MOISTURE STRESS CONDITIONING EFFECTS ON SALVIA-SPLENDENS BONFIRE

We determined the influence of moisture stress conditioning (MSC) (exposing plants to four nonlethal dry-down cycles) on gas exchange and water loss of Salvia splendens F. Sellow 'Bonfire'. During day 1 following final irrigation, no differences in leaf water potentials (psi-L) were observed due to MSC. However, MSC plants had lower midday net photosynthesis (Pn), transpiration (E), and leaf conductance (g(L)) than controls. Stomatal inhibition of photosynthesis (SI) of MSC plants was greater than that of controls. Further, the lack of differences in mesophyll resistance to CO2 (r(m)) due to MSC indicate gas exchange differences during day 1 were stomatal in nature. During day 2, MSC plants exhibited greater Pn, E, and g(L), while SI and r(m) were greater for controls. MSC plants maintained positive Pn rates and turgor and lower psi-L than control plants during day 2. Higher water-use efficiency estimates were observed for MSC plants than for controls.