Rashid A. Suleiman

Periodic Physical Disturbance: An Alternative Method for Controlling Sitophilus zeamais (Maize Weevil) Infestation

Sitophilus zeamais Motschulsky is the most important insect pest of stored maize in tropical regions. The objective of this study was to determine the practicality of periodic physical disturbance on S. zeamais mortality and its adoption by smallholder farmers in developing countries. In this experiment, treatments and control were arranged in a randomized block design with three replications and three storage times in three regions of Tanzania. Region was used as the blocking variable. A total of 108 clean 20-L plastic containers were each loaded with 10 kg of fresh white dent corn and 0.50 kg of maize infested with S. zeamais. For the treatment, containers were disturbed twice a day, whereas for the controls the containers were not disturbed until the end of storage. The overall mortality rate (%) after 30, 60, and 90 days of storage were 88%, 96%, and 98%, respectively. A statistically significant difference (p < 0.05) was observed for the number of live S. zeamais between the control and experimental treatments. Additionally, the number of live S. zeamais in the treatment significantly decreased as storage time increased. This study shows the potential of a feasible, simple, affordable, and effective method of protecting maize grain for small-holder farmers in developing countries without using chemicals.

PHYSICAL AND THERMAL PROPERTIES OF CHIA, KAÑIWA, TRITICALE AND FARRO AS A FUNCTION OF MOISTURE CONTENT

Abstract. The knowledge of physical and thermal properties in cereals, grains and oilseeds establishes an essential engineering tool for the design of equipment, storage structures, and processes. The physical properties and thermal properties for Chia, KaA±iwa, Farro and Triticale grains were investigated at three levels of moisture content: 10 %, 15 % and 20 % (d.b). Physical properties determined where 1000 seed weight, seed dimensions, arithmetic and geometric mean diameter, surface area, volume sphericity and aspect ratio. The result shows 1000 seed weight increased linearly with moisture content from 2.0 to 3.5 g for chai, 2.5 to 4.0 g for KaA±iwa, 42.7 to 48.3 g for Farro and 51.0 to 53.7 g for Triticale. Likewise, the bulk and true density decreased as moisture content increased. The porosity for Farro and Triticale increased from 38.71% to 44.17 %, 40.37 % to 44.65 % respectively as moisture increased from 10 to 20 %. The angle of repose for Chia, KaA±iwa, Farro and Triticale all increased as moisture content increased. In general, the values of L, a* and b* increased with moisture content. Thermal properties showed a very good correlation to moisture content. The negative relationship was observed for the specific heat capacity and thermal conductivity while the thermal diffusivity had a positive linear increase trend with moisture content. This study showed that physical and thermal properties varied from grain to grain as a function of moisture content. The findings of this study will broaden the knowledge of physical properties of Chia, KaA±iwa, Triticale and Farro and provide useful data for industries and researchers.