Modeling chickpea growth and development: Phenological development

Quantitative information on temperature and photoperiod effects on development rate in chickpea (Cicer arietinum L.) is scarce. Data from a serially sown field experiment (2001-2003) on four cultivars was used to evaluate various approaches to phenology prediction. A range of functions describing the response of development rate to temperature and photoperiod was compared. Phenological data from numerous other field experiments across Iran were used for independent model evaluation. A multiplicative model that included a dent-like function for response to temperature and quadratic function for response to photoperiod was the most adequate at describing the response of development rate to temperature and photoperiod. The differences among cultivars for cardinal temperatures and critical photoperiod were small and a base temperature of 0 degrees C, lower optimum temperature of 21 degrees C, upper optimum temperature of 32 degrees C, ceiling temperature of 40 degrees C and critical photoperiod (below which development rate decreases due to short photoperiods) of 21 h were obtained. Inherent maximum rate of development and the photoperiod sensitivity coefficient characterized cultivar differences. The cultivars required 24.7-32.2 physiological days (i.e., number of days under optimum temperature and photoperiod conditions) from emergence to flowering, 8.2-12.0 from flowering to first-pod, 4.3 from first-pod to beginning seed growth and 30.3 from beginning seed growth to maturity. Differences among cultivars were not found for first-pod to beginning seed growth or for beginning seed growth to maturity. The phenology model developed using these findings gave good predictions of phenological development for a diverse range of temperature and photoperiod conditions across Iran. This model can be incorporated in simulation models of chickpea. (c) 2006 Elsevier B.V. All rights reserved.