drivers of soil respiration of root and microbial ... - Unitus DSpace

The distribution of N between shoots and roots also varied depending on the growth stage:
under NH4 + -N 72% of the 15 N was recovered in shoots of V6 corn, on V8 stage only 58% of the
found 15 N had a shoot origin. Under NO3 - -N the difference between two growing stages in
distribution of absorbed 15 N was not so clear: 67% and 62% of recovered 15 N respectively for V6
and V8 plants had a shoot origin (Fig. 5).
15 N recovered in BG and AG biomass (mmol g dw -1 )
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0.1
0.2
0.3
e
(41%)
(59%)
a
lupine
f
(36%)
(64%)
a
NH 4 + NO 3 -
corn V6 corn V8
a
(72%)
(28%)
a
b
(67%)
(33%)
b
+ -
NH NO
4
3
c
(58%)
(42%)
a
NH 4 +
d
(62%)
Fig. 5. 15 N amount recovered from shoot (above zero) and roots (below zero. In red) of Lupinus albus and Zea
mays on V6 and V8 growing stage. Percentages indicate 15 N distribution between shoots and roots of plants.
Letters indicate the significance of the differences at p=0.05 between the treatments.
5.3.4. Total CO2 efflux from planted soil with Lupinus albus and Zea mays (V6)
The difference between total CO 2 efflux from the root-soil system and microbial respiration
from bare soil incubated at the same conditions was used to calculate the CO2 respired by roots and
associated rhizosphere microorganisms (root-derived respiration) and to compare with the results
from 14 C labeling for root-derived CO 2 .
(38%)
b
- NO3 133