) molecular weight 6000 dissolved in a dilute nutrient solution. The lowest level of moisture tension, the controls, contained only nutrient solution and no P.E.G;Net photosynthesis and respiration rates were similar for all moisture levels throughout the 12-week study. There were no significant differences (P < 0.05) in respiration rates for the five clones. However, clones AG-2915 and AG-6331 had significantly higher net photosynthesis rates than the other three clones;Acetylene reduction rates increased throughout the experiment. Acetylene reduction rates at 6, 9, and 12 weeks were significantly higher (P < 0.05) than at 3 weeks. The acetylene reduction rates for clones and moisture levels were not significantly different at P < 0.05;Clone AG-1162 (from Ireland) was the superior clone for height-growth. Clones grown under control conditions and clones grown under -2.2 bars of tension had more height-growth than clones grown under the -4.4 bars of tension. Clones produced significantly (P < 0.05) more root and shoot dry weight under moisture level 1 than under moisture levels 2 and 3. Nodule dry weights were similar for clones and moisture levels;Clones AG-1162 and Ag-1291 from Ireland showed early tree crop characteristics of rapid height-growth, slow respiration rates, high nitrogen fixation (acetylene reduction) and high root, shoot and nodule dry weights. Clones AG-2915 from Russia, AG-6331 from Poland and AG-5622 from Switzerland had nurse crop characteristics of slow height-growth and high photosynthesis.



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Jerome Thomas



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115 pages

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Biology Commons