Medicinal Plants
E. Nabizadeh; M. Haghshenas; Narges Dolatmand; K. Ahmadi
Abstract
Introduction
Stevia (Stevia rebaudiana) is one of the medicinal plants of the Asteraceae family that contains natural compounds, especially stevioside and ribaodioside A, which are estimated to be 150 to 400 times sweeter than sucrose. Plants are exposed to various environmental stresses during growth ...
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Introduction
Stevia (Stevia rebaudiana) is one of the medicinal plants of the Asteraceae family that contains natural compounds, especially stevioside and ribaodioside A, which are estimated to be 150 to 400 times sweeter than sucrose. Plants are exposed to various environmental stresses during growth and development under natural and agricultural conditions. Among these, drought is one the most severe environmental stresses affecting plant productivity. About 80–95% of the fresh biomass of the plant body is comprised of water, which plays a vital role in various physiological processes including many aspects of plant growth, development, and metabolism. Stevia is susceptible to various environmental stresses but the major effects are contributed by drought. Today, the fungal species Stevia rebaudiana is used as a biofertilizer and increases the production of secondary metabolites of economically valuable plants and also increases the growth and seed production of many plants. This fungal endophyte produces a significant amount of acid phosphatase for mobility in a wide range of insoluble or complex forms of phosphate, enabling the host plant to have adequate access to inactive phosphorus reserves in the soil. However, medicinal plants that are cultivated have often been reported to have lower abundance of arbuscular mycorrhizal fungi in the rhizosphere, which significantly reduces plant survival. Considering the coexistence role of mycorrhizal fungi in modulating the effects of drought stress, the aim of this study was to investigate the morphological, physiological and biochemical traits of stevia in response to the effects of mycorrhizal inoculation and drought stress.
Materials and Methods
This experiment was conducted to investigate the effect of P. indica endophytic fungus under water stress conditions on vegetative characteristics, physiological parameters and micronutrients of stevia. A factorial experiment was employed based a completely randomized design with four replications in the research greenhouse of Islamic Azad University, Mahabad Branch in 2017. The first factor was drought stress at four levels (25, 45, 60 and 80% of field capacity) and the second factor was inoculation of seedlings with fungus at two levels (no inoculation and inoculation with P. indica). Water stress was applied based on a combination of plant appearance symptoms (no wilting to severe wilting) and soil moisture. Investigated traits included root colonization, dry weight, leaf number, plant height, stem diameter, chlorophyll a, b, total chlorophyll, carotenoids, proline, soluble sugars, antioxidant power and micronutrients including copper, iron, zinc and manganese. To analyze the data variance, SAS 9.1 statistical software was used to analyze the variance of the data.
Results and Discussion
The results showed that the evaluated traits in the present study were affected by the main treatments of fungus and drought stress. Seedlings inoculated with P. indica endophytic fungi had the highest percentage of root colonization, growth parameters, photosynthetic pigment content, soluble compounds and micronutrients compared to no inoculation. Drought stress increased soluble sugars, proline content and antioxidant power of stevia leaves and decreased the other traits by increasing the stress level from 25 to 80%. The highest rate of root colonization (26.90%), stem diameter (3.21 mm) and carotenoid content (1.71 μg/ml) was observed in the treatment of plant inoculation with fungi and 25% drought stress. While the highest antioxidant power was found in the treatment of plant inoculation with fungi and 80% drought stress. According to the results of the present study, use of P. indica fungus had the most positive effect on the quantitative and qualitative characteristics of stevia medicinal plant compared to no fungus inoculation.
Conclusion
This study showed the positive effect of P. indica endophyte inoculation on quantitative and qualitative characteristics of root colonization, dry weight, number of leaves, plant height, stem diameter, chlorophyll a, b, total chlorophyll, carotenoids, proline, soluble sugars, antioxidant power and The micronutrients of calcium, iron, zinc and manganese showed stevia, and drought stress reduced the studied traits except for proline content, soluble sugars and antioxidant power. Inoculation of stevia seedlings with P. indica endophytic fungi at drought stress levels had the highest rate of root colonization, stem diameter, carotenoid content and antioxidant power compared to non-fungal inoculation. Therefore, due to the effect of biological compounds of natural origin and the production of plants with healthier active secondary compounds, the use of P. indica endophytic fungi can be recommended.
F. Baniasadi; Vahid reza Saffari
Abstract
Introduction: Catharanthus roseus (L.) belongs to Apocynaceae family is an important medicinal plant and also cultivated as an ornamental plant almost throughout the tropical and subtropical areas all over the world. Recently, the uses of natural substances are considered very helpful to improve plant ...
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Introduction: Catharanthus roseus (L.) belongs to Apocynaceae family is an important medicinal plant and also cultivated as an ornamental plant almost throughout the tropical and subtropical areas all over the world. Recently, the uses of natural substances are considered very helpful to improve plant growth and development. Application of plant growth regulators (PGRs) and vitamins are reported in many horticultural crops. Ascorbic acid is the most abundant antioxidant in plant which protects plant cells. This substance affects cell differentiation and growth. Now a day it is considered as a plant growth regulator. Thiamine or vitamin B1 is water soluble and one of the B complex vitamins. This study was conducted to investigate the effect of the ascorbic acid, thiamine, BA and GA on growth and biochemical parameters of periwinkle.
Materials and Methods: The experiment was perform as a completely randomized design with 5 replications at research greenhouse of Shahid Bahonar University of Kerman in 2014.The treatments used include spraying water (control), ascorbic acid 100 mg.l-1, gibberellic acid 100 mg.l-1, thiamine 100 mg.l-1, BA 200 mg. l-1 and combinations of two, three and four of them to determine the response of plants to these substances alone or in combination of them. When the seedlings become on 6-leavs stage, the first foliar spray was carried out. In other two steps was repeated with interval of 10 days. In this study, longevity of the flower, flower diameter, the number of lateral branches, branches length, fresh and dry weight, chlorophyll content and reduced sugars were measured. Chlorophyll content and reduced sugars were measured according to method of Somogy (1952) and Lichtenthder (1987), respectively.
Results and Discussion: The results showed that the effect of thiamine on the number of flowers was more pronounced than other substances. The lowest number of flowers per plant was found in plants treated with gibberellic acid. All growth promoter substances increased flower diameter. Combined application of BAwith gibberellic acid had more influence on this parameter than other treatments, and increase flower diameter about 25%. Ascorbic acid plays an important role in cell division, plasma membrane, proton pumps and enlargement cell. According to the theory of acidic growth, ascorbic acid weakens cell wall and increases cell enlargement. Among the applied treatments combination of banzyladenine, thiamine and ascorbic acid increased the number of lateral branches to 100%. Results showed that GA in all concentrations and combinations used in this experiment increased lateral branches length. Several reports in plants such as croton, hibiscus and pot marigold indicated that BA can increase the number of branches per plant. Therefore, BA is used to enhance branching and to reduce the total height of the plants. The highest fresh and dry weight were observed in plants treated with the combinations of BA, thiamine and ascorbic acid. Thiamine increased chlorophyll a content more than other substances. There was no significant difference between thiamine or thiamine combined with ascorbic acid treatment on chlorophyll b content. Thiamine in combinations with all the other treatments significantly improved carotenoids content compared to control. Chlorophyll plays a key role in plants for the absorption and utilization of light energy which used in photosynthesis. Therefore, effects of PGRs on chlorophyll biosynthesis or degradation influence directly on photosynthesis. Thiamine was reported that in some plants assist resynthesize of chlorophyll in plant without chlorophyll and increased growth and yield eventually. All the treatments significantly increased reducing sugar. Although all of the substances improved the amount of reducing sugar, the role of thiamine was more dramatic compared to other treatments. The greatest amount of reducing sugar 85.3 mg. g-1 fresh weight was observed in the combination of BA, thiamine and ascorbic acid. Thiamine is an essential part of the biosynthesis of pyrophosphate thiamine coenzyme which has an important role in carbohydrate metabolism. Application of vitamin c it was reported the increased soluble sugar in Chinese hibiscus.
Conclusion: Periwinkle is a bedding plant that the number of flowers and lateral branches is very important. BA with thiamine and ascorbic acid combination has the best effects on these traits and improved growth condition of it. On the other hand, application of gibberellic acid, either simple or combined with other materials, due to the excessive increase in plant height, led to the bending of the plant.
