Hossein Nastari Nasrabadi; Seyyed Farhad Saberali
Abstract
Introduction: Melon (Cucumis melo L.) is one of the most important vegetables in Cucurbitaceae family and one of the most important economic crops in the Torbat-e Jam. Growth and yield of agricultural crops are affected by biotic and abiotic environmental stresses. Salinity stress can be one of the most ...
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Introduction: Melon (Cucumis melo L.) is one of the most important vegetables in Cucurbitaceae family and one of the most important economic crops in the Torbat-e Jam. Growth and yield of agricultural crops are affected by biotic and abiotic environmental stresses. Salinity stress can be one of the most important environmental factors limiting the yield of plants, especially in arid and semi-arid regions. It has been reported that by application of bio-fertilizers, root and shoot dry weight and nitrogen concentration in alfalfa increased under salt stress. Sarabi et al (44) in a study of different genotypes of melons under salinity stress reported that salinity stress increases soluble sugars and proline content and decreases photosynthetic pigments. Growth-promoting bacteria can help plants under stress conditions by stabilizing atmospheric nitrogen, increasing the accessibility of nutrients, and interfering by the production of plant hormones such as auxin, cytokinin, and gibberellins. Soliman et al. (49) also reported that growth-promoting bacteria increase the absorption of elements, especially nitrogen, in Acacia saligana. Basilio et al. (7) showed that growth-promoting bacteria increase plant height and yield of wheat. The use of salicylic acid to create plant reactions to environmental stresses has been suggested. Raghami et al (39) reported that salicylic acid improves vegetative indexes and photosynthetic pigments in eggplant under salt stress. It has been reported that salicylic acid treatment increased K in wheat under salt stress. Due to the expansion of saline soils as well as the reduction of fresh water resources, the purpose of this experiment is to better establish melon seedlings under adverse environmental conditions and to maintain and develop this valuable crop.
Materials and Methods: In order to study the effect of biological fertilizers and salicylic acid on physiological parameters and growth of Khatooni melon under salinity stress conditions, a factorial experiment was conducted based on completely randomized design with three replications in Torbat-e-Jam University. Salicylic acid treatment was selected at two levels, without (SA0) and one mM (SA1) salicylic acid. Bacteria treatments were including Azotobacter (B1), Azospirilium (B2), Azotobacter and Azospirilum (B3) and without inoculation (B0) and salinity treatments were prepared in five concentrations: control (S0), 50 (S1), 100 (S2), 150 (S3) and 200 (S4) mM of sodium chloride.
Results and Discussion: Interaction effects of salinity, salicylic acid and bacteria showed, proline content was increased by salinity stress. The highest of proline content was obtained by combination of 200 mM salinity, one mM of salicylic acid and Azetobacter + Azospirilum (S4 SA1 B3) and the minimum of it was recorded in contorol (S0 SA0 B0). Under salinity conditions, the accumulation of compatible solutions such as proline, glycine, betaine and other organic solutions in the plant occurs, which play an important role in protecting the plant against the harmful effects of stress. On the other hand, the increase in proline content by growth-promoting bacteria may be due to an increase in the absorption of nutrients, especially nitrogen, because proline has a nitrogenous structure.
Without salinity stress no significant difference observed between salicylic acid treatments on soluble sugars, but soluble sugars content were significantly increased by increasing salinity stress. The maximum and minimum of soluble sugars content were recorded in combination 200 mM salinity and one mM of salicylic acid (S4 SA1) and control (S0 SA0) respectively. Plants try to overcome salinity stress by producing organic compounds that are osmotically active such as soluble sugars.
It has been reported that the use of salicylic acid in eggplant and barley under salinity stress has increased the production of soluble sugars, which is consistent with the results of this study. In general, accumulation of proline and soluble sugars content might be due to increased synthesis and decreased degradation under stress conditions. According to the results, photosynthetic pigments and relative water content percentage (RWC %) were decreased under salinity stress. Simple effects of salicylic acid (SA1) and bacteria treatments especially combination of bacteria (B3) significantly improved Chlorophyll a, b, carotenoids and RWC. Sarabi et al. (43) reported that chlorophyll content, carotenoids and RWC were decreased in melon under salinity stress. Kheirizadeh Arough et al (29) reported that application of bio-fertilizers and nano zinc oxid increased content of chlorophyll a, chlorophyll b and carotenoids in Triticale under salinity conditions.
Conclusion: Based on the obtained results in this study, we can use Azotobacter and Azospirillum together for seed inoculation and spraying with salicylic acid for obtaining better growth and yield under salt stress.
Mina Motamednezhad; Seyyed Vahid Eslami; Mohammad Hassan Sayyari Zahan; Sohrab 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.
