The seed pretreatment with salicylic acid has an important role in improving seed germination and increasing plant resistance to environmental stresses. This study was performed to investigate the effect of salicylic acid on seed germination of Milk thistle under salinity and drought stress. A factorial experiment was conducted in a completely randomized design with three replications. Treatments consisted of 4 levels of salicylic acid (0, 100, 200 and 300 mg/l) and four levels of each drought and salinity stress (0, - 4, - 6, - 8 Bar). The results showed an interaction effect between pretreatment with salicylic acid and drought and salinity stresses was significant at the 1 % level. On high salinity level (-8 Bar), seed germination percentage and rate, root and shoot length, fresh and seedling dry weight reduced significantly. The short length, fresh weight and percent germination reduced in all three levels of drought stress. Pretreatment with salicylic acid (200 and 300 mg/L) significantly reduce the harmful effects of drought and salinity stress (-6 and -8 Bar) on germination and seedling growth parameters of Milk thistle. The results of this experiment showed that seed treatment with salicylic acid can lead to increase the resistance of Milk thistle to salinity and drought stress in seed germination.
Objective: Given the extent of saline lands worldwide, this study aimed to evaluate the tolerance of Persian Camelthorn (Alhagi camelorum) to salinity stress during germination and early growth stages following seed hardness removal, to promote its cultivation as a forage plant for livestock.
Method: A factorial experiment was conducted in a completely randomized design with four replications in 2023 at the Seed Analysis Laboratory of the Seed and Plant Certification and Registration Institute. Factors included: (1) seed population (Gorgan and Mashhad), (2) salinity levels (0, 100, and 200 mM NaCl), and (3) seed hardness removal treatments (immersion in 100°C water for 1 minute and concentrated sulfuric acid for 35 minutes). Germination percentage, mean daily germination time, seedling vigor index, stem length, and superoxide dismutase (SOD) activity were measured.
Results: Salinity stress significantly reduced germination percentage, as well as stem length. Germination indices differed significantly between control and 200 mM treatments. Increasing salinity decreased mean daily germination in all treatments. The highest salinity level reduced stem length by 65% and 44% in the Mashhad population, and 71% and 64% in the Gorgan population, compared to control, respectively. Treatment with 100°C water and 200 mM salinity increased SOD activity by 56.9% in the Mashhad population and 45.4% in the Gorgan population. Sulfuric acid treatment with 200 mM salinity increased SOD activity by 25.4% and 13.0% in Mashhad and Gorgan populations, respectively.
Conclusions: Sulfuric acid treatment for 35 minutes significantly increased germination percentage in both populations compared to 100°C water treatment. The greater increase in SOD activity in the Mashhad population suggests higher salinity tolerance, making it a suitable candidate for cultivation in saline lands.
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