The Effect of Zinc Nutrition on Two Olive (Olea europaea L.) Cultivars Components and Alleviate Oxidative Damage in Salinity Conditions

The role of zinc (Zn) in enhancing defense capacity of several plants against salinity has been demonstrated but there is limited information on the impact of Zn nutrition on alleviating salinity-induced oxidative damage in olive. One-year-old seedlings of two varieties of olive (Olea europaea L. cvs. Frontoio and Conservolea) supplied with three Zn levels (0, 1 and 5 mM in the form of ZnSO4.7H2O) were exposed to four salinity levels (0, 40, 80 and 120 mM NaCl). The increase in plasma membrane permeability and elevated leakage of potassium (K) and Zn from the olive roots were considered as indices of oxidative damage caused by salinity on root cells. In contrast, root membrane permeability and leakage of Zn and K ions in plants supplied with Zn was less than those non-supplied with Zn. Addition of Zn resulted in higher activity of CAT and APX. Higher salt-tolerance of Frontoio cultivar was associated with higher concentration of sulfhydryl (-SH) groups and lower membrane permeability of its roots in comparison with Conservolea cultivar. Based on the results obtained, addition of Zn improved plant enzymatic defense system and partly alleviated oxidative injuries induced by salinity on the olive

Phytosiderophore release by wheat genotypes differing in zinc deficiency tolerance grown with Zn-free nutrient solution as affected by salinity

There is limited information concerning the effect of salinity on phytosiderophores exudation from wheat roots. The aim of this hydroponic experiment was to investigate the effect of salinity on phytosiderophore release by roots of three bread wheat genotypes differing in Zn efficiency (Triticum aestivum L. cvs. Rushan, Kavir, and Cross) under Zn deficiency conditions. Wheat seedlings were transferred to Zn-free nutrient solutions and exposed to three salinity levels (0, 60, and 120 mM NaCl). The results indicated that Cross and Rushan genotypes exuded more phytosiderophore than did the Kavir genotype. Our findings suggest that the adaptive capacity of Zn-efficient ‘Cross’ and ‘Rushan’ wheat genotypes to Zn deficiency is due partly to the higher amounts of phytosiderophore release. Only 15 days of Zn deficiency stress was sufficient to distinguish between Zn-efficient (Rushan and Cross) and Zn-inefficient (Kavir) genotypes, with the former genotypes exuding more phytosiderophore than the latter. Higher phytosiderophore exudation under Zn deficiency conditions was accompanied by greater Fe transport from root to shoot. The maximum amount of phytosiderophore was exuded at the third week in ‘Cross’ and at the fourth week in ‘Kavir’ and ‘Rushan’. For all three wheat genotypes, salinity stress resulted in higher amounts of phytosiderophore exuded by the roots. In general, for ‘Kavir’, the largest amount of phytosiderophore was exuded from the roots at the highest salinity level (120 mM NaCl), while for ‘Cross’ and ‘Rushan’, no significant difference was found in phytosiderophore exudation between the 60 and 120 mM NaCl treatments. More investigation is needed to fully understand the physiology of elevated phytosiderophore release by Zn-deficient wheat plants under salinity conditions

Effects of Animal Manure, Sewage Sludge, and Cadmium Chloride on Cadmium Uptake of Corn Shoots

Reusing organic wastes such as sewage sludge is a good way of returning organic matter and nutrients into soil. However, the likelihood of heavy metal accumulation in soil and the subsequent contamination of human and animal food chains should be determined before any attempt is made to reuse organic wastes. The purpose of this greenhouse study was to investigate the impact of sewage sludge from the effluent of Isfahan Polyacryl Corp. on yield and shoot cadmium concentrations in corn as compared to the animal manure and mineral salt of cadmium. A completely randomized design with three treatments (cow manure, sewage sludge at 25 Mg/ha, and 5 and 10 mg/kg Cd as CdCl2) was used. Corn seedlings were harvested 60 days after planting and Cd concentration was measured in the shoot. Application of animal manure and sewage sludge significantly increased corn biomass. Cadmium increment, in both organic and mineral salt treatments, significantly increased cadmium concentration in the corn shoot. The plant cadmium concentration in the soil treated with industrial sewage sludge and CdCl2 were significantly higher than that treated with animal manure

The Effect of Preceding Crops on the Chemical Fractions of Copper (Cu) in the Rhizosphere and the Bulk Soil and its Relationship with Copper Uptake by Wheat

Introduction: Preceding crops as a source of organic matter are an important source of micronutrient and can play an important role in the soil fertility and the micronutrients cycle of soil. In addition to the role of the organic matter in increasing the concentration of micronutrients in soil solution, attention also should be paid to the role of the kind and the quantity of the root’s exudates that are released in response to the incorporation of different plant residues in the rhizosphere. Present research was conducted with the objective of studying the effect of the kind of preceding crops: Trifolium (Trifolium pretense L), Sofflower (Carthamus tinectirus L), Sorghum (Sorghum bicolor L), Sunflower (Heliantus annus L) and control (fallow) on the chemical forms of copper in the wheat rhizosphere and the bulk soil and Cu uptake by wheat and also investigating the correlation between the fractions of Cu in soil and Cu uptake in wheat. Materials and Methods: The present research was conducted as split plot in a Randomized Complete Block design (RCBD) with 3 replications and 5 treatments, in field conditions. In the beginning, the preceding crops were cultivated in the experimental plots and after ending growth, preceding crops were harvested. Then the wheat was cultivated in the experimental plots. Finally, after harvesting the wheat, soil samples were collected from the two parts of the root zone (the wheat rhizosphere and the bulk soil). The soil samples were air dried ground and passed through a 2-mm sieve and stored for chemical analysis. Soil pH (in the soil saturation extract) and organic matter (Walkley–Black wet digestion) were measured in standard methods (1). The Total Organic Carbon (TOC) was measured by Analyzer (Primacs SLC TOC Analyzer (CS22), Netherlands). The available Cu in soil was extracted by DTPA and determined using atomic absorption spectroscopy (2). The fractionation of soil Cu was carried out using the MSEP method (3). Results and Discussion: The results showed that the preceding crops significantly decreased soil pH, also significantly increased the DOC and DTPA-extractable Cu.These changes were higher in the Trifolium preceding treatment in the rhizosphere soil. Also, the preceding crops significantly decreased Carbonate -Cuand Residual-Cu fractions in the wheat rhizosphere compared with the bulk soil. The preceding crops (except Trifolium) significantly increased Oxide-Cu fraction. The soil Oxide- Cu fraction was higher in the rhizosphere in comparison with the bulk soil. The preceding crops increased the Organic-Cu in both the wheat rhizosphere and the bulk soil and it was higher in Trifolium treatment. The preceding crops increased Cu uptake by wheat and Organic-Cu positively correlated with Cu uptake by wheat. Conclusion: The Organic-Cu fraction increased in the rhizosphere compared with the bulk soil, whereas Oxide- Cu, Carbonate–Cu and Residual-Cu fractions decreased. According to the results, the observed increase in the copper concentration of organic fraction in the rhizosphere was due to the decrease in the copper concentration of carbonate, oxide and residual fractions. In fact, the main process is the transmission of copper from carbonate, oxide and residual fractions to another fraction. Also, the results showed that the root exudates of the preceding crops and wheat affected the different forms of copper in the soil solid phase. Furthermore, the results of copper forms correlation analysis with Cu uptake by wheat showed that the Organic-Cu fraction had more important role in supplying copper was needed for wheat. Therefore, the preceding crops increased the copper concentration of organic fraction in the rhizosphere compared with the bulk soil, and these changes are associated with increasing the amount of copper uptake in wheat

Micronutrient-efficient genotypes for crop yield and nutritional quality in sustainable agriculture. A review

About 4 billion people will be added onto the present population by 2050. To meet further demand for food, agricultural production should increase on the existing land. Since the Green Revolution, higher crop production per unit area has resulted in greater depletion of soil phytoavailable micronutrients while less attention has been paid to micronutrients fertilization. Now, micronutrient deficiency has become a limiting factor for crop productivity in many agricultural lands worldwide. Furthermore, many food systems in developing countries can not provide sufficient micronutrient content to meet the demands of their citizens, especially low-income families. There are several solutions such as soil and foliar fertilization, crop systems, application of organic amendments to correct micronutrients deficiency and to increase their density in edible parts of plants. This review article presents (1) agronomic approaches to improve crop yield and micronutrient content of food crops, and (2) genotypic variation in uptake and accumulation of micronutrients. Considering ecological concerns, cultivation and breeding of micronutrient-efficient genotypes in combination with proper agronomic management practices appear as the most sustainable and cost-effective solution for alleviating food-chain micronutrient deficiency. Micronutrient-efficient genotypes could provide a number of benefits such as reductions in the use of fertilizers, improvements in seedling vigor, and resistance to abiotic and abiotic stresses. Using bioavailable micronutrient-dense staple crop cultivars can also be used to improve the micronutrient nutritional status of human

Phytosiderophore release by wheat genotypes differing in zinc deficiency tolerance grown with Zn-free nutrient solution as affected by salinity

There is limited information concerning the effect of salinity on phytosiderophores exudation from wheat roots. The aim of this hydroponic experiment was to investigate the effect of salinity on phytosiderophore release by roots of three bread wheat genotypes differing in Zn efficiency (Triticum aestivum L. cvs. Rushan, Kavir, and Cross) under Zn deficiency conditions. Wheat seedlings were transferred to Zn-free nutrient solutions and exposed to three salinity levels (0, 60, and 120 mM NaCl). The results indicated that Cross and Rushan genotypes exuded more phytosiderophore than did the Kavir genotype. Our findings suggest that the adaptive capacity of Zn-efficient ‘Cross’ and ‘Rushan’ wheat genotypes to Zn deficiency is due partly to the higher amounts of phytosiderophore release. Only 15 days of Zn deficiency stress was sufficient to distinguish between Zn-efficient (Rushan and Cross) and Zn-inefficient (Kavir) genotypes, with the former genotypes exuding more phytosiderophore than the latter. Higher phytosiderophore exudation under Zn deficiency conditions was accompanied by greater Fe transport from root to shoot. The maximum amount of phytosiderophore was exuded at the third week in ‘Cross’ and at the fourth week in ‘Kavir’ and ‘Rushan’. For all three wheat genotypes, salinity stress resulted in higher amounts of phytosiderophore exuded by the roots. In general, for ‘Kavir’, the largest amount of phytosiderophore was exuded from the roots at the highest salinity level (120 mM NaCl), while for ‘Cross’ and ‘Rushan’, no significant difference was found in phytosiderophore exudation between the 60 and 120 mM NaCl treatments. More investigation is needed to fully understand the physiology of elevated phytosiderophore release by Zn-deficient wheat plants under salinity conditions