No abstract

Abstract--Well-crystallized ferrihydrite as indicated by its X-ray powder diffraction pattern and low solubility in acidified oxalate (Feo/Fe~ = 0.27) was formed by the oxidation of FeC12 solution containing Si/Fe = 18 x 10 -3. The crystallinity of ferrihydrites formed from the solutions containing Si/Fe > 18 x 10 -3 was lowered as indicated by weaker and broader XRD lines and increased oxalate solubility. Ferrihydrites formed in the presence of silica did not give the differential thermal analysis exothermic peak between 350* and 450~ that is found for ferrihydrites prepared from the hydrolysis of Fe(III) salts. The transformation of ferrihydrite (formed at Si/Fe = 18 x 10 3) to hematite was inhibited by the presence of 1.48% SiO2 in the oxidation products.

This study focused on analysis of global food demand and supply situation by 2030 and 2050, water demand-availability, impact of climate change on world water resource, food security and desalination challenges and development opportunities. The population of the world will be 8.6 billion in 2030 and 9.8 billion in 2050; Africa will be the major contributor. World cereal equivalent (CE) food demand is projected to be around 10,094 million tons in 2030 and 14,886 million tons in 2050, while its production is projected to be 10,120 million tons in 2030 and 15,970 million tons in 2050 having a marginal surplus. India and China are capturing large share of global food demand. The developing country will demand more animal origin foods due to income growth in the future. The growth rate of world demand for cereals will decline till 2050. Global water demand is projected to increase by 55% between 2000 and 2050 from 3500 to 5425 km 3. Evidence showed that climate change will have adverse impact on world water resources and food production with high degree of regional variability and scarcity. A number of options are suggested for development of global water resource and food production.

The bacterial wilt disease caused by Ralstonia solanacearum is an extremely destructive soil borne bacterial pathogen to potato. It appeared as rapid and fatal wilting symptoms in the host. The pathogen entered through different wounds and easily disseminated via infected biological material, soil, contaminated irrigation water, surface water, farm equipment etc. and could survive for many years in association with alternate hosts. It is a widely distributed and very much diversified soil borne pathogen having an unusually broad host range with long-term survivable ability. Direct yield losses caused by the pathogen varied from 30 to 90% depending on different factors such as cultivar, weather factors, soil type, cropping pattern and strain etc. Bacterial wilt continued to be an economically serious problem for field-grown potatoes in many tropical, subtropical and warmer areas of the world including Bangladesh. But the effectiveness of conventional management is limited because of some special biological features of the bacteria. Mostly protective methods and chemical control remain ineffective, antibiotics show hardly any effect, and efficacious biocontrol method has yet to be developed against the organism. However, during the recent decades, some natural bioactive compounds, viz. propolis, honey, turmeric, magnesium chloride, cow dung, aromatic rice extract, iodine, sodium bicarbonate etc. have got attention for their effectiveness in inhibiting a range of serious bacterial pathogens from both Gram positive and Gram negative types. As no conventional method has been found effective alone, such compounds could be tested for their effectiveness against the very successful soil borne bacteria to overcome the traditional management limitations.

No abstract