To evaluate the effects of different treatments on seed dormancy breaking of Notobasis, two separate experiments were conducted at Agricultural Sciences and Natural Resources University of Khuzestan, in 2017 with three replications. The first experiment included nine physical, mechanical and chemical treatments (control, surface scarification, intense scarification, one and two weeks of chilling at 4°C, soaking into hot water for two hours without scarification , soaking in 25°C distilled water for two hours with scarification  and acid treatment for six and 12 minutes) based on completely randomized designs (CRD). The Second experiment was hormone priming arranged as a factorial experiment based on completely randomized design with gibberellin concentrations (0, 200, 400, 600, 800 and 1000 ppm) and priming duration (12 and 24 hour) as the treatments. The highest seed germination (40%) obtained from 12 minutes of acid treatment. Results showed that seed germination reached to 100% after priming seeds with GA3 concentrations for 12 hours. However, increase the priming durations to 24 hours, significantly declined seed germination to 47% in 200 and 400 ppm of GA3 concentrations. The Increase of GA3 concentrations in 12 hours led to a linear reduction of T50 from 31 hours in 200 ppm to 19 hours in 1000 ppm). In 24 hours of priming treatment, T50 followed a Gaussian function and the highest T50 (92 hours) was obtained from 600 ppm. It is recommended to immerse the seeds for 12 minutes in sulfuric acid and prime with 400 ppm GA3 acid for 12 hours to break dormancy and increase the vigor index.

Freshly harvested seeds of Rhubarb exhibited a high degree of dormancy when germination has been studied in different temperatures in distilled water. In the present paper, different treatments including moist - chilling, immersing in NaOCl, acid scarification, surgical procedure, and treatment by CaCl2 and KNO3 were performed to determine the most effective method for removing dormancy in Rhubarb (Rheum ribes L.). When seed coats (pericarp + testa) were completely removed, the root and hypocotyls of excised embryo from dormant seeds did not elongate. This indicates that dormancy is imposed by the embryo and those inhibitors in seed embryo may be responsible for the dormancy. Germination was observed only in CaCl2 and KNO3 treatments. Optimum temperature for germination was 10oC and dormancy was partially removed when seeds were germinated in different concentrations of CaCl2. Moreover, CaCl2 solutions promoted germination more than KNO3.

Arctium lappa is an important medical plant with seed dormancy problem. A study was carried out to investigate the effects of seed dormancy breaking treatments on Arctium lappa germination. Treatments were arranged in a completely randomized design (CRD) with five replication. The highest germination percentage was recorded in seeds treated with GA3 (500 ppm) +  H2SO4 75% (86%), GA3 (500 ppm) + hot water 70 0C (87%) and GA3 (500 ppm) + hot water 90 0C (84%). Seed scarification with hot water were better than H2SO4 because H2SO4  increased  abnormal seedling percentage. Highest abnormal seedling showed in H2SO4 75%, GA3 (500 ppm) + H2SO4 75% and KNO3 (1%) +  H2SO4 75 % treatments (11.7%, 11.3% and 10.9% respectively). Seed treatment with KNO3 and GA3 increas α- amylase activity and Auxin concentration in Arctium lappa seedlings and decreased Abscisic Acid content in seedlings. The maximum seedling vigor index obtaines in seeds treated with GA3 (500 ppm) + hot water 70 0C . Results indicated Arctium lappa seeds scarification with hot water 70 0C (10 min) followed by socking in GA3 (500 ppm) for 12 hour was most effective treatment for seed dormancy breaking and improved seedling growth.

Rubia tinctourum is a valuable medicinal plant that it is from iran and it has been used in pharmaceutical industries and staining industrial. seeds of this species have germination problems. In order to breaking seed dormancy, this experiment has been conducted in Tehran University on the base of Completely Randomized Design in four replications. The treatments of this experiment were as: Continued light, gibberellic acid (500 ppm), stratification (4°C inthree duration of 2, 4 and 6 weeks) and scarification by sulfuric acid 98% (10,15 and 20 min), sand paper and hot water. The highest germination was obtained for.15 min scarification by sulfuric acid (90%). However the effect of scarification with hot water and sand paper were the same as acid sulfuric effect. The results showed that exposing the seeds under continued light and gibberlic acid had no significant effect on seed germination. Exept generation percent, Root length, shoot length, time of germination and seedling fresh weight were studded. Seed scarification by acid sulfuric at 20 min decreased root length, shoot length and seedling fresh weight. Seed scarification by hot water (90°C) in 10 min only decrease root length and seedling fresh weight. It was concluded using sand paper was the best using for breaking seed dormancy of madder.

Wild cherry (Prunus avium) is a native fast growing broadleaved tree in Hyrcanean forests producing valuable wood. Prunus seeds have long dormancy and there is variety of methods for breaking dormancy of its seed. This study was conducted in order to overcoming dormancy and germination ofPrunus seed. For this purpose, seeds were collected from Aliabad Katool region in forests of Golestsan province, north of Iran. The seeds with mosocarp, without mesocarp and without endocarp were subjected to warm stratification (4 weeks, 20oC) followed by cold stratification (10 weeks, 5oC). Results showed that mesocarp and endocarp had significant effects on overcoming seed dormancy and germination characteristics. Germination percent, germination speed and germination value in seeds stratified without endocarp were greater than those in seeds stratified with mesocarp and without mesocarp. The results revealed that the seeds without endocarp were the most favorable treatment to break dormancy and to improve germination characteristics inPrunus avium seeds.

In order to investigate the environmental factors including temperature, moisture, and plant hormones on dormancy breaking of seeds ofXanthium strumarium L. a number of experiments were conducted.X. strumarium seeds were dormant soon after being harvested. Seed germination of cocklebur increased through a combination of cooling, temperature fluctuations following ripening. Most seed germination (82.5%) occurred in buried seeds in 5-7 cm depths of soil in natural conditions for 4 months in addition to keeping them in cool room temperature (5±2) for 3 months, followed by retaining the seeds on the surface of soil (0 cm) in field conditions for 6 months. A combination of cold (5±2NC for 2 months) and GA3 resulted in a slight significant increase in seed germination of X. strumarium L. (p<0.05). Washing of seeds, immersing them in hot water and scarification (crust split of seeds) had no significant effect on seed germination. Sulfuric acid (%98), scarification and Ethephon did not show any effect on seed germination (p<0.05). In all the treatments, between two seeds treated through burring only the larger seeds germinated while none of the treatments resulted in the germination of smaller seeds. Based upon on the experimental treatments in this study, it can be said that dormancy of X. strumarium L. seeds is a physical as well as a physiological dormancy phenomenon.