ISHS Acta Horticulturae 584: VI International Symposium on Computer Modelling in Fruit Research and Orchard Management
A SOURCE/SINK MODEL TO SIMULATE SEASONAL ALLOCATION OF CARBON IN GRAPEVINE |
| Authors: | PH. Vivin, M. Castelan, J.P. Gaudillère |
| Keywords: | C allocation, source-sink relationships, growth, modelling, Vitis vinifera L. |
| Abstract:
A source-sink relationship-based model with potential demand functions has been developed to simulate the seasonal carbon supply and partitioning among vegetative and reproductive plant parts of an individual grapevine (Vitis vinifera L.) on a daily basis. The plant is described as a set of sink organs - i.e. annual growing populations of leaves, shoots, fruits, fine roots, and a perennial structure made up of stem, canes and woody roots - , which get carbon from one common source pool fed by photosynthesis and reserve mobilization. Development of sinks is based on a thermal time expressed in degree-days. Daily gross canopy photosynthesis is estimated from the product of photosynthetic radiation intercepted by the canopy using a simple Beer-Lambert law, and estimates of radiation use efficiency. Reserve mobilization is activated when demand of the sink organs exceeds the carbohydrate available from current photosynthesis. The model is based on the hypothesis that C allocation is primarily ruled by the sink strength of plant organs. Sink strength is defined by the potential growth rate (i.e. the genetically determined maximum rate at which the organ can accumulate dry matter per unit of time), plus carbon losses through growth and maintenance respiration processes, and carbon demand related to active reserve storage. The fraction of C distributed into a sink is proportional to its potential demand relative to the sum of potential demands of the plant. When the amount of C within a sink does not match its potential demand, maintenance respiration costs are satisfied first to the detriment of growth and storage functions. This model integrates environmental and physiological factors controlling carbohydrate supply and demand for growth of grapevines at the whole plant level. It can reproduce the actual seasonal behavior of grapevine dry matter recorded in the vineyard. The storage contribution to C balance appears realistic. The primary distinctive trait of this model is the explicit use of C by each sink for respiration, growth and storage. | |
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