Effects of nanoparticles foliar application (iron and silicon) on yield, grain filling components and ‎some physiological traits of safflower (Carthamus tinctories L.) under rainfed and supplementary ‎irrigation conditions

Drought stress is one of the most severe environmental stresses which is a significant role to ‎yield reductions in arid and semi arid. In this regard, the application of silicon ‎in combination with microelements such as iron is a recent, innovative strategy to ‎overcome the damaging effects of drought. So, in order to study the effect of nanoparticles foliar application (iron and silicon) on yield, grain filling components and some physiological traits of safflower under rained and supplementary irrigation conditions, an experimental as factorial was conducted based on randomized complete block design with three replications at the Agricultural Research Station of Ardabil (Alarouq) in 2021-2022. The experimental factors were included irrigation levels (no irrigation or rainfed condition as control, supplementary irrigation at 50% heading-bud and flowering stages according with 55 and 65 BBCH code respectively) and nanoparticles foliar application (foliar application with water as control, foliar application of 1 g.L-1 nano iron oxide, 50 mg.L-1 nano silicon, foliar application 0.5 g.L-1 of nanoiron oxide and 25 mg.L-1 nano silicon). The results showed that nanoparticles foliar application of iron and silicon under supplementary irrigation conditions at the heading-bud stage increased chlorophyll index (35.44%), relative water content (44.25%) and stomatal conductance (32.93%), rate and grain filling period (7.47 and 36.33%  respectively), the number of grain per bud (45.06%), 1000 grains weight (53.06%) and grain yield (43.77%) in comparison with no foliar application of nanoparticles under rainfed conditions. Based on the results of this study, it seems that foliar application of nanoparticles and supplementary irrigation could be utilized as a rapid, easy and effective approach to reduce drought-induced damages on safflower under rainfed conditions due to improving of grain filling components and some physiological traits (such as chlorophyll index, relative water content and stomatal conductance).