Impact of Bt-cotton on soil microbiological and biochemical attributes

Transgenic Bt-cotton produces Bt-toxins (Cry proteins) which may accumulate and persist in soil due to their binding ability on soil components. In the present study, the potential impacts of Bt- and non-Bt genotypes of cotton on soil microbial activity, substrate use efficiency, viable microbial population counts, and nutrient dynamics were studied. Two transgenic Bt-cotton genotypes (CIM-602 CIM-599) expressing cry1 Ac gene and two non-Bt cotton genotypes (CIM-573 and CIM-591) were used to evaluate their impact on biological and chemical properties of soil across the four locations in Punjab. Field trials were conducted at four locations (Central Cotton Research Institute-Multan, Naseer Pur, Kot Lal Shah, and Cotton Research Station-Bahawalpur) of different agro-ecological zones of Punjab. Rhizosphere soil samples were collected by following standard procedure from these selected locations. Results reveled that Bt-cotton had no adverse effect on microbial population (viable counts) and enzymatic activity of rhizosphere soil. Bacterial population was more in Bt-cotton rhizosphere than that of non-Bt cotton rhizosphere at all locations. Phosphatase, dehydrogenase, and oxidative metabolism of rhizosphere soil were more in Bt-cotton genotypes compared with non-Bt cotton genotypes. Cation exchange capacity, total nitrogen, extractable phosphorous, extractable potassium, active carbon, Fe and Zn contents were higher in rhizosphere of Bt-cotton genotypes compared with non-Bt cotton genotypes. It can be concluded from present study that the cultivation of Bt-cotton expressing cry1 Ac had apparently no negative effect on metabolic, microbiological activities, and nutrient dynamics of soils. Further work is needed to investigate the potential impacts of Bt-cotton on ecology of soil-dwelling insects and invertebrates before its recommendation for extensive cultivation.     

The Effect of Drought Stress on Nutraceutical Properties of <Emphasis Type="Italic">Zea mays</Emphasis> Bran

The effect of drought stress on total phenols, hydroxycinnamic acids, and antioxidant capacity in Cebú, DK2027, and DK2034 maize hybrids was evaluated. Compared to irrigation treatment, total phenols decreased in drought stress treatment by 35.34%, 5.59%, and 31.57% in Cebú, DK2027, and DK2034, respectively. In addition, the levels of t-ferulic, c-ferulic and p-coumaric acids decreased by 17.74%, 23.93%, and 29.83% in Cebú, by 8.92%, 8.62%, and 24.03% in DK2027, and by 13.66%, 11.03%, and 10.38% in DK2034, respectively. The predominant hydroxycinnamic acid from bran extracts was t-ferulic (67% to 72%), followed by c-ferulic (20% to 21%), and p-coumaric (7% to 11%) for both irrigation and drought stress treatments, while caffeic and sinapic acids were found in traces or were not detected. The antioxidant capacity decreased by 8%, 3%, and 9% in trolox equivalents and 7%, 17%, and 14% in percentage of radical scavenging activity for Cebú, DK2027, and DK2034 genotypes, respectively. The reduction of total phenols, hydroxycinnamic acids, and antioxidant capacity is due to the radical scavenging and photoprotective actions of hydroxycinnamic acids against highly reactive oxygen species generated under drought stress treatment.     

Determination of some heavy metal concentrations in razor clam (Solen brevis) from Tanjung Lumpur coastal waters, Pahang, Malaysia

An effort to analyze selected heavy metal accumulation by the razor clam (Solen brevis) from Tanjung Lumpur was conducted on January to April 2010. A total of fifty individuals of Razor clam Solen brevis were sampled and metals such as Iron (Fe), Zinc (Zn), Copper (Cu), Manganese (Mn), Lead (Pb) and Cadmium (Cd) Concentrations were determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Among the metals Fe occurred in elevated concentration in the soft tissue of razor clam followed by Zn. Cd was found to be in least concentration in the sample. Mean concentration of Fe, Zn, Mn, Cu, Cd and Pb in the soft tissue were 415.2 +/- 56.52, 87.74 +/- 11.85, 18.71 +/- 2.10, 8.64 +/- 1.75, 0.67 +/- 0.29 and 1.61 +/- 0.45 microg g(-1) dw, respectively indicating that the bioaccumulation of essential metals in the soft tissue was greater than the non essential heavy metals. Metal accumulation in the soft tissue of razor clam followed Fe > Zn > Mn > Cu > Pb > Cd order in present study. The observed concentration of acute toxicity of metals in Solen brevis (Family: Solenidae) from Tanjung Lumpur Coastal waters was lower than the permissible limit recommended by National and international standards proved that this species could be utilized for human consumption.     

Selenite Distribution in Multicomponent System Consisting of Filamentous Fungus,Humic Acids,Bentonite, and Ferric Oxyhydroxides

Selenite is an environmental toxicant whose mobility is affected in soil by various natural components, including humic acids, clay minerals, amorphous ferric oxyhydroxides [FeO_x(OH)_y], and microorganisms. However, interactions of selenite with these components are usually evaluated separately. Therefore, we addressed selenite behavior in multicomponent system in this study with emphasis on its immobilization and fungal accumulation. Our results highlighted significant acidification of culture medium by common soil fungus Aspergillus niger’s production of protons in selenite presence which affected selenium immobilization. While bentonite and humic acids did not enhanced immobilization efficiency significantly, composite of FeO_x(OH)_y/humic acids was extremely successful in selenium immobilization. This was most likely by enhanced redox transformation of selenite into elemental selenium as the contribution of each component was synergistic. Subsequently, selenium bioavailability in culture medium decreased and negatively affected bioaccumulation efficiency by fungus. Our results highlighted the significance of multicomponent systems in more realistic evaluation of selenium mobility and transfer to microorganisms.     

Interaction with soil enhances the toxic effect of iodide and iodate on barley (Hordeum vulgare L.) compared to artificial culture media during initial growth stage

Iodine is an essential trace element for humans, and while plants play an important role in its supplementation, they can also be subject to iodine toxicity. Herein, comparison of iodide and iodate effects on barley (Hordeum vulgare L.) development was evaluated in laboratory experiments when it was cultivated in iodine-spiked agar cultivation media and agricultural soil. Our results show that iodine toxicity is highly dependent on its chemical form and also reflects growth substrate type. Barley responses to iodine presence in agar and soil media suggest that iodide has more severe inhibitory effects than iodate on plant growth. Furthermore, the detrimental effect of iodine notably increased in soil with biomass synthesis as the most sensitive physiological parameter to adverse iodide and iodate effects. However, mild iodate and iodide stimulation of barley growth was observed which implies they are beneficial for growth at low concentrations. These effects were more intense when iodine was applied as iodide, especially in soil cultivation system where natural geochemical processes lead to alteration in iodine speciation which significantly increases plant sensitivity to iodine toxicity.     

Transfer of Heavy Metals from Soils to Vegetables and Associated Human Health Risks at Selected Sites in Pakistan

Contamination of the food chain with heavy metals is considered as one of the major environmental pathways of human exposure to metals leading to potential health risks. This study aimed to investigate the concentrations of heavy metals such as copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni), and manganese (Mn) in agricultural soils and food crops (fruit, leaf, and root vegetables), and their associated health risks to the local population in selected southern districts of Khyber Pakhtunkhwa Province, Pakistan. The concentrations of the selected metals in soil varied over a wide range, in the following decreasing order: Mn > Zn > Cr > Ni > Cu. The bioaccumulation of metals in vegetables was within the permissible risk limits, except for Cr which showed higher contamination in all the tested food crops. The trend of metal transfer factors for different vegetables was in the order of Cu > Ni > Cr > Mn > Zn, while the calculated daily intake of metals (DIM) in adults and children through consumption of food crops was in the decreasing order of Mn > Zn > Ni > Cr > Cu. The health risk index (HRI) values for the heavy metals for both adults and children were less than 1. Therefore, no significant health risk is anticipated for the local consumers through ingestion of these food crops.     

Factors affecting reduction of selenate to elemental selenium in agricultural drainage water by Enterobacter taylorae

Microbial reduction of selenate [Se(VI)] to elemental selenium [Se(0)] is a useful technique for removing Se from agricultural drainage water. A series of batch experiments were conducted in the laboratory to determine the effects of yeast extract (50-1000 mg/L), salinity (EC, 5-75 dS/m), and NO(3)(-) (5-100 mg/L) on the removal of Se(VI) (2000 microg/L) from drainage water by Enterobacter taylorae. Results showed that relatively high amounts of yeast extract (500 mg/L) were needed for E. taylorae to effectively reduce Se(VI) to Se(0). During a 7-day experiment, approximately 95% of added Se(VI) was reduced to Se(0) in the low-salinity drainage water (5 dS/m) with NO(3)(-) values of 5-50 mg/L. In the high-salinity drainage water (50-75 dS/m), reduction of Se(VI) to Se(0) was limited. E. taylorae was also capable of reducing Se(VI) to Se(0) in the San Joaquin Valley drainage water, with a reduction of the added Se(VI) to Se(0) (73.8%) and Se(-II) (20%). This study suggests that E. taylorae may be used to treat Se(VI)-contaminated drainage water in the field.     

SSR-based population structure,molecular diversity and identity cards of Ziziphus species from Pakistan and China

Genetic Resources and Crop Evolution - Research work on the genetic diversity within Pakistani and Chinese Ziziphus species is limited, and to date, no single report on the application of DNA...     

A micro‐level data analysis of household energy demand in Khyber Pakhtunkhwa,Pakistan: An application of linear approximate almost ideal demand system

This study examines energy choice, consumption pattern and household energy expenditure in Khyber Pakhtunkhwa (KPK) using the Linear Approximate Almost Ideal Demand System (LA‐AIDS). The study used micro‐level data to estimate the price and expenditure elasticities by employing (SUR) methodology. Empirical findings showed that energy choice, consumption patterns, and demand are different for urban‐rural households in the province. Each household living in KPK spent 1838.81 Rupees (9.92%) on energy purchases out of its total average monthly expenditure of Rs. 18,542.79. Compared to urban households, households living in rural areas spend more on energy consumption in a proportionate manner. The expenditure elasticities estimated for all energy sources are positive and statistically significant. Furthermore, the result showed that expenditure elasticities estimated for urban and rural households are less than one, suggesting that all the sources of energy are necessities. Natural gas and electricity are the main energy sources for urban households, while firewood and electricity are key energy sources for rural households in the province. The study suggested that rural households need to switch from conventional energy sources to modern and renewable energy sources, which would reduce the cost of energy use.