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۱Arsenic toxicity and salinity stress effects on macronutrient uptake in watercress Nasturtium officinale
اطلاعات انتشار: دومین کنگره سراسری در مسیر توسعه علوم کشاورزی و منابع طبیعی، سال
تعداد صفحات: ۷
Watercress (Nasturtium officinale), is a fast–growing, aquatic or semi–aquatic, perennial plant native to Europe and Asia, and one of the oldest known leaf vegetables consumed by humans. The agricultural and industrial effluent discharges are considered for arsenic contamination in natural waters. The aim of this study is to investigate the ability of watercress (Nasturtium officinale) to uptake macronutrient from aquatic environments with different levels of salinity and arsenic. The watercress was propagated and exposed to Epestin nutrient solution contaminated with sodium arsenate (Na2HAsO4.7H2O) at six concentrations (5, 10, 20, 40, 80, and 160 mg As.L−1), including the control without As contamination for 30 days period. In this experiment the salinity were 0, 10, 20, 40 and 80 millimolar NaCl (sodium chloride). The experiment was conducted using completely randomized design and three replications. The results showed that the arsenic and salinity treatments significantly decreased the concentrations of total nitrogen (N), phosphorus (P) and potassium (K) in plant. The maximum amounts of N, P and K are absorbed in the treatments with 0 mg As.L–1 and 0 millimolar sodium chloride (control). The least amounts of nitrogen, phosphorus and potassium observed in treatments with 160 mg As.L–1 and 80 millimolar NaCl (sodium chloride).<\div>

۲Correlation between the percentage of clay and Atterberg limits in diffrent soils texture
نویسنده(ها): ،
اطلاعات انتشار: دومین کنگره سراسری در مسیر توسعه علوم کشاورزی و منابع طبیعی، سال
تعداد صفحات: ۹
Clay content influences many physic– chemical properties of soils. This study was conducted to characterize the percentage of clay with consistency limits (liquid limit, LL; plastic limit, PL and plastic index, PI) of in four different soils texture class (clay, silty clay, silty clay loam and clay loam). The result revealed soil plasticity has direct correlation with percentage of clay. The consistency limits, and plasticity index (PI = LL – PL) were measured for the soil taken from the 0–20 cm layer. The LL varied from 38 to 63 in clay soil texture, 27 to 55 in silty clay, 21 to 44 in silty clay loam and 15 to 35 in clay loam texture. The PL varied from 13 to 34 in clay soil texture, 12 to 33 in silty clay, 10 to 27 in silty clay loam and 10 to 26 in clay loam texture. The lowest PI was recorded in clay loam texture. The results of this study showed that soil clay content significantly change Atterberg limits and plastic index. Soil clay content in all experimental soils significantly (p < 0.01) increased liquid limit (LL) plastic limit (PL), and plastic index (PI) values. The highest LL, PL and PI values were obtained in clay–textured soil. There was a significant relationship between the soil clay content and the Atterberg limits and plastic index. The positive relationship between soil clay content and PL, LL and PI was found to be significantly linear whereas the relationship with the soil sand content was significantly negative. Regression analysis for Atterberg limits in four soil texture class showed that the percentage of clay were important character on liquid limit, plastic limit and plasticity index<\div>
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