Int.J.Curr.Microbiol.App.Sci (2016) 5(2): 794-801 International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 5 Number 2(2016) pp. 794-801 Journal homepage: http://www.ijcmas.com Original Research Article doi: http://dx.doi.org/10.20546/ijcmas.2016.502.090 Impact of Post-Emergence Application of Dichlorophenoxy Acetic Acid (2,4-D) Herbicide on Growth and Development of Three Weeds Associated with Maize Growth Hanan. M. Abou El-Ghit* Botany and Microbiology department, Science Faculty, Helwan University, Cairo, Egypt *Corresponding author ABSTRACT K e yw or ds Post emergence application of 2,4-Dichlorophenoxyacetic acid (2,4-D) as a Maize, herbicide even at low concentrations showed an effective control on three Weeds, weeds (slender amaranth, goosefoot and prickly burweed) associated with Chemical control, maize growth. 2,4-D was applied at 0.0, 125, 250, 500 and 1000 ppm. 500 (2,4-D), ppm 2,4-D treatment significantly decreased numbers and fresh weights of Auxin the three weeds by 50% approximately. At 1000 ppm 2,4-D, there were Article Info sever reductions in weeds numbers, fresh weights and photosynthetic Accepted: pigments contents of the three weeds. Fresh weights and photosynthetic 28 January 2016 Available Online: pigments contents of maize were favored significantly after application of 10 , February 2016 2,4-D on its associated weeds at all tested rates. Introduction Maize (Zea mays L.) is the second most Weed compete with crop plants for soil important cereal crop in Egypt in terms of nutrients, light and water. Slender amaranth total food production. It is grown for fodder (Amaranthus viridis), goosefoot as well as for grain. The grains of maize are (Chenopodium album) and prickly burweed used in a variety of ways by the human (Xanthium spinosum) are troublesome broad beings. Weeds are a major problem in crop leaved weeds associate with maize growth production and drastically decrease crop (Malik et al. 2006). Amaranthus viridis is a yield. Weed control is an important cosmopolitan weed belong to management practice to ensure optimum family Amaranthaceae, Chenopodium grain yield. Yield losses due to weeds have album is a fast-growing weed belong to been reported up to 35 % (Oerke, 2005; Chenopodiaceae, whereas Xanthium Dangwal, et al. 2010). The use of herbicides spinosum is a noxious weed in may reduce such losses, as herbicides may Asteraceae family. reduce the weed infestation provided that the herbicide-treated weeds are not herbicide Some herbicides are synthetic mimics of resistant. natural plant hormones (Kellogg et al., 794 Int.J.Curr.Microbiol.App.Sci (2016) 5(2): 794-801 2000). Selective herbicides kill specific action. However, with increasing targets, while leaving the desired crop concentration and auxin activity in the relatively unharmed. Herbicide use has tissue, growth is disturbed and the plant is undoubtedly contributed to crop yield lethally damaged (Grossmann, 2003). increases and the efficiency of production (Andrew, 2012). Some substantial benefits In general, grasses are much less sensitive to can be gained through the use of herbicides synthetic auxin herbicides than are dicots. to manage unwanted vegetation. So, for example, at the doses used to kill Unintended but economically important dandelions, grasses are largely unaffected damage to crop plants is sometimes a (Cobb, 1992 and Grossmann 2003). Auxin- consequence of the inappropriate use of based herbicides are referred to as herbicides (Robert, 1941 and Mehmeti, “selective” herbicides because they kill so- 2004). Herbicides have different modes of called “broadleaf” plants (dicots) but not actions on enzymes (catalysts of biological grasses, hence, that’s why they’re popular reactions), this means that the target herbicides with growers of lawns. enzymes may no longer function properly, or at all. Herbicide distort enzymes Phenoxy herbicides work by binding to molecules in some way, so component some or all of the same sites in the plant chemicals for the reaction accumulate and cells as naturally occurring IAA. While may be directly or indirectly damaging. naturally occurring IAA concentrations in Absence of the reaction’s products will the cell are highly regulated, when phenoxy restrict growth, either through starvation of herbicides are applied, plant growth key building blocks or because the reaction becomes deregulated. This deregulation makes chemicals which normally protect the causes twisting, thickening and elongation plant (Santra and Baumann, 2008). of leaves and stems and eventually leads to plant death as the plant cannot mobilize Over decades, the so-called auxin herbicides reserves, repair or function properly (Song, had resisted all efforts to elucidate their 2014). molecular interactions and the biochemical and physiological basis of their 2,4-D was the first compound that, at low phytotoxicity (Cobb, 1992). doses, could selectively control dicots broadleaf plants, but not most monocots Auxin herbicides started a new era of weed narrow leaf crops like wheat, maize (corn), control in modern crop production due to rice, and similar cereal grass crops (Andrew their systemic mobility in the plant and to et al., 2010). 2,4-D generally has low their selective action, preferentially against toxicity for humans (Aylward, 2010). dicot weeds in cereal crops (Cobb, 1992 and Grossmann, 2007). Auxin herbicides mimic Materials and Methods the action of the main auxin, indole-3-acetic acid (IAA) in higher plants (Cobb, 1992). A pot experiment was carried out to However, they are long-lasting, particularly examine the effect of foliar application of due to their higher stability in the plant, and, 2,4-Dichlorophenoxyacetic acid (2,4-D) as a therefore, more effective than IAA. Auxins herbicide on the growth of three weeds stimulate a variety of growth and (slender amaranth, goosefoot and prickly developmental processes when present at burweed) which grow associated with maize low concentrations at the cellular sites of plant. 2,4-D was applied at different 795 Int.J.Curr.Microbiol.App.Sci (2016) 5(2): 794-801 concentrations (0.0, 125, 250, 500 and 1000 their corresponding controls and this effect ppm). Seeds of Zea mays var. amylacea and was in a concomitant trend with that of the three weeds were obtained from the growth parameters in response to 2,4-D Agriculture Research Center, Ministry of treatments (Tables 3,4,5). The lowest Agriculture, Giza, Egypt. Maize and weeds pigments content was recorded by the were grown in pots (40 cm in diameter) of highest 2,4-D concentration (1000 ppm). 15 kg of clay loamy soil. The reducing effect of 2,4-D on slender Fifteen seeds of each weed were sown with amaranth, goosefoot and prickly burweed ten seeds of maize. 2,4-D was sprayed on plants may be a consequence effect of weeds with a hand sprayer after 2 weeks of increasing the endogenous auxin sowing and repeated after one week. concentrations to supraoptimal and Precautions were taken to avoid damage of extensive perception by auxin receptors maize plant. There were three replicates of (Badescu, 2006 and Dharmasiri et al. 2005). each treatment of 2,4-D. Irrigation was done Also, it may be attributed to stimulation of regularly to maintain soil field capacity. The ethylene production which trigger the effect of 2,4-D herbicide was measured after overproduction of abscisic acid (ABA), five weeks of sowing by counting of slender causing its accumulation. Over production amaranth, goosefoot and prickly burweed of ethylene causes number of plant numbers (plants/pot) and estimation of fresh responses, including epinasty and weights of each weed (g/ 3plants). Also, senescence. fresh weight (g) of maize plant was estimated after 2,4-D application on the Accumulated ABA in the shoot tissue is associated weeds. Chlorophyll a, b and translocated within the plant and mediates carotenoids contents in the fresh leaves of events in the auxin herbicide syndrome, weeds and maize (mg/g. F.W) were such as growth inhibition, tissue decay and determined in samples according to plant death. The recent identification of Metzener et al., (1965). Data were receptors for auxin perception and the statistically analyzed by Snedecore and discovery of a new hormone interaction in Cochran (1981) method. signalling between auxin, ethylene and the upregulation of abscisic acid biosynthesis Results and Discussion account for a large part of the repertoire of auxin-herbicide-mediated responses, which Tables (1 and 2) indicate that 2,4-D include growth inhibition, senescence and herbicide controlled both number and fresh tissue decay in sensitive dicots (Chae et al. weights of slender amaranth, goosefoot and 2005). prickly burweed plants even at low rates. 500 ppm 2,4-D treatment led to approximately Stimulation of ethylene biosynthesis plays a 50% reduction in plant numbers and plants key role in eliciting the herbicidal symptoms fresh weights. Few plants of the slender in sensitive plants (Grossmann, 2010). amaranth, goosefoot and prickly burweed These results are in agreement with Hansen plants survived at 1000 ppm 2,4-D, but they and Grossmann (2000), Grossmann (2003) were very small and damaged. Concerning and Kepinski et al. (2005). Chae (2005) the photosynthetic pigments content of reported that ethylene is a factor in weeds, it was found that chlorophyll a, b and defoliation caused by 2,4-D. Because plants carotenoids of 2,4 D sprayed weeds were can’t break down 2,4-D, it’s action persists. considerably diminished compared with 796 Int.J.Curr.Microbiol.App.Sci (2016) 5(2): 794-801 Table.1 Effect of 2,4-D Application on Numbers of Slender Amaranth, Goosefoot and Prickly Burweed 2,4-D conc. Plant numbers/pot (ppm) Slender Goosefoot Prickly amaranth burweed 0.0 15 15 15 125 13.6 12.3 13.3 250 11.3 9.6 10.6 500 9.3 7.3 9.3 1000 3.3 4.6 5.3 L.S.D.