فهرست مطالب tahereh raiesi

As the foundation of nutritious foods lies in the soil, the consumption of crops grown in contaminated soils may pose an elevated risk of health issues through the soil-plant-human pathway. The impact of heavy metals (HMs) and metalloids on the physiological and biochemical responses of plants can have adverse effects on both growth and yield. The excessive accumulation of these substances in plant tissues poses a significant challenge to public health. HMs possess the capability not only to function as carcinogens but also to act as co-carcinogens, thereby activating specific chemical compounds. According to the World Health Organization (WHO) reports, the target values, representing the desirable maximum concentrations of HMs in the soil, follow the order: Cr > Pb > Zn > Cu > Ni > Cd. This implies that Cd poses the highest potential risk, given its target value of 0.8 mg/kg, while Cr carries the lowest potential risk, with a target value of 100 mg/kg. Various agricultural management practices are recognized as significant pathways that induce the accumulation of metals in the soil and the surrounding environment. Hence, understanding the origin and status of HMs in the environment, along with assessing their potential risks and developing strategies to mitigate these risks, becomes crucial. This study aims to evaluate different facets of the soil-human health continuum concerning potentially toxic metals.

In order to study effect of foliar application of calcium (Ca) and potassium (K) and fruit position in the canopy on physicochemical characteristics of ‘Thomson Navel’ orange trees (Citrus sinensis L. Osbeck, a two-year factorial experiment based on randomized complete blocks design carried out with two factors including the type of foliar spray in four levels (Ca(NO3)2, KNO3, Ca(NO3)2+KNO3, and Control) and fruit position in the tree canopy in two levels (inside or outside) with three replications. The results showed that peel thickness, citrus color index (CCI), and a ratio of total soluble solid to titratable acid (TSS/TA) were higher in the fruits harvested from the outer canopy compared to the canopy inside (P<0.05). Also, the results showed that the peel thickness of the fruit increased with foliar application and the highest increase was found in the foliar spray of K and K+Ca. With Ca foliar application (Ca and K+Ca), TSS and TA significantly decreased compared to the control and potassium foliar application alone, but the ratio between the two indices increased. The results showed that the effect of foliar application on total phenol and antioxidant capacity depends on the position of the fruit on the tree canopy. In conclusion, foliar application of K and Ca cause improve the fruit quality of the ‘Thomson Navel’ sweet orange. Besides, fruit at different canopy positions vary in their physicochemical characteristics and should be harvested separately to have uniform quality and get the maximum economic return.

In order to evaluate the effect of different preharvest fertilization methods on quantitative and qualitative characteristics of kiwifruit (var. Hayward) at postharvest stage, an experiment was conducted in a randomized complete block design with 8 treatments in four replications in Citrus and Sub-tropical Fruits Research Center during three crop years (2014- 2016). Fertilizer treatments included broadcast application (control), localized placement, strip, foliar, fertigation, broadcast application + foliar, fertigation + foliar and localized placement + foliar. Then in the first of November in each year, sampling of the treated fruits was carried out to measure the quantitative and qualitative characteristics of the fruit at postharvest stage during three years. Harvested fruits were kept cold storage at 0.5 ° C and 90% relative humidity for three months. The results showed, the fertilizer method had a significant effect on the fruits weight loss. So that the fruits fed by strip (6.08%), fertigation (6.74%) and combination of fertigation and foliar application (6.61 %) methods had less weight loss during cold storage, respectively. L * and chroma content of flesh were affected by the fertigation method. Result also showed that the control fruits had the lowest amount of antioxidant capacity and strip fertilization treatment had the highest antioxidant capacity during cold storage. Sensory attributes analysis showed that the amount of aroma, flavour, off-flavour, sweetness, sourness and overall fruit acceptability in fruits treated by broadcast application + foliar method obtained the most desirable scores.

There are many anthropogenic activities that have caused the accumulation of potentially toxic metals (e.g., lead, cadmium, chromium, nickel, arsenic, cobalt, and mercury) in the environment. Lead (Pb) is known as a very toxic and non-biodegradable element that has no metabolic function in living creatures. It can be easily taken up and transferred within plant tissues; consequently, it can easily enter the food chain, causing phytotoxicity, which in turn through different biochemical and enzymatic reactions, can result in severe threats to public health. After entering soil and sediments, Pb may be diffused among soil components and associated with them through different geochemical fractions, which determine the final fate of Pb in terms of bioavailability and uptake by plants. Metal bioavailability in soils is largely dependent on the soil and plant properties and interactions with other elements. In spite of the fact that there are numerous studies on the influence of heavy metals on public health but there are limited studies that consider the role of the soil-plant chain on the final fate of potentially toxic metals in respect to threat the public health. This manuscript defines a joint challenge between agricultural and medical sciences and shows that the soil (as the base of agriculture) affects human health in a variety of ways, with human health being linked to the health of the soil.

Witches’ broom disease of lime (WBDL), caused by ‘Candidatus Phytoplasma aurantifolia’, is major limiting factor for Mexican lime (Citrus aurantifolia Swingle) production in southern Iran. In this investigation, leaf nutrient profiling of the healthy and infected rooted Mexican lime during WBDL progression (90-330 days) as well as to distinguish the infected from the healthy Mexican limes under greenhouse condition. For this aim, the healthy and infected plants were sampled 90, 150, 210, 270 and 330 days after inoculation with phytoplasma and leaf nutrient concentrations including nitrogen, phosphorus, potassium, calcium, magnesium, boron, iron, manganese, zinc and copper were measured during WBDL progression. The results showed phytoplasmal infection mostly caused to a marked decrease in the concentration of nitrogen, calcium, boron, manganese, and significant increase in phosphorus, magnesium, potassium, iron, and zinc in the infected leaves. In Mexican lime leaves, copper concentration did not significantly change after inoculation with phytoplasma with respect to the healthy plants. In addition, the principal components analysis (PCA) based on the concentration of nutrients could not distinction infected and healthy plants in the early stages of sampling (before the appearance of symptoms), but PCA revealed a clear distinction between the leaf nutritional profiles of healthy and infected plants after the appearance of symptoms during the progression of WBDL. In conclusion, this study provides new insights into the lime response to phytoplasma infection during the progression of WBDL and it can be useful in adopting strategies to improve and increase the economic efficiency of trees infected with WBDL.

Kiwifruit requires a high quantity of nutrients that must be supplied through fertilization to obtain an optimum yield on a sustainable basis. This research was conducted to evaluate different fertilization methods including broadcast application (as control), deep placement of the fertilizer and fertigation, alone or in combination with foliar application and their effects on the yield, leaf mineral contents, and some quality properties of kiwifruit (A. deliciosa cv. Hayward). Results showed that fertilization methods had a significant effect on yield and the highest level of yield (76 Kg tree-1) was obtained in the combination of fertigation with foliar spray. In addition, foliar application significantly increased leaf mineral contents of kiwifruit in all treatments. Furthermore, the fertilization method had significant effects on phenol, ascorbic acid contents, and antioxidant capacity of fruits. The highest levels of antioxidant (70.9%), phenol (103.6 mg 100g-1), and ascorbic acid (54.2 mg 100 g-1) in fruits were recorded in ‘soil application’ method. Total soluble carbohydrate and starch contents of the fruits were reduced following foliar nutrition in all treatments. However, foliar nutrition significantly increased fruit crude protein. In conclusion, based on obtained results, fertilization method directly influenced the yield and leaf mineral status and indirectly influenced the fruit chemical composition of Hayward kiwifruit. In fact, the supplemental foliar application reduced some fruit quality attributes (lower antioxidant activity and carbohydrate content) but enhanced the yield of kiwifruit.

Witches’ broom disease of lime (WBDL), caused by ‘Candidatus Phytoplasma aurantifolia’, is major limiting factor for Mexican lime (Citrus aurantifolia Swingle) production in southern Iran. In this investigation, biochemical composition profiling of the healthy and infected rooted Mexican lime wasmonitored during WBDL progression (90-330 days) as well as to distinguish infected from healthy Mexican limes under greenhouse conditions. For this aim, stem cuttings is taken from healthy Mexican lime. After three months, half of Mexican lime cutting were inoculated by bark-grafting from WBDL-affected Mexican. Six healthy and infected plants were sampled 90, 150, 210, 270 and 330 days after inoculation with Phytoplasma. Pigments, total phenol, antioxidant capacity, soluble carbohydrate and starch content in leaves were measured. Results showed Phytoplasmal infection caused growth inhibition and reduced stem and root dry mater. Moreover, infection mostly caused to a marked decrease in pigments and significantly increased soluble carbohydrates and starch. In Mexican lime leaves, phenol contents and antioxidant capacity were increased after inoculation with Phytoplasma. In addition, the principal components analysis (PCA) revealed a clear distinction between the leaf biochemical profiles of healthy and infected plants during the progression of WBDL. In conclusion, this study provides new insights into the lime response to phytoplasma infection during the progression of WBDL. Finally, we showed that healthy plants can be isolated from infected plants using biochemical profiles.

The current study was aimed at determining the optimum time of urea foliar spray to improve fruit quantity and quality (fruit set%, yield, size, peel thickness of fruits, titrable acidity (TA), total soluble solid (TSS)) of ‘Thomson Navel’ orange trees (Citrus sinensis L. Osbeck.) for 2 consecutive years. Thus, a 0.5% solution of urea was sprayed on to 20 years old orange trees during January (T1), March (T2) and June (T3). There was a set of control trees that only sprayed with simple water (T0). The results showed that the trees receiving foliar applied urea, independent of application time, had significantly greater leaf nitrogen content and fruit set % than the control trees. In addition, the impact of the urea foliar application on the yield and quality properties of fruits was significant (P<0.05). The effect of urea spray time on TSS/TA (maturity index) and yield depended on studied year. In first year (low yield), the highest level of yield observed in T1 and T3 treatments and the highest level of TSS/TA observed in T0 treatment. In second year (high yield), the highest level of yield and TSS/TA observed in T2 and T3 treatments. Therefore, it is important to determine the optimal level and time of application of nutrients to stimulate a specific physiological process in citrus, depending on the studied year (high yield or low yield).

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.

Root systems in citrus trees develop from rootstocks. They have, thus, direct effects on water and nutrient uptake and translocation. The present study was conducted to evaluate the effects of three rootstocks common in northern Iran (i.e., sour orange, Swingle citrumelo, and Troyer citrange) on the nutrient uptake, translocation, and accumulation (NAI) as well as their translocation indices (NTI). For this purpose, one-year old seedlings of sour orange, Swingle citrumelo, and Troyer citrange were cultivated in a loamy soil under glasshouse conditions. After six months, the seedlings were harvested to measure their dry weights as well as their leaf, stem, and root concentrations of phosphorus, potassium, calcium, iron, manganese, zinc, and copper. Also, the rootstocks investigated were discriminated based on their nutrient accumulation and translocation indices as determined by factor analysis. Results showed the superiority of Troyer citrange in terms of phosphorus and iron uptake; citrumelo in terms of potassium and copper uptake; and common sour orange in terms of calcium and manganese uptake. The order recorded for the rootstocks in terms of their nutrient accumulation indices was sour orange>Troyer citrange~Swingle citrumelo. It was also found that the nutrient translocation indices of the three citrus rootstocks decreased in the following order: Swingle citrumelo > Troyer citrange > sour orange. Clearly, the citrus rootstocks investigated exhibited differential nutritional behaviors and different capacities with respect to utilizing plant nutrient elements.

Rhizosphere region soils have different chemical and biological properties from bulk soils. Information about phosphorus (P) release in the rhizosphere region soil of bean is limited. Therefore, the objective of this research was to evaluate the effects of bean (Phaseolus vulgaris L.) rhizosphere on P release kinetics in 9 types of calcareous soils from Chaharmahal-Va-Bakhtiari province under greenhouse conditions in a rhizobox. The kinetics of P release in the bulk and the rhizosphere region soils were determined by successive extractions with 0.5 M NaHCO3 in a period of 2 to 1008 h at 25 ± 1°C. The results of kinetics study showed that the mean amount of the extracted P after 1008 h in the extraction period in the rhizosphere region soils (215 mg kg-1) was significantly lower than that in the bulk soils (226 mg kg-1). The release kinetics of P from the rhizosphere region and bulk soils could be defined well by use of the first order, power functions and also, the simplified Elovich equation. The results showed that the amount of the P released after 1008 h and the constant P release rate in power function of the rhizosphere region and the bulk soils had a significant correlation with bean plant growth indices. This research indicated that bean rhizosphere could modify the P release characteristics. In addition, the released P amount and rate are important factors in supplying available P to plants.