Page 16 - Volume 4, Issue 1, January 2011
Basic HTML Version
© Benaki Phytopathological Institute
Troyanos & Roukounaki
14
effects of soil and foliar fertilization on olive
tree growth and leaf [N] are discussed.
Material and Methods
Two hundred sixteen (216) one-year-old mi-
cro-propagated olive trees (cv. ‘Koroneiki’),
grown in plastic bags filled with a mixture
of compost and perlite, were transplanted
on 16 March 2007 into 14 l plastic pots to fa-
cilitate the access to their root system dur-
ing their growth. The plastic pots contained
a clay loam soil with the following charac-
teristics: pH = 7.7, Electrical Conductivity
(EC) = 0.66 dS/m (Saturated Paste
)
, Organic
matter = 1%, CaCO
3
= 29%, P = 3 ppm (Ol-
sen method), K = 156 ppm (extraction with
1 M NH
4
OAc at pH = 7.0
)
and B = 1.3 ppm
(extraction with hot water). Prior to trans-
planting, the length of the new shoots and
the length and diameter of stems were mea-
sured. These measurements were used to
estimate the initial size of the plants.
Following their transplanting, the exper-
imental olive trees were placed outdoors
with the pots covered with plastic bags to
reduce water evaporation and to ensure
that no rain water would enter the pots. The
young olive trees were irrigated using tap
water (NO
3
-N concentration = 1.1 ppm, EC
= 0.915 dS/m) and received no fertilization
for one month following their transplanting.
The soil moisture was monitored using ten-
siometers and water was applied to the soil
until field capacity. The mean air tempera-
tures during the experiment are given in
Figure 1.
According to their size, the experimental
young olive trees were sorted in descend-
ing order. The trees were then split into 6
groups, with the 1
st
group consisting of the
largest ones and the 6
th
group of the small-
est. The 36 plants in each group were then
randomly assigned to 6 rows and columns
according to a 6x6 Latin Square design. This
randomization reduced the effect of varia-
tion in the initial size of the plants on their fi-
nal growth (1). Five different soil N fertiliza-
tion rates, 0 (N
0
), 0.95 (N
1
), 1.90 (N
2
), 3.80 (N
3
)
and 6.25 (N
4
) g N (Table 1) and a foliar treat-
ment of 0.3 g/l of 21-21-21 (N-P-K) soluble
fertilizer (N
f
), as recommended by the man-
ufacturer, were gradually applied to each
plant. During the course of the experiment,
a total of six destructive harvests were car-
ried out 31, 65, 93, 136, 167 and 201 days af-
ter the first fertilization (DAF) by randomly
selecting 36 plants (6 treatments x 6 replica-
tions) at each harvest.
Based on the results of soil analyses,
on 15 April 2007, 0.74 g KH
2
PO
4
and 1.33 g
K
2
SO
4
dissolved in 1 l tap water were applied
to each pot of the treatments N
0
, N
1
, N
2
, N
3
Figure 1.
Changes in the mean daily temperature (
o
C) during the course of the experiment. DAF: days after first fertiliza-
tion.
