Calibration of a hydraulic architecture-based growth model of cotton plants

The AMAPpara model describes long-term plant growth as the cumulative outpu t of the cyclic interactions between plant ecophysiological functioning and architectural development. It is based on the classical relationship betwe en transpiration and biomass production, under the assumption of a constant water use efficiency. Biomass increment is allocated to organs (leaves, in ter-nodes) according to their sink strength and their expansion laws. Allom etric rules are used to derive the geometry of the organs as a function of their volume or biomass. Organ geometry determines the hydraulic architectu re of the plant, from which water transpiration is computed. Feedback betwe en plant growth and architecture is modelled through a recurrence equation which links the successive growth cycles to each other. Under the assumptio n that climatic conditions are approximately stable over the whole growth p eriod, the parameters of AMAPpara can be estimated from the observation of plant architecture and morphology at the end of their growth. A preliminary calibration of the model was carried out for cotton, and yielded quantitat ively and qualitatively satisfactory results. ((C) Inra/Elsevier, Paris.).