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\hypersetup{pdftitle={Weed Control Strategies in Organic Paddy"=rice Seeding and Planting Systems: Brazil and South"=korea},pdfauthor={Michael Giepen},pdfsubject={Tropentag 2016: Abstract},pdfkeywords={Organic rice, planting system, pre-germinated seeding, weed control},pdfpagemode=None,colorlinks=true}
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\parbox[b]{13.4cm}{\centering \large{\textbf{Tropentag, September 18-21, 2016, Vienna, Austria}}\\[1ex] \Large{``Solidarity in a competing world ---\\fair use of resources''\\[2ex]}}
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\Large{\textbf{Weed Control Strategies in Organic Paddy"=rice Seeding and Planting Systems: Brazil and South"=korea\footnote{\textbf{Contact Address:} Michael Giepen, Bonn University, Iol, Katzenburgweg 3, 53115~Bonn, Germany, \mbox{e-mail}: \email{mgiepen@uni-bonn.de}}\\[0.8ex]}}
\normalsize{\textsc{Michael Giepen}}
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\begin{itemize*}
\item[]{\small{\textit{Bonn University, Iol, Germany}}}
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\index[author]{Giepen, Michael}
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\textbf{Abstract}
\begin{abstract}
\normalsize{
In organic paddy"=rice (OR) weed control cannot be mechanised and manual weeding is often not viable.   Therefore, weed control strategies were studied during internships, farm visits, and interviews, including large scale pre"=germinated seeding systems in Brazil and small"=scale planting systems  South-Korea.



In Brazil several weeks of flooding, puddling, and precise field levelling are of outmost importance for weed control. Long"=time flooding results in seed dormance of semi"=aquatic weeds, while promoting emergence of aquatic weeds, which are controlled by the following puddling.     After seeding into the flooded fields pre"=germinated seeds terminate the seedling stage.  After about seven days fields are drained allowing seedlings to root for about a week.  Weeds germinate in this time fields are flooded with a high water table, which kills most weeds, while rice seedlings grow to the surface.    With precise field levelling high water tables can be maintained which effectively control weeds.



In South-Korea puddling is usually only realised directly prior to planting.  The plantules suffer from transplantation stress and need a period of about two weeks with a low water table to establish, which allows for abundant emergence of weeds, which is the biggest disadvantage of this technique.   A promising alternative is the use of larger potted seedlings, which directly after planting support high water tables that effectively controls semi"=aquatic weeds.    The use of herbivores such as snails (/\textit{Pomacea canaliculata}/) or ducks for weed control is a common strategy used in South Korea and control weeds as long as no firm plant tissue has been formed, yet.  Ducks additionally trample weeds into the mud and make the water turbid restraining weeds from sunlight.   A further method used in combination with potted seedlings is the application of rice"=bran, which causes a rapid development of a thick algal bloom, which shades weeds and physically inhibits them from reaching the water surface.







}

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\noindent \textbf{Keywords:} Organic rice, planting system, pre"=germinated seeding, weed control
\index[key]{Organic!rice}
\index[key]{Planting system}
\index[key]{Pre"=germinated seeding}
\index[key]{Weed control}
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