July 2011

A comparison of textual, symbolic, and pictorial presentation of information on an air-seeder display

D. Karimi, D.D. Mann and J. Yan
Abstract

This paper reports a study on the display of information on an air-seeder display in textual, symbolic, and pictorial forms. Seven parameters that are monitored most frequently by experienced air-seeder operators (i.e. fan rpm, tank levels, application rates, blockage, forward speed, tool pressure, and tool depth) were selected. Computer programs were developed to present this information in textual, symbolic, and pictorial modes. Twenty university students participated as subjects in the study. The interactive computer programs recorded the subjects’ response time and whether the response was correct or wrong. The shortest response time was achieved with the pictorial display (2.46 s) while the average response time with symbolic and textual displays was 3.10 s and 3.03 s, respectively. Further analysis revealed that five of the subjects showed particularly poor performance with the symbolic display. For the remaining 15 subjects, the symbolic display resulted in a shorter response time compared to the textual display (2.21 s versus 2.64 s) and 50% reduction in the number of wrong responses. Results of the experiment also indicated that further practice resulted in significant reductions in response time and response error. However, these improvements were significantly larger for the symbolic display than either textual or pictorial displays. Pictorial and symbolic representations are superior to the textual representation of the information on an air-seeder display. However, careful design of the symbolic and pictorial displays is necessary in order to ensure fast and correct operator response.

Published online 26 July 2011 | Pages 90-95 | Full text PDF

Influence of drying conditions on the effective moisture diffusivity and energy of activation during the hot air drying of garlic

Majid Rasouli, Sadegh Seiiedlou, Hamid.R. Ghasemzadeh, Habibeh Nalbandi
Abstract

Garlic (Allium sativum L.) is a vegetable spice that is a strong source of vitamin C and has antiseptic properties. The drying behavior of the garlic slices was investigated in a thin layer hot air drying at slice thicknesses of 2, 3 and 4 mm and air temperatures of 50, 60 and 70°C. Fick’s second law was used to calculate the moisture diffusivity coefficient, which varied from a minimum of 2.524 × 10^-10 m²/s when the sample thickness was 2 mm and air temperature of 50°C to a maximum value of 7.566 × 10^-10 m²/s at the sample thickness of 4 mm and air temperature of 70°C. The variation of effective diffusivity coefficient was depended on temperature by Arrhenius relationship. The energy of activation (E_a) for garlic slice varied from 30.424 to 36.365 kJ/mol. The input energy values and specific energy requirement were found to be in the range of 3.896 - 13.070 (kWh) and 43.289 - 145.222 (kWh/kg) from 50°C to 70°C with a drying air velocity of 1.5 m/s, respectively.

Published online 26 July 2011 | Pages 96-101 | Full text PDF

Review article

Trends in Mushroom cultivation and breeding

Bipasha Chakravarty

Abstract

Mushrooms are highly nutritious and environment friendly crops that carry numerous medicinal benefits. The cultivation of edible mushrooms carries great relevance in todays’ world in the context of a burgeoning population growth and extreme pressure on the environment. But advances in research on mushroom breeding and production is very limited as compared to other crops. This maybe partly due to a lack of previous knowledge of the genetics and breeding system in this crop. Classical breeding in mushrooms has been difficult due to the predominantly secondarily homothallic life cycle of this fungus. The cultivated strains thus display limited genetic variability. Also, developing an efficient genetic transformation technique and disease resistance is a challenging task in mushrooms. With the ongoing sequencing of the mushroom genome, knowledge of the gene organization and functions can be available and will help in developing better marker assisted selection breeding systems. This will lead to superior strains and along with an improvement in cultivation techniques, will pave the way for higher yield and quality.

Published online 26 July 2011 | Pages 102-109 | Full text PDF

Effects of spent engine oil pollution on the nutrient composition and accumulation of heavy metal in cowpea [Vigna unguiculata (L.) Walp]

Ogbuehi H.C, Onuh M.O, and Ezeibekwe I.O

Abstract

This study was carried out to determine the nutrient composition and heavy metal accumulation in leaves and seeds of cowpea, grown in spent engine oil polluted soil of Owerri, Imo State, Nigeria. The experiment was arranged in Completely Randomized Design, replicated five times. Five levels (0, 50, 100, 150 and 200ml) of spent engine oil were used. The cowpea seeds and leaves were harvested at the end of 12 weeks after planting (WAP) and the proximate composition and heavy metal were estimated. The result revealed that mean moisture content, protein, ash and fat content of seeds of cowpea grown in spent engine oil polluted soil were significantly (P<0.05) reduced (3.17%, 22.98%, 2.13%, 3.13% respectively), lower than seeds from non-spent oil polluted soils. The mean values of the corresponding parameters in non-polluted soils were as 21.69%, 24.71%, 2.43% and 3.88% for moisture content, protein, fat and ash, respectively. Moreover in seeds, the dry matter, fibre and carbohydrate were significantly increased (P<0.05) (DM, 96.83%, fibre, 2.43%, CHO, 69.14%), respectively in 200 ml polluted soil, compared to the corresponding values 78.21%, 1.87%, 67.08% recorded in control. In leaves, the protein, ash, fibre and moisture content were significantly (P<0.05) reduced as level of spent engine oil pollution increased in the soil, compare to the control. Whereas, carbohydrate, dry matter, were increased significantly P<0.05 as the level of spent engine oil increased, (Dry matter 42%, CHO, 67.41%) compare to the control, which were 26.10% and CHO 58%, respectively. The heavy metals such as Leads, Nickel and Zinc were found to be accumulated more in the leaves than in seed as the level of spent engine oil increased. The indiscriminate disposal of spent engine oil could lead to build up of heavy metals in plant seeds which in turn cause cancer or mutation in humans due to biomagnifications in food chain, hence there is need to avoid planting crops in polluted soils.

Published online 26 July 2011 | Pages 110-113 | Full text PDF

Bioaccumulation and translocation factors of cadmium and lead in Aeluropus littoralis

Mohammad Rezvani, Faezeh Zaefarian
Abstract

Phytoremediation is an ecofriendly and low cost potential strategy for clean up of heavy metals contaminated soils. Selection of promising plant is an important approach for successful phytoremediation. In two separate pot culture experiment, five levels of soil cadmium (Cd) concentration at 15, 30, 60, 120 and 240 mg Cd kg^-1 soil and five levels of lead (Pb) including 500, 1000, 2000, 4000, 8000 mg Pb kg^-1 soil were tested. Plant growth, bioaccumulation and translocation factors of Cd and Pb in A. littoralis were investigated. Cd and Pb were reduced markedly A. littoralis dry matter production. Bioaccumulation factor of Pb Was <1, that shows A. littoralis could be an excluder of Pb. Our results also showed translocation factor of Cd was more than one and hence, A. littoralis could be considered as accumulator of Cd. The enhancement of Cd translocation to A. littoralis shoot by soil Cd increasing indicates a great performance of the plant for Cd phytoextraction and might be introduce as Cd-hyperaccumulator plant.

Published online 26 July 2011 | Pages 114-119 | Full text PDF