\documentclass[english,german]{scrartcl}
\usepackage[latin1]{inputenc}
\usepackage{geometry}
\geometry{verbose,a4paper,tmargin=1.75cm,bmargin=2cm,lmargin=2cm,rmargin=2cm,headheight=0.8cm,headsep=0.5cm,footskip=0.5cm}
\usepackage{babel}
\usepackage{url}
\urlstyle{same}
\newcommand\email{\begingroup \urlstyle{same}\Url}\usepackage{graphicx}
\usepackage{units}
\usepackage{tabularx}
\usepackage{wasysym} % enable use of \permil instead of \textperthousand
\usepackage{marvosym}
\usepackage{arabtex}
\usepackage{hyphenat}
\usepackage{booktabs}
\usepackage{mdwlist}
\renewcommand{\thefootnote}{\relax}
\usepackage{index}
\newindex{key}{kdx}{knd}{Keywords}
\newindex{author}{idx}{ind}{Authors}
\usepackage{fancyhdr}
\pagestyle{fancy}
\renewcommand{\headrulewidth}{0pt}
\fancyfoot{}
\usepackage{ifpdf}
\ifpdf
%\usepackage[activate]{pdfcprot}
%\usepackage[owner=Tapioka, print=true, copy=true, edit=false, annotate=false,set]{pdfcrypt}
%encryption: not supported any more (since pdftex 1.10)
\usepackage[pdftex]{thumbpdf}
\usepackage[pdftex]{hyperref}
\hypersetup{pdftitle={Allelopathic Potential of Various Plant Species on Wild Oat: Implications for Weed Control in Wheat Production},pdfauthor={Ali Reza Safahani Langeroudi, Behnam Kamkar},pdfsubject={Tropentag 2010: Abstract},pdfkeywords={Allelopathy, wheat, wild oat},pdfpagemode=None,colorlinks=true}
\else
\usepackage{ae}
\usepackage{textcomp}
\fi
\begin{document}
\ifpdf
\parbox[b]{2.5cm}{\resizebox*{2.5cm}{!}{\includegraphics{dtt2010.jpg}}}
\else
\parbox[b]{2.5cm}{\resizebox*{2.5cm}{!}{\includegraphics{dtt2010.eps}}}
\fi
\hfill
\parbox[b]{13.4cm}{\centering \large{\textbf{Tropentag, September 14-16, 2010, Zurich}}\\[1ex] \Large{``World Food System  ---\\A Contribution from Europe''\\[2ex]}}
\hspace{0.1cm}
\begin{center}
\Large{\textbf{Allelopathic Potential of Various Plant Species on Wild Oat: Implications for Weed Control in Wheat Production\footnote{\textbf{Contact Address:} Behnam Kamkar, Gorgan University of Agricultural Sciences and Natural Resources, Dept. of Agronomy, Basij Square, Gorgan, Iran, \mbox{e-mail}: \email{bkamkar@yahoo.com}}\\[0.8ex]}}
\normalsize{\textsc{Ali Reza Safahani Langeroudi$^{1}$, Behnam Kamkar$^{2}$}}
\end{center}
\begin{itemize*}
\item[]{\small{\textit{$^{1}$Islamic Azad University,  Ghaemshar Branch, Iran, Dept. of Agronomy, Iran}}}
\item[]{\small{\textit{$^{2}$Gorgan University of Agricultural Sciences and Natural Resources, Dept. of Agronomy, Iran}}}
\end{itemize*}
\index[author]{Safahani Langeroudi, Ali Reza}
\index[author]{Kamkar, Behnam}
\begin{center}
\vspace{1.1cm}
\textbf{Abstract}
\begin{abstract}
\normalsize{
Allelopathy, the ability of plants to inhibit germination of other plants, is an untapped resource for weed control in crops that could revolutionize organic crop production. The main objective of the study was to evaluate allelopathic potential of various plant species on wild oat (\textit{Avena fatua} L.), a major pest of wheat (\textit{Triticum aestivum} L.). To screen for potential allelopathy, plants were grown to flowering stage in a greenhouse, separated into shoots and roots, dried, and ground. Five percent aqueous extracts (w/v) were prepared by extracting 5 g of dried, ground plant samples with 100 mL of deionized water. Wild oat seeds were germinated on extract amended sand. Extracts from most plant species tested inhibited wild oat and wheat seed germination. Extracts from broadleaf plants were more inhibitory than extracts from cereal plants. In most plant species, shoot extracts were more inhibitory to growth of the root and shoot of wild oat than root extracts.  St. John's wort (\textit{Hypericum perforatum} L.), wild mustard (\textit{Sinapis arvensis} L.), Inula (\textit{Inula graveolens}), and (\textit{Acroptilon repens} L.), extracts, which completely inhibited the germination of wild oat seed, have the potential for use in the control of wild oat in wheat"=based cropping systems. John's wort extract inhibited wheat germination by \mbox{77\,\%} and root and shoot growth by 97 and \mbox{96\,\%}, respectively. Wild mustard reduced wheat germination by 75 to \mbox{100\,\%}, root growth by 54 to \mbox{80\,\%} and shoot growth by 45 to \mbox{81\,\%}. Plants evaluated in this study have the potential to be used for biologically based weed control methods in organic cropping systems.}

\vspace{0.5cm}
\end{abstract}
\end{center}
\noindent \textbf{Keywords:} Allelopathy, wheat, wild oat
\index[key]{Allelopathy}
\index[key]{Wheat}
\index[key]{Wild Oat}
\end{document}