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\hypersetup{pdftitle={Soybean Seed Yield Response to Planting Date in a Semiarid Environment},pdfauthor={Atieh Jafari, Behnam Kamkar, Ebrahim Hezarjaribi, Ali Reza Safahani Langeroudi},pdfsubject={Tropentag 2010: Abstract},pdfkeywords={Glycine max (L.) Merr., Morphology, Nonoptimal plantings, Planting period, Seed Yield reduction},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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\begin{center}
\Large{\textbf{Soybean Seed Yield Response to Planting Date in a Semiarid Environment\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{Atieh Jafari$^{1}$, Behnam Kamkar$^{2}$, Ebrahim Hezarjaribi$^{3}$, Ali Reza Safahani Langeroudi$^{1}$}}
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\begin{itemize*}
\item[]{\small{\textit{$^{1}$Islamic Azad University,  Ghaemshar Branch, Dept. of Agronomy, Iran}}}
\item[]{\small{\textit{$^{2}$Gorgan University of Agricultural Sciences and Natural Resources, Dept. of Agronomy, Iran}}}
\item[]{\small{\textit{$^{3}$Agricultural and Natural Resource Research Center of Golestan, Dept. of Agronomy, Iran}}}
\end{itemize*}
\index[author]{Jafari, Atieh}
\index[author]{Kamkar, Behnam}
\index[author]{Hezarjaribi, Ebrahim}
\index[author]{Safahani Langeroudi, Ali Reza}
\begin{center}
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\textbf{Abstract}
\begin{abstract}
\normalsize{
Expansion of the optimal planting dates for soybean [\textit{Glycine max} (L.) Merr.] would allow for more flexibility in management to fit into weather and cropping patterns. A field study was conducted to determine yield components associated with soybean seed yield reductions at nonoptimal planting dates in the northeastern Iran. This information provides insight into how seed yield reductions occur at nonoptimal planting dates. Optimal planting period in the area is between late May and late June. Cultivars Habbit, Sahar, Williams, Davis*Williams, D.P.X, Williams*Essex, were planted at Late April (nonoptimal), late-May (optimal), and early-July (nonoptimal) planting dates in 2009 at the Gorgan Institute in Iran, (36\textdegree{}\,45ŽN, 54\textdegree{}\,25ŽE, 5\,m\,asl) on an Olivier silt loam (fine"=silty, mixed, thermic Aquic Fragiudalf) soil. At maturity, plant samples were separated into main and branch stem components. Main and branch stem length, branch number, node number, fertile node number, pod number, pods per fertile node, seed per pod, seed size, and seed yield were determined. In all genotypes, seed yield reduction at the early-July planting date was related to a decline in branch seed yield associated with a reduction in number of branches and branch nodes. The decreased number of fertile branch nodes resulted in fewer branch pods and seed. Williams*Essex and D.PX showed no seed yield reduction at the late April planting date. Reduced seed yield of the other genotypes at the late April planting date was related to a reduction in branch nodes and proportion of the branch nodes that were fertile. The decreased number of fertile branch nodes resulted in fewer branch pods and seed. In conclusion, seed yield reduction at nonoptimal planting dates was associated with reductions in branch rather than main stem yield components.}

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\noindent \textbf{Keywords:} \textit{Glycine max}, morphology, nonoptimal plantings, planting period, seed yield reduction
\index[key]{Glycine max@\textit{Glycine max}}
\index[key]{Morphology}
\index[key]{Nonoptimal plantings}
\index[key]{Planting period}
\index[key]{Seed!yield reduction}
\end{document}