Page 30 - Volume 1, Issue 1, January 2008
Basic HTML Version
A. Assimakopoulou
et al.
28
using the Statistica package (Statsoft, Inc).
Analysis of variance (ANOVA) was applied
to different plant variables (Fe, Mn, Zn and
Cu concentration of foliage and root, fresh
and dry weight of foliage etc), the signifi-
cance effects of nitrogen treatments were
tested by F-test and significant differenc-
es in mean values between nitrogen treat-
ments were evaluated by LSD test.
Results
Experiment A
The Fprs of the ANOVA for fresh, dry
weight and Mn, Zn, Cu concentration in the
plant foliage were found statistically differ-
ent (P<0.05) whereas the Fpr for Fe concen-
tration was not. There was an increase of fo-
liage fresh and dryweight up to level Ν
7
with
increasing nitrogen supply in the growth
medium; the maximum RGR of plants was
achieved at external supply of nitrogen ≥ 4
mM; the relevant data are shown in Troya-
nos
et al.
2004b (13). The concentrations of
Fe, Mn, Zn and Cu at Ν
1
level were found
higher than those at higher nitrogen levels.
In the case of Zn and Cu, these differences
were significant, the concentration of Mn
was statistically significant higher at Ν
1
, Ν
2
levels whereas the concentration of Fe was
independent of the nitrogen supply (Table
1). Besides, the negative correlations be-
tween the foliage fresh weight and the con-
centrations of Mn, Zn and Cu were found
statistically significant; Mn (r=-0.85
***
), Zn
(r=-0.74
***
) and Cu (r=-0.44
*
).
Experiment B
The fresh weight of the plants in-
creased significantly up to Ν
5
fertilization
rate and decreased thereafter. The de-
crease in plant fresh weight at N
6
fertiliza-
tion rate was probably due to negative ef-
fect of excess fertilizer applied to the soil.
The Fprs of the ANOVA for the concen-
tration of Zn and Cu in the plant foliage
were found statistically different (P<0.05)
whereas the relevant ones for Fe and Mn
were not. Foliage Zn concentration at Ν
5
fertilization rate was found significantly
highest compared to Ν
1
, Ν
2
, Ν
3
, Ν
4
, Ν
6
ones
whereas the relevant Cu concentrations at
Ν
4
, Ν
5
rates were found significantly higher
compared to Ν
1
, Ν
2
, N
3
ones (Table 2). At Ν
6
rate the foliage micronutrient concentra-
tions presented a similar to fresh weight
trend; they were found decreased as com-
pared to the relevant ones at Ν
5
rate . Fur-
thermore, a statistically significant posi-
tive correlation was found between the
foliage fresh weight and the concentra-
Table 1.
Effect of nitrogen concentration in the nutrient solution on foliage fresh and dry weights
and Fe, Mn, Zn and Cu concentration in lettuce Butterhead (cv. Divina) (means, n=4). The values
followed by different letters within a column are significantly different at P<0.05.
N in the
nutr. solution
Foliage
f. w.
Foliage
d. w.
Foliage
Fe
Foliage
Mn
Foliage
Zn
Foliage
Cu
(mM)
(g)
(mg kg
-1
d.w.)
Ν
1
– (0.1)
5.8 a
0.71 a
175.3 a
103.2 a
167.3 a
20.5 a
Ν
2
– (0.5)
23.2 a
2.08 ab 99.3 e
86.8 ab 112.0 b
11.2 b
Ν
3
– (1.0)
54.6 b
4.02 b 120.0 a-e
73.8 b
117.5 b
9.7 b
Ν
4
– (2.0)
97.2 c
6.54 c 145.8 a-e
36.0 c
97.8 bd
10.1 b
Ν
5
– (4.0)
153.2 d 8.96 c
171.8 ab 14.3 c
63.0 e
10.0 b
Ν
6
– (7.0)
198.5 e 10.78 d 160.3 a-d 19.8 c
76.3 de
10.6 b
Ν
7
– (14.0)
232.7 f
14.21 de 160.3 abc
12.3 c
65.7 de
10.3 b
