Haniyeh Saadat, Mohammad Sedghi,
Volume 11, Issue 2 (3-2025)
Abstract
Extended abstract
Introduction: Salinity stress leads to the excessive production of reactive oxygen species, which at high levels can cause oxidative damage, disrupt membrane lipid functions, inactivate enzymes, and hinder metabolic activities in plants. Salinity affects seedling growth through osmotic stress, ionic toxicity, deficient absorption of essential nutrients and water, production of free radicals, destruction of the cell membrane, and reduced cell division. Utilizing pretreatment methods serves as a simple approach to mitigate the adverse effects of environmental stress. Seed pretreatment induces biochemical changes, such as the activation of enzymes involved in cellular metabolism, inhibition of metabolism, and improved water absorption, thereby aiding the germination process. This study aims to assess the impact of pretreatment on germination characteristics, activity of certain hydrolytic enzymes, and the glyoxylate cycle in marigold seedlings under salinity stress.
Materials and Methods: A factorial experiment was conducted based on a completely randomized design with three replications at the University of Mohaghegh Ardabili in 2023. Experimental treatments included four salinity levels (0, 50, 100, and 150 mM sodium chloride) and four pretreatment methods (control with distilled water, pretreatment with salicylic acid at 100 mg/L, gibberellin at 20 mg/L, and chitosan at 0.8% w/v, dissolved in 1% acetic acid).
Results: The findings indicated that salinity reduced germination percentage, mean daily germination, petiole length, and seedling dry weight. However, pretreatment with salicylic acid, gibberellin, and particularly chitosan significantly improved these parameters. The germination coefficient, radicle length, and seedling fresh weight in chitosan-pretreated groups without salinity were approximately 75%, 68%, and 34% higher compared to the control (distilled water) and 150 mM salinity treatments, respectively. Additionally, the activities of amylase, protease, and malate synthase in chitosan-pretreated groups without salinity increased by approximately 82%, 46%, and 70%, respectively, compared with the control and 150 mM salinity.
Conclusions: The results of this research demonstrate that seed pretreatment using salicylic acid, gibberellin, and especially chitosan is an effective strategy for enhancing germination indices and the activity of certain hydrolytic enzymes and the glyoxylate cycle, thereby alleviating the detrimental effects of salinity on marigold seedlings and promoting their growth.
Highlights:
- Seed pretreatment with salicylic acid, gibberellin, and especially chitosan significantly improved germination indices of marigold seeds under salinity conditions.
- This pretreatment enhanced the enzymatic activity of amylase, protease, and malate synthase.
- Chitosan pretreatment exhibited superior effects on germination indices and biochemical characteristics.
Aidin Hamidi, Bita Oskuoei, Ali Shayanfar,
Volume 11, Issue 2 (3-2025)
Abstract
Extended abstract
Introduction: Salicornia is a halophyte plant which cultivation is important for reclamation of saline soils and producing fodder. Seed germination has always been of interest to plant ecologists due to its key role in plant population establishment. Also, due to the importance of this process in seed certification, this phenomenon is of interest to control and seed certification experts. Temperature, access to sufficient humidity, and the presence of light in light-sensitive species for seed germination are considered to be the most important natural factors for seed germination. Additionally, the time required for germination and sufficient early seedling growth are important to determine the potential seed germination. Therefore, determining the temperature, the need or lack of light, as well as the time required for germination and the suitable substrate for planting seeds, are of great importance in the process of seed certification laboratory tests. This experiment was conducted to investigate the optimal conditions of temperature, light, duration, and substrate for seed germination of three Salicornia species.
Materials and Methods: A preliminary study was conducted to determine the light requirements, duration, and suitable substrate for the standard germination test of Salicornia persica, S. persepolitana, and S. bigelovi, seeds. Since no difference was observed in the percentage of seedlings emerging in light and darkness (seeds of the studied Salicornia species germinated under light and dark conditions) and maximum seed germination was achieved within 7 and 12 days in the substrate between germination paper (BP) and top of paper (TP), at constant temperatures of 20°C and 25 °C and alternating temperatures of 20-25 °C (8-16 hours/day-night), the main experiment was carried out under these conditions.
Results: The results showed that the seeds of S. bigelovi species had the highest percentage of normal seedlings at 25 °C constant temperature for 7 days in the top-of-paper (TP) substrate. Also, the seeds of S. persica had the highest percentage of normal seedlings at 20-25 °C alternating temperature for 7 days in the top-of-paper (TP) substrate. S. persepolitana seeds at 25 °C constant temperature for 7 days on the top of paper (TP) substrate had the highest percentage of normal seedlings. S. persica, S. bigelovi, and S. persepolitana seeds had a higher percentage of normal seedlings in both germination durations and temperatures, respectively.
Conclusions: The results of the research showed that the seeds of the studied Salicornia species did not require light for germination. Also, the studied Salicornia species in the research had significant differences in terms of temperature, duration, and optimal substrate for the standard germination test. So that the optimal temperature for germination of S. persica seeds was alternative temperature and the optimal temperature for germination of S. bigelovii and S. perspolitana seeds were constant temperature. The constant temperature for germination of S. bigelovii species seeds was higher than the constant temperature for germination of S. perspolitana seeds. Also, the top of paper (TP) substrate was suitable for the standard germination test of all three species.
Highlights:
- Light was not necessary for the studied Salicornia species seeds' germination.
- The germination response of the seeds of the studied Salicornia species to the optimum germination temperature and duration varied.
- The studied Salicornia species did not differ significantly in terms of suitable growing medium for seed germination.
Mohammad Reza Mirzaei,
Volume 11, Issue 2 (3-2025)
Abstract
Extended abstract
Introduction: One of the most critical factors in achieving optimal sugar beet root performance at harvest time is appropriate plant density, which depends on high seedling emergence rates and subsequent seedling growth facilitated by using seeds with desirable vigor. Various seedling traits are key determinants of seed vigor and quality in sugar beet.
Materials and Methods: To evaluate germination vigor and seedling growth under laboratory conditions, traits such as maximum germination, hypocotyl length, radicle length, and fresh and dry seedling weights were measured in ten single-cross hybrids derived from crosses between ten male-sterile maternal lines and one paternal line, produced in three different seed production environments. Additionally, correlations between these traits and seedling emergence traits in greenhouse conditions, as well as seed chemical properties, were examined.
Results: The results indicated that seedling traits, which reflect seed vigor, are primarily influenced by two factors: the sugar beet seed production environment and genetics. Analysis of correlation coefficients between laboratory seedling traits and greenhouse seedling emergence traits, as well as seed electrical conductivity, revealed that genotypes with low electrical conductivity and low total soluble solids in the seed pericarp germinated faster and emerged more quickly under greenhouse conditions. Thus, high electrical conductivity in the sugar beet seed pericarp was associated with low seed vigor. Furthermore, significant correlations were observed between seedling emergence speed and mean emergence time in the greenhouse and hypocotyl length in the laboratory, showing positive (+0.91**) and negative (−0.82**) relationships, respectively. Therefore, genotypes with longer hypocotyls in the laboratory exhibited faster seedling emergence in the greenhouse. Consequently, single-cross hybrids such as MS KWS × OT 231, which had greater radicle length (8.49 cm), seedling length (14.66 cm), and radicle-to-hypocotyl ratio (1.37) under laboratory conditions, also showed a significant increase in mean dry shoot weight (1.89 mg) and seedling vigor weight index (8.26) in the greenhouse compared to other single-cross hybrid.
Conclusions: Therefore, it appears that seedling traits and chemical characteristics of sugar beet seeds can be used to predict seedling emergence performance in the greenhouse and potentially in the field. However, for validation and precise assessment, it is recommended that this experiment be conducted under field conditions.
Highlights:
- Differences were observed among genotypes in terms of seed characteristics and the maternal environment in which the seeds were produced.
- Poor sugar beet seed vigor can reduce both the potential emergence percentage and the speed and uniformity of seedling emergence compared to high-vigor seeds.
- Seedling traits in sugar beet are indicators of seed vigor and are influenced by both the seed production environment and genetics.