پاسخ‌های تغذیه‌ای و فیزیولوژیکی نارنگی انشو میاگاوا (Citrus unshiu cv. Miyagawa) با پایه نارنج (Citrus aurantium L.) به خاک‌های آهکی در استان مازندران

Background and Objectives: Some of the physical and chemical characteristics of the soils of Mazandaran Province, especially clay content from north to south and lime (calcium carbonate) content from west to east, exhibit the greatest variation (clay: 3–40% and lime: 0–45%). Based on research and field results, Swingle citrumelo (Grapefruit and Trifoliate orange) is recommended for low-lime soils; C-35 (Ruby Blood orange and P. trifoliata), Carrizo citrange (Citrus sinensis Osb. and Poncirus trifoliata L. Raf.), and Troyer citrange (C. sinensis and P. trifoliata L.) are suitable for low- to medium-lime soils with light texture. Gou Tou (Citrus aurantium L. var. Gou Tou) has relative tolerance to lime but shows chlorosis symptoms in high and very high-lime soils. Smooth Flat Seville (Citrus spp., hybrid of uncertain origin) is tolerant to soil lime but shows early deterioration in some soils. Therefore, for medium-, high-, and very high-lime soils of eastern Mazandaran, Sour Orange (C. aurantium L.) rootstock is the only desirable and available option for orchards, making it necessary to understand its response to the region's soils for field guidance and management. Establishing and re-establishing citrus orchards in the region's soils requires this knowledge. For this purpose, this study was conducted for the first time in the country to evaluate the nutritional and physiological responses of Citrus unshiu cv. Miyagawa on Sour Orange rootstock in calcareous soils of eastern Mazandaran.




Methodology: According to the soil map and soil reports, seven soil samples were selected with different textures (sandy loam to clay) and calcium carbonate (2–45%). Thirty kilograms of soil from the selected soil samples were poured into plastic pots. Then, Citrus unshiu cv. Miyagawa seedlings on Sour Orange rootstock were planted in each soil. The experiment was conducted for two years in pots in a randomized complete block design with seven soils in four replications, totaling 28 pots. Plant responses included dry weight, chlorosis rate, fluorescence index (Fv/Fm), chlorophyll, and nutrient concentrations in leaves and roots. Finally, all the obtained data were analyzed using SPSS software, and the means of the studied parameters were compared using Duncan’s multiple range test.
 




Results: The results of this study showed that the physical and chemical properties of the soil have a great influence on the nutritional and physiological responses of Citrus unshiu cv. Miyagawa on Sour Orange rootstock. The results showed that the highest and lowest average dry weight of aerial parts and roots were obtained from soils with clay texture and total lime of 30% and sandy loam soils with lime of 40%, respectively. There was a significant difference in the chlorosis rate of the leaves of seedlings on this rootstock in different soils. The average concentrations of Fe, Mn, and Zn in the roots were 12.48, 6.14, and 3.19 times, respectively, higher than the average concentrations in the leaves. In general, among the essential elements, Mg and S had the highest and lowest translocation factors (TFs) from the root to the leaves, respectively, while active and total Fe showed the highest and lowest TFs, respectively. The P, S, Fe, Mn, Zn, and Cu translocation factors were less than one, indicating that these elements are less mobile and accumulate in the roots. The leaf chlorosis index of Citrus unshiu cv. Miyagawa on Sour Orange rootstock in soils with low and high lime did not differ significantly. Additionally, increasing active lime did not have a significant effect on the concentration of active Fe or the chlorosis rate of seedlings on this rootstock.




Conclusion: According to the results of this study, Sour Orange rootstock is tolerant to soil lime, and lime is not a limiting factor for it. Therefore, it is recommended for calcareous soils of the eastern Mazandaran region, especially in soils with heavy texture and high lime content. However, its use in light-textured soils and in soils susceptible to manganese deficiency (where there is a possibility of manganese deficiency symptoms) is not recommended, because the results of this study showed that in these soils, its vegetative growth is severely reduced, and soil texture (especially light textures such as sandy loam) is one of the limiting factors for this rootstock.