The role of stomatal conductance for water and radiation use efficiency of durum wheat and triticale in a Mediterranean environment

Stomatal conductance has proven to be important in determining the amount and efficiency with which water is used by cereal crops and the productivity of those crops. We designed a series of field experiments in Sardinia, Italy that were aimed at comparing the stomatal conductance and stomatal conductance-related traits (i.e., carbon-isotope discrimination and infrared canopy temperature) of durum wheat and triticale on different environments to evaluate the differences between these two species and the impacts of these differences on leaf transpiration efficiency and on water- and radiation-use efficiency at the crop level. A large variation in stomatal conductance was observed between species, although differences decreased as development proceeded. The greater stomatal conductance of triticale before anthesis did not imply a greater soil water depletion because the good water availability allowed the development of dense canopies exerting a relevant aerodynamic resistance on water vapor fluxes. The greater radiation-use-efficiency of triticale associated with its greater stomatal conductance in pre-anthesis resulted in a greater biomass than durum wheat in correspondence with similar amounts of radiation intercepted and of water used. Transpiration efficiency of triticale was also higher at the crop level, in spite of similar transpiration efficiency at the leaf level. The remarkable greater stomatal conductance of triticale confers an advantage to this species in terms of both water and radiation use-efficiency in spite of the typical terminal drought affecting winter cereal crops in this Mediterranean environment.

► Triticale has a greater stomatal conductance than durum wheat.
► Differences between the species are the highest in the pre-anthesis period, when the stomatal conductance is at a maximum.
► Maximum stomatal conductance affects both radiation and water use efficiency.