Impact of essential oils on seed quality and seed-borne pathogens of Althea officinalis seeds of different ages

Abstract

Abstract Background The cultivation of medicinal plants is a promising alternative to overcoming problems in the overharvesting of wild plants and ecosystem degradation. Cultivation depends upon two major factors: seed quality and the presence of seed-borne pathogens. Organic production of marshmallow plants (Althea officinalis L.) does not allow for the use of conventional pesticides. This study aimed to find an environmentally safe solution and the equilibrium between seed germination and the presence of fungal pathogens. The study was performed on a population of marshmallows which were cultivated for a period of 3 years (2018–2020) in Pančevo, The Republic of Serbia. The following six essential oils: Origanum vulgare L., Cinnamomum cassia Presl., Ocimum basilicum L., Carum carvi L., Mentha piperita L., Lavandula angustifolia Mill. at five concentrations (1%, 0.5%, 0.2%, 0.02%, 0.002%) were used for seed treatment along with water and PEG-40 (emulsifier) as controls. Germination, dormant seeds, dead seeds, abnormal seedlings and the presence of seed-borne pathogens were determined under laboratory conditions. Results Among the aforementioned treatments using oregano, cinnamon, basil, caraway, mint, and lavender essential oils, the most effective treatment resulted with lavender essential oil at a concentration of 0.02% in 3-year-old seeds. The highest values for seed germination and dead seeds were 46% and 20% in 3-year-old seeds, respectively. This treatment increased seed germination by 13%, and seedling growth i.e., the growth of seedling stems and radicles by 24–35%, respectively. It also reduced the presence of seed-borne fungal pathogens from 53 to 100%. Conclusions The results revealed that an increase in seed germination rate and simultaneous reduction in seed-borne fungal infection was achieved with the lavender essential oil seed treatments. This is the first discovery of the stimulating effect of lavender essential oil on seed quality parameters. Furthermore, the study demonstrates its potential application in seed processing in the organic production of marshmallow plants. Graphical Abstract

Keywords

• Seed quality
• Seedlings
• Essential oils
• Treatments
• Fungi
• Marshmallows