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International Journal of Horticulture 2014, Vol.4, No.14, 1
-
10
http://ijh.biopublisher.ca
5
ET
peak
= 5.1 *80/85 = 4.8 mm/day
The volume of water required per plant (irrigation
requirement, I
R
) was estimated as:
Irrigation requirement (I
R
) = ET
peak
* area/crop/En
(I
R
) = ET
peak
* area/crop/E
n
…………8
= 4.80 *0.27/0.94 = 1.38 litres/day
where area per crop is 0.18 m
2
(90 * 30 crop spacing:
0.18m
2
)
Effective moisture content within 0-60 cm soil depth
at incremental depths of 10 cm, is the sum of moisture
contents (4.15cm) in each layer 0-10, 10-20, 20-30,
30-40, 40-50, 50-60 cm) These gave soil moisture
content of 0.80, 0.83, 0.88, 0.65 and 0.76 % before
irrigation. Moisture contents at site of experiment at
field capacity (21g/100 g soil), and permanent wilting
point (PWP) (7.8 g/100 g soil) while the depth of crop
root zone (RZd) for water extraction is approximated
from values obtained for tomato in the study area
within 0 - 60 cm (Agele, 1999).
Maximum (management) allowable deficit (MAD) for
pepper was set at 50 %.
Net water requirement (NWR) was calculated as:
NWR = (Fc
-
PWP) * Bd * RZd * MAD………….9
NWR = (21 – 7.8) * 1.26 * 60 * 0.5 ( g/g*g/cm3*cm)
= 498.96 = 49.9 mm = 4.99 cm
Irrigation frequency or irrigation interval (Ir Int.) is
calculated as net water requirement (NWR)/ peak
consumptive use rate (ET
peak
) by the crop
IrInterval = NWR/ETpeak ……………10
= NWR/ET
peak
= 4.99/4.8 = 1.
The calculated irrigation interval (Ir Int) is once per
day.
Weather variables at site of experiment during crop
growth cycle (soil and air temperatures, vapour
pressure deficit (vpd), solar radiation, wind speed will
be monitored from Meteorological Observatory, 500m
from site of experiment). Data collected were
subjected to analysis of variance (ANOVA) while
significant treatment means were separated using the
Least Significance Difference (LSD) test at 5% level
of probability.
The second year experiments which involved identical
treatments as in 2009 were sown on December and
January 2009 and 2010 respectively. The results for
the two-years experiments were separately analyzed,
and were not significantly different from one year to
the other. Therefore, data collected for the two-years
of study were averaged and means are presented in
tables and figures in the text.
Results and Discussion
Weather condition of the site of study
site
The weather conditions at site of study during pepper
growth is presented shown in Figure 1. Atmospheric
vapour pressure deficits range from 2.7 to 3.7 kPa
while solar radiation ranges between 14.21
and 15.16
MJ/m²/day. Rainfall at the site of study is
characterized by gradual rise from the month of
January until it reaches the peak in the month of June.
Thereafter, it declined in the month of July and
August when a little break in rainfall is experienced.
However, the months of September and October are
characterized by heavy but infrequent rainfalls and
this is the second modal rainfall. November marks the
unset of the dry season.
Figure 1 Weather conditions during pepper growth
Wetting Pattern
The patterns of soil moisture redistribution following
irrigation (wetting pattern) monitored by scrapping
every 10 cm depth of soil. Figure 2a and b present
trends on the wetting pattern two and five days
following irrigation. The results show that irrigation
regimes affected soil moisture replenishment, its
storage and depletion by pepper plants across soil
depths and sampling dates. There was wider surface
wetting and shallower zone of active root water uptake