Predicting growth and development of pigeonpea: a simulation model

A simulation model of pigeonpea is described that is designed to simulate t he development, growth, nitrogen accumulation and yield of a wide range of maturity types from extra-short to medium-duration in response to weather, soil conditions and agronomic management. Parameters of the model for pheno logical development, leaf area expansion, radiation interception, biomass a ccumulation and partitioning, crop water use, root growth and water extract ion, and nitrogen accumulation are derived from published studies. In addit ion, the calibration exercise is described to derive the parameters account ing for the effect of plant population density on leaf area expansion. The model was tested on 38 data sets, not previously used to derive model param eters, collected at Patancheru, India. Data sets encompassed a wide range o f plant type, sowing density, and seasons, grown on alfisol and vertisol so il types under dryland and irrigated conditions. The time to flowering and maturity from the extra-short to medium-duration types were simulated well, explaining 96 and 92% of the variance (RMSD = 4.3 and 9.8 days), respectiv ely. Total aboveground biomass was simulated with less accuracy, explaining 74% of the variance (RMSD = 2056 kg ha(-1)) and grain yield was simulated explaining 76% of the variance (RMSD = 332 kg ha(-1)). There remains scope for model improvement in the areas of waterlogging and testing on crop N ac cumulation. This pigeonpea module, when coupled with other crop, soil and m anagement modules can be used to address a range of cropping systems issues . (C) 2001 Elsevier Science B.V. All rights reserved.