Effect of salicylic acid application times on biochemical, agronomic and yield characteristics of barley (Hordeum vulgare L.) in different humidity regimes

In order to investigate the effects of external application time of salicylic acid hormone on morphological and physiological properties of barley (Nosrat cultivar) under stress conditions in Neyriz city during two cropping years 2019-2020 and 2020-2021 a split plot experiment based on randomized complete block design with the main factor of different irrigation conditions (without irrigation, two irrigation and four times of irrigation) and the sub factor of salicylic acid foliar application times (without foliar application, tillering end 50% emergence of stem and end of flag leaf emergence) was conducted. The results showed That without irrigation treatment reduced leaf chlorophyll index and chlorophyll a and b by 74.2%, 66.02 and 42.31%, respectively. without irrigation Treatment also significantly reduced grain yield. It was 86.9% (average of two years of experiment). Foliar application at the end of tillering increased grain yield by 10.36% on average. Increased grain yield due foliar application at the end of tillering in without treatment irrigation was 6.2% and in four times irrigation treatments was 10.1%, which indicates the positive effect foliar application in higher humidity conditions. Foliar application increased the concentration of proline compared to the control without foliar application. The highest proline concentration was foliar application at the end of tillering. Proline concentration increased with decreasing irrigation frequency. The results indicate application of salicylic acid at the end of tillering by improving biochemical properties is effective in reducing the effects of drought stress and its use in barley is recommended in similar water and soil conditions.