Physiological Effects of Salicylic Acid and Thiourea on Growth and Productivity of Maize Plants in Sandy Soil

This study aimed to investigate the response of vegetative growth, yield, and some metabolic constituents of maize grains cv. Single Cross 124 to foliar applications of salicylic acid (SA; 100, 200, and 400 mg L^?1) and thiourea (TU; 500, 1000, and 1500 mgL^?1), two bioregulators, either alone or in combination. The foliar application of SA and TU alone significantly increased stem diameter, number of leaves?/?plant, leaf area, total dry weight?/?plant, leaf area index, net assimilation rate, specific leaf weight, and yield (i.e., ear length, ear diameter, number of grains?/?row, number of rows?/?ear, 100-grain weight, grain yield?/?plant, grain yield?/?fed (1 feddan = 4200 m²), harvest index, and shelling percentage) by increasing SA or TU concentrations up to 200 and 1500 mg L^?1, respectively. Salicylic acid and TU, when applied alone, significantly improved the nutritional value and quality of maize grains by increasing crude protein, total soluble sugars, total free amino acids, and total soluble phenols.     

Effect of Foliar Salicylic Acid Applications on Growth,Chlorophyll, and Mineral Content of Cucumber Grown Under Salt Stress

The objective of this study was to determine the effect of foliar salicylic acid (SA) applications on growth, chlorophyll, and mineral content of cucumber grown under salt stress. The study was conducted in pot experiments under greenhouse conditions. Cucumber seedlings were treated with foliar SA applications at different concentrations (0.0, 0.25, 0.50, and 1.00 mM). Salinity treatments were established by adding 0, 60, and 120 mM of sodium chloride (NaCl) to a base complete nutrient solution. The SA was applied with spraying two times as before and after transplanting. Salt stress negatively affected the growth, chlorophyll content and mineral uptake of cucumber plants. However, foliar applications of SA resulted in greater shoot fresh weight, shoot dry weight, root fresh weight, and root dry weight as well as higher plants under salt stress. Shoot diameter and leaf number per plant increased with SA treatments under salt stress. The greatest chlorophyll content was obtained with 1.00 mM SA treatment in both saline and non-saline conditions. Leaf water relative content (LWRC) reduced in response to salt stress while SA raised LWRC of salt stressed cucumber plants. Salinity treatments induced significant increases in electrolyte leakage. Plants treated with foliar SA had lower values of electrolyte leakage than non-treated ones. In regard to nutrient content, it can be interfered that foliar SA applications increased almost all nutrient content in leaves and roots of cucumber plants under salt stress. Generally, the greatest values were obtained from 1.00 mM SA application. Based on these findings, the SA treatments may help alleviate the negative effect of salinity on the growth of cucumber.     

Foliar Applied Phosphorous Enhanced Growth,Chlorophyll Contents,Gas Exchange Attributes and PUE in Wheat (Triticum aestivum L.)

A pot experiment was conducted to evaluate the foliar applied phosphorous with and without pre-plant dose (50 kg hac.^?1) of phosphorous on growth, chlorophyll contents, gas exchange parameters and phosphorous use efficiency (PUE) of wheat. The experiment was conducted in net house at Department of Crop Physiology, University of Agriculture Faisalabad, Pakistan. Two promising wheat cultivar AARI 2011 and FSD 2008 were used as a test crop with 5 foliar phosphorus (P) rates (0, 2, 4, 6, 8 kg ha^?1). The foliar applied P with pre-plant performed better than without pre-plant and control treatments. Foliar treatment of phosphorus at 6 kg ha^?1 P proved to be the best among other foliar treatments followed by 8 kg ha^?1 P. The foliar application of phosphorous at 6 kg hac.^?1 with pre-plant soil applied P increased the shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight and root dry weight. The chlorophyll contents (Chl. a and b) were increased with the foliar application of phosphorous. The gas exchange parameters (net carbon dioxide (CO₂) assimilation rate, transpiration rate, stomatal conductance and sub-stomatal CO₂ rate) were significantly improved by foliar applied P. The maximum values of net CO₂ assimilation rate (5.27 μ mol m^?2 sec.^?1), transpiration rate (3.44 μ mol m^?2 sec.^?1), stomatal conductance (0.81 μ mol m^?2 sec.^?1) and sub-stomatal CO₂ (271.67 μ mol m^?2 sec.^?1), were recorded in the treatment where P was foliar applied at 6 kg hac.^?1 with pre-plant soil applied Phosphorous. The foliar application of phosphorous with pre-plant soil applied P enhanced Phosphorous use efficiency (PUE) in both varieties. The maximum value of PUE (15.42%) was recorded in the treatment where foliar feeding of P was done at 6 kg hac.^?1 with pre-plant soil applied P in both genotypes.     

Response of maize (Zea mays) to the application of foliar fertilizers in the Sudan and Guinea savanna zone of Nigeria

Soil fertility problems resulting in low maize yields in smallholder farms are common in the West African moist savanna. The effectiveness of commercial foliar fertilizers in improving maize growth and yield was evaluated in three savanna agro‐ecological zones of Nigeria in two steps. In step one, eight commercial foliar fertilizers were assessed in a greenhouse study with two soil types using maize (Zea mays L. cv. 2004 TZE‐Y POPDT STR C4). The treatments included a control and a reference that received the optimum concentrations of nutrients. In step 2, three promising products from the greenhouse study (Turbotop, Agroleaf General, and Agroleaf high‐P) were evaluated under field conditions to validate the efficacy of products to enhance crop growth and yield. The foliar products were applied at the rate of 5 kg ha^?1. The treatments also included three rates of P application (0, 30, and 60 kg P ha^?1) as triple super phosphate (TSP) with or without foliar fertilizers. In the greenhouse study, differences in maize shoot dry matter yield and N and P concentrations, attributable to the spraying of the commercial foliar fertilizers, were observed for both soils. Spraying Turbotop, Agroleaf General, and Agroleaf high‐P gave the highest shoot dry biomass and N and P uptake compared to other products. Under field conditions, foliar spraying of Agroleaf high‐P significantly increased the shoot dry biomass of maize compared with the 0 P treatment in all locations. The grain yield of maize ranged from 1 to 4 t ha^?1 with significant differences across sites. Products with high concentrations of P and N in their formulation improved maize yield suggesting that appropriate management of P and N resources is a prerequisite for a sustainable maize intensification in the savanna agro‐ecologies.     

CO2浓度倍增、增温和轻度干旱对冬小麦根系生长和氮素吸收的影响

  【目的】  根系是作物氮素吸收的主要器官,研究CO₂浓度倍增和增温对根系生长和氮素吸收的影响,为应对气候变化提供科学的养分管理策略。  【方法】  以冬小麦(Triticum aestivum L.)为材料,在人工气候室内进行盆栽试验。设置对照(大气CO₂浓度400 μmol/mol+正常环境温度,CK)、CO₂浓度倍增(CO₂浓度800 μmol/mol+正常环境温度,ECO₂)、增温4℃ (CO₂浓度400 μmol/mol+增温4℃,ETem)和CO₂浓度倍增+增温4℃ (CO₂浓度800 μmol/mol+增温4℃,ECO₂+ETem) 4种气候情景,每种气候情景设置充分供水(80%田间持水量)和轻度干旱(60%田间持水量) 两个水分条件。调查了冬小麦根系生长(根生物量、根冠比、总根长、根总表面积和根总体积)和氮素吸收的情况,分析冬小麦氮素吸收与根系生长的关系。  【结果】  1) CO₂浓度倍增对冬小麦各生育期根系生长均无显著影响,而增温4℃和轻度干旱显著抑制了开花和灌浆期的根系生长。2) CO₂浓度倍增、增温、轻度干旱共同作用均显著抑制了冬小麦根系生长,其中增温和轻度干旱对根系生长具有协同抑制作用。3) CO₂浓度倍增显著降低了冬小麦灌浆期根氮含量,而对地上部氮含量无显著影响;增温4℃显著增加了冬小麦各生育期根氮含量和地上部氮含量;轻度干旱增加了根氮含量和地上部氮含量,且仅对地上部氮含量有显著影响;CO₂浓度倍增与增温交互作用仅对根氮含量增加有显著促进作用;增温与轻度干旱交互作用对根氮含量和地上部氮含量增加均有显著促进作用;CO₂浓度倍增与轻度干旱交互作用,以及CO₂浓度倍增、增温和轻度干旱三者交互作用对根氮含量和地上部氮含量增加均无显著影响。4)根氮积累量及地上部氮积累量均与根系形态指标对CO₂浓度倍增、增温、轻度干旱及其交互作用的响应具有相同变化特征,且根氮积累量和地上部氮积累量与各生育期根系形态指标有显著正相关关系。  【结论】  在本试验条件下增温和轻度干旱对冬小麦根系生长具有较强的抑制作用,且二者对根系生长具有协同抑制作用;CO₂浓度倍增对冬小麦各生育期根部和地上部氮素吸收的影响总体不显著,而增温和轻度干旱对根部和地上部氮含量增加均有一定的促进作用,对根部和地上部氮积累量增加均有抑制作用,增温是影响氮素吸收的主导因子。     

Efficiency of Potassium Fertilization and Salicylic Acid on Yield and Nutrient Accumulation of Sugar Beet Grown on Saline Soil

Rising soil salinity has been a major problem in the soils of Egypt in recent decades. Potassium fertilization and salicylic acid (SA) play an important role in promoting plants to tolerate salt stress and increased the yield of sugar beet crop. A field experiment on sugar beet (Beta vulgaris L.) grown on saline soil was carried out during 2014 growing season in Port Said Governorate, Egypt, to study the effect of potassium fertilization of the soil at applications of 0, 100, 150, and 200 kg potassium (K) ha^?1 and foliar spray of SA by solution of 1000 mg L^?1, twice (1200 L ha^?1 each time) on yield and nutrient uptake. Application of 200 kg K ha^?1 in combination with salicylic foliar spray gave the highest root length, root diameter, shoot and root yield, sucrose, juice purity percentage, gross sugar yield, and white possible extractable sugar, nitrogen (N), phosphorus (P), and potassium (K) content, and uptake of sugar beet. The highest increase in sucrose (20%) as well as white possible extractable sugar (184%) was obtained by 200 kg K ha^?1 in combination with salicylic foliar spray compared with untreated soil with potassium fertilization and without salicylic foliar spray.     

Phosphorus Efficiency of Buckwheat (Fagopyrum esculentum)

The ability of buckwheat (Fagopyrum esculentum) roots to acquire phosphorus (P) was characterized by investigating P uptake, morphological features, and chemical changes in the rhizosphere. Over a range of nutrient solution P concentrations (5–500 μmol · L^?1), maximum shoot growth was achieved with a P supply between 5 and 100 μmol · L^?1. Root weight and root length, as well as length and frequency of root hairs, were higher at low P levels. Root surface and the root surface/shoot dry weight ratio reached high values. Though P uptake rates were only moderate (0.15 pmol · cm^?1 root · sec^?1), shoot P concentrations were high (1.8% of dry weight with 100 μM P) predominantly being inorganic (80%). Phosphorus efficiency was characterized by a high specific absorption rate (810 mmol P · kg^?1 root dry wt · d^?1) rather than by an efficient utilization for dry weight production. Root exudates of low-P plants had lower pH values than exudates of high-P plants and increased the solubility of FePO₄ and MnO₂ to a greater extent. Amounts of exuded organic acids and phenolics were low and could not account for the observed solubilization of FePO₄ and MnO₂. Enhanced hydrolysis of glucose-6-phosphate by exudates from low-P plants was due to an increased “soluble” acid phosphatase activity, and root surface phosphatase activity was also slightly enhanced with P deficiency. In the rhizosphere soil of buckwheat, some depletion of organic P forms was observed, and in pot trials with quartz sand, buckwheat utilized glucose- 6-phosphate as a P source at the same rate as inorganic P.     

不同铁效率玉米品种苗期适应低铁胁迫的根系特征与铁积累差异

  【目的】  石灰性土壤高pH和高重碳酸盐含量严重影响土壤中有效铁含量,导致作物缺铁黄化、减产,铁高效玉米品种的推广应用是实现石灰性土壤玉米高产稳产的重要途径。 本研究探讨不同铁效率玉米品种适应低铁胁迫的根系特征与铁积累差异,旨在为铁高效玉米品种的推广应用提供科学依据。  【方法】  试验以铁高效玉米品种正红2号 (ZH2)、正大619 (ZD619) 和铁低效玉米品种川单418 (CD418)、先玉508 (XY508) 为材料,设置极低铁处理 (Fe0,Fe浓度为0 μmol/L)、低铁处理 (Fe10,Fe浓度为10 μmol/L) 和正常供铁 (Fe100,Fe浓度为100 μmol/L) 3个处理,通过砂培试验,研究不同铁效率玉米品种适应低铁胁迫的根系形态特征、干物质重、铁积累及铁吸收利用差异。  【结果】  低铁胁迫下,玉米幼苗的根干重、单株干重、铁积累量、根系相对铁吸收效率均显著降低,而根冠比与铁素生理效率均显著升高,且随胁迫程度的增加变幅加大;总根长、根表面积、根体积和根直径则表现出明显的品种差异,与正常铁处理 (Fe100)相比,低铁处理下铁低效品种的总根长、根表面积和根体积显著降低,根直径显著增加,而铁高效品种的总根长和根表面积差异不显著,根体积显著增加,根直径在极低铁处理(Fe0)下显著降低,低铁处理 (Fe10)下差异不显著;铁高效品种总根长、根表面积、根体积、根干重、单株干物重、铁积累量和根系铁吸收效率的降幅及根冠比的增幅均明显低于铁低效品种,而铁生理效率的增幅高于铁低效品种。相关性分析结果表明,玉米幼苗铁积累量与总根长、根表面积、根体积和根干重均呈显著正相关,而与根冠比呈负相关,其中与总根长 (R2 = 0.8546) 和根表面积 (R2 = 0.8983) 相关性最强。  【结论】  与铁低效玉米品种相比,铁高效玉米品种低铁胁迫下具有较优的总根长、根表面积及较高的根系铁吸收效率与铁生理效率,促进了其对铁的高效吸收与利用,提高了其对低铁环境的适应能力。     

水分胁迫条件下玉米毛状根再生植株耐旱性研究

以玉米毛状根再生植株为材料探讨其抗旱性,通过形态学指标：株高胁迫指数、干物质胁迫指数、根数、根长、根体积、根干质量、根的总吸收面积、根的活跃吸收面积及根冠比在水分胁迫下的变化的分析、灰色系统分析,表明根干质量、干物质胁迫系数、单株叶面积、根冠比、根体积与抗旱指数关系较密切。研究表明,毛状根再生植株由于强大的根系,即使在水分胁迫下仍能保持良好的根源水分信号,具有较强的抗旱能力。     

Effect of Foliar Applications of Humic Acid on Growth,Visual Quality,Nutrients Content and Root Parameters of Perennial Ryegrass (Lolium Perenne L.)

In recent years, applying humic acid (HA) has been common in turfgrass management. A series of experiments were conducted to evaluate the effect of HA on qualitative and quantitative characteristics of “Speedygreen” perennial ryegrass (Lolium perenne L.). Different concentrations of HA (0, 100, 400, and 1000 mg L^?1) were applied monthly as foliar application. Results showed that leaf phosphorus (P), potassium (K), and zinc (Zn) content, fresh and dry weight, chlorophyll content, and root fresh weights were not affected by HA. Meanwhile, HA improved the root and shoot development, except for root fresh weight. While just 100 mg L^?1 improved height, visual quality, nitrogen (N) content, roots length, and surface of roots, all of HA concentrations were effective on iron content. These results suggest that HA foliar application might be of benefit to enhance some nutrients uptake and root development of ryegrass possibly leading to improved drought resistance.     

Improving the performance of Bt-cotton under heat stress by foliar application of selenium

Heat stress at reproductive stages of cotton is a leading encumbrance to accomplish yield potential. An experiment was conducted to alleviate adversities of terminal heat stress on cotton. Experiment was conducted at University of Agriculture Faisalabad, Pakistan during 2013 and repeated in 2014 using Randomized Complete Block Design (RCBD) with split arrangement. Treatments were comprised of heat stress in main plots, viz., H₀ = no heat imposition, H₁ = heat imposition at squaring, and H₂ = heat imposition at flowering. Selenium was foliar applied in split plot, viz., Se₀ = 0, Se₅₀ = 50, Se₁₀₀ = 100, and Se₁₅₀ = 150 mg L^?1. Cell membrane thermostability, soluble proteins, and total phenolics were reduced significantly under heat stress leading to reduced cotton yield and related components. Maximum membrane thermostability, total phenolics, soluble proteins, opened bolls, boll weight, sympodial branches, and seed cotton yield were recorded with the application 150 mg Se L^?1.     

Growth,yield and bulb quality of onion (Allium cepa L.) in response to foliar application of boron and zinc

A field experiment was conducted to investigate the role of boron and zinc on growth, yield and quality of onion. There were eight treatment combinations consisted of four levels of boron (0, 0.1, 0.2 and 0.5%) and 4 levels of zinc (0, 0.1, 0.2 and 0.5%) were applied as foliar spraying. application of 0.5% boron significantly increased the growth (plant height, 63.93cm and number of leaves per plant, 7.25), yield (30.74 t ha^?1) and quality (total soluble solids, 13.45 ⁰B and pyruvic acid 5.94 µmol g^?1) of onion. Among various levels of zinc 0.5% exhibited the best growth (plant height, 67.25cm and number of leaf per plant, 7.75), yield (33.34 t ha^?1) and quality (total soluble solids, 14.57 ⁰B and pyruvic acid, 5.86 µmol g^?1) attributes of onion. These results suggest that the foliar application of boron and zinc significantly influenced the growth, yield and quality of onion.     

Exogenous application of humic acid and salicylic acid to alleviate seedling drought stress in two corn (Zea mays L.) hybrids

Efficacy of 1?mM humic (HA) and salicylic (SC) acids on SC 260 and SC 705 corn seedlings to alleviate drought stress via polyethylene glycol was studied via hydroponics at Shiraz University, Iran in a factorial, randomized design, with four replicates each. Under stress, SC 260 had higher electrolyte leakage compared to SC 705, and exogenous application of HA combined with SA decreased SC 705 electrolyte leakage. As a general trend, photosynthetic pigment content, relative water content, root and shoot length, mean number and diameter of central and peripheral root metaxylem, and K⁺ accumulation were higher in SC 705 treated with HA and SA compared to SC 260. Application of HA with SA could be an effective and low cost approach to ensure seedling establishment and plant growth in fields affected by soil drought in the early season, especially for the SC 705 corn hybrid in semi-arid regions.     

Effects of vermicompost and salinity stress on growth and physiological traits of Medicago rigidula L.

The use of vermicompost as a biological fertilizer under salinity stress conditions was tested in this research. Accordingly, the seeds of Medicago rigidula were grown in the greenhouse. The experiment was performed based on factorial arrangement in a completely randomized design using 5 replications. Application rates of vermicompost were 0, 10, 20 and 30%. Salinity stress was conducted in three levels (0, 50 and 100 mM sodium chloride (NaCl)). The highest and the lowest values of the plant survival capacity (%), shoot dry weight (g), leaf relative water content (LRWC) (%), total chlorophyll content (%), leaf area (cm²), total nitrogen content (TNC) (%) and potassium (K) content (%) of the plant tissues were found in VC4 × SL1 and VC1 × SL3 treatments, respectively. Whereas, the maximum and minimum values of root dry weight and root:shoot ratio were seen in VC1 × SL3 and VC4 × SL1 treatments, respectively.     

Boron-induced improvement in physiological,biochemical and growth attributes in sunflower (Helianthus annuus L.) exposed to terminal drought stress

Terminal drought stress (drought at reproductive growth stage) has been considered a severe environmental threat under changing climatic scenarios and undoubtedly inhibits sunflower production. A field study was conducted to explore the potential role of foliar applied boron (B) (0, 15, 30, 45 mg L^?1) at late growth periods of sunflower in alleviating the adversities of terminal drought stress (75, 64, 53 mm DI) grown from inflorescence emergence to maturity stages. The plant water relations such as leaf relative water content (RWC), water potential (Ψ_w), osmotic potential (Ψ_s), and turgor pressure (Ψ_p) were increased significantly with B foliar sprays while exposed to terminal drought stress. Foliar B application considerably improved the nitrogen and B concentrations in leaf and seed tissues, and also chlorophyll a and b pigments under terminal drought stress conditions. Drought-induced proline accumulation prevented the damages caused by drought stress, nevertheless, B foliar spray increased its contents. Compared to well-watered conditions, terminal drought stress substantially declined the growth performance in terms of reduced leaf area index (LAI), crop growth rate (CGR), net assimilation rate (NAR), and total dry matter (TDM) production; however, foliar B supply (30 mg L^?1) might be helpful for improving drought tolerance in sunflower with reduced growth losses.     

水分和磷对苗期玉米根系形态和磷吸收的耦合效应

水分亏缺和土壤缺磷已经成为玉米(Zea mays L.)生产的主要限制性因素,但水分和磷如何调节玉米根系形态和磷吸收尚不完全清楚。本研究采用盆栽土培试验,设置4个水分梯度[田间持水量的35%(W1)、55%(W2)、75%(W3)和100%(W4)]和2个磷处理[高磷:205 mg(P)·kg~(-1);低磷:11 mg(P)·kg~(-1)],探究水分和磷对苗期玉米根系生长和磷吸收的耦合效应。结果表明:(1)不管土壤磷供应如何,玉米苗干重、根干重、总根长和根表面积随水分供应强度的增加呈现先增加后降低的趋势,土壤有效磷含量也表现出相似的变化趋势,根质量比和平均根直径随水分供应强度的增加呈现下降的趋势,植株磷含量和磷累积量随水分供应强度的增加呈现稳定增加的趋势;(2)水分亏缺(W1)和过量供应(W4)均不利于玉米根系生长和干物质累积,水分亏缺(W1)抑制玉米对土壤磷素的获取,水分过量供应(W4)引起土壤磷素的奢侈吸收(W4),轻度的水分胁迫(W2)能够促进玉米根系的生长和干物质累积,减少对土壤磷的奢侈吸收,充足的水分供应(W3)能够促进玉米根系的生长、干物质累积和土壤磷素的吸收;(3)磷供应显著增加了玉米苗干重、根干重(W4除外)、总根长、根表面积、植株磷含量(W4除外)和磷累积量,但降低了玉米的根质量比。(4)两因素方差分析结果表明,水分对苗干重、根干重、根质量比、总根长、根表面积、平均根直径、植株磷含量、植株磷累积量和土壤有效磷含量的相对贡献分别为45.94%、36.71%、67.95%、59.63%、58.34%、81.86%、24.75%、35.66%和3.00%,磷对这些参数的相对贡献分别为34.78%、21.19%、14.84%、9.22%、9.21%、1.56%、35.54%、49.75%和94.40%,可见水分是控制玉米根系形态和干物质累积的关键因子,磷是控制玉米地上磷吸收和土壤有效磷含量的关键因子。总体来说,低磷条件下玉米根系对土壤磷的获取偏向于以根形态为主导的适应策略,高磷条件下玉米根系对土壤磷的获取偏向于以根生理吸收为主导的适应策略。水分和磷之间较好的耦合能够促进玉米根系生长、干物质累积,减少对土壤磷素的奢侈吸收。     

Shoot and root growth of rice seedlings as affected by soil and foliar zinc applications

Abstract

The present study investigated how foliar zinc (Zn) application affects seedling growth and Zn concentration of rice grown in a Zn-deficient calcareous soil with different soil Zn treatments. Seeds were sown in soil with five rates of Zn (0, 0.02, 0.1, 0.5 and 5.0?mg kg^?1 soil) with and without foliar application of 0.5% ZnSO₄. Seedlings were harvested at 35?days and separated into (i) the youngest leaves, (ii) the remaining shoot parts and (iii) roots. In soil with no Zn supply, shoot and root dry weight of the rice seedlings were significantly increased by foliar and soil Zn treatments. Plant growth was not clearly increased in low soil Zn treatments, while at each soil Zn treatment, foliar Zn application promoted growth of plants. Plants with adequate Zn supply had the highest Zn concentrations in the youngest leaf. Foliar Zn spray improved Zn concentration of the new growth formed after foliar spraying which shows that Zn is phloem mobile and moved from treated leaves into youngest new leaves. The results indicate clearly in rice seedlings that shoot growth shows more responsive to low Zn than the root growth. The results obtained in the present study are of great interest for proper rice growth in Zn-deficient calcareous soils but needs to be confirmed in other rice genotypes.     

Foliar Application of Iron (Fe) Improved the Antioxidant Defense and Cd Accumulation Potential of <Emphasis Type="Italic">Ricinus communis</Emphasis> Under Hydroponic Condition

Heavy metal-polluted water has become a problem for sustainable environment, agriculture, and human health. Phyto-accumulation is an eco-friendly technique for decontamination of metal-polluted water and soil. The efficiency of phyto-accumulation and rhizo-filtration can be enhanced by the application of certain nutrients to accumulator plants. In this study, we focused on the role of iron (Fe) in rhizo-filtration and phyto-accumulation of cadmium (Cd) from polluted water/media, using Ricinus communis plant. Medium was contaminated with 10 ppm Cd while Fe (2.50, 5.00, and 7.50 ppm) was applied both as foliar spray and medium addition separately. Accumulation of Cd and concentrations of soluble proline, phenolic compounds, and chlorophylls were measured in plant tissues. Addition of Fe into media significantly increased biomass in the plants but decreased Cd absorption by roots and its accumulation in other tissues of the plants. Foliar application of Fe, especially 7.5 ppm, significantly increased biomass as well as accumulation of Cd in tissues of the plants. Contents of soluble proline (41.88?±?3.56 ppm) and phenolics (171.00?±?4.98 ppm) in leaves were highly increased by foliar spray of 7.5 ppm Fe on the plants. On the other hand, highest concentrations of free proline (67.00?±?2.00 ppm) and total phenolics (82.67?±?2.52 ppm) in plant roots were observed in 7.5 ppm Fe added to media and as foliar spray, respectively. Strong correlations were observed between phenolics content in roots and leaves with Cd accumulation after foliar application of 7.5 ppm Fe.     

Effects of foliar selenium application on some physiological and phytochemical parameters of Vitis vinifera L. cv. Sultana under salt stress

Abstract

In this research the effect of foliar application of selenium (Se) at four levels (Na₂OSe₄; 0, 5, 10 and 20?mg L^?1) was evaluated on some phytochemical characteristics of Sultana grapevine under different salinity levels (NaCl; 0 or 75?mM). The vines were fed twice a week with Hoagland nutrient solution and Se was foliar applied twice with 24 intervals. During growing period, plant height, leaf number and leaf area were recorded. Moreover, at the end of experiment, mature leaves from middle nods of canes were used for measurement of some phytochemical indices. According to results, Se application had a positive effect on plant height, leaf numbers, leaf area and photosynthetic pigments content especially at 5?mg L^?1 and to some extent 10?mg L^?1 Se levels. Under salinity stress, foliar application of Se at 5?mg L^?1 considerably decreased vines leaves electrolyte leakage and lipid peroxidation values compared to non se-treated plants under salinity stress condition. Selenium had an additive effect on salinity stress (75?mM NaCl) induced accumulation of total phenol, total flavonoid, soluble sugars and proline content in leave of vines. Moreover, the interaction of salinity and Se at 5 and 10?mg L^?1 improved leaves antioxidant enzymes activities in Sultana grapevine. Likewise, foliar application of Se improved leaf mineral content in 75?mM NaCl -treated vines. Totally, foliar application of selenium (Se at 5 or 10?mg L^?1) increased salt tolerance through improvement in nutritional balance and by enzymatic and non-enzymatic antioxidant capacity in grapevine leaves.     

Moringa oleifera Lam. leaf extract as bioregulator for improving growth of maize under mercuric chloride stress

The contamination of agriculture soils with heavy metals is increasing due to both natural and anthropogenic activities. This has resulted in lowering the yield and quality of agriculture crops. The aim of the present investigation was to determine the effect of Moringa oleifera (M. oleifera) aqueous leaf extract (MALE) on growth and Hg phytoextraction potential of maize cv. Azam under mercuric chloride (HgCl₂)-induced stress. Soil was contaminated with different concentrations of HgCl₂ (1 and 0.5?mg/kg). The MALE was applied at 5% and 2.5% as seed soaking prior to sowing of seeds in the pots. The M. oleifera leaf was a good source of macronutrients (Na, K, Ca and Mg) and micronutrients (Fe, Zn, Mn, Co and Ni) as well as natural phenolics. The induced HgCl₂ stress significantly reduced seed germination (%), shoot dry weight, root dry weight, chlorophyll content and carotenoids content. The HgCl₂-induced stress was associated with accumulation of phenolics and Hg in roots. The accumulation of Hg in roots was significantly correlated with phenolics content (r?=?.8007, p?=?.000). The exogenous application of MALE significantly ameliorated adverse effects of HgCl₂ stress on maize plants. The accumulation of Hg in roots was significantly increased by MALE. It is inferred from findings of the present investigation that MALE served as bioregulator and can be applied to reduce adverse effects of HgCl₂ on maize. Moreover, MALE can enhance the Hg phytoremediation potential of maize.