Anne Kimani A56/81173/2012. Supervisors: Prof. F. Olubayo : Dr. D. Kilalo : Dr. T. Tadele

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1 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

2 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.

3 MATERIALS AND METHODS The experimental site: Kenya Agricultural Research Institute (KARI) Kiboko Research Centre ( KARI- Kiboko). 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.

4 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.

5 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 O 2 and CO 2 Aerated glass jars

6 Pictures of metal silos with different sealing methods Burning candle grease Rubber Grease & rubber Without sealing Trial layout

7 Obj 2: To determine the effect of burning candle and grain volume on rate of O 2 depletion and CO 2 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 ).

8 Data collection in obj: 1 & 2 Moisture content, aflatoxin levels and nutritional content (starch, protein and oil content)of the grain. O 2 and CO 2 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).

9 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.

10 % gas concentration. % weight loss and damage Results Trt O 2 CO 2 Temp Trt % damage % weight loss Fig 1. Gas concentration in metal silos Trt 1 Trt 2 Trt 3 Trt 4 O2 CO2 temp Fig 2. Grain damage and weight loss Trt 1 Trt 2 Trt 3 trt 4 % damage % weight loss

11 Plan to completion of the remaining activities Activity 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 O N D J F M A M J J A S O N D J F M A M J J A S O N D