Iran Agricultural Research
Volume:27 Issue: 1, Winter and Spring 2009

Zinc (Zn) availability and mobility in soils is controlled by its interaction with the soil matrix and amendments. Contradicting evidence has been reported for factors influencing Zn behavior in soils. The aim of this study was to investigate the Zn sorption in selected acid, calcareous and gypsiferous soils with different background electrolytes (Na+, K+ and H2PO4, NO3 and Cl backgrounds). Isotherm curves for Zn sorption were examined on 2 calcareous, 2 acid and 2 gypsiferous soils. Lability of the adsorbed Zn was evaluated by DTPA following sorption. The Zn adsorption data showed a highly significant fit to the Langmuir, Freundlich and Temkin adsorption isotherms. The fit of the present experiment’s data to Langmuir isotherm proved to be more suitable as compared with Freundlich or Temkin isotherms. The presence of Na+ increased total Zn adsorption as opposed to K+ in all soils. Gypsiferous soils exhibited greater Zn adsorption than calcareous and acid soils. The high adsorption of Zn by gypsiferous soils could be related to the presence of a palygorskite mineral with a large surface area, but for acid soils with high contents of kaolonite and illite minerals, minimum Zn sorption was observed. In acid soils, the largest Zn sorption was observed with H2PO4, whereas in gypsiferous and calcareous soils, H2PO4 decreased Zn sorption. The lability of Zn affected the clay minerals amount and type. The results showed that a large percentage (90 to 98%) of the sorbed Zn was associated with nonlabile pool. It is concluded that other nutrients and clay minerals have significant effect on Zn applied to soils.

Limited information is available on water and nitrogen (N) management of sugarcane (Saccharum officinarum L.) in Khuzestan, southwestern Iran, where this crop is currently and extensively grown under heavy irrigation and N fertilization. Therefore, a field experiment was conducted from September 2000 to March 2002 at the Research Department of Karoon Agro-industry in Khuzestan to determine the effect of four irrigation [irrigation water/cumulative pan evaporation (IW/CPE) ratios of 0.6, 0.8, 1.0, and 1.2)] and four N (0, 86, 172, and 258 kg N ha-1) levels on sugarcane yield and water and N use efficiencies. The experiment was carried out as split-plot arranged in a randomized complete blocks design with four replications. Pan evaporation data was recorded daily using class A open pan. Increased water and N application increased both plant cane crop and sugar yields. The highest sugar yield was obtained under IW/CPE = 1.2 (29 irrigations) and with 172 kg N ha-1 with no significant difference with IW/CPE = 1.0 (25 irrigations) and 86 kg N ha-1, respectively. Higher irrigation and N levels showed a small but not significant reduction in both juice sucrose and purity percentages. Higher N levels significantly increased the N use efficiency (NUE) for cane yield, but NUE for sugar yield was highest at 86 kg N ha-1. Water use efficiency (WUE) increased with higher water application. Thus pan evaporation data and N management can effectively meet both irrigation (IW/CPE = 1.0) and N requirements (86.0 kg ha-1) of sugarcane without any adverse effect on yields and environment and reduces production costs as well.

In this paper, non parametric Data Envelopment Analysis (DEA) was subjected to the energy data of wheat producers in Punjab state, India, and technical, pure technical and scale efficiencies were calculated for farms both category wise and zone wise. The main objective was to determine the strength of the correlation between non-parametric efficiencies and indices such as energy ratio and specific energy. Results revealed that larger farms had a higher energy ratio and lower specific energy as compared to smaller ones. Frequency distribution of technical efficiency scores revealed that large farms were more consistent on efficiency scores, and the dispersion of technical efficiency was highest on medium farms followed by semi Medium and small farms. The correlation coefficients between energy ratio and each technical, pure and scale efficiency, as well as those between specific energy and each technical, pure and scale efficiency showed that energy ratio and specific energy are not appropriate indices for explaining farm efficiencies in different farm categories and zones.

To use soil hydrology processes (SHP) models, which have increasingly extended during the last years, comprehensive knowledge about these models and their modeling approaches seems to be necessary. The modeling approaches can be categorized as either classical or non-classical. Classical approaches mainly model the SHP through solving the general unsaturated flow (Richards) equation, numerically or analytically. Due to some shortcomings of classical approaches, a trend toward the application of non-classical models has been initiated in recent years. Artificial neural networks and fuzzy logic systems are two main categories of non-classical approaches. In this study, existing modeling approaches of SHP are examined and compared, with an emphasis on recent trends. Also, modeling approaches of soil hydraulic functions are reviewed briefly as a main part of SHP models. Finally, different perspectives on classifications for SHP models are presented.

Hysteresis has been widely recognized in the soil water relationship. In this paper, a detailed review of hysteresis was performed in relation to its models. So far, different models have been suggested to describe hysteresis in the water retention curve (WRC) that could be categorized into two main groups: conceptual and empirical models. The models in the first group are based on the domain theory of capillary hysteresis and those in the second group rely on the analysis of observed WRC shape and properties. Conceptual models include the independent and dependent domain theories and the Parlange's model, while empirical models consist of the interpolation, linear, Slope and Scaling – down models. Different results of studies carried out by several researchers showed that the Parlange model, that uses the concept of rational extrapolation, was the best model to predict hysteresis of the WRC.

Thirteen species in five genera of the Libellulidae family were collected in a survey of dragonflies (Odonata) of Shiraz and its vicinity, involving 19 locations, The presented records of the libellulid dragonflies taken from the Fars province comprise a first time collection of two genera, Sympetrum and Pantala, and seven species, Orthetrum anceps Schnider, Orthetrum taeniolatum Schneider, Orthetrum chrysostigma Burmeister, Sympetrum fonscolombii Selys, Sympetrum meridionale Selys, Crocothemis servilia Drury, Trithemis kirbyi Selys, and Pantala flavescens Fabricius. A map of the localities of Fars province was provided as a table of the species’ distributions and an identification key was presented for the genera and species the Libellulidae family of Shiraz and its vicinity.

In the present study, the production of dextran from date extract and sucrose as carbon sources by the bacterium Leuconostoc mesenteroides NRRL B512 (f) was investigated. In comparison to blue dextran (Mw≈2000 Da), dextran molecular weight was reduced (Mw2000 KDa). Flow behavior indices of dextran solutions from date extracts were investigated and rheological parameters were evaluated at concentrations of 1.5, 2.5, 5, together with 10% total solids at 25˚C using a Brookfield rotational viscometer as well as a cone and plate geometry. The experimental results followed the power law model for the best fit and the values of flow behavior index (n) were less than unity (0.49. 93) at all concentrations, revealing the shear thinning nature of the produced dextran. Furthermore, dependence of apparent viscosity on concentration was confirmed using the power law model.

Xanthomonas campestris was used for producing xanthan gum using date syrup, prepared from low quality dates, as a substrate. Fermentation was carried out with date syrup and sucrose syrup at 28 ˚C and pH 6.8 in a rotary benmarin shaker (240 rpm). The effect of fermentation period (24, 48, 72, 96 and 120 h) on xanthan gum production was studied. The results showed that EPS concentration increased with an increase in fermentation time with a maximum yield of 0.89 g/100 mL after 96 h which was much higher than that of the sucrose-containing medium (0.18 g/100 mL). The effect of pH on the yield of the purified xanthan was also examined. The optimum pH for xanthan production was determined to be 5.5. The xanthan obtained through this study was compared to commercial xanthan, and showed a very similar chemical composition confirmed by thin layer chromatography (TLC) and Fourier transform infrared spectroscopy (FT IR). The results revealed that date syrup has a potential to be used as a suitable substrate for xanthan production.

In this research, the accelerated ripening of the Kabkab dates from Khalal to Tamr using NaCl and acetic acid solutions was studied. Fruits at Khalal stage were harvested and washed with distilled water before being treated with ripening inducers: 1. NaCl solutions, 2. acetic acid solutions and 3. Aqueous solution of NaCl (1%) and acetic acid. moisture, pH, colour, brix and textural firmness of the samples were monitored. Results indicated that during ripening the moisture content and colour changed significantly. The major change was observed for firmness where a maximum force for puncture test varied from about 1000 to 50 g force for all samples after 72 hours of incubation at 40 °C. Harvesting at Khalal stage followed by treating the fruits with NaCl and/or acetic acid solutions and an incubation stage at 40 °C showed to be a promising method for accelerated ripening.

Using a wide range of techniques, including differential scanning calorimetry, X-ray diffraction, Rapid Visco Analyser and Fourier Transform Infera Red Spectroscopy, some physicochemical properties of the starch fraction of six Iranian rice cultivars (Tarom, Tarome Hashemi, Neda, Ramezani, Fajr and Kamfirouzi) [1]were studied and compared. DSC data showed that starch granules of different rice cultivars had different gelatinization properties in terms of enthalpy, onset, peak and conclusion temperatures of gelatinization. All samples had similar X ray patterns (A type), different degrees of starch crystallinity. The rheological behaviour of rice powders during heating and the effects of heat processing were studied and compared in excess water from 25 to 95 °C. The samples were different in their pasting properties. This study indicates that starch properties should be mentioned as a crucial parameter determining the quality of rice cultivars.