M. Aubinet, D. DeHalleux, J. Deltour, J. Nijskens
We study the impact of the stomatal opening variations on the transpiration of the entire canopy in protected crops cultivation. Three effects contribute to a reduction of this impact: a damping effect due to the boundary layer adhering to the leaf, a thermal negative feedback effect linked to the energy balance and a hydric negative feedback effect linked to the water balance. Summing up these effects gives a coupling factor between the relative stomatal conductance changes and the relative transpiration rate modifications.

Detailed expression of the coupling factor is established in the frame of a dynamic greenhouse climatic model (GGDM) and its value is calculated for typical days of a temperate climate. The results show that large stomatal conductances are poorly effective in the control of the canopy transpiration (coupling factor =.1 ). Significant values of the coupling factor are only obtained for very small stomatal conductances (gST < 10-3 ) . These values are independant of the climatic conditions but are strongly affected by the development stage of the vegetation.

Aubinet, M., DeHalleux, D., Deltour, J. and Nijskens, J. (1989). STOMATAL REGULATION IN PROTECTED CROPS: ANALYSIS AND SIMULATION. Acta Hortic. 248, 361-364
DOI: 10.17660/ActaHortic.1989.248.45

Acta Horticulturae