Medicinal and aromatic plants are valuable sources of herbal products worldwide due to their secondary metabolite content, high antioxidant activities and many other biological activities. As a result of the developing technology, the demand for natural active substances obtained from plants has increased. For use, plants collected from nature do not have the desired quality standards. For this reason, sustainability can be achieved by using microbial inoculants as well as many biotechnological and molecular approaches such as micro propagation, synthetic seed technology to increase the yield and quality standards of medicinal and aromatic plants. Thanks to microbial inoculants, yield increase can be realized and at the same time, product quality can be contributed due to increased soil quality. In this review, it was aimed to evaluate the important roles of plant growth promoting rhizobacteria (PGPR), Arbiscular mycorrhizal fungi and Trichoderma inoculants in increasing productivity, nutrient uptake and resistance of medicinal and aromatic plants to environmental stresses in the light of literature. In this review, the variation in the resistance of plants to environmental stresses is summarized by evaluating the ultimate effects of microbial inoculants alone and in combination. In addition, it has been added to the evaluation in studies to prevent the decrease of secondary metabolite content formed under environmental stress conditions in medicinal and aromatic plants by microorganisms.

Vermicompost products have gained a great importance in plant nutrition over the years. They are reported to have plant growth promoting effects both in horticulture and field crops. The nutritional value and chemical properties of vermicomposts highly depend on the feedstock used in their production. The aim of this study was to evaluate vermicompost manure, derived from the mixture of cattle manure and kitchen scraps, on seed germination and growth of tomato seedlings (Lycopersicon lycopersicum Mill.). Four solid vermicompost amendment rates of 0, 10, 20, and 30% were applied in plastic trays. Vermicompost application delayed and reduced seed emergence in all application rates, while in general, vermicompost substitution promoted growth tomato seedlings up to 20% of application rate. The results showed that vermicompost substitutions greater than 20% had adverse effects on seedling emergence and seedling growth parameters, which was attributed to high EC of vermicompost induced by cattle manure. Results suggest that both physical and chemical properties of the feedstock used for vermicompost production should be taken into consideration in order to sustain high vermicompost quality to ensure targeted plant growth for horticultural and agricultural purposes.