M. Hosseinifarahi; Gh. Mohamadineia
Abstract
Introduction: Bell pepper (Capsicum annuum) belongs to solanaceae family, which is cultivated and consumed in the world due to its high economic value. Bell peppers also have valuable nutritional and medicinal compounds, including natural colors, antioxidants and vitamins A, B and E. Salinity stress ...
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Introduction: Bell pepper (Capsicum annuum) belongs to solanaceae family, which is cultivated and consumed in the world due to its high economic value. Bell peppers also have valuable nutritional and medicinal compounds, including natural colors, antioxidants and vitamins A, B and E. Salinity stress is one of the most important environmental factors limiting growth, which has very adverse effects on plant growth and yield. Salinity stress reduced the yield of agricultural products due to the effect on the competitive absorption and transfer of nutrients in the plant. Nowadays, the increased tolerance of plants to environmental stresses from different pathways involve breeding programs and the use of plant growth regulators and organic substances. In comparison to breeding methods that are often long-term and cost-intensive, it is easy and inexpensive to use plant growth regulators such as Salicylic Acid (SA) and humic acid (HA).
Material and Methods: To investigate the effect of Salicylic Acid (SA) and Humic Acid (HA) on the improvement of tolerance to salinity and absorption of mineral elements under salinity stress in greenhouse culture, a factorial experiment based on Randomized Complete Block Design (RCBD) was conducted in Yasooj. The first factor was SA in three levels (0, 1, and 2 mM), the second factors HA in two levels (0 and 5 g l-1), and the third factors salinity in three levels (0, 50, and 100 mM). The bell pepper seedlings cv. California were obtained from a commercial producer and planted in 4-liter plastic pots containing perlite and cocopeat (1:1) in 2015. Plants were grown in a hydroponic greenhouse with day/night temperature (24.3 and 15.4 oC) and 60 to 80% RH in the village of Nahrgah in Yasouj. After the plants were established (having about 4–5 leaves), sodium chloride salt was used in the concentrations of 0, 50, and 100 mmol in the nutrient solution for salinity stress. To prevent a sudden shock, the first one week all the pots were irrigated with a 10 mM-food solution and in the second week with a 25 mM salt solution. After that, the plants irrigated 50 and finally 100 mg of sodium chloride. Traits such as plant height, number of leaves, number of flowers, number of fruits, and average fruit weight, and yield, fresh and dry weight of leaf were measured. The content of K, Ca, Fe and Na elements in the leaves and roots of treated and untreated plants were measured by an atomic absorption device equipped with a graphite furnace system. Data analysis (ANOVA) was performed using MSTAT-C statistical software. The means were compared with the Tukey test (P≤ 0.05) and the graphs were plotted with Excel.
Results and Discussion: Results showed that the salinity has negative effects on growth factors. The application of HA and SA reduced the negative effects of salinity and increased growth parameters. The application of HA and Salicylic acid increased the number of pepper fruits under salt stress conditions. The highest number of fruits was obtained in the plants treated with 5 g l-1 HA and 2 mM salicylic acid compared to the other treatments. The results of this experiment showed that the application of HA and Salicylic acid had a significant effect on the content of mineral elements in the leaves and roots of sweet peppers under salt stress. The highest amount of Fe was observed in the leaves of pepper plants treated with 100 mM and the lowest in untreated plants. The highest amount of leaf calcium was obtained in peppers treated with SA 2 mM and HA 5 g l-1 in comparison to other treatments. Application of SA 1 and 2 mM increased the concentration of calcium of the leaves and roots of the pepper plant. The highest root potassium were obtained in plants treated with 5 g l-1 HA and 1mM SA at salinity level of 100 mM in comparison to the other treatments.
Conclusion: Salinity is an environmental factor limiting the production of crops in plants. According to the results of present study, it can be concluded that salinity reduced the growth parameters of the bell pepper plant. The use of SA and HA increased bell pepper tolerance to salinity and improved the vegetative and reproductive characteristics and absorption of mineral elements. Therefore, the application of HA 5 g l-1 and 2 mM SA is suggested to reduce the negative effects of salinity stress on bell pepper.
M. Motamednezhad; S. V. Eslami; Mohammad Hassan Sayyari Zahan; S- Mahmoodi
Abstract
Introduction: Cultivation of medicinal and aromatic plants has always had a special situation in the traditional system of agriculture and these systems have played a major role in the diversification and sustainability of agricultural ecosystems. Tend to produce medicinal and aromatic plants and demand ...
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Introduction: Cultivation of medicinal and aromatic plants has always had a special situation in the traditional system of agriculture and these systems have played a major role in the diversification and sustainability of agricultural ecosystems. Tend to produce medicinal and aromatic plants and demand for natural products, especially in terms of ecological culture in the world is increasing. Ajowan is an annual herbaceous plant from the Apiaceae family. Biological fertilizers produced by the activity of microorganisms are associated with nitrogen fixation or availability of phosphorus and other nutrients in the soil. Enrichment means increasing the concentration of nutrients in plants especially micronutrients. Application of biological fertilizers instead of using chemicals is one of the most important nutritional strategies in sustainable management of agro ecosystems. In this regard, the effect of enrichment with bio-fertilizers and micronutrients on Ajowan (Carum copticum L.) germination characteristics was studied at Birjand Agricultural Research Laboratory.
Materials and Methods: A factorial experiment based on a CRD (completely randomized design) was conducted with three replications at Birjand Agricultural Research Laboratory during 2011. Experimental treatments consisted of bio-fertilizer application with three levels including without inoculation, and seed inoculation with Azospirillum and Azotobacter and seed enrichment with ten different treatment levels including without enrichment, and enrichment using 1, 2 and 3 mM of Fe, Zn and Mn elements. Bacteria were provided by Soil and Water Research Institute of Tehran. Initially, the seeds were disinfected through immersing them in 1% sodium hypochlorite for 3 minutes and then washing them with the tap water for 2-3 times. For the Enrichment of seeds, depending on the treatments, Petri dishes were treated with 10 ml of micronutrients solution for 24 hours. Then for bacterial inoculation depending on the type of treatments, seeds were soaked in 7 ml of inoculums containing 108 alive and active bacteria per ml for 5 hours. In each treatment, 15 seeds were placed in Petri dishes sealed with parafilm and placed in a germinator set at 70% RH and 25/15 °C. The traits studied were: germination percentage, germination rate, root and shoot length, as well as root and shoot fresh and dry weight. Before analyzing the data, normality test was performed and analysis of variance was performed using Genstat and graphs were drawn using Excel software.
Results and Discussion: The Analysis of variances results showed that seed inoculation with biological fertilizers and micronutrients significantly increased germination rate, root and shoot length, root fresh weight and dry weight of root and shoot of Ajowan compared with the control. Results showed that there were not significant differences between treatments in terms of germination percentage. Using micronutrients for seed enrichment caused increased germination rate. The maximum germination rate value was obtained from the Mn 1mM treatment (2.164 seeds per day), and. its minimum value was obtained from Zn1 (1.55 seeds per day). The maximum and minimum values of root length were obtained from the combined treatments of azotobacter + Fe2 and Azospirillum + Zn3, respectively. The maximum and minimum values of shoot length were obtained from the combined treatments of azotobacter + Mn2 and Azospirillum + Zn3, respectively. The highest and lowest values of shoot dry weight were obtained from azotobacter + Fe3 and azotobacter, respectively. The highest and lowest values of root dry weight were obtained from Zn1 (2.35 mg) and Mn2 (0.4 mg), respectively. The highest and lowest values of root fresh weight were obtained from Azospriliium+ Mn3 and Azospriliium+ Zn2, respectively. The highest and lowest values of shoot fresh weight were obtained from Azotobacter+Mn2 and Mn3, respectively.
Conclusion: During the evaluation of the measured traits regarding to bio fertilizers application on ajowan, it was observed that all biological treatments were superior to the control (non-biological fertilizer) and Azotobacter was the most effective amongst them. Bio fertilizers applications used in this study showed significant effects on root and shoot length, as well as fresh weight of root and shoot. The use of micro-nutrients on ajowan, showed that the application of 1 and 2 mM of Mn and all three concentrations enhanced the examined characteristics, while the application of 1 mM of Zn was just effective on root and shoot dry weight. Overall,application of these micronutrients had significant effects on germination rate and root length and fresh weight of root and shoot as well as dry weight of shoot and root.
