Mitigation of Adverse Effects of Drought and Low Temperature Stresses by Seed Priming in Sunflower During Germination

The study aimed to determine the effects of seed priming on germination and seedling development in sunflower exposed to drought and low temperature stresses. The primed seeds (KNO3, and hydration) of Sanbro MR were evaluated at low temperatures of 15 °C and 18 °C under drought conditions induced by PEG-6000 at the water potentials of 0 (distilled water), −0.2, −0.4, and −0.6 MPa. Unprimed seeds were used as a control and a temperature of 25 °C was considered optimal. The results showed that germination was negatively affected by both stress factors, although this varies according to priming applications. Drought inhibited germination and seedling growth more than low temperatures. Seedling growth was also more adversely affected by low temperatures compared to germination. Under low temperatures, there was a 63% decrease in shoot length and a 59% decrease in root length. Drought stress resulted in an 85% reduction in shoot length, while roots were reduced by 65%. The primed seeds with KNO3 gave the highest germination percentage at -6 MPa at 15 °C. However, hydration showed superiority under different drought levels at 18 °C and 25 °C. It was concluded that hydrated seeds should be used for increased germination and seedling growth under low temperatures and drought stresses in sunflower.