saeed saadat; mehdi homaee
Abstract
Plant response to salinity varies at different growth stages. Information on plant response to salinity at various growth stages can be used in managing saline waters for irrigation. In order to measure the quantitative response of salinity on germination of Sorghum (Sorghum bicolor L. Moench), a greenhouse ...
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Plant response to salinity varies at different growth stages. Information on plant response to salinity at various growth stages can be used in managing saline waters for irrigation. In order to measure the quantitative response of salinity on germination of Sorghum (Sorghum bicolor L. Moench), a greenhouse experiment was conducted in a natural saline sandy loam soil, using plastic pots with 15 cm height and 8 cm diameter. Salinity treatments included a non-saline water (EC = 0.3 dS/m) and 12 saline waters with electrical conductivities of 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, and 24 dS/m. The Maas and Hoffman, Van Genuchten and Hoffman, Dirksen et al., and Homaee et al. models were used to predict Relative Germinated Seeds (RGS) in different soil salinity treatments and to measure quantitative effect of salinity on seed germination. The results indicated that salinity threshold value (EC*) for sorghum was 5.5 dS/m at germination, and the germination rate was reduced to 50 percent at 9 dS/m soil salinity. The predicted EC* by the models were less than the actual values measured in the experiment and also by those reported by Maas and Hoffman (6.8 dS/m). The R2 values for predicting RGS by non-linear models of Van- Genuchten and Hoffman, Dirksen et al., and Homaee et al. were 0.98, 0.99, and 0.98, respectively.
f dehghani; r r; m.j malakouti; saeed saadat
Abstract
Calcium and magnesium ions are two plant nutrients and are omnipresent in all natural systems. Calcium to magnesium ratio (Ca:Mg) is an important factor in evaluation of water quality for irrigation. A Ca: Mg ratio of less than unity, in particular in saline condition, adversely affects soil physico-chemical ...
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Calcium and magnesium ions are two plant nutrients and are omnipresent in all natural systems. Calcium to magnesium ratio (Ca:Mg) is an important factor in evaluation of water quality for irrigation. A Ca: Mg ratio of less than unity, in particular in saline condition, adversely affects soil physico-chemical characteristics, and could decrease plant yield through nutritional imbalance. Frequent drought and groundwater over-draft have lowered groundwater level and its quality severely, including increase in salinity and, in many cases, relative increase in magnesium ion concentration. In order to assess distribution and changes in Ca:Mg ratio, laboratory analysis data of more than 6200 irrigation water samples were collected from 11 provinces. Data analysis revealed that Ca:Mg ratio was less than unity in about 55% of the samples. It was also found that increase in salinity had a significant correlation with Ca and Mg ions concentrations, but had no relation with their ratio. Correlation analysis indicated that maximum correlation was between Na ion concentration and salinity (R2= 0.86), and 60% of Ca and Mg variation could be explained with variation in salinity. However, no significant relation was found between salinity and Ca:Mg ratio. Using such irrigation water gradually increases exchangeable Mg ion and decreases soil quality (degradation of soil structure and lowering infiltration rate), and causes plant nutritional disorder. Consequently, more detailed assessment of these waters and their effects on soil and plant is enormously important from both economic and environmental points of view.