Comparing two versions of a non-linear model for simulating leaf number and developmental stages in maize based on air temperature

Abstract

The Wang and Engel (WE) model simulates crop development considering the non-linear response of plant development to temperature. Daily air temperature is the input for the temperature response function [f(T)] in the WE 2005-2006 and 2006-2007 growing seasons. The f(T) in the WE model was calculated using daily mean air temperature calculated as the arithmetic average of daily minimum (TN) and maximum (TX) air temperatures (WE Tmean ), and calculating an f(T) using TN and an f(T) using TX and then averaging the two f(T)s (WE Tmm) RESUMO O modelo Wang e Engel (WE) simula o desenvolvimento das culturas considerando uma resposta não-linear do desenvolvimento das plantas à temperatura. A temperatura diária do ar é o dado de entrada na função de resposta à temperatura [f(T)] no modelo WE e, em função de haver várias maneiras de calcular a temperatura diária, há várias maneiras de calcular a f(T). O objetivo deste estudo foi comparar duas versões do modelo WE para a simulação do número de folhas e dos estágios de desenvolvimento em milho, considerando dois métodos de entrada da temperatura diária do ar (temperatura média diária do ar e temperatura mínima/ máxima diária do ar). Um experimento de campo com a variedade de milho BRS

Observed and estimated leaf appearance of landrace and improved maize cultivars

“…Although, there wasn't significantly difference, we decided to use the calibrated values for each cultivar because these coefficients are genetic specific. Phyllochron and LARmax estimated for these cultivars are in the range of the observed total leaf appearance of the OPV 'BRS Missões' (39.6 to 59.8°C day leaf -1 ) as a function of the sowing date (STRECK et al, 2009b), and 0.626 leaf day -1 (STRECK et al, 2009a), respectively. In the Experiment 1, the WE had a better performance with the RMSE value less than one leaf (Figure 2).…”

“…f(T)s were calculated with Tmin and Tmax, and the arithmetic average between them was determined to get of the daily f(T) (STRECK et al, 2009a).…”

Maize leaf development under climate change scenarios

“…Leaf appearance rate was calculated on leaf tip (LNtip) and on expanded leaf (LNexp) basis. A leaf was assumed expanded when ligule is visible (Streck et al, 2009). Values of LARmax for the variety BRS Missões were 0.626 and 0.452 leaves per day for tip and expanded leaves, respectively; and cardinal temperatures for both tip and expanded LAR were: Tmin, 8°C; Topt, 31°C; and Tmax, 41°C (Streck et al, 2009).…”

“…A leaf was assumed expanded when ligule is visible (Streck et al, 2009). Values of LARmax for the variety BRS Missões were 0.626 and 0.452 leaves per day for tip and expanded leaves, respectively; and cardinal temperatures for both tip and expanded LAR were: Tmin, 8°C; Topt, 31°C; and Tmax, 41°C (Streck et al, 2009). The f(T) was calculated daily for TM and for TX and then averaged (Streck et al, 2009).…”

“…LAR calculations started at the emergence day and ended when the flag leaf has emerged (FLNtip) or expanded (FLNexp). For this variety, the flag leaf number (FLN) was assumed as the sowing date dependent, based on records from field experiments during two growing seasons (2006/07 and 2007/08) with several sowing dates at Santa Maria, RS (Streck et al, 2009). The number of leaves for FLN, for each emergence date, was: 08/15, 21; 09/15, 21; 10/15, 21; 11/15, 22; 12/15, 22; 01/15, 21; 02/15, 20; 03/15, 20; and 04/15, 19 leaves.…”