Document Type : Research Paper
Authors
1 , Department of Agronomy Sciences and Plant Breeding, Faculty of Agricultural Technology, University of Tehran, Pakdasht, Iran
2 Associate Professor, Department of Agronomy and Plant Breeding Sciences, College of Aburaihan, University of Tehran, Pakdasht, Iran
3 Department of Agronomy Sciences and Plant Breeding, College of Aburaihan, University of Tehran, Pakdasht, Iran
Abstract
Objective: Drought and salinity are among the most significant environmental factors adversely affecting crop performance and leading to reduced agricultural productivity worldwide. Guizotia abyssinica (L.f.) Cass. Commonly known as Niger seed, is an oilseed forage plant from the Asteraceae family that has attracted attention due to its short growth cycle, unique fatty acid composition, and resistance to drought and salinity. Accordingly, the present study aimed to investigate the ecophysiological responses of blackseed germination under drought and salinity stress conditions. Research Method: Two separate experiments were conducted in a completely randomized design with four replications under controlled laboratory conditions. In the first experiment, drought stress was induced using polyethylene glycol 6000 (PEG-6000) at six levels of osmotic potential: 0 (control), –0.2, –0.4, –0.6, –0.8, and –1 MPa. In the second experiment, salinity stress was applied using sodium chloride (NaCl) at five concentrations: 0 (control), 50, 100, 150, and 200 mM. Measured traits included maximum germination percentage (Gmax), initial germination rate (R10), and the rate of reaching 50% germination (R50). The experiments were conducted in Petri dishes lined with filter paper moistened with the respective stress solutions. Temperature and photoperiod were maintained at 25°C and 12 hours of light, respectively, throughout the trials. Findings: Under drought stress, the highest germination percentage (95%) occurred at –0.2 MPa, while the lowest (6%) was observed at –1 MPa. The highest R10 value (6.5 seeds/day) was recorded in the control treatment and decreased to 0.04 seeds/day at –1 MPa. Regarding R50, the highest value was 1.3 seeds/day at 0 MPa, which dropped to zero under –1 MPa. In response to salinity stress, germination percentage significantly declined, with the highest value (98%) in the control and the lowest (58%) at 200 mM NaCl. R10 was highest under control conditions (8.1 seeds/day) and decreased to 0.44 seeds/day at 200 mM. Similarly, R50 declined from 1.62 seeds/day in the control to 0.09 seeds/day under 200 mM salinity. Conclusion: The results demonstrated that blackseed is sensitive to high levels of drought and salinity stress during early growth stages. However, under mild to moderate stress conditions, reductions in germination rate and percentage were not statistically significant. These findings suggest that blackseed may serve as a viable crop option in regions with limited water resources and moderately saline soils. Further studies focusing on later growth stages and field conditions are recommended to confirm these laboratory findings. Additionally, exploring genetic variability among different blackseed genotypes could help identify more stress-tolerant cultivars.
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