Effect of silicon application on morphological and physiological characteristics of sunflower (Helianthus.annuus L.) under different moisture levels

Available water is the main factor limiting crop growth and production in arid areas. In this regard, in order to investigate the effect of silicon application on morphological, physiological and yield characteristics of sunflower under different moisture levels, an experiment was conducted in the crop year 1397-1398 in Gonabad. This study was conducted as a split plot in a randomized complete block design with three replications. The main factor of irrigation with different moisture levels based on water requirement includes four levels (100% water requirement, 80% water requirement, 60% water requirement and 40% water requirement) and the secondary factor of silicon consumption time. There were four levels (no application (control), application in vegetative stage, application in reproductive stage, application in vegetative stage and reproductive stage). The results showed that reducing the moisture level from 100% to 40% of water requirement reduced the quantitative traits studied; So that the lowest seed yield (1730.8 kg / ha) and oil yield (583.41 kg / ha) were obtained in the treatment of moisture level of 40% of water requirement. Also, the application of silicon under low moisture levels based on water requirement improved the effects of reducing moisture levels in all evaluated traits and seed yield. The highest seed yield (7572.96 kg / ha) was obtained in the treatment of 80% water requirement and application of silicon in the vegetative and reproductive stages and the lowest value (1193.54 kg / ha) was obtained in the treatment of 40% water requirement and without the use of silicon. Also, the application of silicon in the vegetative and reproductive stages compared to the non-application treatment (control) increased 2.5, 1.5 and 2.5 times the oil yield at different levels of moisture, including 80, 60 and 40% of water requirement. In general, the results showed that the use of silicon in the vegetative and reproductive stages at a moisture level of 80% of the water requirement compensated for the adverse effects of reducing the moisture level in the studied traits.