Heavy metal accumulation in the environment is currently a serious global concern. It affects physiological systems of plants and other living systems. Heavy metal contamination in the soil causes stress to plants. Plants need relatively small amounts of metals for their growth and soils harbor these metal ions either naturally or as a consequence of contamination. Consequently elevated levels of metals are toxic for plants, limiting their growth. The general physiology of plants is affected by high levels of exposure to heavy metals. Soil contamination with heavy metals is now a worldwide problem, leading to agricultural losses and hazardous health effects as metals enter the food chain and reach subsequent trophic levels.

In the above context, the paper "Response of Nitrate-Hardened Brassica Seeds to Heavy Metal HgCl₂ Stress", by Yaksha Singh, Varsha Chaturvedi and C P Malik, deals with the effects of various concentrations of mercury on seed germination, seedling growth and related physiological changes in Indian Mustard genotypes for their response to mercury accumulation and tolerance. Brassica or mustard is an important oil seed crop for India which is being grown in heavy metal-contaminated sites. Metals from contaminated soil can produce errors in the genetic information system of plants. The paper gives important data for the protection of this agriculturally important crop from heavy metal exposure and toxicity.

In the next paper, "Effect of Environmental Factors on Chitinase Production by Serratia marcescens GG5", by Gursharan Singh, Aditya Bhalla and Gurinder Singh Hoondal, chitinase production has been carried out under varying environmental conditions by microorganism, Serratia marcescens GG5. Subsequently, the antagonistic activity of Serratia marcescens GG5 against various fungi were reported. Chitin is one of the most abundant natural polysaccharides in the world. The enzyme, chitinase hydrolyses the glycosidic linkages of chitin, has been found to occur widely and presents various characteristics. Chitinases have application in control of fungal pathogens as chitin is a major structural component of fungal cell wall. The study of chitinases is important because of their importance in the application to biological control in ecology, in the epidemiology of disease, and in the preparation of medicines. The paper gives due attention on the broad application of chitinases in the biological control of pathogenic fungi.

In the paper, "Allelopathic Effect of Croton bonplandianum Baill. on Mature Growth Phases of Wheat and Mustard", by Eva Sarkar and Pampa Chakraborty, the authors have reported the effect of aqueous plant extract of Croton bonplandianum on seed germination and seedling growth of Triticum aestivum and Brassica campestris. Allelopathy is an interference mechanism based on any direct or indirect effect that is primarily inhibitory by one plant on another through the release of chemicals that escape into the environment. The paper gives an intensive information on how allelopathic compounds from the leaf leachate of toxic weed, Croton bonplandianum inhibit the growth of wheat and mustard plants. The paper gives good application value for weed management which is a threat to agriculture.

In the next paper, "Rhamnolipid Production by Pseudomonas aeruginosa JC2 in Different N-Heterocyclic Aromatic Hydrocarbons", by Aparna P, Sasikala Ch and Ramana Ch V, the authors have extensively studied the levels of rhamnolipid production in the presence of heterocyclic aromatic hydrocarbons. Rhamnolipid is a biosurfactant containing rhamnose and b-hydroxydecanoic acid is produced by microorganism Pseudomonas aeruginosa. It has applications in agriculture, cosmetics, pharmaceuticals, personal care products, food processing, textile manufacturing, etc. It has a potential role in bioremediation. The paper has valuable analytical data and further optimization studies will add to the commercial value.

The paper, "Effect of Drying on the Essential Oil and the Mineral Contents of Basil (Ocimum basilicum L.)" by G L Pachkore and S K Markandeya, deals with the effect of drying on mineral and essential oil content of Ocimum basilicum. The mineral content and essential oil content were estimated for Ocimum basilicum or sweet basil which is a culinary and medicinal herb of major importance. There is a need to optimize processes to improve the product quality of the above plant.

In the paper, "Benthic Faunal Diversity in Muthupettai Mangroves on Southeast Coast of India", by B Thilagavathi, K Samidurai and A Saravanakumar, the authors have carried out a study in the Muthupettai mangrove in Tamil Nadu along the open sea to evaluate the diversity of macrobenthic organisms and its distribution with respect to hydrographical parameters. Mangrove ecosystems have physical, chemical and biological processes which promote the adaptation of inhibiting organisms to tolerate greater amplitude of environmental characters both morphologically and physiologically. Mangroves have highly productive ecosystem which provide organic matter to the coastal ecosystem. The authors have furnished complete data on the assessment of the health of a particular ecosystem achieved only by analysis of benthic fauna. It is a valuable tool for monitoring pollution and intertidal ecology.

In the last paper, "Newcastle Disease and Infectious Bursal Diseases are Threat to Village Chicken Production in Two Districts of Amhara National Regional State, Northwest Ethiopia", by Hailu Mazengia, S B Tilahun and T Negash, studies were conducted to determine the seroprevalence and risk factors associated with the occurrence of Newcastle disease and infectious bursal disease in village chickens. Newcastle disease and infectious bursal disease are major problems affecting poultry production in Ethiopia. Village chicken products are the main and often the only source of animal protein for poor households. Production is affected due to low inputs of feeding, poor management, infectious diseases, lack of appropriate selection and breeding practices. The study is an attempt to understand the disease mechanisms in chicken to enhance the productivity for sustainable poultry farming and food provision.

-- S B Mukherjee
Consulting Editor