ABSTRACT
Because lack of water is potentially a problem for higher plants, survival and optimal growth require that stomatal conductance be sensitive to all factors in®uencing plant growth (Gardner 1973), including CO2. As we mentioned in Chapters 1 and 5, elevated CO2 closes stomata and, therefore, is an antitranspirant. In this chapter, we consider speci£c studies that have documented stomatal conductance (or its reciprocal, stomatal resistance) under elevated CO2. Before we turn to elevated CO2, we £rst consider leaf resistances, the units of stomatal conductance, and, brie®y, the physiology of stomatal movements.
