Fruit quality and partitioning of mineral elements in processing tomato in response to saline nutrients

A sand culture experiment was conducted to study the effect of saline water on the growth and fruit quality of processing tomato (Lycopersicon esculentum Mill.) Seedlings of five tomato cultivars were transplanted in quartz‐sand pots in a greenhouse at the Agricultural Experiment Station of Sultan Qaboos University. There were four saline nutrient solutions and a control consisting of half‐strength Hoagland solution. Salinity treatments were: 50 raM NaCl + 3 mM K₂SO₄ (EC 6.75), 50 mM NaCl + 1.5 mM orthophosphoric acid (EC = 7.18), 50 mM NaCl + 1.5 mM orthophosphoric acid + 3 mM R₂SO₄ (EC 7.29), and 50 mM NaCL (EC = 5.6). Treatments were applied daily commencing two weeks after transplanting. Data were collected on growth, and fruit yield and quality. Partitioning of mineral elements was determined in the vegetative tissue. The results obtained clearly show that concentrations of total soluble solids were increased in fruits treated with saline nutrients. Dry matter content of fruits exposed to salinity were higher than those from the control plants. Fruit acidity was increased with salinity, possibly due to a lower water content and increased organic acid accumulation. In the saline treatments, sodium (Na) content was decreased when potassium (K) was applied with NaCl but Na was higher in stems followed by root and leaf tissues. The partitioning of K followed a trend opposite to that for Na but with higher content in leaves. A similar situation was observed for calcium (Ca) and magnesium (Mg). Accumulation of phosphorus (P) was the lowest among all the ions. These results indicated that survival under saline conditions was accompanied by high ion accumulation. The study confirmed that saline nutrients are important for improving fruit quality of processing tomatoes.     

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.     

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.     

Effect of N rate and split application on bahiagrass production

Abstract

Vegetative and reproductive growth were studied in five tomato (Lycopersicon esculentum Mill) cultivars under saline conditions imposed at the five‐leaf stage by addition of 50 mM NaCl to half strength Hoagland nutrient solution. The plants were raised in pots filled with washed quartz sand kept in a greenhouse. Stem height and number of leaves in tomato plants were significantly reduced when irrigated with saline regimes in contrast with control plants that received only the Hoagland solution. The highest number of flowers were obtained in the cultivar Pearson and the least in cultivar Strain B. Fruit set and yield were little affected by varietal differences and were not related to vegetative growth. Fruit weight was suppressed with NaCl stress, but improvement in weight was achieved when potassium (K) and calcium (Ca) were added to the saline water. The most detrimental effect of NaCl stress was the reduction of biomass yield in tomatoes. However, the relative dry weights of Pearson and Monte Carlo were increased to 60% and 54%, respectively, when NaCl was supplemented with Ca. Large varietal differences in biomass occurred among the NaCl‐treated and control plants. Tomato fruit quality (TSS) was improved by salinization.     

Gas exchange,water relations,and Ion concentrations of salt‐stressed tomato and melon plants

Abstract

Tomato and melon plants were grown in a greenhouse and irrigated with nutrient solution having an EC of 2 dS m^?1 (control treatment) and 4, 6, and 8 dS m^?1, produced by adding NaCl to the control nutrient solution. After 84 days, leaf water relations, gas exchange parameters, and ion concentrations, as well as plant growth, were measured. Melon plants showed a greater reduction in shoot weight and leaf area than tomato at the two highest salinity levels used (6 and 8 dS m^?1). Net photosynthesis (Pn) in melon plants tended to be lower than in tomato, for all saline treatments tested. Pn was reduced by 32% in melon plants grown in nutrient solution having an EC of 4 dS m^?1, relative to control plants, and no further decline occurred at higher EC levels. In tomato plants, the Pn decline occurred at EC of 6 dS m^?1, and no further reduction was detected at EC of 8 dS m^?1. The significant reductions in Pn corresponded to similar leaf Cl^? concentrations (around 409 mmol kg^?1 dry weight) in both plant species. Net Pn and stomatal conductance were linearly correlated in both tomato and melon plants, Pn being more sensitive to changes in stomatal conductance (g_s) in melon than in tomato leaves. The decline in the growth parameters caused by salinity in melon and tomato plants was influenced by other factors in addition to reduction in Pn rates. Melon leaves accumulated larger amounts of Cl^? than tomato, which caused a greater reduction in growth and a reduction in Pn at lower salinity levels than in tomato plants. These facts indicate that tomato is more salt‐tolerant than melon.     

Calcium Sulfate Improves Salinity Tolerance in Rootstocks of Plum

ABSTRACT

Three vegetative rootstocks of plum (Prunus domestica), Marianna GF 8-1 (Prunus cerasifera × munsoniana), Myrobolan B (P. Cerasifera) and Pixy (P. Insititia) were grown in pots containing sand and irrigated with complete nutrient solution to investigate the effect of calcium sulfate supplied to the nutrient solution on plants grown under salt stress. Treatments were (1) control (C): nutrient solution alone; (2) S (salinity stress): 40 mM NaCl; (3) S+Ca1: 40 mM NaCl +2.5 mM calcium (Ca) and (4) S+Ca₂: 40 mM NaCl + 5 mM Ca. Calcium was supplied as CaSO₄. The plants grown under 40 mol L^?1 NaCl produced less dry matter and had lower chlorophyll content than those without NaCl. Supplementary CaSO₄ at both 2.5 and 5 mM concentrations ameliorated the negative effects of salinity on plant dry matter and chlorophyll content. Salt treatment impaired membrane permeability by increasing electrolyte leakage. The addition of calcium sulfate partially maintained membrane permeability. Sodium (Na) concentration in plant tissues increased in both leaves and roots of plants under the high NaCl treatment. Pixy had much lower Na. The CaSO₄ treatments lowered significantly the concentrations of Na in both leaves and roots. Pixy was more tolerant to salinity than the other two rootstocks. The accumulation of Na in leaves and roots indicates a possible mechanism whereby Pixy copes with salinity in the rooting medium, and/or may indicate the existence of an inhibition mechanism of Na transport to leaves. Concentrations of Ca and K were lower in the plants grown at high NaCl than in those under the control treatment, and these two element concentrations were increased by calcium sulfate treatments in both leaves and roots, but remained lower than control values in most cases.     

ENHANCEMENT OF GROWTH AND NORMAL GROWTH PARAMETERS BY FOLIAR APPLICATION OF POTASSIUM AND PHOSPHORUS IN TOMATO CULTIVARS GROWN AT HIGH (NaCl) SALINITY

Three tomato (Lycopersicon esculentum) cvs., Rio Grande, Monika F1, and Marylin F1, were grown hydroponically in a controlled temperature (CT) room for 6 weeks to investigate the effectiveness of foliar application of supplementary potassium (K) and phosphorus (P) to the leaves of plants grown at high NaCl concentration (60 mM). Supplementary 5 mM K and P as KH₂PO₄ was supplied via leaves to the plants grown at high NaCl (60 mM) twice a week for 4 weeks. The plants grown at high NaCl produced less dry matter and chlorophyll than those at normal nutrient solution for all three cultivars. Membrane permeability increased with high NaCl application and these increases in membrane permeability were decreased by supplementary K and P. Daily water use by plant was decreased with high NaCl application and increased with supplementary P and K. Foliar application of supplementary K and P resulted in increases in dry matter and chlorophyll concentrations for all three cultvars. These increases were greater in Monika F1 and Marylin F1 than Rio Grande. Sodium (Na) concentration in plant tissues increased for all three cultivars in the elevated NaCl level. Concentrations of P and K were at deficient ranges in the plants grown at high NaCl levels and these deficiencies were corrected by supplementary K and P application via leaves.     

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.     

Salinity and nitrogen fertilization affecting the macronutrient content and yield of sweet pepper plants

The effects of salinity due to sodium chloride (NaCl) and nitrogen (N) concentration in the nutrient solution were studied with sweet pepper plants. Four saline treatments combined with two N fertilization were used. Nitrate‐nitrogen (NO₃ ^‐‐N) presence in the nutrient solution produced an increase of sodium (Na) and potassium (K) contents in leaves as well as N. Salinity promoted a reduction of K, phosphorus (P) and Ca and increased the Na concentration in leaves. Calcium (Ca) concentrations were lower in the higher NO₃ ^‐‐N treatment although N level was reached adding calcium nitrate and salinity increased P, K, Na, Ca, and magnesium (Mg) contents in fruits. Yield was increased in the highest N treatment.     

Kinetics of Zinc Uptake and Anatomy of Roots and Leaves of Coffee Trees as Affected by Zinc Nutrition

Abstract

The influence of silicon (Si) (2.5 mM), sodium chloride (NaCl) (100 mM), and Si (2.5 mM) + NaCl (97.5 mM) supply on chlorophyll content, chlorophyll fluorescence, the concentration of malondialdehyde (MDA), H₂O₂ level, and activities of superoxide dismutase (SOD; E.C.1.15.1.1.), ascorbate peroxidase (APx; E.C.1.11.1.11.), catalase (CAT; E.C.1.11.1.6.), guaiacol peroxidase (G-POD; E.C.1.11.1.7.) enzymes, and protein content were studied in tomato (Lycopersicon esculentum Mill c.v.) leaves over 10-day and 27-day periods. The results indicated that silicon partially offset the negative impacts of NaCl stress with increased the tolerance of tomato plants to NaCl salinity by raising SOD and CAT activities, chlorophyll content, and photochemical efficiency of PSII. Salt stress decreased SOD and CAT activities and soluble protein content in the leaves. However, addition of silicon to the nutrient solution enhanced SOD and CAT activities and protein content in tomato leaves under salt stress. In contrast, salt stress slightly promoted APx activity and considerably increased H₂O₂ level and MDA concentration and Si addition slightly decreased APx activity and significantly reduced H₂O₂ level and MDA concentration in the leaves of salt-treated plants. G-POD activity was slightly decreased by addition of salt and Si. Enhanced activities of SOD and CAT by Si addition may protect the plant tissues from oxidative damage induced by salt, thus mitigating salt toxicity and improving the growth of tomato plants. These results confirm that the scavenging system forms the primary defense line in protecting oxidative damage under stress in crop plants.     

MITIGATION EFFECTS OF SILICON ON TOMATO PLANTS BEARING FRUIT GROWN AT HIGH BORON LEVELS

Interactive effects of silicon (Si) and high boron (B) on growth and yield of tomato (Lycopercison esculentum cv. ‘191 F1’) plants were studied. Treatments were: 1) control (B1), normal nutrient solution including 0.5 mg L^?1 B (boron), 2) B1 +Si treatment: 0.5 mg L^?1 boron plus 2 mM Si, 3) B2 treatment: 3.5 mg L^?1 B, 4) B2 +Si treatment: 3.5 mg L^?1 B plus 2 mM Si, 5) B3 treatment: 6.5 mg L^?1 B, and 6) B3 +Si: 6.5 mg L^?1 B plus 2 mM Si. High B reduced dry matter, fruit yield and chlorophyll (Chl) in tomato plants compared to the control treatment, but increased the proline accumulation. Supplementary Si overcame the deleterious effects of high B on plant dry matter, fruit yield and chlorophyll concentrations. High B treatments increased the activities of superoxide dismutase (SOD; EC 1.15.1.1), peroxidase (POD; EC. 1.11.1.7) and polyphenol oxidase (PPO; EC 1.10.3.1). However, supplementary Si in the nutrient solution containing high B reduced SOD and PPO activities in leaves, but POD activity remained unchanged. These data suggest that excess B-induced oxidative stress and alterations in the antioxidant enzymes. Boron (B) concentrations increased in leaves and roots in the elevated B treatment as compared to the control treatment. Concentrations of calcium (Ca) and potassium (K) were significantly lower in the leaves of plants grown at high B than those in the control plants. Supplementing the nutrient solution containing high B with 2 mM Si increased both nutrients in the leaves. These results indicate that supplementary Si can mitigate the adverse effects of high B on fruit yield and whole plant biomass in tomato plants.     

Effects of Calcium Chloride on Growth,Membrane Permeability and Root Hydraulic Conductivity in Two Atriplex Species Grown at High (Sodium Chloride) Salinity

Calcium (Ca) has an important role in plant physiology, including involvement in the responses to salt stress, and controls numerous processes. To overcome the negative impact of high salinity, the addition of supplemental Ca to the growth medium as an ameliorative agent could be necessary. Atriplex halimus subsp. schweinfurthii and Atriplex canescens subsp. linearis were grown in hydroponic conditions to investigate the effectiveness of supplementary calcium chloride (CaCl₂) applied into nutrient solution on plants grown at high (400 mM) sodium chloride (NaCl) concentration. Treatments were: 1) nutrient solution alone [control (C)]; 2) nutrient solution plus 400 mM sodium chloride (NaCl); and 3) nutrient solution and 400 mM NaCl plus supplementary 40 mM CaCl₂ supplied in nutrient solution (NaCl + CaCl₂). The experiment was set up as a completely randomized design, consisting of two species (A. halimus and A. canescens), three treatments (control, NaCl, and NaCl + CaCl₂), and five replicates. Dry weight and chlorophyll content of plants grown at high NaCl were lower than those at normal nutrient solution. Supplementary CaCl₂ ameliorated the negative effects of salinity on plant growth in both species. Root hydraulic conductivity (L ₀) decreased with elevated NaCl and increased with supplementary CaCl₂ compared to the stressed plants. Membrane permeability increased with high NaCl application and these increases in root membrane permeability decreased with supplementary CaCl₂ compared to the NaCl treatment. Sodium (Na) concentration in plant tissues increased in both species in high NaCl level. Application of supplementary CaCl₂ lowered Na concentration. Concentrations of calcium (Ca) and potassium (K) were at deficient ranges in the plants grown at high NaCl levels and these deficiencies were corrected by supplementary CaCl₂.     

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.     

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.     

Effect of increasing potassium levels for alleviating sodium chloride stress on the growth and yield of tomato

Abstract

The efficacy of using various levels of potassium (K) (4, 8, and 16 mM) under saline conditions to alleviate the detrimental effects of salt‐stress were studied using five tomato (Lycopersicon esculentum Mill) cultivars, ‘Strain 19’, ‘Pearson’, ‘Montecarlo’, ‘Maruthuam’, and ‘Pusa Rub’. Results of the study revealed that 50 mM sodium chloride (NaCl) in a Hoagland nutrient solution significantly reduced stem height, fruit weight, and whole plant dry weights, but increased number of fruits/plant and improved fruit quality by increasing total soluble solids. It did not significantly affect leaf count, percent fruit set, or dry weight. The addition of 4, 8 and 16 mM potassium nitrate (KNO₃) to the nutrient solution containing 50 mM NaCl resulted in sodium/potassium (Na/K) ratios of 12.5, 6.3, and 3.1, respectively. The Na/K ratios of 12.5 and 6.3 produced significant improvement in stem height, percent fruit set, number of fruits/plant, fruit weight, and whole plant dry weight. The Na/K ratio of 3.1 was found to be detrimental as it resulted in sharp reduction of plant dry weight compared to the control. Percent total soluble solids was not significantly affected by the addition of any level of K to the saline nutrient solution. The performance of the tomatoplant grown under saline conditions supplemented with K in the nutrient solution indicated a higher response at the lowest K concentration used in this study.     

Growth,water use efficiency,and sodium and potassium acquisition by tomato cultivars grown under salt stress

Three cultivars of tomato (Lycopersicon esculentum Mill., cvs. Sera, 898, Rohaba) were grown under different levels of NaCl in nutrient solution to determine effects of salt stress on shoot and root dry matter (DM), plant height, water use efficiency (WUE, g DM kg^‐1 water evapotranspired), shoot sodium (Na) and potassium (K) concentrations, and K versus Na selectivity (S_K,Na). Increasing NaCl concentration in nutrient solution adversely affected shoot and root DM, plant height, WUE, K concentration, and K/Na ratio of all cultivars. Shoot Na concentrations increased with increasing NaCl concentration in the nutrient solution. Although increasing salt concentration in the solution adversely affected growth of all cultivars, the cultivar Sera had the highest shoot and root DM than the other two cultivars (898 and Rohaba). Shoot and root DM of cultivar 898 was most affected by salt, while cultivar Rohaba had an intermediate salt sensitivity. The cultivar Sera generally had higher WUE values, shoot K concentrations, and S_K,Na, but had lower shoot Na concentrations than the other two cultivars when plants were grown under different salt levels. Greater Na exclusion, higher K uptake and shoot S_K,Na are suggested as being plant strategies for salt tolerance.     

Effects of Boron and Calcium Supply on Calcium Fractionation in Plants and Suspension Cells of Rape Cultivars with Different Boron Efficiency

Abstract

In this study, the effects of boron (B) and calcium (Ca) supply on Ca fractionation in suspension cells and different tissues of rape (Brassica napus L.) plants of two cultivars with different B efficiency were studied, with a purpose to elucidate the mechanism by which B affects Ca concentration in plants. As Ca supply increased in nutrient solution or culture medium, the relatively easily extractable Ca fractions, that is H₂O and 80% ethanol extractable Ca in leaves, 1 mol L^?1 NaCl extractable Ca in upper leaves, roots and suspension‐cell were significantly increased. While the recalcitrant Ca fractions extracted by 2% acetic acid, 0.6 mol L^?1 HCl and Ca in the residue were not affected by Ca supply. Increasing B supply in nutrient solution or culture media significantly reduced 1 mol L^?1NaCl extracted Ca in suspension cell and roots of both cultivars, which were most likely related to the alteration of cell wall metabolism. Calcium extracted by 2% acetic acid, 0.6 mol L^?1 HCl and Ca in residue in suspension‐cell and roots of B inefficient cultivar Bakow were easily improved by B deficiency as compared to that of B efficient cultivar Tezao16. Increasing of these relative recalcitrant Ca fractions was related to the different response of cultivars to the B deficiency, which may reflected different extent that Ca deposited in the two cultivars due to impaired membrane integrity under B deficiency. The effects of B on Ca concentration in lower and upper leaves of the two cultivars were quite different and were the integrated effects of B on Ca metabolism, Ca transport in plants and growth of certain organ. Increasing B supply increased total Ca concentration in upper leaves of Bakow and reduced that of Tezao16, which might relate to the different adaptability of the two cultivars to comparatively higher B supply.     

Genotype-Dependent Differential Responses of Three Forage Species to Calcium Supplement in Saline Conditions

Salt toxicity comprises of osmotic and ionic components both of which can severely affect root and shoot growth. In many crop species, supplemental calcium (Ca) reduces the inhibition of growth typical of exposure to salt stress. The objective of this study was to compare whole plant growth and physiological responses to interactive effect of salinity and Ca level on three forage species [African millet (AM), tall wheat grass (TW), and perennial ryegrass (PR)] differing in tolerance to sodium chloride (NaCl) salinity. Plants were grown under glasshouse condition and supplied with nutrient solution containing 0, 100, and 250 mM NaCl supplemented with 0.5, 5, or 10 mM calcium chloride (CaCl₂). Plant growth, ionic concentration, water relations, and solute (proline and glycinebetaine) concentrations of the plants were determined two weeks after the salinity treatments. At 100 mM NaCl, there was a moderate reduction in dry matter (DM) production of all three species. A drastic decrease in DM occurred at 250 mM NaCl. Supplemental Ca reduced the adverse effects of salinity on all three species. The TW showed higher shoot and root growth in 100 and 250 mM NaCl than AM and PR. It also showed the highest DM at 5 and 10 mM Ca supplement. The shoot and root DM of TW increased by about 45 and 15%, respectively compared to the control. Chemical analysis indicated that in TW, Ca restricted both uptake and transport of sodium (Na) from root to shoot. It also increased Ca and potassium (K) concentrations in both organs. The transport of K and Ca from root to shoot of AM and PR were decreased by NaCl, but were restored with increasing Ca in the medium. The opposite occurred for Na. In PR, more K uptake was observed in shoot at 250 mM NaCl with 10 mM Ca supplement. The sap osmotic potential (Ψ_S) was the highest in TW at 10 mM Ca in the presence of 250 mM NaCl. Contribution of various solutes to the difference in Ψ_S among the species from the control and 250 mM salt treatment differed greatly. Supplemental Ca induced decline in the leaf Ψ_S of TW which was predominately due to K, glycinebetaine, Na and proline accumulation. Addition of 10 mM Ca to the growth medium maintained a low Na and a high K level. Accumulation of glycinebetaine and proline in leaf contributed the NaCl tolerance of TW. The presented results suggest that supplement Ca, not only improved ionic relations but also induced plant ability in production of compatible solutes (glycinebetaine and proline) and osmotic adjustment. Accordingly, genotype dependent capacity could be found using supplemental Ca.     

Growth and nutrient uptake of tomato in response to application of saline water,biological fertilizer,and surfactant

The importance of using low-quality water, such as saline waters, for food production has been increased in the recent decades. An experiment was conducted to evaluate the effect of diluted seawater (electrical conductivity (EC) of 6 dS m^?1) on growth and nutrient uptake of tomato. We examined if surfactant (0, 1, 2, 4 mg L^?1) and biological fertilizer (compost tea + arbuscular mycorrhizal fungi propagules) have potential to alleviate the adverse effects of salinity on tomato plant. Salinity stress significantly reduced all plant growth parameters. Under salinity stress, nitrogen (N) and potassium (K) contents in tomato shoot were lower, while phosphorus (P), sodium (Na), and calcium (Ca) contents were higher than non-salinized plants; showing ionic imbalance in this condition. Biological fertilizer improved root weight in saline condition. Under salinity stress surfactant application at the rate of 1 mg L^?1 helped tomato plants to maintain their ionic balance, especially declining Na uptake, and improved plant growth.     

Salinity‐induced changes in growth,superoxide dismutase activity,and ion content of two olive cultivars

Olive trees (Olea europaea L.) are considered moderately tolerant to salinity, with clear differences found among cultivars. One‐year‐old self‐rooted olive plants of the Croatian cv. Oblica and Italian cv. Leccino were grown for 90 d in nutrient solutions containing 0, 66, or 166 mM NaCl, respectively. The shoot length and the number of nodes and leaves for both cultivars were not affected by salinity up to 66 mM NaCl. However, at 166 mM NaCl, growth of Leccino was reduced earlier and to a higher extent than growth of Oblica. After 10 d of exposure to 66 and 166 mM NaCl, increased activity of superoxide dismutase (SOD) was observed in Leccino, whereas there was almost no response in Oblica. Reduced SOD activity in Leccino at 166 mM NaCl was observed after prolonged stress (90 d), whereas in Oblica SOD was increased at 66 mM compared to control or 166 mM NaCl. Electrolyte and K⁺ leakage were increased and relative water content decreased as NaCl concentration increased with similar intensity of response measured in both cultivars. Oblica exhibited an ability to keep a higher K⁺ : Na⁺ ratio at all salinity levels compared to Leccino, but since no difference was found in leaf K⁺ concentration, this was mainly achieved by less Na⁺ ions reaching the younger leaves. The antioxidative system represents a component of the complex olive salt‐tolerance mechanism, and it seems that the role of SOD in protection from oxidative stress depends on sodium accumulation in leaves.