Water deficit, ultraviolet radiation and carbon dioxide enrichment are the most important environmental factors in global climate change. This research was conducted in Tarbiat Modares University, Research Greenhouse and the objective of that was to study the effects of three levels of carbon dioxide (500, 900 and 1300 ppm), UV-radiation (UV-A, B and C with intensity of 18, 25 and 40 W.cm 2 respectively) and water deficit (common irrigation and 40 percent of available water remain in soil) on grain yield, some quality traits of sweet corn ( Zea mays L. var. Sacarata). The experiment was conducted as factorial arrangement in randomized complete block design with three replications in one year (2009). The results showed that interaction among UV-C radiation, elevated CO 2 and water stress had a significant effect on grain yield and Fv/Fm. The highest grain yield was obtained in water deficit and 900 (l/l) CO 2 concentration. The most content Fv/Fm was obtained under water deficit and 1300 (l/l) CO 2 concentration. Water deficit and elevated CO 2 increased proline, and decreased chlorophyll a, chlorophyll b, chlorophyll a+b, carotenoids and flavonoids. Grain protein decreased with wavelength UV reduction. Above result showed that three main environmental stresses reduced plant productivity strategy in most condition and as a result decreased the performance of corn plant.
