A. Rahbary; H. Fatemi; B. Esmailpour
Abstract
Recently, various methods have been used to alleviate the detrimental effects of pollutants. The application of biofertilizers with respect to their positive impacts on soil characteristics and environment can be served as a suitable alternative to many of these methods. In order to investigate the two-way ...
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Recently, various methods have been used to alleviate the detrimental effects of pollutants. The application of biofertilizers with respect to their positive impacts on soil characteristics and environment can be served as a suitable alternative to many of these methods. In order to investigate the two-way effect of bacterium Pseudomonas fluorescens on plant growth, physiological and biochemical characteristics of dill (Anethum graveolens L.) under Pb stress conditions, a factorial experiment based on a completely randomized design with three replications was conducted at Mohaghegh Ardabili University. Experimental treatments included Pb stress at two levels (0 and 600 ppm) and bacterial inoculation at three levels (inoculation with Pseudomonas fluorescens strains150 and 159 separately and without inoculation (control)). The results of this study showed that the growth characteristics such as leaf number, plant height, and shoot fresh and dry weight were significantly affected by Pb contamination and shoot fresh and dry weight, leaf number and plant height decreased by 22, 31, 19 and 9%, respectively. The content of proline and carbohydrates in dill showed a significant increase under the influence of lead. Bacterial inoculation also increased the content of proline and plant carbohydrates, which was more pronounced in inoculation with strain150. The activity of antioxidant enzymes was significantly influenced by Pb contamination and bacterial inoculation. Pb increased peroxidase but decreased catalase activity, but inoculation with Pseudomonas bacteria, especially strain 150, significantly increased the activity of both enzymes. In addition, the bacteria were able to reduce the amount of Pb in dill. In general, the results of this experiment indicated that Pseudomonas bacterial inoculation was effective in alleviating the effects of Pb stress on dill via growth promotion and improving enzymatic activity.
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.