Sari Agricultural Sciences and Natural Resources University
Abstract: (196 Views)
The purpose of the experiment was to investigate the role of melatonin in improving the morphological characteristics of marigold (Calendula officinalis L.) under salt stress. The present experiment was conducted as a factorial arrangement in a completely randomized design with three replications. Melatonin at three levels (zero, 100 and 150 µM) and salinity at four levels (zero, 30, 60 and 90 mM) were considered as the first and second factors, respectively. According to the obtained results, the highest plant height, the highest number of leaves and the longest root length were obtained in 150 μM melatonin without salt treatment. On the other hand, at 90 mM salinity and without the presence of melatonin, the lowest number of leaves and height were observed. Root fresh weight at different salinity levels showed a downward trend with increasing salinity concentration, so that the lowest root fresh weight was observed in 90 mM salt concentration without melatonin. Also, the root fresh weight increased with the increase in melatonin concentration. The highest leaf relative water content and leaf potassium percentage in melatonin was 150 micromolar, and with increasing salt concentration, leaf relative water content and potassium ion concentration decreased.The highest amount of soluble sugar was found in 60 mM salinity + 100 μM melatonin and proline in 60 mM salinity + 150 μM melatonin. According to the obtained results, melatonin pretreatment can be effective in improving the vegetative and physiological traits of marigold under salt water stress.
Keywords: Antioxidant, Potassium, Proline, Environmental stress, Biomass, Sodium
Background and Objective:
High NaCl levels, due to osmosis and ionization, can significantly diminish plant height, leaf area, and the fresh and dry weights of shoots and roots. Melatonin, a ubiquitous molecule produced in plants. Melatonin acts as a growth regulator similar to indole acetic acid (IAA), which promotes cell expansion and growth (Brugnoli and Lauteri, 1991, Meloni et al., 2003, Ye et al., 2016). Under NaCl stress, plants close the stomata to prevent water loss, and this can result in decreased stomatal conductance and photosynthesis activity. However, it has been shown that the application of melatonin makes the stress conditions bearable for plants and leads to the opening of stomata, which has been reported to improve the photosynthetic machinery in sunflower and citrus plants(Brugnoli and Lauteri, 1991, Meloni et al., 2003, Ye et al., 2016). The aim of the present study was to investigate the role of melatonin in marigold, in order to improve vegetative and physiological traits.
Methods: A factorial experiment in a completely randomized design with two factors and three replications was conducted in greenhouse conditions at Sari Agricultural Sciences and Natural Resources University. Melatonin at three levels (zero, 100 and 150 µM) and salinity at four levels (zero, 30, 60 and 90 mM) were considered as the first and second factors, respectively. The average day and night temperatures in the greenhouse were recorded as 25 and 17 °C, respectively, with a relative humidity of 75%. Marigold seedlings were sprayed three times every ten days. One week after the last melatonin treatment, irrigation with sodium chloride was applied every 7 days for 35 days. One week after the last application of sodium chloride, some traits such as plant height, number of leaves, flower diameter, root length root fresh and dry weight, relative leaf water content, soluble sugar, Proline, ion leakage, sodium and potassium were measured.
Results: The interaction between salinity and melatonin affected plant height, number of leaves; root length, root volume and root dry weight. The highest plant height (17 cm), the highest number of leaves (34) and the longest root length (18.83 cm) were obtained in the 150 μM melatonin treatment without salt (Table 2). The highest root volume and dry weight were observed in 100 μM melatonin treatment without salt. The highest relative leaf water content and potassium percentage were obtained in 150 μM melatonin treatment. The highest amount of soluble sugar and Proline were created in sodium chloride 60 mM + melatonin 100 μM and sodium chloride 60 mM + melatonin 150 μM, respectively. At 30 mM salinity without the use of melatonin, the lowest Proline was recorded. The highest amount of sodium was recorded at 60 mM sodium chloride. At the concentration of 150 μM melatonin, the amount of sodium in the leaf decreased. With the increase of salt concentration, ion leakage increased and it was the highest at 90 mM salinity. At the concentration of 150 μM melatonin compared to the control treatment, a decrease in ion leakage was observed.
Conclusions: The results of this study showed that salinity stress reduced the vegetative traits of marigolds, but the use of melatonin reduced the damage under salinity stress conditions. Melatonin, by protecting the membrane and structure of plant cells, maintaining the antioxidant system and helping to absorb potassium and reducing sodium absorption, could increase the resistance of marigold against salt stress. As a result, the use of melatonin has moderated the effects of salinity and improved plant growth in saline conditions. Therefore, based on the obtained results, it is recommended to use melatonin 100 and 150 μM for marigolds under salinity stress conditions.
Type of Study: Applicable |
Subject:
Plant growth under stressful conditions
Received: 2024/05/5 | Accepted: 2024/07/8
Received: 2024/05/5 | Accepted: 2024/07/8
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Journal of Soil and Plant Interactions by http://jspi.iut.ac.ir is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License which allows users to read, copy, distribute and make derivative works for non-commercial purposes from the material, as long as the author of the original work is cited properly.
This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License which allows users to read, copy, distribute and make derivative works for non-commercial purposes from the material, as long as the author of the original work is cited properly.
