The effect of Seed Priming with Hydrogen Sulfide on Germination and Biochemical Indicators of Drought Stress in Sunflower Seedlings

As globally the fourth largest oleaginous plant, sunflower (Helianthus annuus L.) is particularly vulnerable to water shortages during the germination phase. Various seed-priming techniques and agents have been proven to enhance germination and promote a uniform seedling growth, especially during the abiotic stress conditions. Since hydrogen sulfide (H2S) has been documented to be involved in plant metabolism, this study investigates its effects on the sunflower seeds’ vigor when germinating in the drought-stress conditions. The research was conducted under the controlled conditions using the Apolon hybrid seeds, developed by the Agricultural Institute in Osijek. This study’s objective was to determine a physiological role of H2S in seedlings grown from the seeds that had been previously primed in sodium hydrosulfide (NaHS) solutions, having germinated under the drought-stress conditions. The results imply that the sunflower seedlings are most sensitive to the osmotic stress during the initial germination phase, particularly in the first four days. An increase in the level of osmotic stress while rising the concentrations of PEG 6000 reduced the seed vigor of the tested hybrid. The most notable positive effects of seed priming with a hydrogen-sulfide donor were observed at the low (2.5% PEG) and moderate (5% PEG) levels of osmotic stress. This study’s results may provide future guidelines for the use of various H2S donors as a priming agent, aimed at an enhancement of drought resistance in early growth phases, which is crucial for the production of this strategically important oilseed faced by a significant climate change.