ICRISAT Archival Report 2006 - The seedlings of success in the ...

9A. 2. Modeling crop production in pearl millet-based systems of the Sahel (PhD research)
PBI Akponikpe, C Bielders, UCL; B Gérard, ICRISAT
i. APSIM-millet model calibration and validation in Niger
Tests to calibrate and validate the Agricultural Production Systems sIMulator (APSIM model) for Sahelian
conditions for Pearl Millet was done using on-station experimental data (1994-1995) that looked at the interactions
of combining cattle manure, millet residues and chemical fertilizer on pearl millet production. The APSIM model
was able to simulate grain and biomass production, and plant available water PAW, but failed to simulate other
components of the water balance mainly evapotranspiration and drainage (Figure 9A.4). Sensitivity analysis showed
that grain yield was sensitive to variation in water balance parameters (cn_bare and swcon) and very sensitive to
growth parameters (head_grain_no_max, grain_gth_rate and rue).
A
B
C
D
Figure 9A.4 Observed (symbols )and predicted (lines) responses to three selected treatments for A.
Change in Pearl Millet biomass over time, B.Model performance RMSE for all treatments (N=27), C.
Drainage below roots over time, D. Model performance RMSE for all treatments (N=27)
ii. Effect of photoperiod and sowing date on seven Nigerien millet genotypes
This activity was aimed at providing the basis of eco-physiological parameterization of the APSIM model for
optimal nutrient and water conditions for Sahelian millet genotypes. It showed significant behavior differences
between genotypes regarding photoperiod (contrast between the landrace Maewa on one hand and landraces
Hainikirey, Ankoutes, Zongo + improved genotypes CIVT, ICMV-IS89305, ZATIB on the other). Landraces
produced more biomass and less grain yield than improved cultivars. Delayed sowing resulted in decreased biomass
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