铝和镉胁迫对两个大麦品种矿质营养和根系分泌物的影响

A hydroponic experiment was carried out to study the effect of aluminum （Al） and cadmium （Cd） on Al and mineral nutrient contents in plants and Al-induced organic acid exudation in two barley varieties with different Al tolerance. Al- sensitive cv. Shang 70-119 had significantly higher Al content and accumulation in plants than Al-tolerant cv. Gebeina, especially in roots, when subjected to low pH （4.0） and Al treatments （100 μmol L^-1 Al and 100 μmol L^-1 Al ＋1.0 μmol L^-1 Cd）. Cd addition increased Al content in plants exposed to Al stress. Both low pH and Al treatments caused marked reduction in Ca and Mg contents in all plant parts, P and K contents in the shoots and leaves, Fe, Zn and Mo contents in the leaves, Zn and B contents in the shoots, and Mn contents both in the roots and leaves. Moreover, changes in nutrient concentrations were greater in the plants exposed to both Al and Cd than in those exposed only to Al treatment. A dramatic enhancement of malate, citrate, and succinate was found in the plants exposed to 100 μmol L^-1 Al relative to the control, and the Al-tolerant cultivar had a considerable higher exudation of these organic acids than the Al-sensitive one, indicating that Al-induced enhancement of these organic acids is very likely to be associated with Al tolerance.     

Yield components of soybean plants infected with soybean cyst nematode and sprayed with foliar applications of boron and magnesium 1

Investigations into the effect of soybean cyst nematode (SCN, Heterodera glycines, Ichinoe) on the yield components of soybean [Glycine max (L.) Merr.] have shown that pod numbers are reduced with increasing SCN initial populations (Pi) present in the soil at planting. The main method by which SCN alters pod numbers is through reductions in the number of branches per plant. Foliar applications of boron (B) and B in combination with magnesium (Mg) (B+Mg) increase yield of soybean not infected with SCN by increasing pod number per plant, especially the number of pods on branches. The objective of this research was to determine if foliar applications of B and B+Mg ameliorates the effect of SCN by increasing yield on branches. Field experiments were conducted in 1993 and 1994 in 1 m² microplots to compare foliar applied B and B+Mg to a control treatment. Foliar applications were made at four intervals spaced throughout soybean reproductive development of Pioneer brand 9391, an SCN susceptible cultivar. There were 12 levels of SCN Pi in 1993 and 11 levels in 1994. For each treatment, including control, grain yield was regressed on SCN Pi. Yield was reduced with increasing SCN Pi in both years, but the rate of decrease did not differ among treatments. In addition, ANOVA of yield components revealed no treatment effects on the number of branches per plant, the number of branch pods per plant, or the total number of pods per plant. Thus, foliar applications of B or B+Mg did not ameliorate the effects of SCN on soybean.     

The effect of Ca and K levels on the herbage yield and nutrient composition of barley plants grown in high Mg soils

Abstract

The effects of Ca and K levels on barley (cv. Johnston) yield were studied in soil media containing high levels of Mg. The dry matter yield of barley decreased with increasing concentrations of Mg in soils, but the decrease was small. Dry matter yield was positively related to concentration of K in the soil. However, additions of fertilizer Ca or K did not increase dry matter yield, indicating that depressed yield associated with high Mg levels was not due to reduced availability of Ca or K. In commercial agriculture, applications of either Ca or K to such soils are unlikely to prove beneficial in increasing crop yields.

Concentrations of Mg in soil solutions of unfertilized soils were lower than levels which were previously shown to reduce crop yield. Additions of N fertilizer increased Mg concentrations to levels which could reduce barley yield     

Response of Cadmium Uptake in Different Barley Genotypes to Cadmium Level

A greenhouse hydroponic experiment was performed out to study the cadmium (Cd) uptake by four different barley cultivars at two Cd levels. The results showed that Cd concentrations in roots and shoots increased with Cd levels in the solution and Cd concentration in roots was much higher than that in shoots. The amount of Cd accumulated by plants increased continually with the duration of treatment, and the highest Cd concentration in roots and aboveground tissues was found approximately at the 100th and 70th day after Cd addition, respectively. Genotypes differed significantly in relation to Cd concentration in roots and aboveground tissues. Wumaoliuling showed a higher Cd concentration than the other three genotypes, while Mimai 114 had the lowest concentration. Cadmium uptake rate per plant increased slowly before the booting stage, then increased sharply during the 70–100 d period (approximately late elongation to booting stage), and after that Cd uptake rate tended to slow dramatically. However, the Cd uptake rate per unit of dry biomass showed a significant reduction after booting stage (70 d after Cd exposure), and the Cd uptake pattern varied by Cd levels in the medium. At the lower Cd level (0.1 μM), there were two peaks in Cd uptake rate, appearing at the seedling (20–30 d after Cd exposure) and stem elongation stages (50–70 d after Cd exposure), respectively, while there was only one peak at the stem elongation stage at the higher Cd level (1 μ M).     

The changes in physiological and biochemical traits of Tibetan wild and cultivated barley in response to low phosphorus stress

Low phosphorus (LP) limits crop growth and productivity in the majority of arable lands worldwide. Here, we investigated the changes in physiological and biochemical traits of Tibetan wild barleys (Hordeum vulgare L. ssp. spontaneum) XZ99 (LP tolerant), XZ100 (LP sensitive), and cultivated barley ZD9 (moderately LP tolerant) under two phosphorus (P) levels during vegetative stage. These genotypes showed considerable differences in the change of biomass accumulation, root/shoot dry weight ratio, root morphology, organic acid secretion, carbohydrate metabolism, ATPase (Adenosine triphosphatase) activity, P concentration and accumulation under LP in comparison with CK (control) condition. The higher LP tolerance of XZ99 is associated with more developed roots, enhanced sucrose biosynthesis and hydrolysis of carbohydrate metabolism pathway, higher APase (Acid phosphatase) and ATPase activity, and more secretion of citrate and succinate in roots when plants are exposed to LP stress. The results prove the potential of Tibetan wild barley in developing barley cultivars with high tolerance to LP stress and understanding the mechanisms of LP tolerance in plants.     

Uptake of Heavy Metals by Mycorrhizal Barley (Hordeum vulgare L.)

It has been previously indicated that arbuscular mycorrhizal (AM) fungi can enhance the bioremediation abilities of their host plant. Barley (Hordeum vulgare L.) is a crop plant with some unique physiological properties, such as tolerance to salinity. However, its tolerance to other stresses such as heavy metals must be tested. Accordingly, it was hypothesized that barley can be efficiently used to treat heavy metals in symbiotic and non-symbiotic association with AM fungi. In a greenhouse experiment barley plants were inoculated with the AM species Glomus mosseae and grown in a soil polluted with cadmium (Cd), cobalt (Co), and lead (Pb). Relative to Cd and Co, mycorrhizal barley absorbed significantly higher amounts of Pb. AM species also significantly decreased Cd and Co uptake by barley indicating the alleviating effects of G. mosseae on the stress of such heavy metals.     

The effect of root hairs on rhizosphere phosphatase activity

Background: Phosphatases in soil are of great importance for plant P acquisition. It is hypothesized that root hairs increase rhizosphere phosphatase activity as they release enzymes into soil and stimulate microbial activity. Methods: To test the effect of root hairs on soil phosphatase activity, we grew barley (Hordeum vulgare ‘Pallas') wild type and its root‐hairless mutant in rhizoboxes and determined phosphatase activity using soil zymography. Measurements were done at three moisture levels (30, 15, and 5% VWC). Rhizosphere phosphatase activity was estimated for the two genotypes and two locations along the root [root tip region (0–4 cm behind tip) and mature roots (> 7 cm behind tip)]. Results: Rhizosphere phosphatase activity was similar in the two locations along the root (root tip region vs. mature root parts). In contrast, rhizosphere phosphatase extension was two times larger for the root tip region of the wild type than for the mutant at 30% and 15% VWC. However, as phosphatase activities at the root surface of tips and mature root parts were slightly higher for the mutant than for the wild type, average enzyme activities were unaffected by the genotype. Conclusions: We conclude that the mutant seems to compensate for the lack of root hairs by increased phosphatase activity close to the root surface. However, the increased rhizosphere phosphatase extension for the wild type may be equally efficient as it allows P mobilization and uptake from large soil volumes.     

The assessment of genetic variation in Spanish primitive cultivars of barley, Hordeum vulgare L., by a combination of isozymes and hordeins

Five isozyme and endosperm reserve protein systems were analysed using electrophoretic techniques in order to investigate the genetic diversity of 222 accessions of Spanish, local varieties of barley, Hordeum vulgare L., maintained at the Centro de Conservación de Recursos Fitogeneéticos of the I.N.I.A. (Alcalá de Henares, Spain). The esterase (EST) isozymes provided more information than did the other systems analysed, showing a total of 14 variable markers. The cathodic peroxidases (CPX) and acid phosphatases (ACPH) were also polymorphic. Malate dehydrogenase (MDH) and glutamate oxaloacetate transaminase (GOT) were monomorphic. The hordeins showed patterns of up to 15 bands, the majority of which were very useful in distinguishing genotypes. 17.2% of accessions showed a uniform genotype, 29.8% showed practically identical genotypes and 53% showed mixtures of different genotypes. It is noteworthy that the use of only two systems (EST and hordeins) and the analysis of only six loci (Est-1, Est-2, Est-4, Hor-1, Hor-2 and Hor-3) is sufficient to reveal the genetic diversity of the collection.     

Interaction of Salinity and Cadmium Stresses on Antioxidant Enzymes,Sodium, and Cadmium Accumulation in Four Barley Genotypes

A hydroponic experiment was carried out utilizing four barley genotypes with differing salt tolerances to investigate the influence of salinity (NaCl) and cadmium (Cd) on the activities of antioxidant enzymes, sodium (Na) and Cd concentrations, and accumulation in plants. The activities of the two antioxidant enzymes, superoxide dismutase (SOD) and peroxidase (POD), were significantly increased when plants were exposed to both Na and Cd stresses for all genotypes, relative to the control. The increased enzymatic activity was more predominant with a prolonged time of stress exposure. The combined stress (NaCl+Cd) led to a further increase in POD activity, but had little effect on SOD activity. Two salt-tolerant genotypes, ‘Gebeina’ and ‘Zhou 1,’ showed a more rapid increase of POD and SOD activities than the two salt-sensitive genotypes, ‘Newgoutei’ and ‘Quzhou’ in response to the combined stress treatment. Additions of NaCl to the Cd-containing medium caused a significant reduction in both Cd concentration and accumulation. The extent of the reduction in Cd concentration was also dependent on genotypes. The salt-tolerant genotypes had lower Na concentrations than sensitive genotypes, and the effect of Cd stress on Na concentration and accumulation varied with genotypes. It may be concluded that a significant interaction exists between Na and Cd in their influence on antioxidant enzyme activity and the accumulation of each element in the plant.     

Starter fertilizer to spring barley and spring wheat in south-east Norway: Effects on growth and nutrient uptake

Abstract

Field experiments were carried out on three representative soils, to evaluate the effect of various starter fertilizers, together with different rates of band placed phosphorus (P), on nutrient uptake and yield of spring barley (Hordeum vulgare L.) and spring wheat (Triticum aestivum L.). The starter fertilizers were placed in the immediate vicinity of the seed, while the band placed P was placed at about 5 cm below the seeds and spaced at 25 cm between alternate seed rows. As starter fertilizer, monoammonium phosphate (MAP), calcium nitrate (CAN), ammonium nitrate (AN) and triple superphosphate (P20) were compared. In both species, effects of starter fertilizer on P uptake were most marked early in the growing season. At GS 13 application of 20 kg P ha^?1 as MAP increased the P uptake by 50% in barley and by 35% in wheat, compared to no seed-placed nutrients. For grain, the increase in P content was 8% for both species. The higher P uptake at GS 13 was supported by observations of higher plant vigour in the treatments with either P20 or MAP as starter fertilizer. The use of N only as starter fertilizer did not increase the vigour of the plants. Band placement of P also gave more vigorous plants in spring barley. The grain yield increased on the silty clay loam and on the silt soil when starter fertilizer was applied, especially with the use of MAP. Smaller and non-significant yield differences were found when starter fertilizer was used on the loam soil. No delay or reduction of emergence was observed with starter fertilizer. Therefore, on soils where root growth or nutrient uptake becomes limited during the first weeks after sowing, application of starter fertilizer is recommended in Norway for both spring barley and spring wheat. Crops grown on silty soils seem to have an especially high demand for easily available P given as starter fertilizer.     

Effects of seedbed properties on crop emergence: 2. Effects of aggregate size,sowing depth and initial water content under dry weather conditions

Abstract

Rapid and uniform crop establishment is a prerequisite for efficient crop production and minimal environmental impact. Extensive experiments were carried out in shallow plastic boxes placed in the field directly on the ground for studies of the effects of seedbed properties on emergence of small-grain cereal crops in a cool, temperate climate. This paper presents studies of the seedbed as a protective layer against evaporation and the requirements for good emergence under dry weather conditions. Without rainfall after sowing, nearly complete emergence of barley (Hordeum vulgare L.) was obtained, when rapidly germinating seed was placed on a moderately compacted basal layer containing at least 5% (w/w) plant-available water and covered by a 4 cm deep surface layer consisting of aggregates < 5 mm. This applied even when initial water content in the surface layer was below the wilting point and potential evaporation was high. If the soil at 4 cm depth is drier or if a sufficiently fine seedbed cannot be obtained, then seedbed and sowing depth should be somewhat greater, and if the soil is wetter, then the depth may be smaller. There were only small differences in emergence between surface layers consisting of aggregates < 2 mm, 2–4 mm or 2–5 mm, or dominated by these aggregate fractions, but when the surface layer consisted of coarser aggregates, emergence was usually much lower. Determinations of water losses from the soil during the experimental period showed that the differences in emergence were caused by differences in efficiency of the seedbed to control evaporation. The results indicate that, in an initially wet soil, it is always possible to find a time and method for seedbed preparation and sowing that lead to good emergence of small-grain cereal crops, even with a lengthy period without rainfall after sowing.     

Potassium placement effect on dynamics of barley (Hordeum vulgare L.) nutrition

The effects of local placement of potassium (K) on mineral nutrition dynamics of barley (Hordeum vulgare L.) in fertile Сhernozem were studied. A pot experiment with local K-placement at 4–5 cm soil depth was carried out and the dynamics of nitrogen, phosphorus, potassium (NPK) concentrations in tillers, organs and parts of spring barley was measured. K-placement increased the productivity index from 0.49 to 0.54, despite optimal and slightly varying NPK concentrations during the second half of the vegetation period (60–100 d). This occurs due to partitioning of assimilates, N, K, and especially P in generative organs of primary and secondary tillers forming quality grains. Nutrient concentrations in certain primary tiller parts of a 60-d plant (senescing leaves and the main spike axis) proved to be more sensitive indicators of the K-placement effect than average whole-plant characteristics. While being beneficial, K-placement had little impact on the overall NPK removal in barley, which shows a significant role of factors related to K uptake kinetics. Thus, the chosen parameters in the soil–plant system (the high content of available K in Chernozem, in the second part of the vegetation period) have for the first time allowed the evaluation of the impact of local K-placement on mineral nutrition dynamics in barley.     

Effects of seedbed properties on crop emergence: 3. Effects of firming of seedbeds with various sowing depths and water contents

Abstract

Extensive experiments were carried out in shallow plastic boxes placed directly on the ground in the field to study the effects of seedbed properties on the emergence of various crops in a cool temperate climate. In a group of experiments with barley (Hordeum vulgare L.), we studied the effects on crop emergence of firming (slight compaction) of the seedbed, simulating the recompacting effects of rolling after sowing or press wheels on the seed coulters. Most of the experiments were carried out without irrigation after sowing. The firming usually had a slightly positive effect on emergence when the water content in the surface layer at sowing was below the wilting point. When the water content in the surface layer was higher, firming often reduced emergence drastically, particularly with deep sowing and in coarse-textured soils. The main reason for negative effects was harmful hardening of the surface layer when the more firm seedbed gradually dried out. When irrigation kept the seedbed continuously moist, the negative effect of firming was almost eliminated. Very high initial water content in the basal layer tended to delay surface layer drying and hardening, and to reduce the negative effect of firming. Firming only slightly influenced the evaporative water losses from the soil. In contrast to the results presented here, previous field trials with cereals have usually resulted in more positive effects of rolling after sowing. This indicates that other effects than firming, such as modification of sowing depth and reshaping of the soil surface, are other important effects of rolling.     

Effects of seedbed properties on crop emergence. 5. Effects of aggregate size,sowing depth and simulated rainfall after sowing on harmful surface-layer hardening

Abstract

Rapid, uniform crop establishment is a precondition for efficient crop production. In order to develop guidelines for seedbed preparation and sowing, extensive experiments were carried out in plastic boxes placed in the field directly on the ground for studies of the effects of seedbed properties on crop emergence. This paper deals with the effects on emergence of cereals caused by surface-layer hardening, induced by simulated rainfall (irrigation) after sowing followed by dry weather. The experimental crop was spring barley (Hordeum vulgare L.). Soils for the experiments (Eutric Cambisols, silt loam or clay loam in most cases) were collected from the surface layer of farm fields in various parts of Sweden. On soils with high silt content, irrigation after sowing often caused slumping and subsequent hardening of the whole seedbed. On clay soils, usually only a shallow surface crust formed. The earliest irrigation had the most negative effects on crop emergence. On a silt loam soil with unstable structure, irrigation with only 5 mm reduced emergence to under 20%. Later or heavier irrigation was often less negative, as it allowed the plants to emerge before the surface layer dried and hardened. Deep sowing greatly increased the negative effects on emergence, whereas soil aggregate size usually had negligible effects. It was concluded that when sowing in practice, seedbed preparation and sowing depth should be chosen to promote the fastest possible emergence. Sowing immediately before rain should be avoided, as should shallow sowing that requires rain for the seed to germinate.     

Responses of barley to hypoxia and salinity during seed germination,nutrient uptake,and early plant growth in solution culture

The resistance of most plants to salt can be impaired by concurrent waterlogging. However, few studies have examined this interaction during germination and early seedling growth and its implications for nutrient uptake. The aim of the study was to examine the response of germination, early growth, and nutrient uptake to salt (NaCl) and hypoxia applied to barley (Hordeum vulgare L. cv. Stirling), in solution culture. Hypoxia, induced by covering seeds with water, lowered the germination from 94% to 28% but salinity and hypoxia together lowered it further to 13% at 120 mM NaCl. While the germination was 75% at 250 mM NaCl in aerated solution, it was completely inhibited at this NaCl concentration under hypoxia. Sodium ion (Na⁺) concentrations in germinated seedlings increased with increasing salinity under both aerated and hypoxic conditions during germination, while K⁺ and Mg⁺ concentrations were decreased with increasing salinity in 6 d old seedlings. After 20 d, control seedlings had the same dry weights of the roots and shoots with and without hypoxia but at 10 mM NaCl and higher, shoot and root dry weight was depressed with hypoxia. Sodium ion increased in roots and shoots with increased NaCl under both aerated and hypoxic conditions while K⁺ was depressed when salinity and hypoxia were applied together and Ca²⁺ was mostly decreased by NaCl. In general, hypoxia had greater effects on nutrient concentrations than NaCl by decreasing N, P, S, Mg, Mn, Zn, and Fe in shoots and by increasing B concentrations. The threshold salinity levels decreased markedly for germination, uptake of a range of nutrients, and for seedling growth of barley under hypoxic compared to well‐aerated conditions.     

Role of water stress in differential aluminum tolerance of two barley cultivars grown in an acid soil

Two cultivars of barley (Hordeum vulgare L.), Al‐sensitive ‘Dayton’ and Al‐tolerant ‘Kearney’, were grown under controlled environmental conditions to determine the influence of Al stress and water stress imposed separately and in combination with one another. Plants were grown for 4 weeks in polyethylene‐lined, waxed cartons containing 1 kg of acid, Al‐toxic, Tatum subsoil (clayey, mixed, thermic, Typic Hapludult) at high (pH 4.7) or low (pH 6.6) Al stress. During the final 2 weeks they were also subjected to low (‐20 to ‐40 kPa) or high (‐60 to ‐80 kPa) water stress. Under low water stress, little difference in the growth or appearance of the two cultivars was found, even in the presence of low Al stress (pH 6.6). When high water stress treatment was superimposed on low Al stress treatment, however, significant differences between the two cultivars in biomass production, leaf enlargement, and tillering resulted. When high water stress was combined with high Al stress (pH 4.7), these differences in vegetative growth were further magnified. Thus, drought exacerbates the stress effects of Al toxicity in plants and may account for a significant portion of the reduction in yield commonly observed in acid soils under field conditions and formerly attributed to Al toxicity alone. By increasing soil moisture level, the growth suppressive effect of Al toxicity was significantly reduced.     

Mechanism of manganese toxicity and tolerance of plants VI. Effect of silicon on alleviation of manganese toxicity of barley

Effect of Si on alleviation of Mn toxicity of barley (Hordeum vulgare L.) seedlings was investigated with special reference to the effect on Mn microdistribution and peroxidase activity. Manganese treatment was conducted by growing the seedlings in nutrient solutions containing different concentrations of Mn. Silicon treatment was conducted by growing the seedlings in the solutions with or without Si supply. Silicon supply alleviated the necrotic browning in the leaves but did not affect the chlorosis caused by Mn toxicity. Silicon treatment did not appreciably alter the uptake of Mn by the plants. Electron probe X‐ray microanalysis revealed that Mn accumulated in high concentration around the necrotic brown spots and that Si supply prevented the uneven distribution of Mn in the tissues. Increase in the level of Mn supply caused an increase in peroxidase activity in the tissues, and Si supply prvented the increase in peroxidase activity.     

Phloem transport of assimilates in relation to flowering time and senescence in barley grown with different availabilities of nitrogen and phosphorus

Understanding the way in which N and P availability affects the transport of sugar and amino acids is crucial to improve grain quality and yield. Thus, in the present study, two greenhouse and field experiments were conducted with barley plants grown with different N and P availabilities to assess the dynamics of the phloem transport of assimilates in relation to the beginning of flowering and senescence. The phloem transport of assimilates decreased before the beginning of protein degradation in all treatments, but the onset of flowering and senescence varied according to the N and P availability, as evidenced by the concentrations of proteins, amino acids, and sugar and the gene expression of senescence-related proteases and all glutamine synthetase isoforms. In N-deficient plants, the phloem transport decreased before flowering, but only when P was not limiting; in N- and P-sufficient plants it decreased at flowering; and in P-deficient plants it decreased after flowering. Therefore, only N-deficient but P-sufficient plants have a post-anthesis period with high export rate of assimilates. This alteration of phenology in relation to phloem leads to important consequences in assimilate utilization, as shown by the higher yield and N content of the former compared to P-deficient plants.     

Comparative effect of drought duration on growth,photosynthesis, water relations,and solute accumulation in wild and cultivated barley species

Drought is a major factor limiting crop production worldwide. Barley is a well‐adapted cereal that is largely grown on dry marginal land where water and salinity are the most prevalent environmental stresses. This study was carried out to investigate the effects of drought stress and subsequent recovery on growth, photosynthetic activity, water relations, osmotic adjustment (OA), and solute accumulation of wild (Hordeum maritimum) and cultivated barley (H. vulgare L.). In a pot experiment, 60 d old seedlings were subjected to drought stress for 0, 7, 14, 21, or 28 d, and then re‐watered to recover for up to 21 d. Plants were harvested at the end of each of these drought/recovery treatments. Drought significantly reduced fresh and dry weights at the whole‐plant level, photosynthetic activities, and solute and water potentials, while increasing leaf Na⁺ and K⁺ concentrations. The adverse effects of drought on growth were more marked in cultivated barley than in wild barley and the reverse was true for photosynthetic activities. During recovery, all wild barley seedlings completely recovered. For cultivated barley seedlings, rehydration had a beneficial effect on growth and photosynthesis, independent of treatment duration, but complete recovery did not occur. The reduction in leaf solute potential at full turgor in drought‐stressed barley, relative to the control, suggests active OA which was more significant in wild barley than in cultivated barley. OA was mainly due to the accumulation of inorganic (K⁺ in cultivated barley and Na⁺ in wild barley) and organic (soluble sugars and proline) solutes. The results suggest that OA is an important component of the drought‐stress adaptation mechanism in wild barley, but is not sufficient to contribute to drought tolerance in cultivated barley. In the latter species, the results show that even short periods (as little as 7 d) of water deficit stress had considerable long‐term effects on plant growth.     

Effect of Nitrogen Nutrition on Solute Accumulation and Ion Contents of Maize under Sodium Chloride Stress

Salinity is a major abiotic stress that limits the productivity of crops, particularly cereal crops, while decreasing nutrient availability, especially of nitrogen. An experiment was conducted to study the effects of salt stress [i.e., S₀, S₁, and S₂ (control, 1.09; 5; and 10 dS m^?1)] and four different nitrogen (N) levels [i.e., N₀, N₁, N₂, and N₃ (control, 175, 225, and 275 kg N ha^?1)] on two maize hybrids, Pioneer 32B33 (salt tolerant) and Dekalb 979 (salt sensitive). The experiment was conducted in a wire house. The experiment was laid out with three factors in a completely randomized design. The plant tissue was analyzed for solute and ion contents. With the increase in salt stress and N rate, solute (i.e., glycinebetaine), protein, total soluble sugar, and total free amino acids accumulated in both hybrids. Nitrate (NO₃) and nitrite (NO₂) reductase activity decreased sharply at 10 dS m^?1 compared to lower levels of salinity but it increased significantly with the addition of N. The uptake of potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), N, and phosphorus (P) reduced significantly in shoots with increased salinity while the sodium (Na⁺) and chloride (Cl) contents were increased. It is concluded from the present study that at greater salinity level, hybrid Pioneer32B33 maintained statistically greater solute and ion contents excluding Na⁺ and Cl ions and significantly decreased enzyme activity. However, these parameters were increased by N rate.