Iranian Journal of Seed Research

Extended Abstract
Introduction: Seed germination and seedling emergence depend on the genetics of plant species and are also influenced by environmental factors. Genetics and nutritional status of the maternal plant, maturity stage at a time of harvest, and environmental factors such as temperature, salinity, drought, and soil fertility influence seed germination. Seed vigor as the main parameter of seed quality decreases due to accelerated aging and storage. The objective of this study was to evaluate the response of accelerated aged Chia seed to different levels of salinity stress.
Material and Methods: Two-way factorial experiment with experimental factors, including five levels of seed accelerated aging durations (0, 24, 48, 72, 96 h) and six levels of salinity stress (0, 50, 100, 150, 200, and 250 mM) was arranged based on a complete randomized block design with three replications. The experiment was conducted at seed technology laboratory Khuzestan Agricultural Sciences and Natural Resources, University of Khuzestan, in 2019.
Results: Results of analysis of variance revealed that the effect of seed accelerating aging, salinity stress, and interaction effects of both factors on all measured germination traits were significant (p<0.01). The best pattern of seed germination was evaluated using three-parameter sigmoid models (logistic, Gompertz, and sigmoidal) and two polynomial models (quadratic and cubic), then the performance of all models was compared using (R²_adj), root square of the mean (RMSE) and corrected Akaike index (AICc). Results showed that at accelerated aging duration, models' performance to describe Chia seed germination response varied at different levels of salinity stress. At no aging and 72h of accelerated aging treatments, the sigmoidal model exhibited the best fit on final seed germination, whereas for the other levels of accelerated aging, Gompertz exhibited the best fit. Based on the output of the sigmoidal model, for no aging and 72 hours of accelerated aging, 50% of seed germination was declined at 171.7 and 76.9 mM, respectively, and based on the results of the Gompertz model, after 24 and 48 h of accelerated aging, seed germination declined to 50% at 163.8 and 129.6 mM. Results obtained from fitting polynomial models on seed germination showed that the cubic model provides reasonable descriptions for studied traits such as seed vigor.
Conclusion: Chia seed germination was sensitive to salinity and accelerated aging treatments. At no aging condition, Chia seeds tolerate salinity stress up to 200 mM and were able to germinate. By increasing aging durations, seed germination declined dramatically at all salinity levels and after 96 hours of aging, there was no seed germination at 150 mM.

 
Highlights:
1- The best nonlinear model to study accelerated Chia seed response to salinity stress was selected using the model selection criterion.
2- Chia seed germination threshold to salinity stress was determined for not- aged and aged seeds.

Objective: This study was conducted to investigate the effect of seed priming, sulfur application, and a biofertilizer containing Thiobacillus on seed yield and the fatty acid composition of sesame. Due to the importance of sesame as a valuable oilseed crop, evaluating the combined role of nutritional and biological management in improving both quantitative and qualitative traits of the crop holds significant importance.
Method: A field experiment was conducted during the 2023–2024 growing season in Fasa County, Fars Province, Iran, as a factorial arrangement in a randomized complete block design with three replications. Treatments included four seed priming methods (no prime, hydropriming, calcium chloride at 2.5% and 5%), four levels of sulfur application (0, 100, 200, and 300 kg ha^-1), and three levels of Thiobacillus inoculation (0, 2, and 4 kg ha^-1). Sesame cultivar ‘Darab 2’ was sown at a density of 40 plants m^-2. Thousand-seed weight, dry matter and seed yield were measured. Oil quality was evaluated through fatty acid methyl ester analysis using gas chromatography according to ISIRI and AOAC standards.
Results: Seed priming, sulfur application, and Thiobacillus biofertilization significantly affected all the studied traits. Both two-way and three-way interactions were significant at 1% and 5% levels. The highest plant dry weight (23,580 kg ha^-1) was observed in the treatment of hydro-priming combined with 300 kg ha^-1 sulfur. Additionally, the highest thousand seed weight (5.33 g) and seed yield (2610 kg ha^-1) were recorded in the treatment of hydro-priming combined with 300 kg ha^-1 sulfur and 4 kg ha^-1 Thiobacillus. The highest oil percentage (52.2%) and protein content (25.10%) were obtained in the treatment of 5% calcium chloride priming combined with 300 kg ha^-1 sulfur and 4 kg ha^-1 Thiobacillus. The fatty acid analysis revealed that integrated treatments increased the content of unsaturated fatty acids (linoleic, oleic, alpha-linolenic) while decreasing saturated fatty acids (palmitic and stearic).
Conclusions: The integrated use of seed priming (especially 5% calcium chloride or hydropriming), high-dose sulfur, and Thiobacillus inoculation significantly improved sesame seed yield, and oil quality. These practices enhanced nutrient uptake, stimulated microbial activity, and promoted biosynthesis of health-beneficial fatty acids.

Highlights

• Seed priming, sulfur application, and Thiobacillus inoculation significantly increased sesame seed yield.
• Combined treatments improved seed oil quality by increasing unsaturated fatty acids and reducing saturated ones.