In 1937 allelopathy was first used by the Molish (Arzul et al., 1999). The word allelopathy is derived from two Greek words “allelo” means each other and “patho” mean expression of sufferance of disease, some weeds eliminate the competition and prevent the growth normal and development of other plants stages by producing the toxin in soil.
Allelopathy can be used to increase crop production at minimal expenses and to diminish the current reliance on synthetic agrochemicals that degrade the environmental quality. The allelochemicals can be exploited as herbicides, insecticides, nematicides, fungicides and growth regulator. The allelo-chemicals also provide defense against herbivorous predators (Dicke et al., 1990).
Parthanium hysterophorus L. (Chatak chadani) is a prolific weed belonging to Asteraceae family full of allelo-chemical effects. It is native to Africa, Australia, Asia and Pacific Islands. Due to its wide growth and hard nature it has now become one of the seventh most devastating and hazardous weeds of the world. It produces and releases numerous secondary metabolites which are capable of initiating chemical war for among the neighbouring plant. It causes allergic rhinitis, hay fever, black spots, burning and blisters around eyes in human. It is also known as auto-toxicity weed e.g. daughter plants of parthenium inhibit the growth of parent plant. Parthenium compete with wheat plant for water, nutrients, space and light. It has potential of abundant seed production. A single parthenium plant can produce 10,000 to 15,000 viable seeds and these seeds can disperse and germinate to cover large areas. That’s why it compete more with wheat crop as compare to other weed species of rabi crop. It can reduce the yield of wheat crop up to 75% as its shoot contains water material that is toxic to the root growth of the wheat plant. The allelochemicals produced by the partheinum are in the form of phenolic acid, chlorogenic acid, ferulic acid, benzoic acid, cinnamic acid, flavonoids, steroids and alkaloids etc. that suppress plant growth and development (Mersie & Singh, 1988).
Method of using parthenium allelochemical
Collect the parthenium weed from the field, separate its fresh leaves and stem, place them in the shadow for air drying for a week. After that the air dried leaves and stem of the parthenium should mixed with the distilled water with 10:100 and left for 24 hours in dark in the room temperature (25°C) for extraction. Filter the aqueous extraction of parthenium for future use and it should be used a after dilution, as according to literature 10% (w/v) of parthenium extraction inhibit the germination of other weed seed upto 91.16% (Tefera, 2002).
Arzul, G., M. Seguel, L. Guzman and E. Erard-Le Denn. 1999. Comparison of allelopathic properties in three toxic Alexandrium species. Journal of experimental marine biology and ecology, 232(2), 285-295.
Dicke, M., M.W. Sabelis, J. Takabayashi, J. Bruin and M.A. Posthumus. 1990. Plant strategies of manipulating predatorprey interactions through allelochemicals: prospects for application in pest control. Journal of Chemical Ecology, 16(11), 3091-3118.
Mersie, W. and M. Singh. 1988. Effects of phenolic acids and ragweed parthenium (Parthenium hysterophorus) extracts on tomato (Lycopersicon esculentum) growth and nutrient and chlorophyll content. Weed Science, 278-281.
Tefera, T. 2002. Allelopathic effects of Parthenium hysterophorus extracts on seed germination and seedling growth of Eragrostis tef. Journal of Agronomy and Crop Science, 188(5), 306-310.
Muhammad Shazab Awan, Hafiz Haider Ali, Muhammad Wajid Khan, Mubasshir Sohail, Hafiz Khurram Shurjeel and Faraz Ahmad Shahzaib
Faculty of Agriculture, University College of Agriculture, University of Sargodha