Document Type : Research Article
Authors
1 Mashhad
2 Soil and Water Research Department, Khorasan Razavi Agricultural and Natural Resource Research and Education Center
Abstract
Introduction: Pomegranate is one of the most important horticultural products cultivated in tropical and subtropical regions of Iran. It plays a major role in the economic situation of the peoples of these areas. In recent years, due to the good quality of Iranian pomegranate, this product is considered to be of great interest to many different countries of the world. There are about 2,100 hectares of pomegranate in the Ferdows region, which is the dominant and major part of Ferdows pomegranate, and is called Shish Kap variety. Zinc and iron are two of the essential elements for the growth of all plants and over a century, the necessity of iron and zinc for plant nutrition have been identified. White seed disorders were reported in Ferdows region in 2001 for the first time. The results of pomegranate juice analysis of ferdows pomegranate samples showed the iron and zinc deficiency, compared to the normal pomegranate in that year. Based on this, considering the general condition of soils in the proposed area, the effect of iron and zinc on the removal of seed whitening of pomegranate was investigated.
Materials and Methods: In order to investigate the effect of spraying different concentrations of iron and zinc sulfate on the reduction of seed whitening, a factorial experiment based on a randomized complete block design with three replications was conducted in the pomegranate field of Ferdows region. The first factor included: spraying three concentrations of iron sulfate (0, 0.3 and 0. 6 %) and the second factor included the concentration of zinc sulfate (0, 0.3 and 0. 6 %). The distance gap between the trees was (2.5 * 3) meters and the garden age was about 12 years old. The soil and water were sampled from the garden. Each experimental plot was consisted of three trees, in which leaves and fruits were sampled for analysis from the middle tree. Samples were taken from the leaves before spraying. Spraying with the desired concentrations was carried out twice. Leaf and fruit samples were sent to the soil and water Laboratory. Each of the samples due to the peculiar color of the pomegranate juice was also sent to the laboratory for analysis. Pomegranate juice samples were then assigned to the quality control system of the seed and seedlings research department. Finally the brix and pH of the samples were determined.
Results and Discussion: The amount of nutrients in soil, and the mount of zinc and iron in the leaves were below the critical value. The deficiency of other elements in the soil and leaves were quite evident. The results showed that the concentration of iron and zinc elements increased significantly in pomegranate leaves (α = 1% level). Qinglong and Brown (1995) showed the same results. Spraying of Fe and Zn increased the concentration of these elements in the leaves, without any negative effects on the tree yield. The mean concentration of zinc and iron were lower in control treatments, which was more common in white seeds. The interaction effect of iron and zinc treatments on iron concentration in pomegranate leaves was significant (α = 1% level), and the highest iron concentration in leaf was obtained from zinc and iron sulfate solutions at the concentration level of 6,000.Pomegranate samples were analyzed in soil and water laboratory, and nutrient concentrations of the pomegranate juice were determined. The results showed that the pure effect of iron sulfate spraying on the concentration of pomegranate juice was not significant, but the pure effect of zinc sulfate solution increased zinc concentration of the pomegranate juice. The pure effect of zinc sulfate treatment, and the interaction effect of iron and zinc sulfate spraying treatments on pH of pomegranate juice were significant (α = 5% level). The pomegranate juice quality was evaluated in terms of color in a panel method. The results showed that all treatments increased the redness of pomegranate juice color. The best treatment in this study, was spraying at 0.6% zinc sulfate alone.
Conclusion: By spraying 0.6% zinc and iron sulfates, spray treatments increased the concentrations of iron and zinc in the leaves. However, due to the specific behavior of iron in the plant, the high pH of irrigation water and soil and the presence of carbonate and bicarbonate in irrigation water, the effect of iron absorbed in the leaves were not evident in the fruit. Spraying with iron and zinc sulfate improved pomegranate seed color. According to the results of the project implementation, and due to the high soil pH and organic matter deficiency, spraying with 0.6% zinc and iron sulfates is recommended.
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