Effect of Seed Priming with ZnSO 4 and FeSO 4 on Dormancy Break Optimization and Germination Traits of Shallot ( Allium hirtifolium )

Introduction: In addition to dormancy, seeds of Allium hirtifolium have a weak emergence in the field. Among methods for improving the efficiency and emergence of seeds, nutritional priming can be considered for its performance on weak seeds. The presence of micronutrients is one of the factors that may affect the efficiency of the seeds. Therefore, the aim of this study was to investigate the effect of priming with nutrients on optimization of dormancy status, germination, and enhancement of shallot seeds for its conservational, restoration and domestication programs. Materials and Methods: In order to study effects of nutrients on germination and emergence of Allium hirtifolium , a CRD factorial experiment was conducted with four replications at Seed Science and Technology Lab of Shahrekord University in 2015. Two dormancy breaking treatments (sulfuric acid and sulfuric acid + gibberellic acid) as the first factor and nine nutrition treatments including four levels of ZnSO 4 (5, 10, 50 and 100 mM) and four levels of FeSO 4 (0.5, 1, 1.5 and 2%) versus control were compared on shallot seeds. Results: The results showed that dormancy breaking treatments, nutrient pretreatment of seeds and their interaction had significant effects on germination percentage, germination rate, time to reach l0% and 50% germination, germination uniformity, seedling length and vigor index I at 1% probability level. Sulfuric acid and FeSO 4 1% increased germination versus control. Application of gibberellic acid affected the behavior of iron but did not indicate significant effects for zinc. The concentration of 5 mM ZnSO 4 increased the rate of germination, compared with the control but decreased with higher concentrations. The gibberellic acid did not show any sharp effects on germination rate. Time to reach 50% germination was also affected by FeSO 4 0.5% and 1% and lower levels of zinc. Application of gibberellic acid did not show any significant impact on the germination time reduction, compared with control and increased T 50 in higher concentrations. Although germination traits were rarely affected by gibberellic acid, seedling length and vigor index were positively influenced with GA, and the highest seedling length was achieved at 0.5 and 1% of iron and gibberellic acid. Conclusion: Seed priming with nutrients can improve germination and plant vigur indices. Different concentrations of iron and zinc showed different impacts on the seeds, which showed interaction with dormancy breaking methods. Although application of gibberellic acid did not have an effective role in increasing germination rate and reducing the time to reach 10% and 50% of germination, it enhanced seedling length and vigor index I, especially for iron.


Extended Abstract
Introduction: In addition to dormancy, seeds of Allium hirtifolium have a weak emergence in the field. Among methods for improving the efficiency and emergence of seeds, nutritional priming can be considered for its performance on weak seeds. The presence of micronutrients is one of the factors that may affect the efficiency of the seeds. Therefore, the aim of this study was to investigate the effect of priming with nutrients on optimization of dormancy status, germination, and enhancement of shallot seeds for its conservational, restoration and domestication programs.
Materials and Methods: In order to study effects of nutrients on germination and emergence of Allium hirtifolium, a CRD factorial experiment was conducted with four replications at Seed Science and Technology Lab of Shahrekord University in 2015. Two dormancy breaking treatments (sulfuric acid and sulfuric acid + gibberellic acid) as the first factor and nine nutrition treatments including four levels of ZnSO 4 (5, 10, 50 and 100 mM) and four levels of FeSO 4 (0.5, 1, 1.5 and 2%) versus control were compared on shallot seeds.

Results:
The results showed that dormancy breaking treatments, nutrient pretreatment of seeds and their interaction had significant effects on germination percentage, germination rate, time to reach l0% and 50% germination, germination uniformity, seedling length and vigor index I at 1% probability level. Sulfuric acid and FeSO 4 1% increased germination versus control. Application of gibberellic acid affected the behavior of iron but did not indicate significant effects for zinc. The concentration of 5 mM ZnSO 4 increased the rate of germination, compared with the control but decreased with higher concentrations. The gibberellic acid did not show any sharp effects on germination rate. Time to reach 50% germination was also affected by FeSO 4 0.5% and 1% and lower levels of zinc. Application of gibberellic acid did not show any significant impact on the germination time reduction, compared with control and increased T 50 in higher concentrations. Although germination traits were rarely affected by gibberellic acid, seedling length and vigor index were positively influenced with GA, and the highest seedling length was achieved at 0.5 and 1% of iron and gibberellic acid.
Conclusion: Seed priming with nutrients can improve germination and plant vigur indices. Different concentrations of iron and zinc showed different impacts on the seeds, which showed interaction with dormancy breaking methods. Although application of gibberellic acid did not have an effective role in increasing germination rate and reducing the time to reach 10% and 50% of germination, it enhanced seedling length and vigor index I, especially for iron.

Keywords: Nutrients, Emergence, Gibberellic acid, Vigor Index, Sulfuric acid
Highlights: 1-Addition of iron and zinc sulfate to shallot seeds whose dormancy was broken with sulfuric acid caused higher germination rate of 25.54%, compared with the control. 2-Gibberellin compensated for zinc effect in germination and was able to replace it, but had a slight synergic effect with iron sulfate. 3-Although gibberellin application did not affect germination traits, the seedling length and vigor index showed a positive response to it.