Department of Agriculture and Agribusiness Management University of Karachi
asad@gardener.com
In the upcoming era, weed control methods currently being intensively researched will allow prolonged weed control options away from herbicides and mechanical methods in agricultural, horticultural and nonagricultural weed management. Biological control by insects and plant disease producing micro organisms, foretelling modeling of weed/crop relations, and the use of herbicide antidotes, more viable crops, allelopathy, and genetic engineering/modify will become more widespread as their consistency is enhanced.
The generally purpose of additional approaches is to find out innovative, more environmentally suitable and friendly weed management methods/techniques that not only control weeds successfully, but advance our understanding and knowledge of weed ecology/biology and permit us more sustainable management of the agro ecosystem. Biological control of weeds by insects and plant disease organisms has had significant achievement in several weed management situations, and current research will direct to supplementary uses of natural agents. Significant biological research involves the potential introduction of natural control species commencing an invasive weed species site of origin (Watson, 1993). The use of herbicide antidotes (Hatzios and Wu, 1996) to defend crop plants has been doing well for some herbicides in some crops—for example, chloroacteamide herbicides in corn and sorghum. One of the supreme recent changes in weed control has occurred through the genetic transformation of crops with herbicide-resistant genes and the incorporation of herbicide resistance through conventional breeding. In 1999 and 2000, more than 50% of the U.S. soybean acreage and more than 30% of the corn acreage was planted to cultivars resistant to one of several herbicides. Genetic engineering offers marvelous potential in all areas of weed science for enhanced understanding of plants and of weed control. Genetic engineering, along with current advances in sequencing the genome of Arabidopsis (and in the future, other plants), will allow a clear understanding of specific gene function. 
Such knowledge will authorize gene manipulation and modification in our agricultural activities, such as the finding of genes that add to weediness, competitiveness, allelopathy, dormancy, or a plant’s being a perennial, with functions (Weller et al., 2001; Gressel, 2000). Genes of interest in weed control methods once revealed may then be engineered into crops or used to manipulate weeds to achieve a wanted effect in crop productivity and reduced weed influences. One area in especially where genetic engineering may play a role is allelopathy. Allelopathy (Rizvi and Rizvi, 1992) results from any direct or indirect inhibitory or stimulatory effect by one plant (including microorganisms) on another through the production and release into the surroundings of a chemical compound. Although no marketable breakthroughs have yet occurred in engineering plants to produce higher concentration/amount of allelochemicals, rather a few such genes have been recognized in Arabidopsis. Genetic engineering of crop plants or cover crops with genes for allelochemicals could allow key strides in rising plants helpful in weed management. The future for weed control is thrilling, as there are many opportunities for challenging fundamental and applied approaches for weed management in our environment (Hall et al., 2000).
References:
Gressel, J. 2000. Molecular biology of weed control. Transgenic Res. 9:355–382. Hall, J. C., L. L. van Eerd, S. D. Miller, M. D. K. Owen, T. S. Prather, D. L. Shaner, M. Singh, K. C. Vaughn, and S. C. Weller. 2000. Future research directions for weed science. Weed Technol. 14:647–658.
Hatzios, K. K., and J. Wu. 1996. Herbicide safeners: Tools for improving the efficacy and selectivity of herbicides. J. Envir. Sci. Health. B31:545–553.
Rizvi, S. J. H., and V. Rizvi. 1992. Allelopathy: Basic and Applied Aspects. Chapman and Hall, London.
Watson, A. K., ed. 1993. Biological Control of Weeds Handbook. WSSA Monograph Ser. #7.WSSA, Lawrence, KS.
Weller, S. C., R. A. Bressan, P. B. Goldsbrough, T. B. Fredenburg, and P. M. Hasegawa. 2001.The impact of genomics on weed management in the 21st century. Weed Sci. 49:282–289.
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