Arsenic (As) is a toxic metal that can harm plants by causing oxidative stress, stunting growth, and disrupting metabolism. This study investigates the potential effect of gamma-aminobutyric acid (GABA) and salicylic acid (SA) in mitigating the toxic effects of As on sunflower plants. The aim is to enhance growth, improve metabolite accumulation, strengthen antioxidant defenses, reduce oxidative stress, enhance nutrient status, and minimize As uptake in sunflower plants. To investigate the effect of GABA and SA on arsenic toxicity, two sunflower genotypes (FH-779 and FH-773) were exposed to arsenic at a concentration of 60 mg kg(-)(1) in the soil. The experimental design followed a completely randomized design with three replications of each treatment arranged in a factorial manner. The sunflower plants were treated with foliar sprays of GABA (200 mg L--(1)), SA (100 mg L--(1)), and a combination of both GABA + SA (200 + 100 mg L--(1)). Both FH-779 and FH-773 genotypes exhibited significant accumulation of As + 5 and As+ 3 in roots and leaves, resulting in reduced nutrient uptake. GABA, SA, and GABA + SA treatments alleviated As-induced oxidative stress by reducing hydrogen peroxide (H2O2) production and malondialdehyde (MDA) levels in both genotypes. These treatments also enhanced osmolyte accumulation, improving osmotic adjustment under As stress. Additionally, GABA and SA spray enhanced the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), aiding in scavenging reactive oxygen species (ROS) and preventing oxidative damage. The combination of GABA and SA had a more pronounced effect on the translocation and remediation of As compared to GABA and SA alone. Arsenic removal efficiency reached maximum in the GABA + SA treatment in both FH-779 and FH-773 genotypes, greater than control group, respectively. The findings of this study highlight the beneficial roles of gamma-aminobutyric acid and salicylic acid in mitigating the negative effects of arsenic on growth of sunflower plants. These compounds regulate photosynthetic pigments, osmotic pressure, and antioxidant defense systems, improve nutrient status, and reduce arsenic uptake. Salicylic acid and gamma-aminobutyric acid show potential for alleviating stress in other crops facing abiotic stress. This study highlights the impact of these compounds on plant defense mechanisms in stress conditions, providing a promising approach to reduce arsenic toxicity in crops, thereby improving agricultural productivity in contaminated environments.

Salicylic acid (SA) is a vital phytohormone that can mitigate the detrimental effects caused by abiotic stress in plants; however, these effects vary with SA concentrations, plant species and stress types. Although sunflowers can be cultivated on saline-alkali soil, they remain susceptible to salt stress, especially at the seedling stage. Therefore, we aimed to explore the role of SA in improving salt stress tolerance in sunflowers. Here, we conducted physiology and transcriptomic analyses to assess the effects of four SA concentrations applied through foliar spraying on sunflower seedlings under salt stress. Initially, the height and stem diameter were impeded, and the chlorophyll fluorescence parameters (such as Fv/Fm, Fv/Fo, and PIabs) decreased, but the antioxidant enzyme activity and malondialdehyde and glutathione contents increased when the seedlings exposed to salt stress (250 mM NaCl); meanwhile, the levels of most physiological indices (including plant growth, chlorophyll fluorescence, and reactive oxygen species) significantly recovered after spraying four concentrations of SA solution. Furthermore, the differentially expressed genes identified from transcriptome analysis were mainly involved in photosynthesis, plant hormone signaling, MAPK pathway, and secondary metabolite biosynthesis, which may contribute to the SA-induced response under salt stress. The key genes and TFs crucially involved in the response to salt stress and mitigating its detrimental effects were identified through K-means clustering and WGCNA. We may infer that SA can activate the self-regulatory system, thereby mitigating oxidative damage and enhancing photosynthesis and salt tolerance in plants. Overall, our results demonstrate that 1.0 mM SA is the most effective concentration for alleviating salt stress in sunflowers. This study provides initial insights into the ability of SA to alleviate salt stress and its underlying molecular mechanisms, which is valuable for both field management practices and understanding sunflower tolerance to salinity.

An important reserve for increasing the productivity of agricultural production is a scientifically based crop structure and the use of rational crop rotations, which implement the optimal ratio of agroecological standards. The aim of the research was to determine the influence of elements of agrotechnical measures, in particular, the saturation of crop rotations with sunflower, soil tillage system on the number and species composition of various agrobiological groups of weeds in sunflower crops, including the weed parasite sunflower broomrape (Orobanche cumana Wallr.). Weed control measures and the spread of the parasitic weed sunflower broomrape in sunflower crops have been carried out according to the methods generally accepted in agriculture and weed science. The scheme of the experiment included crop rotations with saturation in the structure of sunflower sowing of 12.5, 20, 25, 33.3, 50, 100% and three systems of basic tillage: moldboard plowing, disc tillage, and no-tillage. As a result of the research, it has been found that the systems of disc tillage and no-tillage cause an increase in the number of weeds in sunflower crops compared to the moldboard plowing by 1.3-1.5 times. On average, over the years of research, the abundance of weeds in the plots when using disk tools was 10.4-15.1 pcs./m(2), moldboard plowing was 7.1-12.4 pcs./m(2), and before harvesting was 2.6-5.2 and 4.1-12.4 pcs./m(2). The highest degree of sunflower broomrape damage has been observed in 2-fields crop rotation (winter wheat-sunflower) and permanent sunflower cultivation, as 16.0-32.4% of affected sunflower plants have been observed here. The intensity of sunflower broomrape damage to sunflower plants was higher in the moldboard plowing system and amounted to 1.2-8.3 pcs./per plant, which exceeded disc tillage and no-tillage by 1.2-1.6 times. The maximum seed yield of 2.92-2.95 t/ha has been obtained in 8- and 5-fields rotations with the use of moldboard plowing. The lowest yields of sunflower seeds were in short-rotation crop rotations with a sunflower saturation of 50% in the structure of sown areas and permanent cultivation and amounted to: moldboard plowing-1.75-2.21 t/ha, disk tillage-1.57-2.01 t/ha, and no-tillage-1.49-1.95 t/ha. Given the urgency of supplying the global market with sunflower oil, in the future it is necessary to increase the concentration of sunflower in the structure of sown areas to 30-40% through the system of basic tillage, selection of resistant hybrids, and use of herbicides. Preview

The Hetao irrigation region is located in Inner Mongolia, China, within a dry and semi-dry region. This region suffers from poor agricultural productivity and environmental damage due to the presence of saline soil. To explore the growth of salty lands using a more environmentally friendly method, this research employed three eco-conscious amendments to improve the soil. These include flue gas desulfurization gypsum (S), humic acid (H), and biochar (C). During a two-year study, the amendments were utilized to enhance the soil quality for planting sunflowers. Humic acid was used prior to every seedling season, whereas the remaining two substances were only used once. These additions increased the soil's water-holding capacity, reduced soil salinity during sunflower growth, and improved the macroaggregate proportion. The most effective treatment for decreasing the soil's salt content after the seedling stage was the application of humic acid (0.6 t ha(-1)). Biochar (15 t ha(-1)) decreased the soil's bulk density (from 1.49 to 1.34 g cm(-3)) and mostly increased the sunflower seed yield up to 3133-3964 kg ha(-1). Humic acid addition significantly increased the aggregate (>0.25 mm) content up to 27.88% after the experiment, but it led to a lower seed yield (2607-3686 kg ha(-1)). In 2019, the temperature was lower compared to 2018, which may have led to a reduction in the yield. However, these three amendments could potentially increase yields by more than conventional methods. These three environmentally friendly amendments are useful for improving saline soil and increasing yields. More studies are required to understand their impacts on larger areas and over extended periods.

Sunflower is an ideal crop for phytoremediation of cadmium-contaminated farmland, as it brings economic benefits while conducting soil remediation. Due to industrial emissions and car exhaust, Cd contaminated areas are often accompanied by acid rain. However, the impact of acid rain on the Cd remediation capacity of sun-flowers and its potential influencing factors are unclear. An experiment was manipulated to elucidate the effects of Cd concentration (0,10,50,100 mu mol/L) and acid rain (pH 4.0) on the phytoremediation ability of sunflowers, in which the properties of them were explored. The results indicated that Cd stress is the main factor affecting the growth of sunflowers. Without AR, Cd treatment decreased sunflower biomass by 67.5-85.6%. Under AR, Cd treatment decreased sunflower biomass 53.9-86.4%. Compared without AR, the relative chlorophyll content with AR increased by 22.3-23.1%, while the YII with AR decreased by 6.5-20.0%. There was an interaction between acid rain and Cd stress on antioxidant enzyme activity. With AR, CAT activity at 0 mu mol/L Cd treatment increased by 25.6%, compared without AR. Whether there is acid rain or not, the POD and SOD activities were increased at 10, 50 mu mol/L Cd treatment, but they were decreased at 100 mu mol/L Cd treatment. Among them, acid rain exacerbated the impact of POD activity (decreased by 31.4%) at 100 mu mol/L Cd treatment and SOD activity (decreased by 15.1%) at 50 mu mol/L Cd treatment, compared without AR. In this experiment, the phytoremediation capacity of sunflowers mainly depended on the concentration of Ca in the leaves and their antioxidant capacity. Acid rain enhanced 77.5% the total Cd accumulation at 10 mu mol/L Cd treatment, compared without AR. Acid rain exacerbated the damage of Cd to the chloroplast structure of sunflowers, and reduced the accumulation of starch particles. The study findings may be useful for improving the phytoremediation of Cd-contaminated soil.