Abstract
Application of nanofertilizers is one of the promising methods for increasing resources use efficiency and reducing environmental pollutions. This study was carried out to investigate the effects of nano titanium dioxide (nano-TiO2), and nano silicon dioxide (nano-SiO2) on chemical constituents and yield characteristics of cotton plant under drought stress. The cotton plants pre-treated with four concentrations of nano-TiO2 (25, 50, 100 and 200 ppm) or nano-SiO2 (400, 800, 1600 and 3200 ppm) then exposed to drought stress. In general, the drought stress reduced the pigments content, total soluble sugars content, glutathione reductase activity and yield characteristics, while increased total phenolics, total soluble proteins, total free amino acids, proline content, total reducing power, total antioxidant capacity, catalase activity, peroxidase activity and superoxide dismutase activity in comparison with control. The obtained results showed that pretreatment of cotton plants under drought stress with nano-TiO2 or nano-SiO2 caused increasing of pigments content, total soluble sugars, total phenolics, total soluble proteins, total free amino acids, proline content, total reducing power, total antioxidant capacity and antioxidant enzyme activities and enhancement of yield characteristics. The optimum concentration of nano-TiO2 and nano-SiO2 to alleviate the drought stress in cotton plant was 50 ppm and 3200 ppm, respectively. Finally, it can be concluded that foliar application of nano-TiO2 or nano-SiO2 could improve the drought tolerance of cotton plants.