IJH-2016v6n1 - page 7

International Journal of Horticulture 2016, Vol.6, No.1, 1- 7
http://ijh.biopublisher.ca
3
May and 18th August for the 2012 rainy and late
season experiments. The centre of the wider spaces
between the two-double rows were planted with five
weeks old pepper seedlings at 60cm apart while the
spaces within each double rows of pineapple were
alternated for planting of pepper and cowpea
separately. Cowpea cultivar (Ife brown) characterized
by semi-erect growth and intermediate maturity period
was sown at two seeds per stand into the spaces
between the transplanted pepper and the adjacent row
of pineapple in the wider spaces and at the centre of
the space within double rows that were not planted to
pepper at 50 cm apart.
Cowpea seeds were sown into the intercropped plots
on 9th and 31st May, 21 st June and 2nd July 2011
respectively for the rainy season experiment while
cowpea seeds were sown on 8th and 28th September
for the 2011 late season experiment. Likewise, cowpea
seeds were sown into the intercropped plots on 19th
May, 9th June, 30th June and 21st July respectively for
the 2012 rainy season experiment while cowpea seeds
were sown on 10th August and 12th September for the
late season experiment.
Induction of flowering in pineapple was carried at
13-14 months after planting (MAP) with Ethrel
(2-Chloroethylphophonic acid) a plant growth
regulator and ethylene producing hormone to
stimulate uniform flowering. The ethrel solution was
prepared by dissolving 30 mls of ethrel paste and 150
g of urea fertilizer in 20 litres of clean water in a
knapsack sprayer and thoroughly agitated into
homogeneous solution. About 50 mls of the
homogeneous solution was dispensed into the centre
of the pineapple leaf rosette to ensure accumulation of
the solution at the leaf axils for contact with the
abaxial epidermis close to stem apex for a period of
time. This procedure was adopted following the report
by Turnbull et al. (1993). The vegetative growth of
pineapple was assessed using the D-leaf as growth
indicator. The leaf area of pineapple D-leaf, the
youngest fully physiologically mature leaf on the plant
and also the longest growing leaf on the plant (Petty,
2006; Pineapple News, 2008) was estimated from the
length and width of the leaf at 3 to 10 MAP. Based on
the triangular shape of the leaves, the leaf area of the
pineapple D-leaf was estimated as:
D-leaf area = ½ * b*h.
where b and h are the width and length of the D-leaf
respectively.
Two pineapple plants were uprooted per plot at the
end of intercropping phase and the biomass were
separated into various components (leaves, stem and
root), weighed and oven dried to constant weight at
105 °C. The number of days to 50 % inflorescence
initiation after flowering induction was monitored and
fruit yield and yield components were determined.
The yield parameters measured were fruit girth,
weight of whole fruit, weigh of fruit without crown,
crown weight and fruit yield. Data collected were
subjected to analysis of variance using Statistical
Analysis System version 9 (SAS, 2003) and means
separated using Tukey’s Honestly Significant
Difference (HSD) test at 5% probability level.
3 Results
3.1 Effects on time of sowing cowpea into
pineapple-pepper intercrop on growth characters
of pineapple
Table 3 shows the temporal trends of the D-leaf area
which differed significantly between 32 and 40 WAP in
the rainy season of 2011. Sowing cowpea early into the
intercrop resulted in significantly lower D-leaf area.
Sowing of cowpea early at the time of transplanting
pepper produced lowest leaf area. However in the late
season planting of 2011, the D-leaf area was not
significantly influenced by the time of sowing cowpea.
The D-leaf area measured at the various sampling dates
was not significantly influenced by time of sowing
cowpea into pineapple-pepper intercrop in rainy and
late season of 2012.
The pineapple biomass (dry weights of pineapple leaves,
stem, root and total plant biomass) measured at
post-intercropping were not significantly influenced by
the date of sowing cowpea into pineapple-pepper
intercrops in both experiments (2011 and 2012, Table 4).
3.2 Effects of time of sowing cowpea into
pineapple-pepper intercrops and season of planting
on flowering, yield and yield components of
pineapple
The number of days to 50 % flowering in pineapple
decreased with delayed introduction of cowpea into
pineapple-pepper intercrop in the rainy season
planting of 2011 and 2012 (Table 5). Although not
significantly different from other sowing dates,