Phytochemical and morpho-physiological responses of stevia rebaudiana bertoni to different planting beds and mycorrhizal fungi inoculation [glomus intraradices n.c. schenck and g.s. sm.]

Background: The composition of the planting beds and its microorganisms has a very important role on the establishment, growth and phytochemical performance of medicinal plants

Objective: The aim of this study was to determine the effect of different planting beds and inoculation of mycorrhizal fungus on the changes of stevioside, rebaudioside, and morpho-physiological traits of stevia

Methods: This study was conducted in a factorial experiment based on randomized complete blocks design [RCBD] with 10 treatments and 4 replications. The first factor consisted of inoculum and non-inoculum treatment of Glomus intraradices, and the second factor was the different combination of peat moss, coco peat, perlite and soil as planting beds

Results: Mycorrhizal fungi inoculation significantly increased the plant height, number of lateral branches, stem and root diameter, number of leaves, leaf fresh/dry weight, shoot dry weight, root dry weight, and content of stevioside, rebaudioside A and C. Also, different combination of planting beds had a significant effect on the plant height, stem dry/fresh weight, leaf fresh weight, root dry/fresh weight, and content of stevioside, rebaudioside A and C

Conclusion: The results of this study showed that the combination of peat moss + coco peat + soil [2:1:1] with mycorrhizal fungi inoculation among the treatments had the highest positive effect on leaf dry weight and glycoside carbohydrates in stevia plants

Assessment of stevioside content, shoot proliferation, and root induction of stevia rebaudiana bertoni under In vitro conditions

Background: Stevia rebaudiana Bertoni, an important anti-diabetic medicinal plant, becomes an inevitable alternative to sugar. Due to the propagation difficulties, tissue culture is the best alternative for rapid mass propagation of stevia plants

Objective: The present study was conducted to optimize a protocol for rapid micropropagation of Stevia rebaudiana by shoot tip explants and to investigate the effect of growth regulators concentration on steviol-glycosides content under in vitro culture conditions

Methods: Young nodal stem explants were collected from a young growing plant and the effects of media and growth regulators on shoot proliferation were studied. Shoots produced on optimal medium for shoot proliferation were used for rooting experiments and the effects of IBA, NAA, and active carbon on root induction in both full MS and half MS media were investigated

Results: Based on the results obtained from the proliferation stage, there was no significant difference between growth regulator levels. Analysis of data obtained from rooting experiment, revealed that there are significant differences between growth regulators in leaf length, shoot dry weight, and root fresh weight. Based on the results of mean comparison, plantlets grown on free active carbon media had the higher biomass than those grown on media supplemented with 2 mg.L[-1] active carbon. The highest content of stevioside [8.18%] was observed at half MS medium supplemented with 0.2 mg. L-1 IBA, and 2 mg.L[ -1] active carbon

Conclusion: Plant growth regulators can be included among the factors affecting shoot proliferation and root induction of Stevia rebaudiana. Micropropagation of stevia can be improved by altering the macro elements concentration and adding activated carbon. In conclusion, half MS medium supplemented with 0.2 mg.L[-1]IBA, and 2 mg.L[-1]active carbon was superior for stevioside content