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\hypersetup{pdftitle={ Spatial Correlation Between Winter Wheat (\textit{Triticum Aestivum} L.) Biomass Production and \textit{Polygonum aviculare} L. Seedling Populations},pdfauthor={Hassan Makarian, Narges Heidarzadeh},pdfsubject={Tropentag 2010: Abstract},pdfkeywords={Geostatistics, Patchy Distribution, Spatial Dependence, Triticum aestivum L., Weeds },pdfpagemode=None,colorlinks=true}
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\parbox[b]{13.4cm}{\centering \large{\textbf{Tropentag, September 14-16, 2010, Zurich}}\\[1ex] \Large{``World Food System  ---\\A Contribution from Europe''\\[2ex]}}
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\Large{\textbf{ Spatial Correlation Between Winter Wheat (\textit{Triticum Aestivum} L.) Biomass Production and \textit{Polygonum aviculare} L. Seedling Populations\footnote{\textbf{Contact Address:} Hassan Makarian, Shahrood University of Technology, Dept. of Agronomy and Plant Breeding, Dept. of Agronomy and Plant Breeding Shahrood University of Technology- P. O. Box: 36155-316 Shahrood – Iran., Shahrood, Iran, \mbox{e-mail}: \email{h.makarian@yahoo.com}}\\[0.8ex]}}
\normalsize{\textsc{Hassan Makarian$^{1}$, Narges Heidarzadeh$^{2}$}}
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\begin{itemize*}
\item[]{\small{\textit{$^{1}$Shahrood University of Technology, Dept. of Agronomy and Plant Breeding, Iran}}}
\item[]{\small{\textit{$^{2}$, }}}
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\index[author]{Makarian, Hassan}
\index[author]{Heidarzadeh, Narges}
\begin{center}
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\textbf{Abstract}
\begin{abstract}
\normalsize{
Geostatistical techniques were used to describe and map the spatial distribution of \textit{Polygonum aviculare} L. seedling populations, under conventional management conditions and its effect on aboveground wheat biomass production over the course of one growing season (2008--2009), in a wheat (\textit{Triticum aestivum} L.) field located in Shahrood, Iran. \textit{Polygonum aviculare} L. Seedling were identified and counted at 121 points of field based on a 5\,$\times$\,\mbox{5\,m} grid, in 0.3\,$\times$\,\mbox{0.5\,m} fixed micro plots, two intervals including prior to post"=emergence control, after post"=emergence control. Wheat biomass dry weight was determined at the same place of weed seedling. Anisotropic semivariograms did not show any differences in spatial dependence with the directions, therefore isotropic semivariograms were chosen. Kriged estimates of weed seedling populations and wheat biomass were calculated using the spherical and exponential model parameters for the data. The dominant weed species that occurred in this field was \textit{Polygonum aviculare} L. The semi"=variogram analysis indicated that \mbox{96.8\,\%} to \mbox{78\,\%} of the variation of sample density was due to spatial dependence, which suggests that \textit{Polygonum aviculare} L. distribution was patchy. Wheat biomass dry weight showed strong spatial patterns (\mbox{74.3\,\%} of the variation of sample density was due to spatial dependence) on the field. Cross"=semivariograms analysis showed strong (89 and \mbox{87.4\,\%} in the first and second stages of sampling respectively) spatial continuity between wheat biomass dry weight and weed density patterns on the field. The maps of \textit{Polygonum aviculare} L. corresponded visually to map of wheat biomass. As a result, patchy distribution of weeds can cause spatial heterogeneity in crop biomass production.}

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\noindent \textbf{Keywords:} Geostatistics, Patchy Distribution, Spatial Dependence, \textit{Triticum aestivum} L., Weeds 
\index[key]{Geostatistics}
\index[key]{Patchy Distribution}
\index[key]{Spatial!Dependence}
\index[key]{Triticum aestivum@\textit{Triticum aestivum} L.}
\index[key]{Weeds }
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