Ameloration of salinity stress in tomato by foliar sprays of ascorbic acid and proline

Increasing world temperatures are bringing about climate changes creating abiotic stress in plants. Date palm offshoot leaves (Khadrawi cv.) were analyzed for chlorophyll Chl a, Chl b, Total Chl, Chl a/b ratio, anthocyanin and carotenoid subject to salinity, drought and temperature stress under field conditions. Results demonstrated that drought and salinity stress accompanied by high temperatures in July and August significantly reduced the Chl a, Chl b, and Total Chl relative to the control. Anthocyanins, carotenoids, hydrogen peroxide, and malondialdehyde were markedly higher in July and August (45 ºC), whereas September showed lower values in these substances. Temperature reduction to 35 °C accompanied by drought or salinity stress, brought about a critical increment in relative water content and a decrease in electrolyte leakage. Although the impact of drought and salinity stress continued, the reduced temperatures in September resulted in a reduction of abscisic acid and proline concentration. Cluster analysis showed the two groups. In this first group, the significant similarity between the treatments is illustrated by the influence of the high temperature of 43–45 ºC. Recovery of photosynthesis following low-temperature, for the most part, determines plant flexibility to water deficiencies and salinity. Thermal stress, associated with salinity or drought stress is more damaging to the photosynthetic pigments than any single factor.

Salinity stress is one of the most important stress barriers to crop production worldwide. Developing and implementing new strategies against salinity stress is critical for increasing agricultural productivity and supporting sustainable farming. Elicitors such as nanoparticles and Salicylic acid have recently been used potentially for better product yield. Therefore, in our research the Salvia virgata plant was exposed to salinity (NaCl) stress, and zinc oxide nanoparticles (ZnONP), salicylic acid (SA), and the ZnONP + SA combination were applied to plants divided into different groups. While salinity stress decreased the amount of chlorophyll a, chlorophyll b, and carotenoid pigments, SA, ZnONP, and SA + ZnONP elicitors combined with salinity stress enhanced the content of all three pigments. While salt stress raised MDA, H2O2, total phenolic, total flavonoid, soluble sugar and proline content, elicitor applications enhanced proline, soluble sugar, total phenolic and total flavonoid content more. Additionally, the application of NaCl + SA + ZnONP increased proline content by 21.55% and sugar content by 15.73% compared to NaCl application, while decreasing MDA content by 42.28% and H2O2 levels by 42.34%, thereby alleviating the plant's salt stress. It was revealed that DPPH, ABTS, and CUPRAC antioxidant activity sequence used to determine the total antioxidant activity displayed similarities, and it was found as NaCI + ZnONP > NaCI + SA > NaCI + SA + ZnONP > NaCI > Control. Furthermore, all elicitor applications increased CAT, GR, APX, and SOD enzyme activities while reducing oxidative stress in S. virgata plants. When all the data were evaluated, it was confirmed that SA and ZnONP had a synergistic effect and that SA and ZnONP have the potential to support plant development and growth under salinity. SA and ZnONP applications may have the capacity to least the detrimental impacts of salinity stress on plants. However, further research is needed to investigate the effectiveness of SA and ZnONPs in ameliorating salinity or different stress factors in various other plants.

Water scarcity and soil salinization are increasingly becoming limiting factors in food production, including olives, a major fruit crop in several parts of the world. Investigating historical olives, which are the last resort for genetic resources, is essential due to their natural resilience to drought and salinity, making them valuable for breeding stress-tolerant cultivars and ensuring sustainable olive production. In this study, four historic olive cultivars ('Nabali', 'Mehras', 'Frantoio', and 'Manzanillo') were investigated under both drought and salinity stresses. These cultivars also preserve local biodiversity, support traditional agriculture, and offer economic opportunities through unique, heritage-based olive oils. Drought and salt stress in olives are assessed through physiological [the ratio of variable to maximum fluorescence (Fv/Fm), relative water content (RWC)], biochemical (proline content), and molecular (stress-responsive genes) analyses to evaluate stress tolerance. Under salinity and drought stress, RWC decreased in all olive cultivars, with drought having the most severe impact. 'Nabali' exhibited the highest salinity tolerance, while all cultivars showed similar sensitivity to drought. Proline levels remained stable in 'Mehras' but decreased under salinity stress in 'Frantoio', 'Manzanillo', and 'Nabali'. Higher proline accumulation under drought suggested better drought tolerance than salinity in these cultivars. Photosynthetic efficiency (Fv/Fm) declined under salinity and drought stress in all cultivars, with drought causing a more significant reduction. 'Manzanillo' showed the highest sensitivity to drought, while the other cultivars maintained moderate efficiency under stress. 'Manzanillo' and 'Mehras' exhibited the highest number of differentially expressed genes (DEGs) under both drought and salinity stress, with 'Manzanillo' showing 2,934 DEGs under drought and 664 under salinity stress, while 'Mehras' had 2,034 and 2,866 DEGs, respectively. 'Nabali' demonstrated the strongest salinity-specific response, with 3,803 DEGs under salinity stress compared to 1,346 under drought. 'Frantoio' consistently had the lowest number of DEGs, with 345 under drought and 512 under salinity stress, indicating a more stable transcriptional response. Comparative analyses between drought and salinity conditions revealed significant variations, with 'Manzanillo' showing 2,599 unique DEGs under drought relative to salinity stress, while 'Nabali' exhibited 2,666 DEGs under salinity stress relative to drought. The major novel upregulated genes under salinity stress were Xyloglucan endotransglucosylase hydrolase (7 fold in 'Nabali' and 6.9 fold in 'Mehras'). The novel drought genes detected in 'Frantoio' included Phytosulfokines 3 (4.9 fold), while Allene oxide synthase (6.5 fold) and U-box domain-containing (6.4 fold) were detected in 'Manzanillo'. The data revealed both novel and common stress-specific biomarkers under both salinity and drought stress, which can potentially be utilized in olive breeding and genetic improvement programs to mitigate stress.

Introduction: The growth, development, and biosynthesis of secondary metabolites in the plant are strongly affected by environmental stress. The pharmaceutical values of medicinal herbs depend on the presence of secondary metabolites that are influenced by environmental stress. Drought and salinity stress are the two most significant abiotic factors that restrict plant growth and productivity. As a memory enhancer, anti-inflammatory, analgesic, antipyretic, sedative, and antiepileptic, Bacopa monnieri has been used for a long time. The aim of the present work was to study the impact of simulated abiotic stress on Bacopa monnieri. Methodology: Potted plants of Bacopa monnieri were treated with various concentrations of NaCl and polyethylene glycol (PEG) solution to simulate salinity and drought stress. In order to evaluate the salinity and drought stress effect, several physiological parameters, such as cell membrane stability and relative water content (RWC), and biochemical parameters, such as proline, β-carotene, MDA, total phenolic, and total flavonoid content, were taken into consideration. Results: In the present study, significant changes in the physiological and biochemical parameters have been observed in NaCl and PEG 6000-induced salt- and drought-stressed plants about control. Stress decreases the relative RWC and Membrane stability index of the Bacopa leaves. However, it increases the plant’s proline, β-carotene, phenolic compounds, and total flavonoids content. Conclusion: The data obtained from the current study indicated that both salinity and drought stress influence the physiological and biochemical traits of Bacopa monnieri L. By increasing the synthesis of proline, β-carotene, phenolic compounds, and total flavonoids, the Bacopa monnieri plant defends itself against oxidative stress.

ObjectivesCurrent study illustrates the impact assessment of TiO2 nano-particle seed priming on the overall germination, physiology in maize thriving under salinity stress. MethodologySeeds of maize cultivar were soaked in 40, 60 and 80 ppm aerated solution of TiO2nano-particle for one day and nano-primed seeds were then exposed to salinity stress, i.e., 200 mM NaCl on paper culture system. ResultsResults indicated that 60 ppm TiO2nano-priming treatment effect positively on the rate of germinate and growth of maize seedling under salinity stress. The experiment was carried out in sand as a growth medium with 60 ppm TiO2 priming. Results exhibited that germination percentage, germination energy, seedling vigor index, lengths of root and shoot, fresh and dry weights of seedling, potassium ion (K+) concentration, relative water content (RWC), total phenolic and proline and contents, superoxide dismutase (SOD), catalase (CAT) and phenylalanine ammonia lyase (PAL) activities were significantly enhanced and mean emergence time (MET), sodium ion (Na+) concentration, membrane electrolyte leakage (MEL) and malondialdehyde (MDA) content were decreased by TiO2 priming as compared to control under salinity stress. ConclusionSo, nano-priming with TiO2 mitigates the salinity injury in maize and could be a significant alternate strategy to mitigate the deleterious impact of salinity stress in maize.

Since regulatory roles of calcium (Ca) and melatonin (MT) in physiological responses of plants to salinity stress are lacking, various Dracocephalum kotschyi genotypes (Bojnord, Urmia, Fereydunshahr, and Semirom) were pretreated with exogenous Ca (5 mM), MT (100 μM), and Ca + MT in the presence of salt (75 mM NaCl). In addition measuring the concentration of phenolic compounds by high performance liquid chromatography (HPLC), histochemical evaluations of essential oils and phenolic compounds in glandular trichomes of leaf samples were performed by light microscope. Salt stress reduced shoot fresh (SFW) and dry weight (SDW), leaf area (LA), relative water content (RWC), and maximum efficiency of photosystem II (Fv /Fm ), but enhanced total phenolic content (TPC) and total flavonoids content (TFC), phenolic compounds concentrations, DPPH radical scavenging capacity, electrolyte leakage (EL), proline and hydrogen peroxide (H2 O2 ) concentrations, and Na+ /K+ and essential oils and TPC of the glandular trichomes of leaves in all D. kotschyi genotypes. Foliar spraying of Ca, MT, and particularly Ca + MT on D. kotschyi seedlings improved SFW, SDW, RWC, TPC, TFC, proline and phenolic compounds concentrations, Fv /Fm , and DPPH radical scavenging capacity, but reduced H2 O2 , EL, and Na+ /K+ in the leaves and essential oils and TPC in the glandular trichomes of all genotypes under both non-stress and salt stress conditions. These findings indicate that the crosstalk between MT and Ca synergistically improves salt tolerance, TPC and TFC, phenolic compounds concentration, and essential oils accumulation in glandular trichomes of different D. kotschyi genotypes.

Salinity is abiotic stress and is an effective factor in the production of all crops, especially in semi-arid and arid areas. Ascorbic acid (ASA) is an important antioxidant in plant tissues and has a great role in tolerance to various stresses. The aim of this work is to study the effects of ascorbic acid on growth traits, leaf photosynthetic pigments, biochemical attributes such as total phenolic content, isozymes electrophoresis and protein electrophoresis of three lupine cultivars under salinity stress. The effects of ascorbic acid on germination percentage and different growth parameters, as well as on chlorophyll pigments, total phenolics, electrophoresis of protein and isozymes profiles of esterase (EST), peroxidase (POX) and catalase (CAT) in three cultivars of Egyptian lupine (Giza 1, Giza 2 and Giza 3), which were grown under salinity stress using concentrations of NaCl (0 and 50 mM), were investigated. The results showed a significant decrease in germination and all growth parameters, as well as chlorophyll pigments (Chl a, Chl b) and total phenolics (TP). Also, salinity stress showed noticeable changes in isozymes profiles and an increase in the total number of protein bands in all cultivars. Application of ascorbic acid (ASA) caused an increase in shoot length (SL), root length (RL), seedling fresh weight (SFW) and seedling dry weight (SDW) in all cultivars compared to the salinity without ASA. Also, pretreatment with ASA led to increase of Chl a, Chl b and TP as well as led to the induction of new isozymes bands of EST, POX and CAT that may be related to the tolerance of lupine cultivars to salinity stress. On the other hand, ASA stimulated the appearance of new protein bands and the disappearance of others with different molecular weights under salinity in all cultivars. It could be concluded that soaking lupine seeds in ascorbic acid at a concentration of 200 mg/L before being exposed to salinity reduced the adverse effects of salinity stress by improving morphological and biochemical characteristics.

Purpose The present research’s main objective was to explore the potential stimulative effect of fulvic acid (FA) as a soil conditioner and salicylic acid (SA) as foliar spraying on morpho-physio-biochemical attributes, fruit yield, and quality of ‘Sediek’ and ‘Ewais’ mango cultivars (cvs.) grown under saline calcareous soil and heat stress conditions Methods Eight treatments, namely, 200 (FA200) and 400 (FA400) g FA tree−1 as a soil addition, 200 (SA200) or 400 (SA400) mg SA L−1 as foliar spraying, and their bilateral combinations (e.g., FA200 + SA200, FA200 + SA400, FA400 + SA200, and FA400 + SA400) compared to untreated control on morpho-physio-biochemical attributes, yield, and fruit quality of ‘Sediek’ and ‘Ewais’ mango cvs. grown under saline calcareous soil and heat stress conditions were assessed. These treatments were carried out using a split-plot arrangement in a randomized complete block design replicated three times during the 2022 and 2023 seasons. Results Cultivar Sediek had higher SPAD value, leaf proline and phenolic content, leaf area, fruit weight, yield and vitamin C than Ewais which had higher tree water status and shoot length. Saline calcareous and heat-stressed mango trees without FA or/and SA treatment had a significant decline in their water status, photosynthetic traits, biochemical responses that adversely affected growth and yield and fruit quality. However, soil FA addition and foliar SA spraying alone or in combination at any application level attenuated the negative effects of saline calcareous and heat-stress conditions via enhancing the morpho-physio-biochemical attributes, positively reflecting in tree growth, yield, and fruit quality. FA treatment alone improved tree water status (membrane stability index; MSI and relative water content; RWC), photosynthetic traits (SPAD value and maximum photochemical efficiency; Fv/Fm), leaf area, fruit weight, fruit yield, and fruit vitamin C (fruit vit.C), while SA treatment alone enhanced leaf proline and phenolic content, shoot length, and fruit total soluble solids (fruit TSS) compared to the non-FA or SA-treated control. Moreover, co-application of FA400 and SA400 effectively alleviated the harmful impacts of dual stress of heat and salinity on mango trees by improving MSI, RWC, SPAD value, Fv/Fm, proline and phenolic content, fruit weight, fruit yield, fruit TSS, fruit vit.C by 19.7, 26.1, 46.7, 18.7, 101.7, 390.7, 42.7, 6.8, 22.6, 69.6% (averages of the two seasons), respectively, compared to the non-FA or SA-treated trees. Conclusion It is recommended to add 400 g FA tree−1 to soil integrated with 400 mg SA L−1 foliar spraying four times at 30-day intervals for improving water status and photosynthetic traits, proline and phenolic accumulation, thereby growth, yield, and fruit quality of mango trees exposed to dual stress of heat and salinity under arid conditions.

Soil salinity represents a significant environmental stressor that impairs crop production and yield. A wide range of treatments have been used to reduce the effects of salinity in plants. Among the treatments used, functionalized nanoparticles (NPs) have shown great results. In light of recently demonstrated beneficial effects of chitosan-melatonin nanoparticles (CTS-Mel NPs) and chitosan-salicylic acid nanoparticles (CTS-SA NPs) in mitigating the deleterious consequences of major stress factors and boosting secondary metabolite biosynthesis, the current study aimed to investigate their potential as seed priming coatings to enhance plant performance under both control and salinity stress conditions. For this purpose, CTS (0.1% w/v), Mel (50 µM), SA (0.5 mM), CTS-Mel NPs and CTS-SA NPs were applied as seed priming agents on corn salad (Valerianella locusta) seeds, and subsequently key morphophysiological and biochemical properties were assayed under salinity conditions (0, 30 and 60 mM NaCl). Accordingly, salinity stress caused significant reduction in fresh and dry weights (FW and DW) of leaves, chl a, total chl, SPAD and enhancement in content of proline, phenolics, MDA, as well as protein content, and activities of SOD and CAT antioxidant enzymes. Concerning the phenolic compounds analyzed, salinity stress did not affect the dominant phenolic constituents with the exception of naringine. Regarding the protective effects of the various priming treatments, the adverse effects of salinity stress were ameliorated with the application of most of the applied treatments, and with CTS-Mel NPs in particular, by enhancing biomass, pigments, total phenols, protein, SOD and CAT antioxidant enzymatic activities, as well as the content of some dominant constituents of phenolic profile. CTS-Mel NPs enhanced chlorogenic acid, naringine, o-coumaric acid and catechin hydrate under both control and salinity conditions. Overall, CTS-Mel NPs outperformed CTS-SA NPs as a seed priming coating and could potentially be widely introduced as an innovative, sustainable approach to mitigate the effects of salinity and other abiotic stress conditions in crop plants.

Tomato is an important horticultural crop of global importance but its susceptibility to salinity stress significantly retards growth and thereby its yield. The impact of gaseous hormone, ethylene, accentuates the effect of salinity stress by negatively regulating various growth and developmental processes. Ethylene overproduction and ionic imbalance triggered by salinity stress exhibit upregulation of 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and downregulation of NHX1, SOS1 and HKT1;2 under salinity stress conditions that negatively affect proline content, ROS scavenging machinery, morphometric and physiological attributes. Variation in the proline content, activation of ROS scavenging machinery, affected morphometric and physiological attributes are some discernible points in response to salinity stress induced ethylene production. Therefore, the experiment was designed to study the role of ethylene inhibitors silver nitrate (AgNO3) and cobalt chloride (CoCl2) in mitigating the negative effects of ethylene over production under salinity stress. Tomato seedlings were treated with 0 mM NaCl, 250 mM NaCl and 250 mM NaCl + 100 µM AgNO3, 250 mM NaCl + 100 µM CoCl2 for three days. The gene expression of ACS2, NHX1, SOS1 and HKT1;2, and ACS activity, endogenous ethylene level, Na+ and K+ ions concentration, proline content, antioxidant enzymes activity, photosynthetic efficiency and different morphological and yield parameters were assessed in tomato plants treated with salinity stress, and ethylene inhibitors at 45 DAS and 90 DAS. Results revealed that ethylene inhibitors might be playing the role in minimizing the ethylene and ACC load. The ACS enzyme activity and ethylene content were considerably decreased due to application of AgNO3and CoCl2. Further, the endogenous proline and K+ content, and K+/Na+ ratio were considerably increased in response to ethylene inhibitors treatment. Also, antioxidant enzymesviz., SOD, CAT, APX and GR, growth matrices, photosynthetic efficiency and yield attributes were significantly improved in treated tomato plants (salinity with ethylene inhibitors).

Silicon (Si) and/or proline (Pro) are natural supplements that are considered to induce plants' stress tolerance against various abiotic stresses. Sweet corn (Zea mays L. saccharata) production is severely afflicted by salinity stress. Therefore, two field tests were conducted to evaluate the potential effects of Si and/or Pro (6mM) used as seed soaking (SS) and/or foliar spray (FS) on Sweet corn plant growth and yield, physio-biochemical attributes, and antioxidant defense systems grown in a saline (EC = 7.14dS m−1) soil. The Si and/or Pro significantly increased growth and yield, photosynthetic pigments, free proline, total soluble sugars (TSS), K+/Na+ratios, relative water content (RWC), membrane stability index (MSI), α-Tocopherol (α-TOC), Ascorbate (AsA), glutathione (GSH), enzymatic antioxidants activities and other anatomical features as compared to controls. In contrast, electrolytes, such as SS and/or FS under salt stress compared to controls (SS and FS using tap water) were significantly decreased. The best results were obtained when SS was combined with FS via Si or Pro. These alterations are brought about by the exogenous application of Si and/or Pro rendering these elements potentially useful in aiding sweet corn plants to acclimate successfully to saline soil.

Two field experiments were carried out on clay soil in El-Gemmeiza Agric. Res. St., ARC, El-Gharbiya Governorate, Egypt during 2015 and 2016 seasons to study the effect of four phosphorus and boron fertilizers sources on leaves chemical composition, photosynthetic pigments and water relations, growth, seed cotton yield/fed and its components and fiber quality of Egyptian cotton cultivar Giza 86. A split-plot design with four replicates was used, where the main plots included treatments of phosphorus namely; A- Soil application of 22.5 kg P2O5/fed. as superphosphate (Control), B- Phosphate rock + Phosphorein (400g/30kg seed), C- Foliar application of 2 ml phosphoric acid/liter water, and D- Phosphorein (400g/30kg seed)., and the sub plots involved the sources of boron namely; 1- Control (without application), 2- Foliar spray with boric acid, 3- Foliar spray with B-Nano, and 4- Foliar spray with B-EDTA. The obtained important could be summarized as follows: 1-The phosphorus sources gave significant effect on leaves N, P, K, photosynthetic pigments, total sugars, total carbohydrates and proline contents, leaves water content, water deficit, relative water content and osmotic pressure in 2016 season, No. of open bolls/plant, boll weight, seed cotton yield/plant, seed cotton yield/fed, lint percentage and seed index in both seasons, in favor of soil application with 22.5 kg P2O5/fed, final plant height and No. of sympodia/plant, in favor of foliar application with phosphoric acid.2- Foliar application with boron treatments fertilization significantly affected leaves N, P, K, photosynthetic pigments, total sugars, total carbohydrates and proline contents, leaves water content, water deficit, relative water content, osmotic pressure and transpiration rate in 2016 season, plant height at harvest, No. of sympodia/plant, No. of open bolls/plant, boll weight, seed cotton yield/plant, seed cotton yield/fed., lint percentage and seed index in both seasons, where the superiority was found in favor of foliar spray with B-Nano 5 g/liter water. 3-The interaction between phosphorus and boron fertilizers sources gave a significant effect on leaves N, P, K, photosynthetic pigments, total sugars, total carbohydrates and proline contents, leaves water content, water deficit, relative water content and osmotic pressure in 2016 season, boll weight, lint % and seed index in 2015 season and No. of open bolls/plant, seed cotton yield/plant, seed cotton yield/fed., in 2015 and 2016 seasons, in favor of soil application with 22.5 kg P2O5/fed and foliar spraying with B-Nano 5 g/liter water.4- Upper half mean length, uniformity index, micronaire reading and fiber strength did not affect by the different phosphorus and boron sources and their interaction in both seasons.

Application of candidate endophytic fungi isolated from extreme desert adapted trees to mitigate the adverse effects of drought stress on maize (Zea mays L.)

Guo, R., Zhou, J., Hao, W., Gong, D., Zhong, X., Gu, F., Liu, Q., Xia, X., Tian, J. and Li, H. 2011. Germination, growth, photosynthesis and ionic balance in Setaria viridis seedlings subjected to saline and alkaline stress. Can. J. Plant Sci. 91: 1077–1088. Setaria viridis seeds and seedlings were subjected to saline and alkaline stress to determine their effects on germination and growth indices, and physiological parameters. The treatments consisted of solutions of NaCl:Na2SO4for saline stress and NaHCO3:Na2CO3for alkaline stress, at different concentrations. Germination, growth, photosynthesis, chlorophyll fluorescence and ionic balance were determined to elucidate the difference in the mechanism of saline and alkaline stress damage to S. viridis seedlings, and their physiological adaptive mechanism to stress. Germination indices decreased and, germ and root growth were severely inhibited with increased concentrations, especially under alkaline stress. We also found that alkaline stress had a more severe effect on S. viridis seedlings than saline stress, which was demonstrated by greater reduction in relative growth rate, water content and root system activity. Similarly, the reduction in photosynthesis and chlorophyll fluorescence was greater under alkaline than saline stress. Alkaline stress also appeared to exacerbate the ionic imbalance generated by saline stress; alkaline stress caused a heavy precipitate of phosphate and metal ions, excluding Na+and K+, and the loss of NO3−and H2PO4−, which caused a sharp decrease in ionic activity and free concentrations of various ions. Our results suggest that damage caused by alkaline stress might come from greater influx of Na+than caused by saline stress. Setaria viridis responds by synthesizing greater amounts of organic acids than are required to counter salinity to address the intracellular ion imbalance; this process is at the cost of the plant's already diminished energy resource.

Application of salt stress (100 mM) through root growing medium caused a considerable decrease in plant fresh and dry biomass, maximum quantum yield (Fv/Fm), chlorophyll contents, leaf water potential, and leaf Ca, K, P and N concentrations of two maize cultivars (Apex 836 and DK 5783). However, salt-induced increase was observed in leaf osmolality (LO), proline, hydrogen peroxide (H2O2), malondialdehyde (MDA), Na+ concentration and activities of enzymatic antioxidants, such as catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD). Of five humic acid (HA) levels used under non-stress and stress conditions in an initial experiment, 100 mg L−1 was chosen for subsequent studies. Exogenous application of humic acid (HA) at the rate of 100 mM as a foliar or pre-sowing seed treatment significantly increased the plant biomass, Fv/Fm, chlorophyll pigments and proline contents, while it considerably reduced the leaf water potential, H2O2 and MDA contents as well as the activities of all the afore-mentioned enzymatic antioxidants. Of both modes of exogenous treatment, foliar spray was better in improving plant biomass, chlorophyll contents, LO, leaf Na+ as well as the accumulation of all nutrients measured, however, in contrast, seed pre-treatment was more effective in altering leaf proline, H2O2 and MDA contents. Of both maize cultivars, cv. DK 5783 excelled in plant biomass, chlorophyll contents and leaf N, Ca and K concentrations as well as in the activities of all three antioxidant enzymes, whereas cv. Apex 836 was superior in leaf Na+ and P concentrations, H2O2 and MDA contents. Cv. DK 5783 was comparatively better in salt tolerance as compared to cv. Apex 836. Overall, exogenous application of HA was effective in improving salinity tolerance of maize plants which can be attributed to HA-induced increase in plant biomass, chlorophyll contents, mineral nutrients and activities of key antioxidant enzymes.