Iranian Journal of Seed Research

Micronutrients play a great role in the production of high quality seeds, especially in terms of germination. Therefore, providing seeds with sufficient amounts of these is an important consideration in seed production. The present study was conducted as two separate experiments in the Seed Laboratory of Yasouj University in 2015. In the first experiment, the sesame seeds (cv. Darab 1) obtained from a previous split plot experiment based on RCBD, consisting of three irrigation levels (after 75, 110 and 145 mm evaporation from class A pan) and four foliar applications comprising water, zinc sulfate, boric acid and mixture of zinc sulfate and boric acid, were investigated in germination experiments in the minimum temperature (i.e., 15°C). The second experiment was a factorial based on RCD with three replications. The first factor in the eight levels included seeds soaked in water, ZnSo4, H3Bo3 and ZnSo4 + H3Bo3 and seeds with high contents of Zn (159 m Kg^-1), B (15.3 m Kg^-1) and Zn (139.5 m Kg^-1)+ B (14 m Kg^-1) and dry see as the control. The second factor was accelerated aging periods at three levels (0, 2 and 4 days) at 45°c and RH = 100%. The results showed that with a delay in irrigation time, compared with water foliar application, foliar application of micronutrients (Zn, B, Zn+B), and significantly increased germination traits. The results also suggested that, compared with seeds soaked in nutrients, seeds with high Zn and B contents significantly increased germination indices and antioxidant (catalase and peroxidase) activities, especially under accelerated seed aging.

Extended Abstract
Introduction: Schrophularia striata is one of the medicinal plants of the Scrophulariaceae family and contains phenolic compounds. Locals have traditionally used this herbal medicine to treat infections caused by wounds, gastrointestinal diseases, and eye diseases. Due to excessive consumption by indigenous people and climate change, especially increasing temperature, the cold required to eliminate seed dormancy is not presently available and its germination and growth has decreased. Therefore, this plant is at the risk of extinction. Since this plant is propagated in natural habitats through seed and due to deep seed dormancy, evaluation of different seed dormancy methods is necessary for conservation and domestication of this species. In this study, suitable methods to eliminate seed dormancy of this plant using chilling and gibberellic acid treatments were studied on the seeds collected from different habitats of Ilam province.
Materials and Methods: To investigate the effect of using chilling and gibberellic acid on Schrophularia striata dormancy, a split plot factorial experiment based on completely randomized design with four replications was conducted at the seed laboratory of Yasouj University in 2018. The first factor included the duration of moist chilling period (0, 4, 8, 12 and 16 weeks), the second factor included gibberellic acid (0, 300 and 600 mg/L) and the third factor included five habitats (Ilam, Ivan, Mehran, Abadan and Dehloran).
Results: The results showed that the 16-week Chilling and zero gibberellic acid treatments had the highest germination percentage in all habitats, as the percentage of germination in Mehran, Ivan, Ilam, Abadan and Dehloran habitats was 66, 50, 36, 30 and 25%, respectively. Also, the highest germination rate was observed in all habitats at 16 weeks chilling and zero mg/L gibberellic acid concentration. The highest germination uniformity was obtained at 16 and 12 weeks of chilling.
Conclusions: Chilling period duration was effective on germination percentage and rate and with increasing chilling period, germination percentage and rate increased. This indicates that the seeds studied had some degree of physiological dormancy, and the seed of higher altitude habitats required longer chilling periods than those of the lower ones for germination. Also, according to the results of this experiment, chilling periods above 16 weeks should be used to increase germination percentage.

Highlights:
1- Chilling period duration in the presence of gibberellic acid was the most important factor for the elimination of Schrophularia striata seed Dormancy and increased germination.
2- With increasing altitude and in the same chilling period duration, habitats with lower altitude had higher germination percentage and rate