JWSS - Journal of Water and Soil Science

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Canola (Brassica napus L.) in response to salinity represents various resistances with respect to its phonologic stages. Most plants such as Canola are resistant at germination stage. However, at seedling or earlier growth stages, plants become more sensitive to salinity but their tolerance increases with age. Salt tolerance of various plants has been extensively studied however, the results have either been qualitative or expressed as average values over root zone salinity for the whole growth season. Thus, developing appropriate models for quantitative characterization of plant response to salinity at different growth stages is essential. Canola which is considered as high economic value plant was selected for this study. Two productive stages for canola are recognized as flowering and ripening. To determine the effect of salinity on canola at vegetative growth stages, a greenhouse experiment was conducted on a natural saline loamy sand soil, using salinity treatment including one non-saline water (tap water) and 8 saline waters of 3 to 17 dS.m^-1. The canola plants were irrigated with tap water before the desired stage and then salinity treatments were imposed. The Maas and Hoffman (1977), van Genuchten and Hoffman (1984), Dirksen et al., (1993), and Homaee et al., (2002b) models were used to predict relative transpiration (T_a/T_p ) and relative yield ( Y/Y_m) as a function of soil salinity. The maximum error (ME), root mean square error (RMSE), coefficient of determination (CD), modeling efficiency (EF) and coefficient of residual mass (CRM) statistics were calculated to compare the models and their efficiencies. The results indicated that the van Genuchten and Hoffman (1984) model provides best prediction at flowering stage. However the Homaee et al. (2002b) model offers better prediction at ripening growth stage.

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Heavy metals contamination of soil and plants has very important and vital role in relation to health and life of human and other organisms. The aim of this study was to assess the efficiency of sorghum (Sorghum bicolor) and sommon lambsquarter (Chenopodium album) in phytoremediation of Zn from soil. Efficiency of 0.01M CaCl2, 0.1M NaNO3, and 1M NH4NO3 for extraction of “bioavailable fraction of soil Zn was also compared. Correlation between the Zn concentrations extracted by these methods and plants response (relative yield and shoot Zn concentration) to soil Zn contamination was then evaluated. For this purpose, a calcareous soil sample was contaminated with different concentrations of Zn. Sorghum and common lambsquarter, were grown in pots containing the contaminated soil and were analysed for their Zn concentrations after harvest. Results of this study showed that, common lambsquarter was more tolerant to low and medium concentrations (≤900 mg/kg), but sorghum tolerated high concentration of Zn. Also sorghum was more capable in removal of Zn from soil in comparison to common lambsquarter, so that soils contaminated with low Zn levels (≤900 mg/kg) can be remediated by sorghum. In addition, there was a significant correlation between 1 M NH4NO3-extractable soil Zn and the plants response (relative yield and shoot Zn concentration) to soil Zn contamination.

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To evaluate the effect of supplemental irrigation and seed priming on yield and some quantity and quality characteristics of vetch (Vicia dasycarpa) rainfed maragheh cultivar, an experiment was carried out at the Research Farm of Faculty of Agriculture, University of Urmia, West Azarbaijan province, Iran, during 2011. The experiment was laid out using split-plot, based on Randomized Complete Block design in three replicates. The factors studied were: Supplemental irrigation at four levels: without supplemental irrigation (I₁), 1 time of supplemental irrigation (I₂), 2 times of supplemental irrigation (I₃) and 3 times of supplemental irrigation (I₃). The subplot included four levels of seed priming: Control (C), Water (W), Phosphate (P) and Nitroxin (N). Plant height, pod number in stems, 1000-grain weight, wet and dry forage yield in the second and third harvest and fiber percentage in the second and third harvest, protein yield in the second and third harvest, biological yield and harvest index were influenced by the supplemental irrigation. Wet and dry forage yield in the second harvest and wet forage yield in the third harvest were highest in I₄ with respectively 14.5, 16.72 and 3.56 (tons/hectare) yield and lowest with respectively 7.73, 7.47 and 2.06 (tons/hectare) yield. As a result, applying 2 times of supplemental irrigation and seed treatment with phosphate and nitroxin had positive effects on quality and quantity yield of vetch and they could improve the quantity and quality of Vetch forage.