Abstracts |
A multifactor experiment was undertaken to investigate the influence of Rhizobium
and arbuscular mycorrhizal fungi (AMF) on biomass production, leaf area generation, whole plant
photosynthetic and respiration rates, growth yield and maintenance respiration in Vicia faba L
under low phosphorus (P) supply. Treatments consisted of low (LN) or high nitrogen (FIN) supply
with or without microbial symbiont(s). Plants were harvested at 54 (T-1) and 63 (T-2) days after
planting. In all instances, plants colonized with both microbial symbionts had significantly
higher total biomasses, leaf areas, whole plant photosynthesis and respiration rates than plants
with only one or no microbial symbionts. Similarly, plants with both microbial symbionts also had
significantly higher (>= 0.7) growth yield (Y-g) values than all the other treatments. There were
no significant differences in Y-g values between harvest intervals within individual treatments.
Maintenance respiration rates were also highest in plants with two microbial symbionts (> 30 CO2
(g DM)(-1) d(-1)). In LN plants colonized by both microbial symbionts there was evidence of
compensatory increases in the photosynthetic rates in response to the carbon sink demands of the
microbial symbionts. Finally, the results of this investigation are consistent with the
hypothesis that the plant potential photosynthetic capacity exceeds the carbon demand of the
Rhizobium-AMF symbiotic complex. (C) 2007 SAAB. Published by Elsevier B.V. All rights reserved. |