Interactive effects of salinity and macronutrient level on wheat. II. Composition

Results of several studies show interactive effects of salinity and macronutrients on the growth of wheat plants. These effects may be associated with the nutrient status in plant tissues. The objective of this study was to investigate interactive effects of salinity and macronutrients on mineral element concentrations in leaves, stems, and grain of spring wheat (Triticum aestivum L. cv. Lona), grown in hydroponics, and the relation of these effects to yield components. Eight salinity levels were established from 0 to 150 mM NaCl, and 1, 0.2, and 0.04 strength Hoagland macronutrient solution (x HS) were used as the macronutrient levels. Sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), chlorine (Cl), and phosphorus (P) in leaves, stems, and grain, NO₃ in leaves and stems, and total nitrogen (N) in grain were determined. Supplemental Ca, Mg, K, and NO₃ added to 0.2 x HS increased mineral concentrations in leaves and stems, but did not improve growth or yield in salinized wheat plants except moderately at 100–150 mM NaCl. In contrast, growth or yield was improved significantly when the concentration of macronutrients was increased from 0.04 to 0.2 × HS. In contrast to leaves and stems, mineral concentrations in grain increased (Na, Cl) or decreased (Ca, Mg, K) only slightly or were not affected (K) by salinity except at high salinity and low macronutrient level. Nitrogen and P concentrations in grain were not affected by salinity. Sodium and Cl concentrations in leaves and stems increased significantly, whereas K and NO₃ decreased significantly, with an increase in salinity regardless of the macronutrient level. The latter was also observed for Ca and Mg in leaves. Extreme Na/Ca ratios in plant tissues negatively affected grain yield production at high salinity with medium or high macronutrient levels and at low macronutrient level together with medium salinity. Even though strong and significant correlations between mineral concentration at grain maturity in leaves, stems, and grain and various yield parameters were observed, our results are inconclusive as to whether toxicity, nutrient imbalance, nutrient deficiency, or all of these factors had a strong influence on grain yield.     

Ionic balance,biomass production,and organic nitrogen as affected by salinity and nitrogen source in annual ryegrass

Studies on the effects of salinity and nitrogen (N) fertilization on ionic balance, biomass, and organic N production of annual ryegrass (Lolium multiflorum Lam.) were conducted. Plants grown in sand were irrigated with nutrient solution with an electrical conductivity of 2 or 11.2 dS#lbm^‐1, and N in the form of sodium nitrate (NaNO₃), ammonium nitrate (NH₄NO₃), or ammonium sulfate [(NH₄)₂SO₄] ranging from 0.5 to 9.0 mM. Salinity increased the concentration of total inorganic cations (C) in plants and specifically sodium (Na) by more than 3‐fold higher in plants grown at high salinity as compared with plants at low salinity. Sodium (Na) concentration in roots was higher than in shoots irrespective of the salinity level, suggesting a restriction of Na transport from roots to shoots. The concentration of total inorganic anions (A) increased with salinity and when plants were supplied with nitrate (NO₃), salinity increased the concentrations of NO₃ and chloride (Cl) in plants. Increasing salinity and N concentration in the growth medium increased organic anions concentration in plants, estimated as the difference between C and A. The effect of different N sources on C‐A followed the order: NH₄NO₃ > NO₃ > ammonium (NH₄). The base of organic anions and inorganic ions with salinity contributed significantly to the osmotic potential of plants shoots and roots. Changes in C affected N and organic acids metabolism in plants, since C were highly correlated (p=0.0001) with C‐A and organic N (N_org) concentrations regardless of the salinity level or N source in the nutrient solutions. A high and positive linear dependency was found between N_org and C‐A in plants grown at high and low salinity levels and different N sources, pointing out the close relationship between N_org and organic anions on metabolism under these conditions. The amount of biomass produced was correlated positively with organic anion concentration in plants exposed to different salinity levels. Plant biomass increased with N concentration in the nutrient solution regardless of the salinity level applied. Biomass accumulation decreased while N_org concentration increased with salinity. Organic N content remained unaffected in plants exposed to salinity when grown in N less than 9.0 mM.     

Ammonium increases the net rate of sodium influx and partitioning to the leaf of muskmelon

The influx and partitioning of sodium (Na) is controlled by potassium (K)/Na selectivity/exchange mechanisms. Since ammonium‐nitrogen (NH₄‐N) has been shown to inhibit K absorption and K/Na selectivity/exchange mechanisms control Na influx and partitioning, our objective was to observe if NH₄‐N affects Na influx and partitioning in muskmelon. Muskmelon (Cucumis melo L.) were grown in a pH controlled nutrient solution with 100 mM NaCl in a complete nutrient solution containing either 10 mM nitrate‐nitrogen (NO₃‐N) or NH₄‐N. With NH₄‐N, Na accumulation and partitioning to the leaf blade increased while K absorption was almost completely inhibited. A second study omitted K to simulate the inhibition of K absorption by NH₄‐N and monitored Na accumulation and partitioning as K was depleted in the plant. Sodium accumulation and partitioning to the leaf increased as K decreased in the plant, mirroring the effect of NH₄‐N. Roots appeared healthy in both studies. Our work indicates that at a given level of NaCl stress, NO₃‐N reduces the level of stress experienced by muskmelon plants through reducing the net rate of Na influx and transport to the sensitive leaf blade, not by reducing chloride (Cl) absorption, thereby permitting these plants to “avoid”; this stress.     

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.     

Enhancement of salinity tolerance in tomato: Implications of potassium and calcium in flowering and yield

Abstract

Five tomato (Lycopersicon esculentum Mill) cultivars were grown in sand nutrient culture experiment in a greenhouse to investigate the effects of salinity on growth and yield. Nutrient solutions were made saline with 50 mM NaCl (EC = 5.5 mS/cm or supplemented with 2 mM KNO₃ (EC = 6.8), 20 mM Ca(NO₃)₂ (EC = 7.5), and combination of potassium (K) and calcium (Ca) (EC = 8.0). Seedlings were irrigated with saline treatments commencing two weeks after transplanting. Determination of sodium (Na) and K in tomato leaves and fruits were by flame photometry. Accumulation of Na in tomato fruits was higher than in leaves under control or saline conditions for all tomato cultivars. The amount of K in the tomato leaves was higher in control than in saline‐grown plants. Addition of K and Ca to the nutrient solution resulted in a 3 to 7 fold increase in K accumulation in all cultivars tested. Stem and leaf growth were significantly reduced with salinity but growth was enhanced following irrigation when K was added to the nutrient solution. Flowering and fruit set were adversely affected by NaCl stress. Reduction of flower number was 44% relative to the control plants. Fresh fruit yield decreased by 78% when plants received 50 mM NaCl. Growth and development of tomatoes under saline conditions was enhanced in this study following the application of K to the saline nutrient solution. Amelioration in growth was also achieved when Ca was used but to a lesser extent. Our results suggest that ion accumulation and regulation of K and Ca contribute to salt tolerance and growth enhancement.     

Improved Nutrient Uptake Enhances Cotton Growth and Salinity Tolerance in Saline Media

Two experiments were conducted to determine if improved nutrient uptake increases salinity tolerance of cotton (Gossypium hirsutum L.). A transgenic cotton line (CMO3) with increased salt tolerance and its wild line (SM3) were grown in pots containing substrate (peat:vermiculite = 1:1, v/v) in the first experiment, while cotton (‘SCRC 28’) was cultured in hydroponics with a split-root system in the second experiment. Contents of essential nutrient elements and Na⁺ in plant tissues, leaf photosynthesis (Pn) and chlorophyll (Chl) concentration and plant biomass were determined after salinity [sodium chloride (NaCl)] treatment in both experiments. In the first experiment, salinity stress with 150 mM NaCl reduced plant biomass and photosynthesis (Pn) of both SM3 and CMO3 compared with their non-stressed controls, but the CMO3 suffered significantly lower reductions than SM3, suggesting an increased salinity tolerance of CMO3 relative to SM3. Total uptake and contents of main nutrient elements [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn)] in CMO3 were higher than those in SM3. Also, less sodium (Na⁺) accumulation and lower extreme ratios of Na/N, Na/P, Na/K, Na/Ca, Na/Mg, Na/Fe, Na/Mn, Na/Cu, and Na/Zn were observed in CMO3 than in SM3. Increased salt tolerance in transgenic AhCMO cotton was probably attributed to its superior nutrient uptake compared with SM3. In the second experiment, the non-stressed root half fed with moderate level of nutrient solution and salt-stressed half fed with low level of nutrient solution (CMN/SLN) exhibited higher salinity tolerance than salt-stressed root half fed with moderate level of nutrient solution and non-stressed root half fed with low nutrient solution (CLN/SMN). Plants absorbed more nutrients but less Na⁺ under CMN/SLN than CLN/SMN. The overall results suggest that improved nutrient uptake played an important role in the enhanced salt tolerance of cotton.     

Salinity induced effects on the nutrient status of soil,corn leaves and kernels

Abstract

The effect of salinity in inducing soil macro and micronutrient deficiencies that can decrease crop growth was evaluated in a corn (Zea mays L.) field located in east central Wyoming. In this study water soluble Na was found to be a better predictor of salinity than pH and other cations. Soil saturated paste extracts had electrical conductivities that were negatively correlated with soil total K, Cu, Fe, and Mn. Total N, NO₃‐N, PO₄‐P, Zn, pH, and water soluble Na, Ca, and Mg of the soil were positively correlated with EC. Significant positive relationships existed between soil EC and N, P, Mo, and Zn, and negative relationships with K, Cu, Fe, and Mn of corn leaves and kernels. Concentrations of nutrients in the kernels were positively correlated with corresponding nutrient concentrations in the leaves and with AB‐DTPA extractable soil nutrients. The analysis of variance of EC data indicated that soil samples possessing high salinity were higher in pH and contained significantly higher soluble Na, Ca and Mg, total N, N0₃‐N, PO₄‐P, and Zn and significantly lower Mn compared to samples having low salinity. The kernel weight per cob and plant height were significantly reduced as salinity increased.     

Salt tolerance and mineral relations for celery

To invertigate the relationship between salt tolerance and plant mineral status in celery (Apium graveolens L.) growth and the concentration of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), and chloride (Cl) in different tissues were determined in plants grown in hydroculture with nutrient solutions containing 5 (control), 50,100, and 300 mM sodium chloride (NaCl) for four weeks. At salinity levels of 50 and 100 mM NaCl, there was a moderate, albeit significantly, reduction of growth, while a drastic decrease in both fresh and dry weight was obtained at 300 mM NaCl. Regardless of the salinity level, growth resumed promptly and completely once the stress was ceased. Sodium chloride stress reduced the accumulation of nitrate (NO₃)‐N in all plant tissues, but there were no relevant effects on the concentration of reduced N and P. The concentration of K in roots and leaf petioles was unaffected by NaCl treatment, but it gradually declined with increasing salinity in leaf blades. This reduction was less pronounced in the young leaves as compared to the mature ones. Increasing the NaCl concentration decreased the concentration of Ca in all tissues, but it prevented the occurrence of black‐heart, a typical Ca‐related physiological disorder which affected severely the controls. Salt‐stressed plants absorbed large amounts of Na and Cl which accumulated in the mature leaves, particularly in the oldest leaves. These findings suggest that the relatively high salt tolerance of celery relies on the ability to maintain an adequate nutritional status and to protect the shoot meristem from salt toxicity.     

Effect of sodium arsenite and sodium chloride on bean plant nutrition (macronutrients)

The effects of different levels of arsenic (As) and salinity on bean plant (Phaseolus vulgaris L., cv. Buenos Aires) nutrition were investigated. We studied the processes of absorption and accumulation of macronutrient elements: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg). The experiment was performed in soilless culture at two levels of As: 2 and 5 mg AsL^‐1 (added as sodium arsenite, NaAsO₂), and three saline levels [only sodium chloride (NaCl) was added]: 1, 2, and 4 dS‐m^‐1. Sodium arsenite and NaCl significantly affected macronutrients allocation within bean plant at concentration levels used in this study. Arsenite depressed K, Na, and Mg concentrations in root, whereas root N, and Ca levels were increased. Nitrogen, P, K, and Na concentrations were significantly higher in As‐stressed plants compared with controls. The addition of NaCl increased Ca concentration in roots and decreased that of K. Salinity tended to increase leaf concentrations of K, Na, Ca, and Mg; whereas leaf N and P levels decreased with increasing salinity.     

Nitrogen nutrition of white rose potato in relation to vegetative growth and mineral content of leaves and roots

Abstract

White Rose potato plants were transplanted to nutrient solutions provided vith nine treatments of Ca(NO₃)₂ ranging from 0 to 64 mmoles per liter. Eighteen days later, symptoms of N‐deficiency ranging from very severe to none vere observed. The plants at this time were harvested, and leaves were sampled, oven dried, ground, and then analysed for K, Na, Ca, Mg, NO₃‐N, and acetic acid soluble H₂PO₂‐P.

Shoot and fibrous root growth increased with nitrate supply to an optimum, and then decreased with increased nitrate supply, suggesting nitrate toxicity due to the high nitrate supply of the nutrient solution. The nitrate content of the tissues increased with increased nitrate supply. Toxicity due to excess nitrate was associated with a very high nitrate content of the leaf tissues.

The critical NO₃‐N concentration at a 10% reduction in vegetative growth due to N‐deficiency is about 2000 ppm (0.2%) on a dry basis for the petioles and about 300 ppm (0.03%) for the blades of recently matured leaves.     

铁和不同形态氮素对玉米植株吸收矿质元素及其在体内分布的影响——Ⅰ.对氮、磷、钾、钙、镁等营养元素的影响

用营养液培养方法研究了铁和两种形态氮素(NO₃^--N和NH₄⁺-N)对玉米植株吸收氮、磷、钾等大量元素和钙、镁等中量元素及其在体内分布的影响。结果表明:与NO₃^--N相比,供应NH₄⁺-N促进了玉米对氮的吸收,在缺铁条件下,降低了对磷、钾、钙及镁的吸收。铁和NH₄⁺-N都显著提高了玉米植株各器官中氮的含量。与NH₄⁺-N处理相比,NO₃^--N处理的新叶中磷含量显著增加,但铁的供应对植物体内磷的含量无显著影响。使用NO₃^--N显著提高了玉米新叶和老叶中钾的含量,根和茎中钾的含量无明显影响。铁的供应降低了新叶和老叶中钾的含量。供铁时,NH₄⁺-N处理的玉米新叶中钙和镁的含量显著低于NO₃^--N处理,而在缺铁时则无显著差异。     

Effect of salinity on stomatal resistance,proline, and mineral composition of pepper

Pepper (Capsicum annuum L.) plants grown in pots were irrigated with the nutrient solutions containing 50, 75, and 100 mM NaCl or a control solution. Salinity markedly decreased plant growth. Increasing salinity levels increased stomatal resistance and sodium (Na), chloride (Cl), proline contents of the plants. Potassium (K), total‐nitrogen (N), and chlorophyll content of the plants were decreased under high salinity conditions.     

Salinity tolerance in tomato: Implications of potassium,calcium, and phosphorus

Abstract

The effect of salinity on the growth and yield of tomato plants and mineral composition of tomato leaves was studied. Five tomato (Lycopersicon esculentum Mill) cultivars, Pearson, Strain B, Montecarlo, Tropic, and Marikit, were grown in sand nutrient culture. The nutrient solutions applied consisted of a modified half‐strength Hoagland solution with 50 mM sodium chloride (NaCl), 3 mM potassium sulphate (K₂SO₄), 1.5 mM orthophosphoric acid (H₃PO₄), and 10 mM calcium sulphate (CaSO₄). Stem height and number of leaves of tomato plants were not found to be significantly different but leaf and stem dry weight were reduced significantly in plants irrigated with saline nutrient solution in contrast with control plants. The total yield was reduced in plants that received saline treatments, but there was no significant difference in fruit number and fruit set percentage. The fruit electrical conductivity and total soluble solids were increased in plants irrigated with saline nutrient solution. Fruit pH was not found to be significantly different among salinity treatments. Mineral composition of tomato leaves were increased by addition of potassium (K), phosphorus (P), and calcium (Ca) to the saline nutrient solution. The addition of K to the solution resulted in an increase in sodium (Na) leaf content. The amounts of K and magnesium (Mg) were not significantly different among salinity treatments. Calcium content was increased when CaSO₄ was added. Application of H₃PO₄ resulted in the highest amount of P in tomato leaves under saline conditions. The present study revealed that application of K, P, and Ca under saline conditions improved fruit electrical conductivity and total soluble solids. Sufficiency levels of the mineral nutrients K and P were obtained in tomato leaves when the appropriate nutrient was used in the saline solution.     

Effect of soil pH and nitrogen source on nutrient status in peach: I. Macronutrients

Following 13‐year treatments of soil pH and nitrogen (N) source in a peach orchard of North Carolina, the concentration of calcium (Ca), magnesium (Mg), N, phosphorus (P), and potassium (K) in leaves, shoots, trunks and roots, as well as soil pH, soil exchangeable Ca, Mg, and K content, were determined. Through liming, higher soil pH treatment enhanced soil Ca and tissue Ca level. Among six N sources examined, the highest values of soil pH and soil Ca, Mg, and K were detected following poultry manure application. Compared to ammonium sulfate [(NH₄)₂SO₄], calcium nitrate [Ca(NO₃)₂] increased soil pH and soil Ca and K content, but reduced soil Mg. For most of macronutrients examined in peach tissues, the highest levels were found in manure treatment. Mineral N sources containing Ca(NO₃)₂ resulted in high tissue Ca and low tissue N. In the above‐ground tissues, Mg concentration was relatively low following application of mineral N materials containing Ca, K, or sodium (Na). Acid‐ forming N, especially (NH₄)₂SO₄, reduced tissue Ca and P. The magnitude of impact of liming and N source on macronutrients was tissue‐type dependent, with leaves and other new growth the most sensitive ones while trunks seldom responded to the treatments.     

Effects of saline nutrient solutions on the growth and accumulation of mineral elements in some tomato cultivars

Abstract

Tomato cultivars were grown in a saline nutrient culture system to investigate growth and fruiting responses in relation to the application of 3 mM potassium (K), 1.5 mM phosphorus (P), and 10 mM calcium (Ca). The deleterious effects of salinity on tomato stem growth and fruit yield were ameliorated following the addition of K, P, and Ca to the nutrient solution. Potassium levels in tomato leaves were increased 4‐fold compared to control plants in the presence of applied K. The use of K resulted in an increase in Na content, however, a comparatively low level of sodium (Na) was obtained in treatments receiving K, Ca, and P. Calcium content was greater than sufficiency levels in all treatments, whereas magnesium (Mg) declined with the increase in salinity. The amount of P in tomato leaves was increased 4–5 fold when the nutrient solution was supplemented with 1.5 mM P. Correlation of vegetative parameters, such as stem height and leaf growth to salinity, revealed no significant responses, however commercial parameters such as total soluble solids and fruit weight correlated significantly with the saline nutrient treatments.     

Growth and macronutrient contents of faba bean plants: Effects of salinity and nitrate nutrition

The effects of the interaction between sodium chloride, nitrate, and concentrations on growth and internal ion content of faba bean (Vicia faba L.) plants were studied, to understand the relationship between the above parameters and salt tolerance. Increased salinity substantially reduced the dry weight of roots and shoots and increased the root/shoot biomass ratio. Additional nitrate‐N considerably moderated the salinity effects on these parameters. The promotive effects of nitrate‐N were more pronounced on shoot dry weight. These results suggest that an exogenous supply of nitrate‐N would improve the vegetative growth of V. faba plants by moderating the suppresive effects of salinity. The evolution of the root and shoot content in potassium (K), sodium (Na), magnesium (Mg), calcium (Ca), and nitrogen (N) was monitored during vegetative growth. A high correspondence between total N and Ca content was found. The acquisition of Ca and K in response to salt and nitrate was similar in shoots and roots, whereas Mg uptake showed notable differences in the two organs. In salt‐affected plants, the roots were found to be high in accumulated Na while the shoots exhibited the lowest Na concentration. Potassium accumulation was higher in the shoots. In this way, there was an antagonistic effect between Na and K uptake. Analyses of the nutrient contents in plant organs have provided a data base on salt‐tolerance mechanisms of V. faba plants.     

Interactions of oxygen‐nitrogen‐salinity stresses on plant growth and mineral content of sunflower (Helianthus annuus L.) in sand culture

Reports relating the separate and combined influences of soil aeration, nitrogen and saline stresses on the germination, growth and ion accumulation in sunflowers are lacking in the literature. The sunflowers of this report were grown in sand culture in the greenhouse. Separate and combined treatments of two levels of aeration, three levels of nitrogen and three levels of NaCl were applied to plants which were harvested at 40 and 56 days. Seed germination was excellent in all treatments. Plant height and dry weight decreased with each type of stress. Low oxygen (0.20 μg O₂ cm^‐2 min^‐1) and nitrogen (10 ppm) combined with 70 meq/1 NaCl caused the greatest reduction of plant growth. Leaf number was reduced by low nitrogen and excess salt. Low oxygen reduced the accumulation of K, Ca and Mg and increased the Na and N‐NO₃ content of sunflower leaves. Potassium to sodium ratios in plant on sunflower growth could be partially ameliorated with the tissue were decreased by greater EC values of the nutrient solution and low soil ODR. The adverse effects of salt and oxygen stresses addition of nitrogen. Ion accumulation was an earlier indicator of plant stress than plant growth and both parameters provided excellent methods for assessing plant tolerance to soil aeration, nitrogen and saline stresses.     

Nitrate and ammonium nutrition in chicory and rocket salad plants

To evaluate chicory (Cichorium intybus L.) and rocket salad [Eruca vesicaria (L.) Cav.subsp. sativa (Mill.)] capability to use ammonium‐nitrogen (NH₄‐N) even in the absence of nitrate‐nitrogen (NO₃‐N) in the nutrient solution, and the chances they offer to reduce leaf NO₃ content, cultivated rocket and two cultivars of chicory ('Frastagliata’, whose edible parts are leaves and stems, and ‘Clio’, a leaf hybrid) were hydroponically grown in a growth chamber. Three nutrient solutions with the same nitrogen (N) level (4 mM) but a different NH₄‐N:NO₃‐N (NH₄:NO₃) ratio (100:0, 50:50, and 0:100) were used. Rocket growth was inhibited by NH₄ nutrition, while it reached the highest values with the NH₄:NO₃ ratio 50:50. Water and N‐use efficiencies increased in rocket with the increase of NO₃‐N percentage in the nutrient solution. In the best conditions of N nutrition, however, rocket accumulated NO₃ in leaves in a very high concentration (about 6,300 mg kg^‐1 fresh mass). For all the morphological and yield features analyzed, chicory resulted to be quite unresponsive to N chemical forms, despite it took more NO₃‐N than NH₄‐N when N was administered in mixed form. By increasing NO₃‐N percentage in the nutrient solution, NO₃ leaf content increased (5,466 mg kg^‐1 fresh mass with the ratio NH₄:NO₃ 0:100). On average, both chicory cultivars accumulated 213 mg NO₃ kg^‐1 fresh mass with the ratio NH₄:NO₃ 100:0 and, differently from rocket, they showed that by using NH₄ produce can be obtained very low in NO₃ content.     

The effect of N and NaCl on growth,yield, and nitrate content of salad rocket (Eruca sativa Mill.)

Hydroponic production of rocket as a salad vegetable has become increasingly important in recent years. Rocket is known to be a high nitrate (NO₃^–)-accumulating vegetable, which can be grown throughout the year. In the present study, rocket was grown in a floating hydroponic system at three levels of nitrogen (N) and sodium chloride (NaCl). The highest yield was obtained at 14 mM N, whereas the yield was lower at 20 mM and 40 Mm NaCl. Leaf elongation was more sensitive to salinity than leaf differentiation. Adding NaCl to the nutrient solution increased the relative chlorophyll content. Na⁺ and Cl^– concentrations increased as salinity increased. NO₃^? levels in fresh biomass increased with increased amounts of NO₃^? in the nutrient solution, and plants at 18 mM N were able to maintain a higher NO₃^? : Cl^? ratio than those at 10 mM N.     

Short-Term Effect of Drought and Salinity on Growth and Mineral Elements in Wheat Seedlings

Both drought and salinity cause nutrient disturbance, albeit for different reasons: a decrease in the diffusion rate of nutrients in the soil and the restricted transpiration rates in plants for drought and extreme soil sodium (Na)/calcium (Ca), Na/potassium (K), and chloride (Cl)/nitrate (NO₃) ratios for salinity. The objective of this study was to examine short-term effects of drought and salinity on nutrient disturbance in wheat seedlings. Wheat was grown in a greenhouse in soil under drought and saline conditions for 26 days after sowing. At harvest, shoot biomass and length, and fresh weight and dry weight of the blade and sheath in expanded leaves 3 and 4 and expanding leaf 5 were determined. Mineral elements (K, Ca, magnesium (Mg), phosphorus (P), nitrogen (N), Na, sulphur (S), iron (Fe), zinc (Zn), and manganese (Mn)) in leaf blades and sheaths were also analyzed. At harvest, the reduction in plant height, shoot biomass, and accumulative evapotranspiration under drought was similar to that under salinity as compared with control plants. However, drought decreased the accumulation of all ions in the blade of the youngest leaf 5 compared with the control, whereas there was either an increase or no difference in all ion concentrations under saline conditions. The change in concentration for most ions in the blade and sheath of expanded leaves 3 and 4 varied among control, drought, and salinity plants, which indicated a different competition for nutrients between the sheath and blade of expanded leaves under drought and saline conditions. It can be concluded from this study that ion deficiency might occur in expanding leaves under drought but not saline conditions.