Record ID No. |
1848 |
Author(s) |
Azcon R., Rodriguez R., AmoraLazcano E., Ambrosano E , 2008 |
Affiliation |
CSIC, Estac Expt Zaidin, Dept Microbiol Suelo & Sist Simbiot, Granada 18008, SPAIN |
Title |
Uptake and metabolism of nitrate in mycorrhizal plants as affected by water availability and N concentration in soil |
Source. Vol.(no):Page |
European Journal of Soil Science.59(2):131-138p. |
Categories |
Arbuscular Mycorrhiza |
Subjects |
Biochemistry |
Sub-subjects |
Miscellaneous |
Organism |
n.a. |
Country |
SPAIN, Europe |
Abstracts |
We compare the effect of arbuscular mycorrhizal (AM) colonization and PO4-3
fertilization on nitrate assimilation, plant growth and proline content in lettuce plants growing
under well-watered (-0.04 MPa) or drought (-0.17 MPa) conditions. We also tested how
AM-colonization and PO4-3 fertilization influenced N uptake (N-15) and the percentage of N
derived from the fertilizer (% NdfF) by plants under a concentration gradient of N in soil.
Growth of mycorrhizal plants was comparable with that of P-fertilized plants only under
well-watered conditions. Shoot nitrogen content, proline and nitrate reductase activity were
greater in AM than in P-fertilized plants under drought. The addition of 100 mu g g(-1) P to the
soil did not replace the AM effect under drought. Under well-watered conditions, AM plants showed
similar (at 3 mmol N), greater (at 6 mmol N) or lesser (at 9 mmol N) %NdfF than P-fertilized
plants. Comparing a control (without AM inoculation) to AM plants, differences in % NdfF ranged
from 138% (3 mmol N) to 22.6% (6 mmol N) whereas no differences were found at 9 mmol N. In
comparison with P fertilization, mycorrhizal effects on %NdfF were only evident at the lowest N
levels, which indicated a regulatory mechanism for N uptake in AM plants affected by N
availability in the soil. At the highest N level, P-fertilized plants showed the greatest %NdfF.
In conclusion, AM symbiosis is important for N acquisition and N fertilizer utilization but this
beneficial mycorrhizal effect on N nutrition is reduced under large quantities of N fertilizer. |