Interactive effects of excess boron and salinity on response curves of gas exchange to increase in the intensity of light of Zea mays amylacea from the Lluta Valley (Arica-Chile)
High levels of B (boron) are accompanied by conditions of excessive salinity, as occurs in the Lluta Valley in northern Chile; the consequences can be drastic for crops. In the present study, seeds of Zea mays L. amylacea were grown in order to study the response curves of gas exchange to increase in the intensity of light at high levels of NaCl and B. Concentrations of 100 mM NaCl (low salinity) or 430 mM NaCl (high salinity), or an excess of B supplied as boric acid to obtain 20 and 40 mg kg-1 B were applied in the nutrient solution for 20 days. Our results complement other studies with the amylacea ecotype and confirm the high degree of tolerance to salinity and excess boron. Higher light intensified the gas exchange parameters photosynthetic rate, transpiration rate and CO2 stomatal conductance, which gradually increased. Intercellular CO2 concentration and water-use efficiency (WUE) showed no differences between treatments, except for high leaf CO2 at high salinity. The plants grown under high salt, independent of the presence of B, showed a high quantum requirement at higher light intensities.