Effect of nano-TiO2 and Salicylic Acid Foliar Application on Some Biochemical Changes of Corn S.C. 704 (Zea mays L.) under Water Deficit Stress

IntroductionDrought is one of the most important causes of decline in agricultural productivity worldwide. TiO2 is one of the materials that nowadays, its properties have been reported to reduce environmental impact. TiO2 with increasing activity of PS II light reduction, activity of chloroplast photophosphorylation, rubisco enzyme, nitrate reductase enzyme activity, catalase and peroxidase and improving the content of some essential elements in plant tissues, increases the yield of different crops. Salicylate is one of the natural growth regulators and is a natural phenolic compound that contributes to the regulation of physiological processes in plants. In the study of the effect of nano-TiO2 spraying on some of the agronomy characteristics of wheat, 0.02% nano-TiO2 foliar application under drought stress conditions increased seed yield by 23% compared to non-foliar application. Considering that a large part of cultivated land in Iran has semi-arid climatic conditions and because of its special geographical position, in most parts of it, important abiotic stresses such as drought, salinity, and temperature decrease the yield and, in some cases, led also to failure of agriculture. Therefore, the aim of this study was to evaluate and identify important biochemical change of corn 704 single cross under water deficit stress and application of the TiO2 and salicylic acid compound.Materials and MethodsIn order to investigate the effect of nano-TiO2 and salicylic acid foliar application on some biochemical changes of corn 704 single cross under water deficit stress, an experiment was conducted in split plot factorial based on RCBD in three replications at the Research Station of the Islamic Azad University, Tabriz Branch, during growing seasons of 2017-2018. Treatments were three levels of water deficit stress (50, 75, and 100% filed capacity (FC)), three levels of the factorial combination of nano-TiO2 (n-TiO2) foliar application (non-application (control), 0.01, and 0.03), and two levels of salicylic acid (SA) foliar application (non-application and 0.5%). Field capacity was determined from the pressure plate machine. TiO2 foliar application on the shoot was performed three times during the growing season and in the stages of 8-10 leaf, tasselling, and grain filling. Irrigation was done according to the needs of the canopy and depending on the weather conditions of the region and irrigation treatments were applied from 8-10 leaves stage. superoxide dismutase (SOD) activity, catalase (CAT), ascorbate peroxidase (APX) activity, and chlorophyll (Chl) content were measured according to the Giannopolities and Ries (1977), Cakmak and Horst (1991), Nakano and Asada (1981), and Porra (2002) methods, respectively. The MSTAT-C software was used to analysis of variance and the means of the treatments were compared using the Duncan’s test at 0.05 probability level. Results and Discussion N-TiO2 and SA foliar application increased CAT, APX activity (p < 0.05) and content of Chl a, b, and total Chl (p < 0.01). Also, the interaction between SA and water deficit stress on SOD and interaction betweenn-TiO2 and SA on SOD (p < 0.05) was significant. Results showed that 0.01% n-TiO2 foliar application under 50% water deficit stress had the highest SOD. Furthmore, 0.01% n-TiO2 and 0.5% SA foliar application under 50% water deficit stress had the highest CAT. 0.01% n-TiO2 and 0.5% SA foliar application under complete irrigation had 79%, 2.5 times and 82 % more than Chl a, b and total Chl compare non-use of n-TiO2 and SA under 50% FC, respectively. Conclusions The results of this study showed that 0.01% n-TiO2 foliar application had the highest superoxide dismutase enzyme activity under 50 % FC. Also, 0.01% n-TiO2 and 0.5% SA foliar application under 50 % FC had the highest catalase enzyme activity. Use of 0.01% n-TiO2 and 0.5% SA under normal stress (50 % FC), increased 79%, 2.5 time and 82% Chl a, b and total Chl compare to control, respectively.