Agriculture Reference
In-Depth Information
Table 12.3.
Fertilizer protocol for pineapple planted at 58,710 plants/ha, applied
using a spray valve of 2500 l/ha for different stages of plant development (after Evans
et al.
, 1988).
Stage of development (month)
0
0-3
4-8
9-10
11-12
Stage
Prior to
planting
Growing
Growing
Growing
Forcing
Method
Into soil
Foliar
Foliar
Foliar
Foliar
Number of
applications
1
3
5
2
2
Desired crop
colour
Pale yellow
green
Darker
yellow
green
Dark
green
All green
Total
(kg/ha/
year)
Fertilizer
Rate (kg/ha/application)
Urea
22
22
33
45
55
450
Potassium nitrate
22
22
33
45
55
450
Iron sulfate
1.5
1.5
2.25
3.0 3.70
30
Zinc sulfate
0.5
0.5
0.75
1.0 1.25
10
Magnesium sulfate 2.75
2.75
3.75
5.5 6.75
55
gases require specialized equipment for ef ective application and safe use.
In the warm tropics, SNA has not been ef ective, while a water solution of
acetylene produced from calcium carbide or calcium carbide as granules has
been successful.
Ethephon (2-chloroethylphosphonic acid) is probably the most widely
used chemical in commercial pineapple production because of its ef ectiveness
and ease of application. This chemical breaks down to produce ethylene
at neutral pHs (Bartholomew and Criley, 1983). The ef ective ethephon
concentration ranges from 500 to 1500 μg/l, with greater amounts required
to force fl owering in warm than in cool months. At least 90% fl owering is
obvious 40-60 days after applying about 1000 μg/l solutions (Fig. 12.7) with
50 kg/ha urea (Bartholomew, 1977). In some regions, adjusting the solution
pH above 7 with sodium borate improves forcing success.
Acetylene and ethylene are less ef ective when applied during the day
but highly ef ective when applied at night or during the early morning hours,
when the stomates are open (Bartholomew and Kadzimin, 1977). In warm
seasons, forcing success may be greater on days when temperatures are less
than 30°C. High N level in the plant at the time of forcing may further reduce
forcing success in warm weather, while withholding nitrogen fertilizer for 4-6
weeks before forcing can improve induction. Plants approaching the natural