Response of Roots of Maize Varieties Released in Different Years to Low Nitrogen and Drought Stresses Effects of combined drought and salinity stress on germination and physiological characteristics of maize (Zea mays). Studying on Effect of Cd in Combination with UV-B on Physiological Mechanism in Regulation of Soybean Epicotyl Growth Effects of UV-B irradiation and acid rain on photosynthetic rate and antioxidant enzyme activities of maize seedlings Effects of combined high temperature and drought stress on amylose and protein contents at rice grain-filling stage Effects of supplementary UV-B radiation and combined stresses on plant antioxidant enzymes