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      • Open Access Article

        1 - Optimizing Seed Germination and Growth of Seedlings in Persian Walnut
        Ahmad Raoufi Kourosh Vahdati Soheil Karimi Mahmoud Reza Roozban
        The efficiency of conventional stratification methods for seed germination of walnut (Juglans regia L.), which uses long moist-chilling periods, is low. This experiment was conducted during winter to spring 2014 to optimize the seed germination of walnut ‘Chandler More
        The efficiency of conventional stratification methods for seed germination of walnut (Juglans regia L.), which uses long moist-chilling periods, is low. This experiment was conducted during winter to spring 2014 to optimize the seed germination of walnut ‘Chandler’ via changing growing media and removing seed mechanical dormancy. Fourteen treatments were tested. None of the seeds germinated without any treatment on shell or while they stored in manure. Germination percent of cracked seeds (CS) and cracked with toothpicks inserted seeds (CTS) without any stratification period reached up to 66.1% and 83.7% with mean germination time (MGT) of 0.73 and 0.98 day, respectively. Considering a 45-day cold storage period improved germination percentage of CS and CTS up to 88.3% and 94.1% with MGT of 1.02 and 1.12, respectively. Seedling growth parameters significantly increased after the cold storage period. Based on the results, mechanical dormancy was suggested as the main limiting factor for walnut seed germination. Therefore, rate and percentage of seed germination and seedling growth of walnut can be improved if the removal of mechanical dormancy is also considered in seed stratification. Manuscript profile
      • Open Access Article

        2 - Improving Growth and Performance of Young Almond Trees in Nursery by Optimizing Mineral Nutrition
        Masoud Shafiei Hossein Ali Asadi-Gharneh Soheil Karimi
        Short growing season restricts production of standard-sized fruit trees in nurseries at cold regions. Enhancing plant growth by optimizing program of mineral nutrition may solve the problem. This study evaluated efficiency of fertilizers [urea, sulfur coated urea (SCU), More
        Short growing season restricts production of standard-sized fruit trees in nurseries at cold regions. Enhancing plant growth by optimizing program of mineral nutrition may solve the problem. This study evaluated efficiency of fertilizers [urea, sulfur coated urea (SCU), or foliar applications of a NPK compound fertilizer] for optimizing the growth of seedling rootstocks and grafted young almond trees at the nursery in a cold region. At the end of the first growing season, the growth and quality of the almond seedlings were evaluated and they were budded in September. At the following season, the treatments were repeated on the grafted trees and grafting success and performance of the young almond trees were evaluated. The result showed that application of 600 kg ha-1 SCU and urea were the most successful treatments on enhancing the growth of the seedlings. Application of 400 and 600 kg ha-1 urea and SCU, and 30 kg ha-1 NPK resulted in the highest grafting success at the second season. The largest shoots of scion were found in the 400-600 kg ha-1 urea and SCU treatments. The highest leaf greenness and chlorophyll concentration were found in the 600 kg SCU ha-1 and 30 kg ha-1 NPK treatments. The highest leaf potassium and phosphorus concentrations were found in 30 kg ha-1 NPK treatment. The highest leaf nitrogen concentration was detected in treated plants with 400 and 600 kg SCU and 600 kg urea per hectare. According to the results, application of 400 kg ha-1 SCU is recommended to obtain young standard-sized almond plants in the nurseries. Manuscript profile
      • Open Access Article

        3 - Effect of Zinc on the Growth of Two Pistachio (Pistacia vera L.) Rootstocks under Drought Stress
        Alireza Kermani Azam Jafari Soheil Karimi Mostafa Shirmardi
        In this research, the effect of two irrigation treatments (90 and 40% of available water) and four different levels of zinc (control, 5, 10, and 20 mg kg-1 soil) was investigated on pistachio rootstock seedlings including ‘Akbari’ and ‘Badami’ in More
        In this research, the effect of two irrigation treatments (90 and 40% of available water) and four different levels of zinc (control, 5, 10, and 20 mg kg-1 soil) was investigated on pistachio rootstock seedlings including ‘Akbari’ and ‘Badami’ in a completely randomized design with four replications during 90 days. At the end of the experiment, plant growth characteristics including shoot height, stem diameter, number of leaves, leaf area, and dry matter accumulation in root, stem, and leaf were evaluated. Additionally, the relative water content, membrane stability index, photosynthetic pigment concentrations, and content of organic osmolytes were appraised as well. The results showed that drought stress reduced plant height, number of leaves, leaf area, and biomass of plants, and increased root dry weight. The zinc application increased plant growth under irrigation treatments. In addition, under drought stress, the application of 5 mg kg-1 zinc increased the membrane stability by16.76%, maintained chlorophyll a by 20.69%, b by 31.96%, and total chlorophyll of the leaf by 27.74%. However, the application of 20 mg kg-1 Zn in soil caused toxicity and exacerbated the effects of drought stress which led to the accumulation of proline and soluble carbohydrates in the pistachio rootstocks with more proline in ‘Akbari’ than ‘Badami’ rootstock, while Zinc could reduce the accumulation of soluble carbohydrates and proline. In general, ‘Badami’ was introduced as a tolerant rootstock for use underwater stress, as well as using 5 mg kg-1 Zn to improve the growth and efficiency of both rootstocks under drought stress or without stress. Manuscript profile
      • Open Access Article

        4 - Optimizing Early Grafting of Persian Walnut by Evaluating Different Rootstocks, Covering Materials and Grafting Methods
        Ahmad Raufi Kourosh Vahdati Soheil Karimi Mahmoud Reza Roozban
        Grafting on epicotyl of young seedlings has been introduced as a simple and rapid method for walnut propagation. Although this technique improves the grafting success and propagation efficiency, it is technically more demanding than the conventional walnut grafting proc More
        Grafting on epicotyl of young seedlings has been introduced as a simple and rapid method for walnut propagation. Although this technique improves the grafting success and propagation efficiency, it is technically more demanding than the conventional walnut grafting procedures and is yet to be optimized. This study was aimed to investigate the influence of rootstock type (dwarf and standard genotypes), graft union covering materials (perlite, sawdust, coco-peat and perlite at 1:1 ratio, and without cover - control) and different epicotyl grafting procedures (Gandev-Arnaudov and Frutos) on grafting success and performance of the grafted plants in order to optimize the walnut epicotyl grafting. Walnut seedlings were grown in a greenhouse. After four weeks, dormant shoots of walnut ‘Chandler’ were grafted to the epicotyl of young walnut seedlings. Grafting success and callusing quality were recorded 30 days after grafting. Growth parameters of the grafted plants, including number of nodes and length of internodes, height and diameter of scion, and survival of the grafted plants, were determined 150 days after grafting. Enhanced grafting success and performance of the grafted scions were obtained by following the Frutos’s procedure. Moreover, the highest grafting success (75.1%) and survival of the plants (91.7%) were obtained by using the dwarf rootstock and application of sawdust as graft union cover. In conclusion, performing walnut epicotyl grafting according to Frutos’s procedure by using dwarf genotypes as rootstock and covering the graft union with sawdust was suggested to obtain maximum propagation efficiency (68.7%). Manuscript profile