Effect of nano-TiO2 and salicylic acid foliar application on some physiological traits of Echinaceae purpurea L. under water deficit stress

In order to investigate the effect of drought stress and nano-TiO2 and salicylic acid foliar application on some physiological traits of Echinaceae purpurea under water, 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. The main factors were water deficit stress at three levels of 50, 75, and 100% filed capacity, thefactorial combination of nano-TiO2 (n-TiO2) foliar application at two levels (0.02 and 0.04%) and salicylic acid foliar application at two levels (0.02 and 0.04%), and also distilled water foliar application as control treatment. Findingsshowed a significant effect of water deficit stress on relative water content (RWC) and proline (p≤0.01). Also, interaction of the effects of water deficit stress and nano-TiO2 and salicylic acid foliar application on Chl. b, total Chl., and hydrogen peroxide contents was significant (p≤0.01). Application of water deficit stress treatment up to 50% FC increased proline content by 40% and reduced RWC by 10% compared to complete irrigation (100% FC). Furthermore, 0.04% n-TiO2 and 0.04% SA foliar application increased hydrogen peroxide content by 50% compared to complete irrigation group and the control. The maximum total Chl. Contents of leaves was obtained under 100% FC irrigation and and 0.04% n-TiO2 and 0.02% SA foliar application showing 79.52% increase compared to 100% FC irrigation and no foliar application.