Growth,Nutrition, and Photosynthetic Response of Black Walnut to Varying Nitrogen Sources and Rates |
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| Authors: | Michael A Nicodemus Francis K Salifu Douglass F Jacobs |
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| Institution: | Department of Forestry and Natural Resources, Hardwood Tree Improvement and Regeneration Center , Purdue University , West Lafayette, Indiana, USA |
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| Abstract: | ABSTRACT Black walnut (Juglans nigra L.) half-sib 1+0 seedlings were exponentially fertilized with ammonium (NH4 +) as ammonium sulfate (NH4)2SO4], nitrate (NO3 ?) as sodium nitrate (NaNO3), or a mixed nitrogen (N) source as ammonium nitrate (NH4NO3) at the rate of 0, 800, or 1600 mg N plant?1 and grown for three months. One month following the final fertilization, N concentration, growth, and photosynthetic characteristics were assessed. Compared with unfertilized seedlings, N addition increased plant component N content, chlorophyll content, and photosynthetic gas exchange. Net photosynthesis ranged from 2.45 to 4.84 μmol m?2 s?1 for lower leaves but varied from 5.95 to 9.06 μmol m?2 s?1 for upper leaves. Plants responded more favorably to NH4NO3 than sole NH4 + or NO3 ? fertilizers. These results suggest that N fertilization can be used to promote net photosynthesis as well as increase N storage in black walnut seedlings. The NH4NO3 appears to be the preferred N source to promote black walnut growth and physiology. |
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| Keywords: | photosynthesis chlorophyll nitrate ammonium nitrogen Juglans nigra |
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