جستجوی مقالات مرتبط با کلیدواژه « سیتروملو » در نشریات گروه « آب و خاک »

The consumption of inorganic fertilizers in agricultural ecosystems led to the destruction of soil physical, chemical, and biological characteristics and severely affected the quality of the products. Therefore, the application of compost fertilizers in agricultural lands has been widely considered, and it has been mentioned as the best environmental measure. Rootstock plays a crucial role in the growth of citrus trees. Among all the nutrients needed by citrus, nitrogen has a vital role, and a large amount of this macronutrient is supplied in the soil every year. The release of nutrients from organic matter, especially nitrogen, is slower than the nitrogen release from chemical fertilizers. Rootstock affects the photosynthetic capacity of the transplanted cultivar, which is related to the annual carbohydrate redistribution and is a determining factor for vegetative growth and reproductive development. The growth, yield and fruit quality of cultivars are, therefore, strongly regulated by rootstock. In the recent study, the effects of compost and nitrogen fertilizers on common rootstocks in Mazandaran province, including citrange, citrumelo, and sour orange, were investigated. An experiment was conducted as a completely randomized design at Qaemshahr Horticultural Research Station. The treatments included sulfur granular compost (0, 2.5, 5, and 7.5%), produced by Mazandaran Wood and Paper Industries Company, and pure nitrogen (0, 20, 40, and 80 mg kg-1) in the form of ammonium sulfate. Vegetative growth, including plant height, crown diameter, and the number of leaves, were measured. Also, to study the changes in leaf nutrient concentration, leaf samples were collected, in July and the concentration of nutrients in leaf tissue was measured. A randomized complete block design was conducted at Qaemshahr Horticultural Research Station in 2017. The treatments included sulfur granular compost (0, 2.5, 5, and 7.5%), produced by Mazandaran Wood and Paper Industries Company, and pure nitrogen (0, 20, 40, and 80 mg kg-1) in the form of ammonium sulfate. One-year-old seedlings of the same size from citrange, citrumelo, and sour orange were planted in 7- kg pots containing arable soil and the treatments. The applied soil was analyzed, and its physical and chemical properties were determined. Irrigation of all pots until reaching the field capacity (weight method) was performed uniformly for all treatments. At the end of the growth period, vegetative growth parameters, including plant height, crown diameter, and the number of leaves, were measured. Also, to study the changes in leaf nutrient concentration, fully developed leaves samples were collected, in July and the concentration of nutrients was analyzed. Nitrogen was determined by the Kjeldahl method with a sulfuric acid-hydrogen peroxide mixture. Phosphorus by calorimetric, potassium using a flame photometer, and calcium, magnesium, iron, manganese, zinc, and copper were measured using the flame atomic absorption method. Results showed that the highest nitrogen concentrations in citrange and citrumelo seedlings were 2.92 and 2.97% due to 40 and 80 mg kg-1 N and 2.5% compost, respectively. In citrumelo rootstock, plant height increased with enhancing nitrogen application levels at different compost levels. Compost levels did not show a significant increase in citrange height, but the highest height growth was observed at 40 and 80 mg kg-1 nitrogen. In the sour orange rootstock, consumption of high levels of compost and nitrogen significantly reduced plant height. In all three rootstocks, the highest concentrations of potassium were observed in high levels of compost and no nitrogen application. The concentration of iron and zinc in citrumelo leaves increased with increasing compost levels. The trend was different in citrumelo so that consumption of 2.5% compost and 40 mg nitrogen fertilizer showed the highest concentration of leaf iron (151 μg g-1), while the application of 5% compost without nitrogen reduced the concentration of iron to 62.2 μg g-1. Changes in citrange zinc concentration were similar to citrumelo. In sour orange, iron concentration changed limitedly and ranged from 83.8 μg g-1 in 2.5% compost and 20 mg kg-1 nitrogen fertilizer to 61 μg g-1 in control. In this rootstock, the highest concentration of zinc was obtained from no compost application and 40 mg kg-1 nitrogen (28.14 μg g-1), whereas the lowest concentration of iron was observed in control. Citrange seedlings performed better in nutrient uptake than citrumelo and sour orange seedlings. Consumption of 5 and 7.5% levels of compost in sour orange rootstock reduced plant height and crown diameter and caused rosette, led to an increase in the number of leaves. The most effective level of nitrogen in sour oranges was 80 mg kg-1 nitrogen. Application of 80 mg kg-1 nitrogen and 2.5% compost, and 80 mg kg-1 nitrogen and 5% compost led to the highest number of leaves in citrumelo and citrange rootstocks, respectively. According to vegetative growth and concentration of nutrients data, especially from the nitrogen concentration point of view, maximum vegetative growth was obtained in citrumelo rootstock from 2.5% compost and 40 mg kg-1 nitrogen treatment and in citrange and sour orange rootstocks from 2.5% compost and 80 mg kg-1 nitrogen treatment.

The objectives of this study were to evaluate P acquisition efficiency (PAE) and internal phosphorus (P) utilization efficiency (PUE) in Thomson Navel Orange (Citrus sinensis L. Osbeck.) grafted on three rootstocks in two soils. For this purpose, a pot experiment was conducted in a completely randomized design using factorial arrangement in three replications. Treatments consisted of two levels of P (0, 100 mg/kg) and three rootstocks of citrus (sour orange, Swingle citrumelo, and Troyer citrange) and two soil types with different percentage of CaCO3. (CaCO3% in soil “1” and “2” were 16% and 2.3 %, respectively). Eighteen months after planting seedlings in pots, plants were harvested and plant indices including dry weight and P uptake were measured. In addition, PAE and PUE were determined. The results of this study showed that shoot dry weight of Thomson Navel Orange on sour orange, citrumelo and citrange was significantly increased in the two studied soils following P application (p < 0.05). After application of P fertilizer, the highest dry weight of shoots was found for Thomson Navel Orange on sour orange (74%) in soil “1”; and on citrumelo rootstock (49%) in soil “2”. When P supply was deficient, Thomson Navel Orange on sour orange rootstock in the soil “1”, and on citrange and sour orange rootstocks in the soil “2” were more efficient in P acquisition than other rootstocks. With an adequate P supply and based on PUE, Thomson Navel Orange on sour orange rootstock in the soil “1”, and Thomson Navel Orange on citrange and on sour orange rootstocks in the soil “2” were more efficient in internal P utilization than other rootstocks. The results showed that the choice of an efficient rootstock in P uptake depends on the soil condition and is site-specific. In order to improve the performance of citrus seedlings in the studied areas, it is recommended either to use a P- efficient rootstock in these areas or, if it is not possible to use an efficient rootstock due to soil and climatic constraints, use P fertilizer based on the soil available phosphorus.

Citrus is the main fruit group grown in tropical as well as sub-tropical climate of more than 150 countries in the world. In Iran, the total area under citrus crops is 0.284 M ha with a production of 4.345 M ton and a productivity of 17 ton per ha. Citrus is also one of the most important horticultural products in Mazandaran, with 112,000ha devoted to its cultivation. Drought stress is frequent in Iran and is common in the dry summer periods in Mazandaran. Therefore, irrigation is essential during mentioned periods in this province. Irrigation scheduling and water requirement of the citrus crops are one of the main concerns of the citrus fruit production. Irrigating based on soil water potential (tensiometer) is one of the irrigation scheduling methodologies. In addition, fertilization is used to promote quantity and quality of fruit production. Potassium has a key role in the osmotic adjustment of plants and alleviate the effects of drought stress. Until now, studies on citrus to evaluate the effects of potassium fertilization to mitigate the negative effects of drought stress have not been conducted. In the present study, we hypothesised that K applications via soil could contribute to osmotic adjustment of citrus and alleviate the effects of drought stress. Thus, the objective of the present study was to evaluate the effects of different soil water potential and rate of potassium (K) application on biochemical indices and growth responses of Thomson navel (Citrus, sinensis (L.) osbeck) orange seedlings on Citrumelo rootstock. This study site was located at the Citrus and Subtropical Fruit Research Center of Horticultural Science Research Institute (36°54′11″N, 50°39′30″E), with a mean annual rainfall of 1200 mm. Thomson navel trees (Citrus, sinensis (L.) were planted at 7 × 6m distances. Soil had a pH (soil-to-water suspension ratio of 1:2) of 6.2 and contained 14.3 g kg−1 organic C and CaCO3<1%. The texture of soil was clay loam. A two-year field study was conducted in a factorial experiment based on randomized complete block design with four selected ranges of soil water potential, two levels of K application, and four replicates. Irrigations were scheduled using soil moisture tensiometers. The irrigation treatments were scheduled when soil water tensions reached 20, 40, and 60 kilopascal (kPa) on the tensiometers per treatment and results were compared with control (none irrigation) treatment. Soil water tensions of 20, 40, and 60 kPa correspond to soil water depletions of 17, 35, and 52%, respectively, of the available soil water for the studied soil. Levels of K fertilizer were 50 (k1) and 100 (K2) g K × age of tree. Potassium fertilizer was broadcast below the tree canopy in March. At the end of each year, yield, available K and some growth indices were measured. In addition, in the last year, proline, ionic leakage and electrical conductivity were also measured. All data were represented as mean of four replicates. Differences in yield, canopy diameter and available K among fertilizer and irrigation treatments and sampling years were analyzed using general linear model two-way analysis of variance (ANOVA) in SAS 9.1. Since the mentioned attributes were measured during two years to take into account annual variation, we used ANOVA procedure for a combined analysis of data. The significance of differences between the mean of treatments were determined by using Duncan test. All the statistical analyzes were performed by SAS 9.2. The results showed that irrigation increased the canopy diameter (P<0.05). Under K1 application, the tree yield was not significantly different (P≥0.05) between irrigation at different water potentials (I1, I2 and I3). However, the K effects on tree yield depended on soil water potential and the positive effects of K2 application were evident only in the I2 and I3 treatments. However, K2 application reduced the yield in irrigation treatments including I0 and I1 significantly (P<0.05) compared with K1 application. In addition, the results of the last year showed that proline and ionic leakage were increased (P<0.05) by reduce of water potential in irrigation time. However, double application of K (K2) increased (P<0.05) proline and decreased ionic leakage as compared with normal application of K (K1). Moreover, available K and electrical conductivity were increased (P<0.05) by excessive application of K and reduce of soil water potential. In summary, regarding this experiment, irrigation at 60 kPa (depletion coefficient =52%) and potassium application rate of 50 g K × age of tree was the best treatment.