Search Results

1 - 9 of 9 items

  • Author: A. R. Khan x
Clear All Modify Search

Abstract

Twenty five spring wheat genotypes were evaluated for terminal heat stress tolerance in field environments in the Agro Ecological Zone-11 of Bangladesh, during 2009-2010 cropping season. The experiments were conducted at Wheat Research Centre, Bangladesh Agricultural Research Institute, using randomized block design with three replicates under non-stress (optimum sowing) and stress (late sowing) conditions. Seven selection indices for stress tolerance including mean productivity (MP), geometric mean productivity (GMP), tolerance (TOL), yield index (YI), yield stability index (YSI), stress tolerance index (STI) and stress susceptibility index (SSI) were calculated based on grain yield of wheat under optimum and late sowing conditions. The results revealed significant variations due to genotypes for all characters in two sowing conditions. Principal component analysis revealed that the first PCA explained 0.64 of the variation with MP, GMP, YI and STI. Using MP, GMP, YI and STI, the genotypes G-05 and G-22 were found to be the best genotypes with relatively high yield and suitable for both optimum and late heat stressed conditions. The indices SSI, YSI and TOL could be useful parameters in discriminating the tolerant genotypes (G-12, G-13, and G-14) that might be recommended for heat stressed conditions. It is also concluded from the present studies that biomass, grain filling rate and spikes number m-2 are suitable for selecting the best genotypes under optimum and late sowing conditions because these parameters are highly correlated with MP, GMP, YI and STI. However, high ground cover with long pre heading stage and having high grain filling rate would made a genotype tolerant to late heat to attain a high grain yield in wheat.

Abstract

Improving production through better agronomic management is continued to feed ever-increasing population. The objective of this study was to quantify the effect of N on maize seeded in line or broadcasted. Treatments included four level of urea nitrogen (N), i.e. 0, 60, 120 and 180 kg ha-1 and two sowing techniques, i.e. drill sowing (improved) and broad cast (farmer practice). Improved method of sowing had improved yield and yield contributing parameters whereas emergence m-2 and biological yield was higher in broadcast method of sowing. Increasing N application had increased biological yield, number of plants at harvest and grains ear-1 linearly. Cobs per plant, grain yield, 1000 grains weight and harvest index showed sigmoid response to N application and was maximum at 120 kg N ha-1. Sowing of maize seed in line method and receiving 120 kg N ha-1 had increased grain yield by 45% over broad cast method of sowing receiving the same dose of nitrogen. However, the farmer practices method had increased the forage (straw) when received higher amount of N, i.e. 180 kg N ha-1. Thus, it is concluded from the experiment that application of 120 kg N ha-1 and seed sown in line had increased the yield and yielding parameters, compared to other treatments and is, therefore, recommended for general cultivation of variety Azam in agro-climatic condition of Peshawar.

Abstract

The experiment was conducted at the Regional Agricultural Research Station, BARI, Ishwardi, Pabna, Bangladesh, during 2013-2014 and 2014-2015 to introduce maize as relay crop with T. Aman rice under different agronomic practices for determine the production potentials. The experiment was design split plot with three replications. The agronomic management practices included four plant spacing viz. S1=75 cm×20 cm (66666 plants/ha), S2=60 cm×20 cm (83333 plants/ha), S3=50 cm×20 cm (100000 plants/ha) and S4=40 cm×20 cm (125000 plants/ha) and four soil management practices viz. M1=soil mulching at 25 DAE, M2=earthing up at 25 DAE, M3=straw mulching at 25 DAE and M4= without earthing up and mulching (control). Seeds were relayed by dibbling manually in 10 days before the harvest of T. Aman rice. Results showed that an increasing plant spacing increased leaf area Index (LAI), total dry matter (TDM), crop growth rate (CGR) and light energy interception (LEI). Grain yield was higher in S3 spacing (8.44 t/ha) than others (S4 8.11 t/ha, S2 7.34 t/ha and S1 6.89 t/ha). Among the soil management practices, M2 increased LAI, TDM, CGR, LEI as well as grain yield. Moreover, M2 and M1 gave similar grain yield (8.22 t/ha and 8.02 t/ha), that were significantly greater than other two soil management practices (M3 7.55 t/ha and M4 6.98 t/ha). From the economic point of view, combination of S3M1 gave better performance with gross margin of Tk. 95000/ha and BCR of 2.17. On the basis of results, S3M1 combination was suitable for growing maize under relay sowing with T. Aman rice.

Abstract

Various fungal diseases reduce groundnut yield but Cercospora leaf spot commonly called, Tikka disease is most detrimental one. A field experiment was conducted to evaluate the efficacy of different fungicides and their doses on Cercospora leaf spot of groundnut. Five different fungicides (Chlorothalonil, Propineb, Mancozeb, Nativo and Triazole) having three different doses (prescribed, half & prescribed+half) were used to control Cercospora leaf spot of groundnut. Groundnut variety (YH-14) highly susceptible to Cercospora leaf spot was used. The experiment was laid down in RCBD design. The data were analyzed statistically by Fisher's analysis of variance technique. Results showed that maximum disease control with high pod yield was observed with Nativo and Triazole treatments. Efficacy of Chlorothalonil was also better than Mancozeb and Propineb. Maximum disease control and pod yield was observed when Nativo was used @ 0.97g/L of water, followed by @ 0.65g/L and 0.32 g/L, respectively. Propineb was the least effective in controlling Cercospora leaf spot of groundnut as well as having minimum pod yield.

Abstract

An exact solution and analysis of an initial unsteady two dimensional free convection flow, heat and mass transfer in the presence of thermal radiation along an infinite fixed vertical plate when the plate temperature is instantaneously raised, is presented. The fluid considered is a gray, absorbing emitting radiation but a nonscattering medium. Three cases have been discussed, in particular, namely, (i) when, the plate temperature is instantaneously raised to a higher constant value, (ii) when, the plate temperature varies linearly with time and (iii) when, the plate temperature varies non-linearly with time. A close form general solution for all the cases has been obtained in terms of repeated integrals of error functions. In two particular cases, the solutions in terms of the repeated integrals of error functions have been further simplified to forms containing only error functions. It is observed that for an increase in the radiation parameter N or a decrease in the Grashof number Gr or Gm, there is a fall in the velocity or temperature, but compared to the no radiation case or no diffusing species, there is a rise in the velocity and temperature of the fluid.

Abstract

Inspection of the radioactivity level in the soil is very important for human health and environmental protection. This study aims at evaluating the radiological hazards and pollution risks related to natural radionuclides and elements in the selected soil samples. Ten samples of soil were collected from different sites of Aurangabad-India and the level of radioactivity was measured using gamma-ray spectrometry with NaI (Tl) detector. Furthermore, the Physico-chemical properties such as pH, organic matter, electrical conductivity, moisture, soil texture, etc., and elemental composition of soils have been decided on using various standard techniques. The mean concentrations of 226Ra, 232Th, and 40K were 8.178, 17.408, and 96.496 Bq/kg, respectively, which are lower than the global average values of 35, 30, and 400 Bq/kg, respectively (UNSCEAR, 2000). The radiological hazard indices such as radium equivalent, absorbed dose, annual effective dose, internal index, external index, gamma index, excess lifetime cancer risk, etc., were calculated to assess the radiation hazards and compared with internationally recommended values which found to be lower than the permissibility limits.

The Pearson correlation was applied to determine the existing relationship between radionuclides and radiological health hazard parameters, as well as with the physicochemical properties of the soil samples. The major and trace elements presented in soils were measured and their mean concentration was ranked in the formed order (Mg>Na>Ca>K>N>Mn>Fe>P>Zn>Cu). The pollution risk parameters (Geo-accumulation index, contamination factor, degree of contamination, pollution load index, and potential ecological risk index) related to the elements in the samples were assessed and results shown that the soils under study are unpolluted with the measured elements. Generally, the radioactivity levels and pollution risks indices in the soils of the study area are within the permissible safety limits and do not cause any significant health threat to humans. Thus, the presented data provide a general background of the detectable radionuclides for the study area and can be helpful in the future as a reference for more extensive studies in the same field.

Electricity generation from the readily biodegradable organic substrate (glucose) accompanied by decolorization of azo dye was investigated using a two-chamber microbial fuel cell (MFC). Batch experiments were conducted to study the effect of dye and substrate concentration on MFC performance. Electricity generation was not significantly affected by the azo dye at 300 mg/L, while higher concentrations inhibited electricity generation. The chemical oxygen demand (COD) removal and decolorization of dye containing wastewater used in the MFC were studied at optimum operation conditions in anode and cathode, 57% COD removal and 70% dye removal were achieved. This study also demonstrated the effect of different catholyte solutions, such as KMnO4 and K2Cr2O7 on electricity generation. As a result, KMnO4 solution showed the maximum electricity generation due to its higher standard reduction potential.

Abstract

Use of Degussa P25 titanium-dioxide nanopowder in dye-sensitized solar cell (DSSC) photoanode improves efficiency of the DSSC cell. Annealing of titanium dioxide is required for fabrication of crystalline mesoporous thin film photoanode on transparent conducting glass using doctor blade method. Different annealing temperatures provide different structural, morphological, and optical properties of the photoanode, which may influence the efficiency of the cell. In this paper, energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and UV-Vis-NIR spectroscopicanalysis have been carried out to investigate annealing temperature effect on various structural parameters, mole-fraction, phase-content, and optical bandgap of the TiO2 film photoanode. It was observed that depending on annealing temperature, theratio of polymorphs of Degussa P25 changed substantially. For the change in annealing temperature from 350 °C to 600 °C, variations occurred in crystallite size from 11.9 nm to 24.9 nm, strain from 0.006 to 0.014, specific surface area from 62.77 m2·g-1 to 125.74 m2·g-1, morphology index from 0.49 to 0.64, dislocation density from 5 × 1013 line/m2 to 8 × 1015 line/m2, crystallite per unit surface area from 2 × 1013 m-2 to 2.5 × 1014 m-2, and optical bandgap from 2.4 eV to 3.1 eV.

Abstract

Efficiency of dye-sensitized solar cell (DSSC) depends on several interrelated factors such as type and concentration of dye, type and thickness of photoelectrode and counter electrode. Optimized combination of these factors leads to a more efficient cell. This paper presents the effect of these parameters on cell efficiency. TiO2 nanoporous thin films of different thicknesses (5 μm to 25 μm) were fabricated on indium doped tin oxide (ITO) coated glass by doctor blading method and characterized by inverted microscope, stylus surface profiler and scanning electron microscope (SEM). Natural organic dye of different concentrations, extracted from turmeric, was prepared with ethanol solvent. Different combinations of dye concentrations and film thicknesses along with different types of carbon catalyst have been investigated by I-V characterization. The result shows that the cell made of a counter electrode catalyst material prepared by candle flame carbon combined with about 15 μm thick photoelectrode and 100 mg/mL dye in ethanol solvent, achieves the highest efficiency of 0.45 %, with open circuit voltage of 566 mV and short circuit current density of 1.02 mA/cm2.