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Nitrogen dynamics and growth of seedlings of an N-fixing tree ( Gliricidia sepium (Jacq.) Walp.) exposed to elevated atmospheric carbon dioxide

Nitrogen dynamics and growth of seedlings of an N-fixing tree ( Gliricidia sepium (Jacq.) Walp.)... Seeds of Gliricidia sepium (Jacq.) Walp., a tree native to seasonal tropical forests of Central America, were inoculated with N-fixing Rhizobium bacteria and grown in growth chambers for 71 days to investigate interactive effects of atmospheric CO 2 and plant N status on early seedling growth, nodulation, and N accretion. Seedlings were grown with CO 2 partial pressures of 350 and 650 μbar (current ambient and a predicted partial pressure of the mid-21st century) and with plus N or minus N nutrient solutions to control soil N status. Of particular interest was seedling response to CO 2 when grown without available soil N, a condition in which seedlings initially experienced severe N deficiency because bacterial N-fixation was the sole source of N. Biomass of leaves, stems, and roots increased significantly with CO 2 enrichment (by 32%, 15% and 26%, respectively) provided seedlings were supplied with N fertilizer. Leaf biomass of N-deficient seedlings was increased 50% by CO 2 enrichment but there was little indication that photosynthate translocation from leaves to roots or that plant N (fixed by Rhizobium ) was altered by elevated CO 2 . In seedlings supplied with soil N, elevated CO 2 increased average nodule weight, total nodule weight per plant, and the amount of leaf nitrogen provided by N-fixation (as indicated by leaf δ 15 N). While CO 2 enrichment reduced the N concentration of some plant tissues, whole plant N accretion increased. Results support the contention that increasing atmospheric CO 2 partial pressures will enhance productivity and N-fixing activity of N-fixing tree seedlings, but that the magnitude of early seedling response to CO 2 will depend greatly on plant and soil nutrient status. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Oecologia Springer Journals

Nitrogen dynamics and growth of seedlings of an N-fixing tree ( Gliricidia sepium (Jacq.) Walp.) exposed to elevated atmospheric carbon dioxide

Thomas, R.; Richter, D.; Ye, H.; Heine, P.; Strain, B.
Oecologia , Volume 88 (3) – Nov 1, 1991
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References (34)

Publisher
Springer Journals
Copyright
Copyright © 1991 by Springer-Verlag
Subject
Life Sciences; Ecology; Plant Sciences
ISSN
0029-8549
eISSN
1432-1939
DOI
10.1007/BF00317587
Publisher site
See Article on Publisher Site

Abstract

Seeds of Gliricidia sepium (Jacq.) Walp., a tree native to seasonal tropical forests of Central America, were inoculated with N-fixing Rhizobium bacteria and grown in growth chambers for 71 days to investigate interactive effects of atmospheric CO 2 and plant N status on early seedling growth, nodulation, and N accretion. Seedlings were grown with CO 2 partial pressures of 350 and 650 μbar (current ambient and a predicted partial pressure of the mid-21st century) and with plus N or minus N nutrient solutions to control soil N status. Of particular interest was seedling response to CO 2 when grown without available soil N, a condition in which seedlings initially experienced severe N deficiency because bacterial N-fixation was the sole source of N. Biomass of leaves, stems, and roots increased significantly with CO 2 enrichment (by 32%, 15% and 26%, respectively) provided seedlings were supplied with N fertilizer. Leaf biomass of N-deficient seedlings was increased 50% by CO 2 enrichment but there was little indication that photosynthate translocation from leaves to roots or that plant N (fixed by Rhizobium ) was altered by elevated CO 2 . In seedlings supplied with soil N, elevated CO 2 increased average nodule weight, total nodule weight per plant, and the amount of leaf nitrogen provided by N-fixation (as indicated by leaf δ 15 N). While CO 2 enrichment reduced the N concentration of some plant tissues, whole plant N accretion increased. Results support the contention that increasing atmospheric CO 2 partial pressures will enhance productivity and N-fixing activity of N-fixing tree seedlings, but that the magnitude of early seedling response to CO 2 will depend greatly on plant and soil nutrient status.

Journal

Oecologia – Springer Journals

Published: Nov 1, 1991

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