Varietals differences in agronomic performance of six wheat varieties grown under saline field environment

Six wheat varieties (SARC-1, SARC-2, SARC-3, SARC-4, LU26S and Punjab-85) were planted in the field to evaluate their comparative performance under saline conditions. LU26S appeared the most salt-tolerant variety and gave the highest grain weight due to its low Na⁺ uptake, high K⁺/Na⁺ ratio, higher dry weight of shoots and spikes and better grain development. Better exclusion of Na⁺ and other ions from the leaves of salt-tolerant variety LU2 6S could also be a reason for its ability to maintain a higher grain weight in the saline soil. Punjab-85 appeared the most saltsensitive variety as its dry weight of main shoots and spikes were also found to be the lowest. High Na⁺ uptake, lower K⁺/Na⁺ ratio, lower dry weight of main shoots and spikes and lower 100 grain weight were the main reasons for saltsensitivity in Punjab-85. Dry weight of shoots, spikes and grain weight of SARC-3 under saline soil conditions was almost similar to the salt-sensitive variety Punjab-85 and could be classified as salt-sensitive. Flag leaf area decreased drastically due to salt stress in all the varieties and this could be a major cause for low yield. There was however, a very low linear correlation between the flag leaf area and the grain weight in pooled data for all the six wheat varieties.     

Geochemical assessment of groundwater contamination with special emphasizes on fluoride,a case study from Midyan Basin,northwestern Saudi Arabia

Water samples for chemical analyses were collected in January 2012. A total of 72 samples of groundwater were collected from 72 boreholes in the Midyan Basin, northwestern Saudi Arabia. Samples were collected in polyethylene bottles and preserved and the used analytical techniques were in accordance with the standard methods from American public health association. Geochemical analyses of the groundwater samples from Midyan Basin reveal the concentration of fluoride (F) between 0.98 and 2.1 mg/l. Other parameters, e.g, pH, EC, TDS, HCO₃, SO₄, NO₃, Cl, K, Na, Mg, and Ca have been found in a variable proportion. Among them, the concentration of EC, HCO₃, K, Na and Mg is higher than the permissible limits. According to thermodynamical considerations, most of the analysed samples are graded under-saturated with respect to calcite and fluoride, while saturation has been observed in some samples. The under-saturation could probably be attributed to low concentration of calcite and fluoride in the studied wells. Fluoride concentration shows weak positive correlation with EC, TDS, Na, Cl, and SO₄. Factors controlling the concentration of fluoride (F) in the studied samples are the area climate, water chemistry and the presence of accessory minerals in the rocks through which groundwater is circulating, besides the anthropogenic activities in the area.     

Using multivariate statistical analyses to evaluate groundwater contamination in the northwestern part of Saudi Arabia

Chemical characteristics of groundwater in the Midyan Basin (northwestern Saudi Arabia) were investigated and evaluated. A total of 72 water samples were collected from existing shallow wells and analyzed for different elements. Two multivariate statistical methods, hierarchical cluster analysis (HCA) and principal components analysis (PCA), were applied to a subgroup of the data set in terms of their usefulness for groundwater classification, and to identify the processes controlling groundwater geochemistry. The subgroup consisted of 46 water samples out of 72 samples and 24 variables included major elements (Ca²⁺, Na⁺, Mg²⁺, K⁺, Cl^?, HCO₃ ^?, NO₃ ^?, SO₄ ^2?), minor and trace element (SiO₂, Al, As, B, Ba, Cd, Cr, F, Fe, Mo, P, Pb, Sb, Sn, Ti, and V). For water samples, four geochemically distinct clusters (i.e., C1, C2, C3 and C4) have been observed by hierarchical cluster analysis. Cr, F and Pb are the dominant ions in cluster C2. Al, As, Cd, Mo, Sb and Ti are the dominant ions in cluster C3, while B, Ca, Cl, HCO₃, K, Mg, Na, SO₄ and V are identified as dominant ions in the cluster C4. In the PCA, a total of five components are extracted form the data set, which explained 73.37 % of the total data variability. Among them the first component reveals strong associations between As, B, Cd, Cr, F, Mo, Pb, Sb and Ti. The second component reveals the associations between Ca, Cl, HCO₃, Mg, Na, SO₄ and V.