Sharad Vats

Herbicides: History, Classification and Genetic Manipulation of Plants for Herbicide Resistance

Weeds have known to affect human activities including agriculture since ages. Looking at the global scenario the major contributors of crop loss are weeds, followed by animals and pathogens. World War II started the ‘chemical era’ for the development of herbicide. Herbicides are used to kill weeds and are still the largest product type accounting for 47.6 % of global pesticide sales followed by insecticide (29.4 %), fungicide (17.5 %) and others (5.5 %). Herbicides have been classified in various ways but classification based on site of action of herbicide is comparatively better as herbicide resistance management can be handled more properly and effectively. Commonly used herbicides globally are generally broad spectrum and non-selective which restricts their use in arable lands. Thus there is need to modify the crops genetically so that the crop plants remain unaffected by herbicide application. Different strategies have been used either individually or in combination to develop transgenic plants. Reports suggest that the global area covered by herbicide-resistant transgenic plant outnumbers the area covered by any other genetically modified plants. However, inadvertent use of herbicides has helped in evolution of resistant weeds. This problem is now a subject of discussion worldwide. Integrated herbicide management is important to avoid selection pressure for the evolution of resistance. Transgenic plants have really helped the mankind in increasing the crop yield but use of transgenic plant is still a debatable topic which needs meticulous research, observations and experimentations for a final statement either in favour or against.

Organic Farming History and Techniques

Organic farming involves holistic production systems that avoids the use of synthetic fertilizers, pesticides and genetically modified organisms, thereby minimizing their deleterious effect on environment. Agriculture area under organic farming ranges from 0.03% in India to 11.3% in Austria. Organic farming is beneficial for natural resources and the environment. Organic farming is a system that favors maximum use of organic materials and microbial fertilizers to improve soil health and to increase yield. Organic farming has a long history but show a recent and rapid rise. This article explains the development stages, techniques and status of organic farming worldwide. The sections are: the development and essential characteristics of organic farming; the basic concepts behind organic farming; historical background; developmental era of organic farming; methods of organic farming; relevance of organic farming in the Indian context; comparative account between organic farming and conventional farming; importance of organic farming in environmentally friendly approaches; working with natural cycles; relevance of organic crop production in food security; yield potential and trends of organic farming; rural economic linkage its scope and limitations; and legislation procedures adopted by various countries. Organisations and financial aspects of organic farming are briefly discussed.

Plant Responses to Drought Stress: Physiological, Biochemical and Molecular Basis

Drought is one of the most serious threats to crop production all over the world and is likely to worsen with anticipated changes in the climate. Drought impairs normal growth, disturbs water relations and reduces water-use efficiency in plants. Plants, however, have a variety of physiological and biochemical responses at cellular and organism levels, making it a more complex phenomenon. Researchers have been trying to understand and dissect the mechanisms of plant tolerance to drought stress using various approaches. The present chapter describes the strategies used by plants to adapt to low water potential at physiological, biochemical and molecular levels. This chapter also describes the strategies involving genetic engineering used by breeders in order to obtain crop varieties with improved drought tolerance, some of which show great promise. Modern genomic and genetic approaches coupled with breeding methodologies are expected to more effectively identify the genes and metabolic pathways that confer drought tolerance in crops.

Nitrogen and Carbon Sources Influencing Mycoremediation of Textile Dyes Using Novel Autochthonous Fungal Isolates

Abstract Four fungal isolates Trichoderma virens, Phlebiopsis cf. ravenelii, Talaromyces stipitatus, Aspergillus niger originally isolated from the textile dye contaminated soil of Meerut, India. They were studies for decolorization purpose of selected textile azo dyes under laboratory conditions. Out of total 74 isolates, four fungal strains were picked up on the basis of primary screening carried out using agar layer decolorization technique. Dye decolorization and degradation activity of the culture was enhanced by optimization of concentration of carbon and nitrogen sources to the synthetic medium. This optimization facilitated decolorization and degradation within 9 d, at pH 5.4 and at a temperature of 30°C. Different concentrations of tested dyes (0.01%, 0.025%, 0.05 and 0.1%) were used and maximum decolorization 99.84% was achieved at dye concentration of 0.01%. Rate of decolorization carried out at different concentrations revealed the increase in dye solution concentration suppresses the decolorization. Optimized amount of nutrients were found to be 0.05%, 0.2%, 0.5%, 1% and 2% of ammonium sulphate and sodium nitrate as nitrogen source and glucose and lactose as carbon source respectively. Addition of nitrogen source above 0.5% caused decrease in percentage decolorization and addition of carbon source increase percentage decolorization up to 0.5%.