\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={Effect of Field Multiplication Generation on Seed Potato (\textit{Solanum tuberosum}) Quality in Kenya},pdfauthor={Geoffrey Wachira, Ian Barker, Elmar Schulte-Geldermann},pdfsubject={Tropentag 2010: Abstract},pdfkeywords={Kenya, potato, seed degeneration, seed quality},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{Effect of Field Multiplication Generation on Seed Potato (\textit{Solanum tuberosum}) Quality in Kenya\footnote{\textbf{Contact Address:} Elmar Schulte-Geldermann, International Potato Center - sub Saharan Africa (CIP-SSA), Integrated Crop Management, Nairobi, Kenya, \mbox{e-mail}: \email{e.schulte-geldermann@cgiar.org}}\\[0.8ex]}}
\normalsize{\textsc{Geoffrey Wachira$^{1}$, Ian Barker$^{2}$, Elmar Schulte-Geldermann$^{3}$}}
\end{center}
\begin{itemize*}
\item[]{\small{\textit{$^{1}$University of Nairobi, Plant Pathology, }}}
\item[]{\small{\textit{$^{2}$International Potato Center, Seed Systems, }}}
\item[]{\small{\textit{$^{3}$International Potato Center - sub Saharan Africa (CIP-SSA), Integrated Crop Management, Kenya}}}
\end{itemize*}
\index[author]{Wachira, Geoffrey}
\index[author]{Barker, Ian}
\index[author]{Schulte-Geldermann, Elmar}
\begin{center}
\vspace{1.1cm}
\textbf{Abstract}
\begin{abstract}
\normalsize{
Kenya has a national average potato production of 8t*ha$^{-1}$. The main reason for this low yield is the use of poor quality seed by farmers. The seed system is therefore of utmost importance if higher yield levels are to be achieved. Currently the formal seed system is only able to supply \mbox{1.5\,\%} of the country's demand. Viruses and other seed borne diseases can cause severe seed degeneration leading to decrease in yield and economic losses. Viral infections like PVY, PVX, PLRV and Bacterial wilt, caused by Ralstonia solanacearum are the main diseases affecting seed quality.



The purpose of this study is to determine the yield gap caused by degeneration of various seed qualities. 



The seed qualities used were from the 1\textsuperscript{st} and 2nd field generations (FG) of a private seed multiplier, Basic seed from the public sector (2nd FG), certified seed from a public seed multiplication institution (5\textsuperscript{th} -6\textsuperscript{th} FG), quality declared seed which is seed obtained from a credible farmer but which had been produced without the normal certified seed production regulations (FG 3--5). Positively selected seed which had been selected by following CIP's manual of `select the best' to improve farmer's own saved seed', and typical farmer's practice seed were used. The yield gap caused by seed quality was determined by carrying out multi"=location On-Farm trials with three main varieties over two seasons in potato growing regions of the country. 



 Results of the first season indicate significant differences in number of stems per plant, virus infection levels,number of harvested tubers and yield. Results from season two will be included before full paper submission.



}

\vspace{0.5cm}
\end{abstract}
\end{center}
\noindent \textbf{Keywords:} Kenya, potato, seed degeneration, seed quality
\index[key]{Kenya}
\index[key]{Potato}
\index[key]{Seed!degeneration}
\index[key]{Seed!quality}
\end{document}