DOCIS :a Model to Simulate Carbohydrate Balance and Development of Inflorescence during Vase Life

The concept of a dynamic and deterministic model (DOCIS) was developed to simulate post harvest development of an inflorescence during vase life based on carbohydrate content at harvest. The model was partly parameterized using lily ‘Enchantment’. The inflorescence as a system was defined by the state variables: the carbohydrate pool, structural biomass and development stage of each floret in the inflorescence and the carbohydrate pool in the stem. An additional auxiliary state variable was used to describe whether a floret is alive or dead due to shortage of carbohydrate supply. The model is temperature driven. It is assumed that the available carbohydrates are distributed among the floret(bud)s proportional to their total sink strengths. An osmotic pool of the petal cells is included which is treated as an independent sink. By priority, carbohydrates imported by a floret are used for maintenance respiration. Distribution of available carbohydrates among the osmotic and the non-osmotic (substrate available for structural biomass production) pool was assumed to be proportional to the sink strengths of both pools. Sink strength was defined as the capacity to accumulate carbohydrates under conditions of non-limiting carbohydrate supply. Available carbohydrates did not influence osmotic potential of petal juice (vacuolar solution) at a certain development stage. The resulting concept of constant osmotic potential makes it possible to predict floret fresh weight (size), an important aspect of decorative value.