April 2010 issue

The comparison of erosion of meandering and standard furrow irrigation under different field slopes

B. Mostafazadeh-Fard, R. Kavei-Deylami, S. H. Saghaian-Nejad and A. Jalalian

Abstract

The Gholam-gardeshi irrigation (meandering furrow irrigation) is a modified form of standard furrow irrigation, which to date, there is no study about the effects of slopes on erosion of this method of irrigation. To measure the erosion of this method of irrigation and to compare the results with standard furrow irrigation, two experimental fields with different soil textures and field slopes were used to collect data such as furrow inflow hydrograph, furrow outflow hydrograph, advance and erosion. The experiment was laid out with a randomized factorial design with three replications. In both methods, the developed second order polynomial equation for the erosion, and advance equation were able to interpolate the field data with coefficient of determination of more than 94 %. The results showed that the velocity of advance, runoff and erosion are lower significantly at 5% probability level for the meandering furrow irrigation as compared to the standard furrow irrigation. As the slope of the field increased, erosion and runoff in both irrigation methods increased significantly.

Pages 29-37 PDF Full Text

Investigation of sulfur dioxide influence on canopy spectral characteristics at early growth stage of rice

JinHeng Zhang, Chao Han, Dapeng Li, ShuTang Liu, ZhenHua Zhang
Abstract

Field experiment was laid out in a split plot design with three varieties of rice. Rice samples were exposed to sulfur dioxide at different concentrations inside fumigation chamber. After measurement rice canopy reflectance spectrum, leaves of rice canopy were sampled to analyze physiological characteristic. The investigation mainly focuses on four parts. (1) SO₂ concentration was significantly negative correlation with pH and chlorophyll content (correlation coefficients R from -0.621 to -0.503). (2) Investigation on characteristics of spectral curves indicated that differences in SO₂ concentration impacted the spectral reflectance especially on the green reflectance peak and red absorption dip. (3) Correlation analysis showed that the average reflectance (pblue, pgreen, pred, pnir) and DVI (pred -pgreen, pgreen -pblue, pnir-pred, pnir-pgreen, p680-p560 and p760-p560) were significantly different at the 0.001 level. Almost all DVI were significantly correlated with chb and cht at 0.05 level or above. (4) pblue correlated significantly with soluble protein and MDA. pH had a very significant correlation with chlorophyll content. Almost all DVI were significantly correlated with pH. Vegetation indices pblue, pnir-pred , pgreen and p760-p560 were selected to estimate MDA content, chlorophyll b content , soluble protein and pH respectively. Cht was selected to estimate SO₂ concentration and pH, respectively.

Pages 38-44 PDF Full Text

Fate of biochemical components of Catharanthus roseus after treatment with different plant growth regulators

Cheruth Abdul Jaleel, Mohammed A. Salem

Abstract

The effect of different plat growth regulators like paclobutrazol (PBZ) gibberellic acid and Pseudomonas fluorescens treatments on the biochemical components of Catharanthus roseus was investigated in the present study. The treatments were given to plants by soil drenching on 38, 53, 68 and 83 DAP. The plants were taken randomly on 45, 60, 75 and 90 DAP and separated into root, stem and leaves and used for determining biochemicals. Proline, aminoacid and glycine betaine were extracted and assayed from both control and treated plants. It was found that plant growth regulators have a profound effect on the biochemicals and caused an enhancement in Catharanthus roseus. Our results have good significance, as this alters the biochemical status of this medicinal plant, as this plant being an essential component of traditional as well as modern pharmaceutical systems.

Pages 45-53 PDF Full Text

Flux behavioir and energy consumption of Ultrafiltration (UF) Process of milk

Bahnasawy A.H and Shenana M.E.

Abstract

Flux decline and recovery of UF process used in concentrating milk at different operational pressures were studied. Filter medium resistance during filtration and cleaning was estimated from the experimental data. Energy consumption during filtration and cleaning processes were estimated. Regarding the flux behavior, retentate and permeate fluxes declined with time at different operational pressures during filtration, on contrary, flux during cleaning increased with time at all pressures studied. Filter medium resistance increased linearly with time of filtration at different operational pressures during concentration. It increased during the first 40 min of cleaning process and decreased with time to reach the minimum resistance at the full flux recovery. The total energy consumed for filtration ranged from 50.08 to 62.54 kJ/L of retentate, while it ranged from 18.18 to 21.65 kJ/L of permeate. The energy consumed for cleaning ranged from 87.08 to 107 kJ at different operational pressures.

Pages 54-65 PDF Full Text

Modeling maize planting date to minimize irrigation water requirements

Eric. Y. Kra and J. Ofosu-Anim

Abstract

A mathematical model that uses daily maximum and minimum temperature data is presented for selecting the best planting day to minimize the total irrigation water required to grow corn. The model calculates the total seasonal irrigation water requirement by summing the daily crop evapotranspiration, , soil moisture storage and deep percolation losses from the planting date to the harvest date. The planting date resulting in the lowest irrigation water requirement for the growing season was selected as the best date to plant the crop in order to maximize total irrigable area for the available quantity of irrigation water, or to minimize the required irrigation water for the given area. The model was used to simulate the seasonal cropwater requirements of maize using 1998-2008 daily weather data from a weather station in the Coastal Savannah zone of Ghana. The optimum planting dates were found to be between 15th March and 15th May, and the worst planting dates 2nd November and 14th January. The differences between irrigation water requirements between the optimum and worst planting dates were 57~95%, implying that up to about 95% more area could be irrigated without additional irrigation water through optimum planting date selection. The coincidence of the model optimum planting window with the indigenous planting time indirectly validates the the 1985-Hargreaves reference evapotranspiration sub-model for this part of the world.

Pages 66-73 PDF Full Text