Improving oil content and fatty acid composition in dragon's head grain under drought stress with exogenous salicylic acid application

The effectiveness of growth regulators, such as salicylic acid, in enhancing plant resistance to a range of biotic and abiotic stresses is well documented. Against the background of Iran's pressing water scarcity problems and the widespread cultivation of dragon's head in various industries, this study sought to investigate the influence of salicylic acid on both grain yield and oil quality of dragon's head under conditions of limited irrigation. Field experiments were conducted using a split-plot design within a randomised complete block format, replicated three times over the course of 2017 and 2018. The experimental design included different irrigation regimes, ranging from full irrigation to cessation of irrigation at critical growth stages such as flowering and branching, as primary plots. At the same time, sub-plots were subjected to different concentrations of salicylic acid (SA), namely 1, 2, 3 and 0 mM. It's noteworthy that the irrigation cut-off significantly reduced key metrics such as unsaturated fatty acid content, protein percentage, as well as grain, oil, protein and mucilage yields. Conversely, it induced an increase in saturated fatty acids in oil and mucilage percentage in grain. However, the application of SA had a discernible positive effect, increasing both grain yield and quality. The results showed that SA application, especially at a concentration of 2 mM, increased the levels of linoleic and oleic unsaturated fatty acids while reducing stearic and palmitic saturated fatty acids under drought conditions. As a result, SA application served as a potent mitigator against the adverse effects of drought stress on grain oil quality, resulting in overall improvements in product quality

Biological Response of <i>Lallemantia iberica</i> to Brassinolide Treatment under Different Watering Conditions

Lallemantia iberica (L. iberica) is an important dry season medicinal plant. Drought, an important abiotic stress, adversely affects the plant’s metabolism, which can be alleviated by plant growth regulators like brassinolides. A two-year field experiment was conducted in 2017–2018 to determine the effects of three different irrigation regimes and four brassinolide concentrations on the L. iberica biochemical properties. A split-plot based on a completely randomized block design in three replicates was used as an experimental design with the following irrigation regimes: full watering, watering until flowering and watering until branching. These were the main plots, and 0, 0.5, 1 and 1.5 μM brassinolide concentrations were applied as the subplots. The results showed that many antioxidant enzymes and some biochemical parameters were affected by brassinolide treatment. Furthermore, the highest membrane stability and grain yield were produced in full watering treatment in the second year, and these treatments were not affected by brassinolide application. Several concentrations of brassinolide differently affected the studied treatments, and our study suggests that the amelioration of the effects of the drought stress on L. iberica could possibly be achieved through brassinolide-induced elevation of reactive oxygen species (ROS) scavenging defense systems. There is a need for complementary research to prove the effectiveness of foliar application of this growth regulator to improve the growth and yield of L. iberica under water shortage conditions