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The decrease in water resources due to the excessive use of water for irrigation purpose and climatic changes represents a serious world-wide threat to food security. In this regards, 50 wheat accessions were analyzed, using completely random factorial design at the seedlings stage under normal and drought stress conditions. Significant variation was detected among all accessions under both conditions. All characters studied showed variations in the mean values in water deficit environments in studied gemplasm at seedling stage. As seedling fresh weight, dry weight, relative water content, cell membrane thermo-stability, chlorophyll a & b were positively associated among themselves under drought conditions which showed the significance of these attribute for water deficit areas in future wheat breeding programs. Based on their performance, five accessions namely Aas-11, Chakwal-86, Pasban-90, Chakwal-97 and Kohistan-97 were selected as drought tolerant and three accessions namely Mairaj-08, Lasani-2008 and Gomal-2008 were selected as drought susceptible genotypes. The choice of wheat accessions based on the characteristics of the seedlings is informal, low-priced and less hassle. Likewise, the seedlings attributes exhibit moderate to high variation with an additive genetics effects on the environments. Best performance accessions under water deficit environment will be beneficial in future wheat breeding schemes and early screening for the attributes suggested in current experiment will be useful for producing best-yielded and drought-tolerance wheat genotypes to sustainable food security.

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The aim of the investigation was to determine the potential effect of lead on maize growth. Lead is considered as important potent environmental contaminant. Various ecological, environmental and evolutionary processes in the microsphere are disrupted because of lead toxicity to the microbial community. The effects of Lead Nitrate (Pb(No 3 ) 2 ) as heavy metal on germination, early growth seedling, root-shoot length, root-shoot fresh and dry weights, total protein content and the uptake of lead by roots and shoots of Zea-mays were investigated. All of the parameters were reduced by the increased lead concentrations. Such growth retardation was due to metals toxicity that resulted in damages to various physiological and biochemical processes.

Air pollution has become a serious challenge for developing countries like Pakistan. Very scarce information is available regarding pollution levels in this geographic region. This study presents the first modelling work to simulate the spatial distribution and temporal variation of aerosol concentrations over Pakistan by using the Weather Research and Forecasting Model coupled with chemistry (WRF-Chem). Simulated aerosols species include sulfate, nitrate, ammonium, organic carbon, black carbon, and PM 2.5 (particles with a diameter of 2.5 μm or less), which are evaluated against groundbased observations and satellite measurements. In year 2006, simulated PM 2.5 concentrations averaged over northeastern Pakistan (71-74.5°E, 28-34°N) are 55, 48.5, 31.5, and 98 µg/m 3 in January, April, July, and October, respectively. The simulated highest PM 2.5 concentration in October results from the relatively low temperatures that favor nitrate formation as well as the lowest precipitation that leads to the smallest wet deposition of all aerosol species. The simulated lowest concentration of PM 2.5 in July can be attributed to the largest precipitation associated with the South Asian summer monsoon. Sensitivity studies show that transboundary transport contributes to PM 2.5 aerosol levels in northeastern Pakistan by 10-20% in January and April and by 10-40% in July and October of year 2006. Wind over India and Pakistan is found to be the major meteorological parameter that determines the transboundary aerosol transport.

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Nitrogen oxide (NO x ) abatement has become the focus of air quality management strategies. In this study, we examined NO x sources and the atmospheric conversion of NO x in Karachi, Pakistan, a megacity in South Asia with serious particulate pollution problems. Oceanic contributions to NO x were quantified for the first time based on a novel approach using nitrogen/oxygen isotopic analysis in nitrate (δ 15 N−NO 3 − ; δ 18 O−NO 3 − ) and a Bayesian model. Our results showed that δ 15 N−NO 3 − in Karachi varied between −10.2‰ and +12.4‰. As indicated by the δ 18 O−NO 3 − findings (+66.2 ± 7.8‰), the •OH pathway dominated NO x conversion throughout the nearly two-year observation, but high NO 3 − events were attributed to the O 3 pathway. Coal combustion was the most significant source (32.0 ± 9.8%) of NO x in Karachi, with higher contributions in the autumn and winter; a similar situation occurred for biomass burning + lightning (30.3 ± 6.5%). However, mobile sources (25.2 ± 6.4%) and microbial processes (12.5 ± 7.5%) exhibited opposite seasonal trends. The oceanic contributions to NO x in Karachi were estimated to be 16.8%, of which lightning, shipping emissions, and microbial processes accounted for 20.3%, 46.3%, and 33.4%, respectively, emphasizing the dominance of shipping emissions as an oceanic NO x source.

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