Agricultural Engineering

The physical properties of grains are important factors in designing efficient food processing, handling and storage systems. In this work we investigated the influence of degree of germination (in terms of the duration of germination treatment) on some geometric, mass-related and flow-related properties of germinated paddy grains. Paddy grains germinated at 38oC and 85% relative humidity over a period of 24, 48 or 72 hours and dried to a moisture content of about 11% (wet basis) after or without parboiling, were used for physical characterization. Results show that degree of germination had a significant influence on the mass properties of paddy grains, with evidence of linear decrease in both bulk density and 1000-grain mass with increasing germination time. A similar trend was observed for the porosity of both raw and parboiled germinated paddy grains. However, degree of germination did not appear to influence the geometric properties of raw germinated paddy grains, even though i...

As Sierra Leone approaches self-sufficiency in rice, against a backdrop of agricultural commercialization, the dynamics of the rice grain production and consumption will increasingly be driven by the quality of grains demanded by consumers to be produced by farmers and marketed by traders in the open market. The present study was a national perception survey aimed at establishing the current status of rice grain quality based on the perspectives of traders and consumers interviewed at selected market places in four major cities across the country. In separate interviews conducted with315 consumers and traders selected at random from 45 markets around the country, individual responses were solicited on the general interests of consumers and traders, as well as the marketing practices and aspirations for the improvement of rice grain quality in the country. Results obtained from the two surveys suggest that the priorities of rice consumers for grain quality were generally similar to t...

The free amino acid (FAA) concentration of rice is becoming an increasingly important grain quality factor because of its apparent influence on the organoleptic acceptability of cooked rice. To determine the variability of this character among rice cultivars the FAA profiles of 49 cultivars were determined using Pico-Tag method. Among these 13 cultivars were selected to determine variation in FAA accumulation pattern after 24-hour germination treatment. The results show significant variation in the concentrations of total as well as individual FAAs among cultivars. There were also significant differences between indica-and japonicatype cultivars in the concentrations of some FAAs. The ratio of the total concentration of aspartate-derived to glutamate-derived FAAs (A/G ratio) evaluated for the japonica group (0.68) was significantly lower than that for the indica group (1.07). This suggests that typically, japonica-type rice grains tend to accumulate more Glu-derived than Asp-derived FAAs. Other results show a decline in the A/G ratios of both groups in response to germination treatment, with the indica group exhibiting a more rapid response. These results appear to suggest key differences in the FAA accumulation patterns of japonica-and indica-type rice grains especially with respect to the contents of aspartate-derived and glutamate-derived amino acids.

Cowpea is one of the major grain legumes grown in Sierra Leone. This trial was conducted in the upland soils of Njala, southern Sierra Leone, in the 2011/2012 cropping season, to determine the effects of plant density and weeding regime on population and severity of aphids and foliage beetles on cowpea. Three plant populations (P 1 = 456,522; P 2 = 239,130 and P 3 = 152,174 plants/ha) and three weeding regimes (no weeding, once at 3 weeks after sowing (WAS) and twice at 3 and 6 WAS) were investigated. The study provides the evidence that-aphids and foliage beetles are better controlled by weeding twice at 3 and 6 WAS, and that planting at lower density (152,174 plants/ha) has the potential to reduce the population of both foliage beetles and aphids. These results have implications for improving cowpea productivity in smallholder farms through the simple manipulation of plant population and weeding regime for the control of aphids and foliage beetles, and probably other cowpea insect...

Sitophilus oryzae (L.) is one of the most important insect pests infesting stored food grains. The level of infestation, population density, the relationship between damage level and weevil population in stored rice grain samples were investigated. The effect of hot air sterilization on weevil population density was also examined. Samples (including; 29 imported, 16 parboiled and 62 raw milled rice) were randomly collected from markets across Sierra Leone and subjected to storage treatments under laboratory conditions at room temperature (with and without prior sterilization). The results show a significantly higher number of rice weevils in raw milled rice (156.0) with correspondingly higher level of grain damage (1.28); than the imported (3.2 and 0.03), and parboiled (21.7 and 0.11) rice grains, respectively. This suggests that locally produced raw milled rice may be more prone to rice weevil infestation, than either parboiled or imported rice grains. Results of pre-storage steril...

With the world population hitting 8 billion and the global climate becoming more erratic with pronounced droughts, floods, water shortages and storage depletions, the need for optimal soil and water conditions for high crop productivity and food security has become ever more urgent. There is a growing effort towards enhancing water storage in the root-zone soil layer (as a rainwater-harvesting strategy) to increase crop productivity. This study analysed the effects of biochar and deficit irrigation on rice productivity under greenhouse conditions. Grain yield, plant height, tiller number and biomass yield under 0% biochar (B 1) were respectively 13.6, 6.4, 27.4 and 3.0% higher for moderate deficit irrigation (I 2) than for flood irrigation (I 1). Also in terms of tiller number, I 2 performed better than I 1 by 45.8 and 69.2% under B 2 (4% biochar) and B 4 (16% biochar), respectively. While for biochar the highest crop productivity was under B 2 , this changed vastly under the combined effects of irrigation and biochar. This suggested that crop productivity was as much dependent on irrigation as on biochar treatment. The variations in productivity could provide farmers with the choice of treatments or treatment combinations that are best suitable for their local agro-edaphic, hydroclimatic and socioeconomic conditions.

Understanding the genetic diversity among accessions and germplasm is an important requirement for crop development as it allows for the selection of diverse parental combinations for enhancing genetic gain in varietal selection, advancement and release. The study aimed to characterize 183 provitamin A cassava (Manihot esculentaCrantz) accessions and five Sierra Leonean varieties using morphological traits, total carotenoid content and SNP markers to develop a collection for conservation and further use in the cassava breeding program. Both morphological parameters and 5634 SNP markers were used to assess the diversity among the provitamin-A cassava accessions and varieties. Significant differences were observed among the accessions for most of the traits measured. The first five PCs together accounted for 70.44% of the total phenotypic variation based on yield and yield components among the 183 provitamin-A cassava accessions and five Sierra Leonean varieties. The present study sho...