Effect of Foliar Application of Magnesium Nanoparticles on Morphophysiologic Characteristics of ‎Sunflower Cultivars under Drought Stress

The present study attempts to investigate the effect of Magnesium nanoparticle spraying solution on some morphophysiological traits of sunflower under experimental drought conditions. Hence, it conducts an experiment as split split plot in a randomized, completely block design, with three replicates at the field of oilseed section of seed and plant Improvement during 2017-2019 growing season. The treatments include drought stress at two levels: normal irrigation and drought stress. The studied sunflower cultivars include Farrokh, Shams, Qasem & Barzegar, and Magnesium nanoparticles application time at Three Levels: no spraying solution, spraying at flowering stage, and grain filling stage. Results show that drought stress reduces the amount of traits such as height, shoot dry weight, number of grains per head, 1000 grain weight, head diameter, grain yield, oil percentage, and oil yield; however, magnesium nanoparticle spraying solution improves the drought stress effect and increases morphological traits. Drought stress increases electrolyte leakage index and decreases relative water content of leaves by 13% and 9%, respectively. However, magnesium nanoparticles decrease the content of electrolyte leakage index by 9% and increase relative leaf water content by 10%. The cultivars’ response to stress levels has not been the same. In general, Barzegar, Shams, Qasem, and Farrokh cultivars show the highest tolerance to drought stress. Also the highest grain yield and oil percentage are related to Barzegar cultivar by 3427.53 kg/h and 43.96%, respectively.