Introduction
Medicinal plants with a high level of antioxidant activity are of great importance due to their effect on a wide range of diseases such as diabetes, inflammatory diseases, Parkinson's, Alzheimer's, cardiovascular diseases, blood pressure and other diseases caused by oxidative stress. Therefore, studying medicinal plants and extracting and identifying chemical properties and effective compounds in medicinal plants emphasizes the necessity of learning and using medicinal plants. Iranian shallot plant with the scientific name Allium hirtifolium is a species of the onion family (Alliaceae) and is one of the largest genera of the monocot group. Shallot plant is an important horticultural product that has been known and used as a vegetable, spice and medicinal plant since ancient times due to its useful properties. In this genus, there are economically important species such as: onions, garlic, shallots, chives and leeks. Germination and sprouting are one of the most important phenological stages (life cycle) of the plant. Having enough information about the phenological cycle of the plant leads to better management of the different stages of this cycle, which determines the degree of success of agricultural systems. Seedling germination and growth in the early stages are strongly influenced and controlled by environmental factors, especially temperature, soil moisture and seed quality (germination and seedling strength) and internal factors (growth regulators) such as Gibberellin and Abscisic acid hormones.
In order to speed up the germination of seeds and eliminate seed dormancy so that germination can happen faster, there are different methods. One of these methods is mechanical or chemical scratching. The aim of this research is to present a precise and scientific description for the failure of Iranian shallot medicinal plant seed dormancy (Allium hirtifolium) and improvement in the acceleration of germination, considering the different characteristics in three populations of Iranian shallot seeds. Also, to increase the quality and accuracy in this research, a scanning electron microscope was also used to accurately determine the surface changes of the seeds before the acid-washing treatment with sulfuric acid and after the acid-washing treatment with sulfuric acid. In the previous research that has been carried out on Iranian shallot seeds, the simultaneous examination of different temperatures and different times of acid washing by sulfuric acid in a precise manner and with several populations that have different genotypes, as well as the use of Scanning Electron Microscopy (SEM) has not been done.
Materials and methods
The study was done to investigate the effect of different degrees of temperature, and different times of sulfuric acid for acid washing on the improvement of germination of three populations of Iranian shallot seeds (Allium hirtifolium). The effect of four different temperatures (5, 10, 15 and 20 degrees Celsius) inside the Germinator device and four different times of acid washing with sulfuric acid (0, 5, 10, 15 minutes) on germination and micromorphological characteristics of three populations of shallot plant (Feridon Shahr, Tiran and Khansar) was investigated. On the other hand, a scanning electron microscope (SEM) with different degrees of magnification was used for the effect of sulfuric acid treatment on the surface of the seed coat. The experiment was conducted as a factorial, in the form of a completely randomized design with four replications. At the end of the experiment, traits such as germination percentage, average germination time, germination speed, root length and shoot length were evaluated. Also, traits such as diameter, length, volume and weight of seeds in three populations of shallot were also analyzed statistically.
Conclusion and discussion
The results of electron microscopy showed that in all three populations of Iranian shallot seeds, the seed coat, after using the acid washing treatment with sulfuric acid for 15 minutes, underwent noticeable and significant changes compared to the control seeds. The surface of the seed is destroyed by sulfuric acid and the surface of the seed does not have its natural ornamentation and protrusions compared to the control. Also, the effect of temperature, duration of acid washing and seed population on germination percentage, germination speed, average germination duration, seedling root length and seedling length was significant at the 1% probability level (p≤0.01). The population of Fereydoun Shahr has the highest germination percentage (69.16 percent), germination speed 3.7 (number of seeds per day) and average duration of germination 9.64 (number of seeds per day) at a temperature of 5 degrees Celsius and acid washing time of 15 minutes. The maximum shoot length and root length were 19.7 and 8.81 (mm) in the Tiran population with a temperature of 20 degrees Celsius and a 15-minute acid washing time, and in the Khansar population with a temperature of 20 degrees Celsius and time of 5 minutes acid washing respectively. The results show that, according to the dormancy of the seeds and their need for cold, the best temperature for shallot seed germination is 5 degrees Celsius with 15 minutes of acid washing by sulfuric acid. Diversity in shallot plant populations has a significant effect on the performance of this plant in improving seed germination.
Acknowledge
We thank Ferdowsi University of Mashhad and the Isfahan University of Technology.
Keywords: shallot diversity (seed morphology), stratification, seed scarification, germination, scanning electron microscope (SEM) |
