02265naa a2200325 a 450000100080000000500110000800800410001910000180006024500490007826000090012750000790013652012750021565000160149065000160150665300310152265300150155365300160156865300230158465300180160765300250162565300430165065300330169365300130172665300270173970000200176670000200178670000210180670000220182777300900184916314532018-06-08       2009    bl uuuu     u00u1 u    #d1 aSTRECK, N. A.  aImproving node number simulation in soybean.  c2009  aTítulo em português: Melhoria na simulação do número de nós em soja.  aThe objective of this study was to improve the simulation of node number in soybean cultivars with determinate stem habits. A nonlinear model considering two approaches to input daily air temperature data (daily mean temperature and daily minimum/maximum air temperatures) was used. The node number on the main stem data of ten soybean cultivars was collected in a three-year field experiment (from 2004/2005 to 2006/2007) at Santa Maria, RS, Brazil. Node number was simulated using the Soydev model, which has a nonlinear temperature response function [f(T)]. The f(T) was calculated using two methods: using daily mean air temperature calculated as the arithmetic average among daily minimum and maximum air temperatures (Soydevtmean); and calculating an f(T) using minimum air temperature and other using maximum air temperature and then averaging the two f(T)s (Soydevtmm). Root mean square error (RMSE) and deviations (simulated minus observed) were used as statistics to evaluate the performance of the two versions of Soydev. Simulations of node number in soybean were better with the Soydevtmm version, with a 0.5 to 1.4 node RMSE. Node number can be simulated for several soybean cultivars using only one set of model coefficients, with a 0.8 to 2.4 node RMSE..  aAgricultura  aGlycine Max  aDesenvolvimento vegetativo  aEstádio-V  aEstádios-V  aModelo não linear  aModelo Soydev  aNode appearance rate  aSimulação do número de nós em soja  aTaxa de aparecimento de nós  aV-stages  aVegetative development1 aPAULA, G. M. de1 aOLIVEIRA, F. B.1 aSCHWANTES, A. P.1 aMENEZES. N. L. de  tPesquisa Agropecuária Brasileira, Brasília, DFgv. 44, n. 7, p. 661-668, jul. 2009.