Agriculture Reference
In-Depth Information
m
2
/m
2
3.0
1.2
1.2
1.0
1.0
2.0
0.8
0.8
0.6
0.6
1.0
0.4
0.4
0.2
0.2
0
60
120
0
60
120
0
60
120
amount of nitrogen in kg/ha applied on April 3
Fig. 9.17
Effect of nitrogen on the leaf-area-index (LAI) and on the chlorophyll content of winter-
wheat in Indiana, USA. The chlorophyll mass per unit of field area in the
right graph
is the product
of the leaf-area-index in the
left graph
and the chlorophyll mass per unit of leaf area in the
central
graph
(Compiled from data by Hinzman et al.
1986
)
4
30
3
20
2
10
1
March
April
May
June
March
April
May
June
Fig. 9.18
Effect of nitrogen on leaf-area-index and on chlorophyll content of winter-rape (winter-
colza) in Schleswig-Holstein, Germany. For the fertilized plots, the crop was dressed with 40 kg of
N per ha respectively at the end of March, at the end of April and at the beginning of May. Hence
for these plots, the total amount of N applied in the spring was 120 kg per ha (From Kappen et al.
1998
, altered)
Research by Hinzman et al. (
1986
) with wheat and by Kappen et al. (
1998
) with
rape (colza) revealed the effect of nitrogen on the chlorophyll concentration within
the leaves as well as on the leaf-area-index. It can be seen from Figs.
9.17
and
9.18
that nitrogen changes the leaf-area-indices much more than the chlorophyll concen-
tration within the leaves. The dominating effect of nitrogen on biomass production