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.     

Combined effect of deficit irrigation and foliar-applied salicylic acid on physiological responses,yield, and water-use efficiency of onion plants in saline calcareous soil

Field-applied salicylic acid (SA) could provide a potential protection against drought stress in onion large-scale production. Two-season field experiments were consecutively conducted in 2013/2014 and 2014/2015 to study the effect of 1 and 2 mM SA on growth, yield, plant water relations, chlorophyll a fluorescence, osmoprotectants, and water-use efficiency (WUE) in onion plants under four levels of irrigation (I₁₂₀ = 120%, I₁₀₀ = 100%, I₈₀ = 80%, and I₆₀ = 60% of crop evapotranspiration). Foliar application of SA enhanced drought stress tolerance in onion plants by improving photosynthetic efficiency and plant water status as evaluated by membrane stability index and relative water content. These results were positively reflected by improving plant growth, productivity, and WUE under drought stress conditions. Therefore, SA application may, in future, find application as a potential growth regulator for improving plant growth and yield under deficit irrigation by 20–40%.     

Roles of glycine betaine in mitigating deleterious effect of salt stress on lettuce (Lactuca sativa L.)

This study was conducted to evaluate the roles of glycine betaine (GB) in mitigating deleterious effect of salt stress on lettuce. Lettuce plants were subjected to two salinity (0 and 100 mmol l^?1 NaCl) and four GB levels (0, 5, 10, 25 mmol l^?1). Salinity resulted in a remarkable decrease in growth parameters, relative leaf water content and stomatal conductance. Plants subjected to salt stress exhibited an increase in membrane permeability (MP), lipid peroxidation (MDA), leaf chlorophyll reading value, H₂O₂ and sugar content. Exogenous foliar applications of GB reduced MP, MDA and H₂O₂ content in salt-stressed lettuce plants. Salt stress increased Na and generally decreased other nutrient elements. GB reduced Na accumulation, but significantly increased other element contents under salinity conditions. The study showed that gibberellic acid (GA) and salicylic acid (SA) content in salt-stressed plants were lower than those of nonstressed plants. However, salinity conditions generally increased the abscisic acid content. GB treatments elevated the concentrations of GA, SA and indole acetic acid (IAA) at especially 10 and 25 mmol l^?1 GB under salt stress conditions. It could be concluded that exogenous GB applications could ameliorate the harmful effects of salt stress in lettuce.     

INFLUENCE OF SODIUM CHLORIDE AND CALCIUM FOLIAR SPRAY ON HYDROPONICALLY GROWN PARSLEY IN NUTRIENT FILM TECHNIQUE SYSTEM

The effects of salinity [30 or 90 mM sodium chloride (NaCl)] and calcium (Ca) foliar application on plant growth were investigated in hydroponically-grown parsley (Petroselinum crispum Mill). Increasing salinity reduced fresh weight and leaf number. Calcium alleviated the negative impacts of 30 mM NaCl on plant biomass and leaf fresh weight but not in case of 90 mM. Plant height, leaf and root dry weight and root length did not differ among treatments. Total phenols increased with calcium application, chlorophyll b reduced by salinity, while total carotenoids increased with salinity and/or Ca application. Salinity reduced nutrient uptake [nitrate (NO₃), potassium (K), phosphorus (P) and Ca] and elemental content in leaves and roots. Calcium application reduced P but increased Ca content in plant tissues. Increments of Na uptake in nutrient solution resulted in higher Na content in leaves and roots regardless Ca application. These findings suggest that calcium treatment may alleviate the negative impacts of salinity.     

RESPONSES OF SOME ENZYMES AND KEY GROWTH PARAMETERS OF SALT-STRESSED MAIZE PLANTS TO FOLIAR AND SEED APPLICATIONS OF KINETIN AND INDOLE ACETIC ACID

The study examined the effects of kinetin (KIN) and indoleacetic acid (IAA) applied as seed treatment or sprayed on leaves of salinity stressed plants. Five -week old maize (Zea mays L. cv. ‘DK 647 F1’) plants were grown in pots containing peat and perlite in 1:1 (v/v) mixture. Different treatments used were: 1) control (nutrient solution alone), 2) salt stress [100 mM sodium chloride (NaCl)], 3) 100 mM NaCl and 1 mM kinetin (KIN), 4) 100 mM NaCl and 2 mM KIN, 5) 100 mM NaCl and 1 mM indole acetic acid (IAA), 6) 100 mM NaCl and 2 mM IAA, 7) 100 mM NaCl and 25 mg L^?1 KIN and 8) 100 mM NaCl and 25 mg L^?1 IAA. In treatments 7 and 8 application was to the seeds, for treatments 3-6 it was applied to foliage. The seeds were soaked in KIN or IAA solution for 12 h. Salt stress reduced the total dry matter, chlorophyll content, and relative water content (RWC), but increased proline accumulation, activities of superoxide dismutase (SOD; EC 1.15.1.1), peroxidase (POD; EC. 1.11.1.7), catalase (CAT; EC. 1.11.1.6) and polyphenol oxidase (PPO; 1.10.3.1) and electrolyte leakage. Both foliar applications of KIN and IAA treatments overcame to variable extents the adverse effects of NaCl stress on the above mentioned physiological parameters. However, seed treatments with KIN or IAA did not improve salinity tolerance in maize plants. Furthermore, foliar application or seed treatments with KIN and IAA reduced the activities of antioxidant enzymes in the salt stressed-plants. Salt stress lowered some macronutrient concentrations [calcium (Ca) and potassium (K) in leaves and roots, phosphorus (P) in roots] but foliar application of both KIN and IAA increased Ca in both leaves and roots and P in leaves. Foliar application of IAA increased K concentrations in leaves of the salt-stressed plants. Foliar application of KIN and IAA, especially at 2 mM concentration, counteracted some of the adverse effects of NaCl salinity by causing the accumulation of proline and essential inorganic nutrients as well as by maintaining membrane permeability.     

GROWTH,NUTRIENT ACQUISITION,AND PHYSIOLOGICAL RESPONSES OF HYDROPONIC GROWN TOMATO TO SODIUM CHLORIDE SALT INDUCED STRESS

□ Growth and nutrient acquisition of tomato (Lycopersicon esculentum L.) cv ‘Amani’ were studied under induced salt stress in Hoagland's solution. The plants were treated for 37 days with salinity induced by incorporating different concentrations [0.0 (control), 50, 100, 150, or 200 mM] of sodium chloride (NaCl) to the nutrient solution. Slight reduction was obtained in growth represented by (shoot length and number, leaf number, and dry weight) when seedlings were directly exposed to NaCl stress from 0.0 to 100 mM. At higher concentrations (150 or 200 mM), growth parameters were adversely affected and seedlings died thereafter. Elevated salinity significantly reduced crude protein and fiber in shoots and roots. Tomato shoot and root contents of potassium (K), iron (Fe), and ash were reduced significantly in response to increased levels of salinity. Tissue contents of sodium (Na) and chloride (Cl) increased with elevated salinity treatments.     

Protective Role of Putrescine Against Salt Stress is Partially Related to the Improvement of Water Relation and Nutritional Imbalance in Cucumber

Polyamines play a variety of physiological roles in plant growth and development. To investigate whether exogenous putrescine (Put) has roles in protecting plants against salt stress, Put (100 μ M) was added to nutrient solution three days before cucumber (Cucumis sativusL. cv. “Jinyan No.4') seedlings were exposed to 100 mM sodium chloride (NaCl) treatment. Putrescine treatment significantly ameliorated the detrimental effects of NaCl on root growth and this was associated with a decrease of Na uptake and an increase in potassium accumulation in roots. Manganese (Mn) content in roots was decreased by salinity stress but increased by Put pretreatment. Furthermore, osmotic stress associated with NaCl treatment decreased leaf water potential and water content, while these effects were alleviated by Put pretreatment. The decreases in net photosynthetic rate (Pn) and stomatal conductance (Gs) by NaCl were also diminished by Put treatment. The results indicate that Put may play an important role in protecting cucumber plants against salt stress.     

Effectiveness of potassium in mitigating the salt-induced oxidative stress in contrasting tomato genotypes

To check the efficacy of potassium in alleviating oxidative stress under salt stress, salt-tolerant (Indent-1) and salt-sensitive (Red Ball) tomato (Lycopersicon esculentum Mill.) genotypes were exposed to three levels of sodium chloride (NaCl) (0, 75, 150 mM) and two levels of potassium (4.5 and 9 mM) in solution and foliar form. Thirty days of treatments revealed that increasing NaCl stress increased lipid peroxidation (malondialdehyde, MDA) and correspondingly the activity of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; and glutathione reductase GR) in both genotypes. However, higher potassium (K) level in solution or foliar spray during the salt-induced stress decreased MDA and antioxidant activity and increased the growth in salt-tolerant genotype than in the salt-sensitive genotype. Decrease in MDA concentration, activity of antioxidant enzymes, and increase in the growth of tomato plants by the application of potassium under salt stress suggest that potassium is an effective ameliorating agent against salt-induced oxidative damage.     

Effect of exogenous application of salicylic acid on salt-stressed sorghum growth and nutrient contents

This study was conducted to investigate the effect of salinity and foliar application of salicylic acid (SA) on sorghum biomass and nutrient contents. Treatments were comprised of salinity levels (0 and 100?mM NaCl) and SA concentrations (0.3, 0.7, 1.1 and 1.5?mM). Salinity increased sodium (Na), chlorine (Cl) and copper (Cu) but decreased nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sulfur (S), iron (Fe), zinc (Zn) and manganese (Mn) contents and the root and shoot dry matter. Fe and Zn were the most affected nutrients by salinity. However, SA reduced Na and Cl but increased plant dry matter and nutrient content. SA had greater positive effects on root than on shoot dry matter. Maximum increases through SA were achieved in N, K, Fe, Mn, Cu, and shoot weight under salt stress but in Zn and root weight under non-saline condition. In most cases 1.1?mM was the most effective SA concentration in reducing the negative effects of salinity.     

Silicon-induced changes in growth,ionic composition,water relations,chlorophyll contents and membrane permeability in two salt-stressed wheat genotypes

We investigated the effect of exogenously applied silicon (Si) on the growth and physiological attributes of wheat grown under sodium chloride salinity stress in two independent experiments. In the first experiment, two wheat genotypes SARC-3 (salt tolerant) and Auqab 2000 (salt sensitive) were grown in nutrient solution containing 0 and 100 mM sodium chloride supplemented with 2 mM Si or not. Salinity stress substantially reduced shoot and root dry matter in both genotypes; nonetheless, reduction in shoot dry weight was (2.6-fold) lower in SARC-3 than in Auqab 2000 (5-fold). Application of Si increased shoot and root dry weight and plant water contents in both normal and saline conditions. Shoot Na⁺ and Na⁺:K⁺ ratio also decreased with Si application under stress conditions. In the second experiment, both genotypes were grown in normal nutrient solution with and without 2 mM Si. After 12 days, seedlings were transferred to 1-l plastic pots and 150 mM sodium chloride salinity stress was imposed for 10 days to all pots. Shoot growth, chlorophyll content and membrane permeability were improved by Si application. Improved growth of salt-stressed wheat by Si application was mainly attributed to improved plant water contents in shoots, chlorophyll content, decreased Na⁺ and increased K⁺ concentrations in shoots as well as maintained membrane permeability.     

Exogenous application of zinc mitigates the deleterious effects in eggplant grown under salinity stress

The present study was conducted to investigate the effects of Zn application to salt stressed eggplant (Solanum melongena L.) seedlings grown in vitro and whether it can alleviate the deleterious effects of salinity or not. Zinc (0, 5, 10 and 20?mg/L) and sodium chloride (NaCl) at different concentrations (0, 50, 100 and 150?mM) were added to solidified half strength MS medium placed in 250?mL glass jars. The treatments were arranged in a 4?×?4 factorial experiment in a completely randomized design with four replications. Application of Zn to growing seedlings at different concentrations (5, 10 or 20?mg/L) increased the length of shoot and root and their dry weights, as well as enhanced the photosynthetic pigment contents and leaf relative water content compared to control. However, the application of NaCl to growing seedlings at different concentrations (50, 100 and 150?mM) significantly reduced the above mentioned attributes compared to control and those of Zn treatments alone. Treatment of seedlings with either Zn (5, 0 or 20?mg/L) or NaCl (50, 100 or 150?mM) significantly increased the proline content and the antioxidant enzyme activities of superoxide dismutase (SOD), peroxidase (POX) and ascorbate peroxidase (APX) in growing seedlings. However, the application of Zn to salt stressed seedlings mitigated the deleterious effects of salt stress in growing seedlings and increased the tolerance of seedlings to its deleterious effects.     

Comparison of nutrient uptake and antioxidative response among four Labiatae herb species under salt stress condition

Herbs of the Labiatae have relatively low salt tolerance. They are widely grown in drylands, but salt stress there is a typical problem and may reduce yields. To examine their salt tolerance mechanisms, we grew basil, sage, thyme, and oregano in nutrient solution containing 50 mM NaCl and determined the biomass; contents of Na, K, and Mg in leaf blades, stems, and roots; contents of total chlorophyll, malondialdehyde (MDA), hydrogen peroxide in leaf blades; and activities of antioxidative enzymes in leaf blades. The salt tolerance decreased in the order of basil ≈ sage > thyme > oregano. The good salt tolerance of basil was explained by a significant increase in the activity of catalase, in addition to the low Na/K ratio of leaf blades due to the retention of Na in stems and roots and of K in leaf blades. The good salt tolerance of sage was explained by the low Na/K ratio in leaf blades and the prevention of lipid peroxidation by high antioxidative enzyme activities, despite its poorer management of nutrient uptake. In thyme, although catalase activity increased significantly to alleviate salt-induced oxidative stress caused by Na influx into all parts, low K and Mg allowed shoot weight in particular to decrease. In oregano, antioxidative responses appeared as significant increases in ascorbate peroxidase and glutathione reductase activity, and K was accumulated in leaf blades, but serious salt-induced oxidative stress caused by high Na influx into all parts reduced the growth of all parts. These results show that despite similar responses among species, salt tolerance is not necessarily the same. In this experiment, we revealed the salt tolerance mechanism of each of four Labiatae herbs by revealing their strengths and weaknesses in nutrient uptake and antioxidative responses.     

Effects of silicon on the growth of maize seedlings under normal,aluminum, and salinity stress conditions

The effects of silicon on seed germination and growth parameters of maize seedlings under normal, aluminum (Al), and sodium chloride (NaCl) stress conditions were investigated. The results indicated a dose-dependent relationship between silicon and growth parameters, except for germination attributes.Application of silicon (2 mM) accelerated amylase activity, decreased abscisic acid content, and increased indoleacetic acid and gibberellic acid contents of seedling, The results suggest that the beneficial effects of silicon, at least in part, are mediated by the balance of phytohormones. Exposure to Al (10 mM) significantly decreased all growth parameters of maize seedlings. Application of 2 mM silicon, however, alleviated Al stress and restored almost all growth attributes. Decrease of Al absorption, increase of fructan content, and improvement of amylase activity were considered as the mechanisms of ameliorative function of silicon in Al-stressed maize seedlings. Exposure to silicon, however, did not show beneficial effects on growth parameters of maize seedlings under salt stress conditions.     

EFFECTS OF CALCIUM ON LIGNIFICATION RELATED PARAMETERS IN SODIUM CHLORIDE-STRESSED SOYBEAN ROOTS

The effects of exogenous calcium (Ca²⁺) on root growth and lignification-related parameters – phenylalanine ammonia-lyase (PAL) and peroxidases (POD) activities, hydrogen peroxide (H₂O₂) and lignin contents – in roots of NaCl-stressed soybean seedlings were analyzed. Three-day-old seedlings were cultivated in half-strength Hoagland's solution (pH 6.0) with or without 5 mM calcium nitrate [Ca(NO₃)₂] and 50 to 200 mM sodium chloride (NaCl) in a growth chamber (25°C, 12/12 h light/dark photoperiod, irradiance of 280 μmol m^?2 s^?1) for 24 h. In general, results showed that the absence of Ca²⁺ reduced root growth and increased lignification of soybean seedlings grown in NaCl-free nutrient solution. NaCl reduced the root growth and all lignification-related parameters. Root growth, PAL and POD activities and hydrogen peroxide (H₂O₂) contents were more affected after NaCl treatments without Ca²⁺ in the nutrient solution. At 5 mM, Ca²⁺ did not alleviate the deleterious effects of NaCl on lignification-related parameters.     

Salicylic Acid–Induced Salinity Redressal in Hydroponically Grown Strawberry

The present study was conducted to evaluate shoot and root mineral composition of salt-stressed Selva strawberry under application timing of salicylic acid (SA). Treatments included plants sprayed with 0.5 or 1 mM SA, plants exposed to 40 mM sodium chloride (NaCl), and plants sprayed with 0.5 or 1 mM SA 1 week before, simultaneously, or after initiation of 40 mM salinity. Results indicated that under saline conditions, sodium (Na) and chloride (Cl) contents increased along with decrease in nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and zinc (Zn) in shoot and root of plants. In plants treated with SA at 1 mM concentration, 1 week before salinity application, root Mg and shoot Ca were greater in comparison to salt-stressed plants treated with the same SA concentration 1 week after their exposure to salt stress. Thus, earlier SA application appears to be a better strategy for optimized protection against deleterious influence of salinity.     

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.     

Salicylic Acid–Induced Growth and Biochemical Changes in Salt‐Stressed Wheat

The interactive effect of salicylic acid and sodium chloride (NaCl) salinity on wheat (Triticum aestivum L.) cv. ‘Inqlab’ (salt‐sensitive) and cv. ‘S‐24’ (salt‐tolerant) was studied in a sand‐culture pot experiment in a net house. Wheat seeds soaked in water and 100 ppm salicylic acid solution for 6 h were sown in sand salinized with 0, 50, and 100 mM NaCl. Pots were irrigated with quarter‐strength Hoagland's nutrient solution. Fourteen‐day‐old seedlings were harvested, and growth parameters (leaf and root length, leaf and root dry weight) were recorded. Chlorophyll a and b content; soluble sugar (reducing, nonreducing, and total sugars) content; nitrate (NR) and nitrite reductase activity (NiR); soluble proteins, and total soluble amino acid content of fresh leaves were determined. Sodium chloride salinity significantly reduced growth parameters. Salicylic acid treatment alleviated the adverse salinity effect on growth. Salinity decreased the chlorophyll a and b content and chlorophyll a/b ratio in both varieties, but a decrease in the chlorophyll a/b ratio was less in salt‐tolerant wheat variety (‘S‐24’), which could be a useful marker for selecting a salt‐tolerant variety. Salinity (NaCl) stress considerably increased the accumulation of reducing sugars, nonreducing sugars, and total soluble sugars in leaves of 14‐day‐old wheat seedlings of both varieties. The salt‐tolerant variety (‘S‐24’) accumulated a higher sugar content, which also could be a useful marker for selecting a salt‐tolerant variety for slat‐affected areas. Salinity caused a reduction in nitrate reductase and nitrite reductase activity. The salt‐tolerant variety (‘S‐24’) showed resistance to a decrease of nitrate reductase activity under salinity. This could be a useful criterion for selecting salt‐tolerant varieties. In response to salinity, wheat seedlings accumulated soluble proteins and amino acids, which might reflect a salt‐protective mechanism.     

Inducing Salt Tolerance in Wheat by Exogenously Applied Ascorbic Acid through Different Modes

ABSTRACT

In order to assess whether exogenous application of ascorbic acid (AsA) through different ways could alleviate the adverse effects of salt-induced adverse effects on two wheat cultivars differing in salinity tolerance, plants of a salt tolerant (‘S-24’) and a moderately salt sensitive (‘MH-97’) cultivar were grown at 0 or 120 mM sodium chloride (NaCl). Ascorbic acid (100 mg L^?1) was applied through the rooting medium, or as seed soaking or as foliar spray to non-stressed and salt stressed plants of wheat. Salt stress-induced reduction in growth was ameliorated by exogenous application of ascorbic acid through different ways. However, root applied AsA caused more growth enhancement under saline conditions. Leaf ascorbic acid, catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activities were also maximal in salt stressed plants of both cultivars treated with AsA through the rooting medium. Furthermore, leaf ascorbic acid, CAT, POD, and SOD activities were higher in salt stressed plants of ‘S-24’ than those of ‘MH-97’. Root applied AsA caused more enhancements in photosynthetic rate. Root applied AsA caused more reduction in leaf sodium (Na⁺) compared with AsA applied as a seed soaking or foliar spray. Overall, AsA-induced growth improvement in these two wheat cultivars under saline conditions was cultivar specific and seemed to be associated with higher endogenous AsA, which triggered the antioxidant system and enhanced photosynthetic capacity.     

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.     

Involvement of nitrogen in salt resistance of Atriplex portulacoides is supported by split‐root experiment data and exogenous application of N‐rich compounds

Using a split‐root system, we aimed to identify the limiting factors for the growth of the halophyte Atriplex portulacoides L. under extreme salinity (800 mM NaCl) conditions. One half of the root system was immersed in complete nutrient solution at 0 or 800 mM NaCl and the other half was immersed in NaCl‐free medium, containing all nutrients or deprived of potassium (K⁺) or calcium (Ca²⁺) or nitrogen (N). Data indicate that at high salinity levels A. portulacoides growth is limited by the restrictions imposed by NaCl on N uptake. Next, the alleviation of the adverse impact by salt stress (800 mM NaCl) on plant growth was investigated through urea (U) and/or thiourea (TU) external addition through foliar application. Whether separately or supplied together, both components mitigated the negative impact of salinity on the plant growth by significantly improving the photosynthetic activity parameters [CO₂ assimilation rate, stomatal conductance and maximum quantum efficiency of PSII photochemistry (F_v/F_m)], as well as shoot N concentration and the photosynthetic nitrogen‐use efficiency (PNUE). A concomitant increase of protein and free amino acid concentrations was also observed. As a whole, the present study highlights the significance of N in A. portulacoides response to high salinity and suggests that combined application of U and TU could promote the growth of this halophyte potentially useful for saline soil reclamation and revegetation purposes.