Improvement and breeding
- -; Masomeh Moradi; Mousa Torabi Giglou; Mahsa Ahadzadeh
Abstract
Background and objectives: Basil (Ocimum basilicum L.) is a plant from the Mint family and the genus Ocimum, which has many species, among which O. basilicum is the most useful economic species, and like other plants of the Mint family, it is a source of cyclic compounds and ...
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Background and objectives: Basil (Ocimum basilicum L.) is a plant from the Mint family and the genus Ocimum, which has many species, among which O. basilicum is the most useful economic species, and like other plants of the Mint family, it is a source of cyclic compounds and essential oil. It is also known as a rich source of phenolic compounds (especially rosmarinic acid and caffeic acid) and flavonoids. The plant's vegetative body contains essential oils. Linalool, methyl chavicol, citral, euginol, cineol, geraniol, camphor, and methyl cinnamate are important components of basil essential oil. As the most critical abiotic stress, drought stress plays a crucial role in reducing the yield of medicinal plants. It causes numerous morpho-physiological and biochemical changes in the plant. The performance of the effective substance is influenced by the plant's economic performance and environmental conditions, including drought stress. Stress effects are different at different stages of growth and development.Methodology: To investigate the effect of ascorbic acid on native O.basilicum the native population "Shahre-ray," under drought stress conditions, a factorial experiment in the form of a randomized complete block design was performed in four replications on the research farm of Horticulture Department of Mohaghegh Ardabili University in 2017. Treatments included drought stress (complete irrigation and cessation of irrigation at the beginning of reproductive growth and cessation of irrigation at 50% flowering) and ascorbic acid foliar application at four concentrations of 0.0, 0.5, 1, and 2 mM. This experiment was field operated in May 2016. Before the experiment, the bed preparation operation included plowing, disking, and leveling the ground. The plots of one meter in length and width were created. The seeds were planted in three lines with 15 cm plant spacing. 3-4 cm of rotted manure was used to cover the seeds. After determining the soil texture by the hydrometric method, the mentioned treatments were applied to stress. On the first day, irrigation was a flood, and after germination, irrigation was reduced. All traits were measured in the Physiology Laboratory after the Horticulture Science Department of the Faculty of Agricultural Sciences analyzed the data with SAS software. Also, the treatment averages were compared with Duncan's multi-range test at a probability level of 5%. Results: The results showed that with increasing drought stress intensity, total plant height, stem length, number of leaves, and plant dry weight decreased by 36.08%, 39.75%, 51.26%, and 53.80% compared to the control treatment, respectively. If ascorbic acid spraying could improve these values, the highest root length was obtained under severe stress conditions (beginning of flowering) and treatment with ascorbic acid (15.83 cm), which showed an increase of about 31.91% compared to the control treatment. Drought stress conditions increased proline and essential oil components. Chlorophyll content also decreased under severe stress. Also, by applying drought stress, in all studied traits, the highest amount of ascorbic acid treatment (concentrations of 0.5 and 1 mM) increased, and higher concentrations decreased the content of studied traits. By analyzing the essential oil of plant samples, the main compounds obtained from basil essential oil included geraniol, methyl chavicol, alphapinene, caryophyllene, citral, coupon, carvacrol, neral, linalool, and limonene. In most compounds, essential oil compounds and components were enhanced by increasing drought stress and spraying. The highest amount of essential oil in the stress condition up to the 50% flowering stage and sprayed with 2 mM ascorbic acid was obtained for methyl chavicol compound (33.76%).Conclusion: Applying ascorbic acid increased basil growth under drought stress and created resistance in the plant. Therefore, due to the lack of water resources and the great need of plants for water, it is possible to create resistance to stress in plants by spraying non-toxic and essential elements on them.
B. Esmaielpour; H. Fatemi; M. Moradi
Abstract
Drought stress, as one of the most important abiotic stresses, plays an important role in decreasing the yield of medicinal plants. In order to investigate the effect of nitric oxide on morphophysiological and biochemical characteristics of basil (Ocimum basilicum L.), the native population "Shahre-ray", ...
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Drought stress, as one of the most important abiotic stresses, plays an important role in decreasing the yield of medicinal plants. In order to investigate the effect of nitric oxide on morphophysiological and biochemical characteristics of basil (Ocimum basilicum L.), the native population "Shahre-ray", a factorial experiment was conducted in a completely randomized design under drought stress conditions with three replications in the research greenhouse of Mohaghegh Ardabili University in 2017. Experimental factors included drought stress at three levels of complete irrigation (drip irrigation at three-day intervals throughout the growing season) and complete stop of irrigation at early flowering stage (60 days after planting at 10-12 leaf stage) and 50% flowering (75 days after planting at 14-15 leaf stage) and nitric oxide spray with sodium nitroprusside at four concentration levels of zero (leaf spray with distilled water), 0.5, 1, and 2 mM. The foliar application was carried out from the eight-leaf stage of the plant, with intervals of two weeks to four times. Results showed that stopping irrigation at both mentioned growth stages significantly reduced plant height, plant dry weight, chlorophylls a and b, total chlorophyll, carotenoid, and relative water content, and significantly increased electrolyte leakage rate, leaf proline content, and essential oil percentage. Foliar application of 2 mM nitric oxide significantly increased plant growth under irrigation interruption, especially at 50% flowering. Increasing the concentration of nitric oxide produced the highest essential oil percentage (1.4%) at the early flowering stage under irrigation interruption conditions and significantly increased the content of essential oil components including methyl chavicol, linalool, geranial, geraniol, α-pinene, β-pinene, and myrcene. In general, the results showed that foliar application of nitric oxide at 50% flowering stage under irrigation interruption improved the growth of basil and increased the percentage and components of essential oil via osmotic adjustment, preventing chlorophyll degradation and maintenance of leaf water content.
