Effect of Burning Candle and Grain
Volume on Rate of Oxygen Depletion and
Carbon Dioxide Build-up in Metal Silos for
Control of Larger Grain Borer
(Prostephanus truncatus)
Anne Kimani
A56/81173/2012
Supervisors: Prof. F. Olubayo
: Dr. D. Kilalo
: Dr. T. Tadele
OBJECTIVES
BROAD OBJECTIVE
• To determine the effectiveness of metal silos in
reducing post harvest losses in stored maize caused by
Larger Grain Borer, Prostephanus truncatus.
SPECIFIC OBJECTIVES
• To determine the effective sealing method in metal
silos for control of larger grain borer in stored maize.
• To determine the effect of burning candle and grain
volume on rate of oxygen depletion and carbon dioxide
build up in the metal silo.
MATERIALS AND METHODS
•The experimental site: Kenya Agricultural Research
Institute (KARI) Kiboko Research Centre ( KARIKiboko).
•Prostephanus truncatus culture from KARI-CIMMYT,
Kiboko post harvest laboratory.
Objective 1: To detemine the effective sealing
method in metal silos for control of larger grain
borer in stored maize
•Untreated maize grain from farmers, dried to12-13%
M.C and cleaned to remove dust and broken grains.
•Fumigated with Phostoxin tablet (55% aluminium
phosphide, 45.0% inert material) in sealed plastic
drums for 7 days.
Objective 1: cont
•90 kg metal silos designed to have a small hole fitted
with an elastic rubber cork for measuring Oxygen and
Carbon dioxide using a portable gas composition
analyzer (MOCON) were used.
•100 unsexed (sex ratio is assumed 1:1) ten day old,
LGB were used to infest the maize in metal silos and in
an aerated 1.5 liter glass jar with 400gm. One glass jar
was put in each metal silo before closing and sealing
them.
•A candle was lit in each metal silo to deplete oxygen
before closing and sealing the metal silos.
Objective 1: cont
•The treatments were arranged in a completely
randomized design with four replicates per treatment
and run for 3 months.
Treatments :
T1 = 90 kg metal silo sealed using rubber.
T2 = 90 kg metal silo sealed using rubber and grease.
T3 = 90 kg metal silo sealed using grease.
T4 = 90 kg metal silo without sealing.
Metal silos
designed for
measuring O2
and CO2
Aerated
glass jars
Pictures of metal silos with different sealing
methods
Burning candle
Grease & rubber
grease
Without sealing
Rubber
Trial layout
Obj 2: To determine the effect of burning
candle and grain volume on rate of O2 depletion
and CO2 build up in metal silos.
•100 unsexed (sex ratio is assumed 1:1) ten day old,
LGB were used to infest the maize.
•Effective sealing method in obj. 1 will be used to seal
the silos.
•Completely randomized design will be used, treatments
replicated three times and run for 6 months.
•Treatments :
T1 = Fully- filled silo with grain and a burning candle
T 2 = Fully-filled silo without candle
T3 = Half –filled silo and a burning candle
T4 = Half –filled silo without candle
T5 = filled 90 kg farmer’s bag (polypropylene ).
Data collection in obj: 1 & 2
•Moisture content, aflatoxin levels and nutritional content
(starch, protein and oil content)of the grain.
•O2 and CO2 levels in each silo every two weeks.
•Grain (kernel) damage and % weight loss.
•Weight loss will be determined using the count and
weight method of Gwinner et al., 1996:
Weight loss % = (Wu x Nd)-Wd x Nu) X 100
Wu x (Nd + Nu)
Where Wu = weight of undamaged grain, Nu= number of
undamaged grain, Wd = Weight of damaged kernel and
Nd = Number of damaged kernels.
Data analysis
•Data analyzed using the statistical analysis software
(SAS).
Summary of studies completed
•Preliminary trial on objective 1 was done from May
to July 2013 at KARI, Kiboko post harvest laboratory
where Prostephanus truncatus culture was obtained.
•A mixture of two maize varieties (Nduma 41 and
Pioneer PHB 3253) was bought from farmers, cleaned,
dried to 11-12% moisture content and fumigated with
phostoxin in plastic drums for 7 days.
Treatments :
T1 = 90 kg metal silo sealed using rubber.
T2 = 90 kg metal silo sealed using rubber and grease.
T3 = 90 kg metal silo sealed using grease.
T4 = 90 kg metal silo without sealing.
Results
Trt
1
2
3
4
O2
19.07
19.23
19.7
20.43
CO2
1.89
1.53
1.27
0.36
Temp
25.4
25.1
25.2
24.8
Fig 1. Gas concentration in metal
silos
% damage
% weight loss
1
3.9
0.15
2
4.89
0.04
3
5.68
1.17
4
6.31
1.58
Fig 2. Grain damage and weight loss
30
8
25
20
15
10
5
0
Trt 1 Trt 2 Trt 3 Trt 4
O2
CO2
temp
% weight loss and damage
% gas concentration.
Trt
6
4
2
0
Trt 1 Trt 2 Trt 3
% damage
trt 4
% weight loss
Plan to completion of the remaining activities
Activity
2012
2013
2014
ON D J F M AM J J AS ONDJ F M AM J J AS OND
Course work
Proposal writing
and submission
Objective 1 set
up
Data collection
and analysis
Objective 2 set
up
Data collection
and analysis
Thesis writing
Thesis
submission
Graduation