Effects of Mg supply on “Colt” cuttings
81
The RUR could be estimated after dif-
ferentiation of the equation (2) with re-
spect to time as follows:
(3)
The M ÷ W
r
was estimated after fitting
an equation between the ratios of the nu-
trient content of the plants ÷ dry weight of
roots (W
r
) over time in days (t) after trans-
planting as follows:
(4)
By multiplication of equations (3) and (4)
the UAR could be derived as follows:
(5)
For derivation of the unit absorption
rates UAR the dry weight of the roots with
approximate diameter <2 mm were used.
Results
Growth
Based on regression analyses, quadratic
equations were found to be the most appro-
formed (
log
e
) to stabilize the variance over
time. F-testswere used todeterminewheth-
er differences were statistically significant.
Analysis of variance (ANOVA) was used also
to assess the effect of the treatment factor
at the different harvest. The derivation of
the mean unit absorption rates was based
on the dynamic growth analysis (15) and
was carried out as follows:
The unit absorption rate (UAR, nmol
mg
-1
day
-1
) i.e. the rate of the mineral nutri-
ent (nmol) absorbed per day and unit root
weight (mg), was estimated using the fol-
lowing equation:
(1)
Where:
RUR = relative nutrient uptake rate
1.
(μmol μmol
-1
day
-1
) i.e. the rate of nutri-
ent content (μmol) increase per nutri-
ent (μmol) per day.
M ÷ W 2.
r
= the ratio between the plant
nutrient content, (M in μmol) and dry
weight of roots, (W
r
, in mg).
The RUR was estimated after fitting
an equation between the logarithmical-
ly transformed nutrient content of the
plants (
log
e
M) over time in days (t) after
transplanting as follows:
(2)
Table 2.
The effect of Mg external supply on the relationship between
log
e
-transformed total
plant (W), leaf (WL), stem (WS), new shoot (WNSH) and root (WR) dry weight, leaf area (LA), shoot
diameter (SD) and new shoot length (LNSH) of `Colt’ and time. The equations fitted were quadrat-
ics (a+ bt+ ct
2
) where a, b, c were the parameters estimated by the statistical analysis and t time in
days. R
2
coefficients of determination, SED standard error of differences.
0 μmol Mg l
-1
150 μmol Mg l
-1
1500 μmol Mg l
-1
R
2
SED a
b c
a
b
c
a
b
c
W 0.84 0.0001 8.636 0.0039 0.00024 8.636 0.0039 0.00012 8.636 0.0039 0.000006
W
L
0.82 0.0001 6.738 0.061 0.00041 6.738 0.061 0.00027 6.738 0.061 0.00021
W
S
0.74 0.0009 8.768 0.016 0.00085 8.768 0.016 0.000007 8.768 0.016 0.000038
W
NSH
0.84 0.0002 3.599 0.106 0.00066 3.599 0.106 0.00048 3.599 0.106 0.00040
W
R
0.86 0.0001 4.891 0.080 0.00054 4.891 0.080 0.00036 4.891 0.080 0.00029
S
D
0.72 0.00005 1.464 0.019 0.00014 1.464 0.019 0.000098 1.464 0.019 0.000073
L
NSH
0.78 0.0001 8.495 0.076 0.00046 8.495 0.076 0.00039 8.495 0.076 0.00033
L
A
0.88 0.0002 7.879 0.103 0.00040 7.879 0.103 0.00025 7.879 0.103 0.00017
1...,19,20,21,22,23,24,25,26,27,28 30,31,32,33,34,35,36,37,38,39,...68