Foliar Application of Salicylic Acid on Growth and Yield Components of Tomato Plant Grown under Salt Stress

Abiotic environmental stresses such as drought stress, mineral deficiency, heat stress, and salinity stress are major limiting factors of plant growth and productivity. Tomato (Solanum lycopersicum L.), one of the important and widespread crops in the world, is sensitive to moderate levels of salt in the soil. So many authors have reported large variation among tomato genotypes in their response to salinity. The present study was conducted to study the effect of different concentrations of salicylic acid on growth parameters, yield, and yield attributes of tomato under saline conditions. Tomato plants cv. Marmande were grown under normal or saline (100 mM NaCl) conditions. Different levels of salicylic acid: SA (0, 0.01, 0.1, and 1 mM) were applied as a foliar spray. The study was conducted at the vegetative and reproductive stage. Salt stress reduced significantly the whole plant growth at the two stages. Application of SA caused a significantly increase in biomass under non-saline conditions. However, in salt medium, treatment of leaves by SA induces a slight increase in biomass, leaf area and ameliorates the fruit diameter compared with plant grown only in the presence of salt. The beneficial effect of SA is more pronounced with the dose 0.01 mM

Salicylic acid induced changes on some physiological parameters in tomato grown under salinity

Salinity is a major environmental constraint to crop productivity throughout the arid and semi arid regions of the world. The development of strategies to ameliorate deleterious effects of salt stress on plants has received considerable attention. Salicylic acid (SA) has been shown as an important signal molecule for modulating plant responses to environmental stress. In addition to facilitating the growth of plant, SA has been shown to play a role in mitigating the deleterious effects of some environmental stresses. Therefore, an experiment was conducted to investigate the impact of exogenous salicylic acid (0.01 mM) on some physiological parameters in tomato (Solanum lycopersicum, cv Marmande) grown under salinity stress (NaCl 100 mM). Dry yield of the plants decreased significantly with exposure to NaCl. Exogenous application of SA (0.01 mM), increased dry weight both in saline and non-saline conditions. In saline conditions, with the applied SA, dry yield increased almost up to the yield obtained from non-saline conditions. Salt stress increased membrane permeability of leaves. Exogenously applied SA decreased the membrane deterioration. NaCl reduced photosynthetic pigments contents. Whereas, the addition of SA induced an increase of these contents. Under salinity stress, the amounts of Na, Cl and Na/K ratio severely increased and the amount of K, Ca and Mg decreased. Addition of SA in the culture medium inhibited Na+ and Cl- accumulation, but stimulated K+, Ca2+ and Mg2+ contents of stressed plants. These results suggest that SA could be used as a potential growth regulator to improve plant resistance to salinity stress

Salicylic acid induced changes on some physiological parameters in tomato grown under salinity

Salinity is a major environmental constraint to crop productivity throughout the arid and semi arid regions of the world. The development of strategies to ameliorate deleterious effects of salt stress on plants has received considerable attention. Salicylic acid (SA) has been shown as an important signal molecule for modulating plant responses to environmental stress. In addition to facilitating the growth of plant, SA has been shown to play a role in mitigating the deleterious effects of some environmental stresses. Therefore, an experiment was conducted to investigate the impact of exogenous salicylic acid (0.01 mM) on some physiological parameters in tomato (Solanum lycopersicum, cv Marmande) grown under salinity stress (NaCl 100 mM). Dry yield of the plants decreased significantly with exposure to NaCl. Exogenous application of SA (0.01 mM), increased dry weight both in saline and non-saline conditions. In saline conditions, with the applied SA, dry yield increased almost up to the yield obtained from non-saline conditions. Salt stress increased membrane permeability of leaves. Exogenously applied SA decreased the membrane deterioration. NaCl reduced photosynthetic pigments contents. Whereas, the addition of SA induced an increase of these contents. Under salinity stress, the amounts of Na, Cl and Na/K ratio severely increased and the amount of K, Ca and Mg decreased. Addition of SA in the culture medium inhibited Na+ and Cl- accumulation, but stimulated K+, Ca2+ and Mg2+ contents of stressed plants. These results suggest that SA could be used as a potential growth regulator to improve plant resistance to salinity stress

Superoxide dismutase isozyme activity and antioxidant responses of hydroponically cultured Lepidium sativum L. to NaCl stress

The present study was focused to assess the physiological behavior and antioxidant responses of the medicinal plant Lepidium sativum L. (commonly called Garden cress) subjected hydroponically to NaCl stress during its vegetative growth stage. The results showed that the addition of NaCl to growth medium significantly reduced plant growth. The magnitude of the response was also linked to the plant organ considered and NaCl concentration supplemented to the medium. Tissue hydration seemed unaffected by salinity. Reduction in dry weight (DW) production was associated with a high accumulation of Na+ and Cl- and a significant reduction of K+ content in shoots. The accumulation of osmoregulatory compounds (proline and total sugars) in shoots and roots was greatly increased by NaCl. Activity staining of antioxidants after a native polyacrylamide gel electrophores (PAGE) showed four superoxide dismutase (SOD) isozymes in the extract of leaf-soluble proteins (one Mn-SOD, two Fe-SODs, and one CuZn-SOD), and three isoforms in roots (Mn-SOD, Fe-SOD, and CuZn-SOD). Four peroxidase (POD) isozymes in the roots and only one isozyme in the leaves were detected. The work demonstrated that activities of antioxidant defense enzymes changed in parallel with the increased salinity. In summary, these findings proved that L. sativum can be classified as a moderately tolerant plant to salinity. © 2013 Taylor & Francis

Comparative proteomic analysis of tomato (Solanum lycopersicum) leaves under salinity stress

Salinity is a major constraint to crop productivity. The mechanisms responsible for the effects of salt stress on tomato plants were examined by means of proteomic analysis. Two contrasting tomato genotypes (cv. Roma and cv. SuperMarmande) seedlings were cultivated using a hydroponic system in the controlled environment growth chamber. The salt stress (NaCl) was applied (0, 100 and 200 mM) and maintained for 14 days. Leaf osmotic potential significantly decreased with NaCl treatment in genotype SuperMarmande. However, genotype Roma maintained its leaf osmotic adjustment under salt treatment. Lipid peroxidation (estimated by MDA content) significantly increased under salt in both cultivars, but the rate of increment was higher in genotype SuperMarmande. Leaves of control and salt-stressed plants were also sampled for phenol protein extraction. Proteins were separated by two-dimensional gel electrophoresis (2-DE). 26 protein spots exhibited significant abundance variations between samples. Our results indicated that some proteins exhibited variation strictly related to salt stress whatever the genotype, while some other proteins also showed variation which could be related to the degrees of genotype tolerance. The up-regulation of Rubisco activases and RuBisCO large subunit under salt treatment, was correlated with an increase in abundance level of proteins that are involved in energy metabolism (pyruvate dehydrogenase, Glucose-6-phosphate dehydrogenase, Malate dehydrogenase), especially in salt-tolerant genotype (Roma). Accumulation of antioxidants enzymes (ascorbate peroxidase, glutathione peroxidase, peroxidase and mitochondrial peroxiredoxin) in the leaves of salt tolerant genotype (Roma) was well correlated with the level of lipid peroxidation of membranes. Up-regulation of Heat Shock Proteins and maintenance of water status as reflected by leaf osmotic potential are considered to be strongly correlated with to the degrees of tomato genotype tolerance in this study

Does salicylic acid (SA) improve tolerance to salt stress in plants? A study of SA effects on tomato plant growth, water dynamics, photosynthesis and biochemical parameters

Environmental stresses such as salinity directly impact crop growth, and by extension, world food supply and societal prosperity. It is estimated that over 800 million hectares of land throughout the world are salt-affected. In arid and semi-arid regions, salt concentration can be close to that in the seawater. Hence, there are intensive efforts to improve plant tolerance to salinity and other environmental stressors. Salicylic acid (SA) is an important signal molecule for modulating plant responses to stress. In the present study, we examined, on multiple plant growth related endpoints, whether SA applied through the rooting medium could mitigate the adverse effects of salinity on tomato (Solanum lycopersicum) cv. Marmande. The latter is a hitherto understudied tomato plant from the above perspective; it is a classic variety that produces the large ribbed tomatoes in the Mediterranean and consumed worldwide. We found salt stress negatively affected the growth of cv. Marmande tomato plants. However, the SA-treated plants had greater shoot and root dry mass, leaf area compared to untreated plants when exposed to salt stress. Application of SA restores photosynthetic rates and photosynthetic pigment levels under salt (NaCl) exposure. Leaf water, osmotic potential, stomatal conductance transpiration rate, and biochemical parameters were also ameliorated in SA-treated plants under saline stress conditions. Overall, these data illustrate that SA increases cv. Marmande tomato growth by improving photosynthesis, regulation and balance of osmotic potential, induction of compatible osmolyte metabolism, and alleviating membrane damage. We suggest salicylic acid might be considered as a potential growth regulator to improve tomato plant salinity stress resistance, in the current era of global climate change

Exogenous application of calcium silicate improves salt tolerance in two contrasting tomato (Solanum lycopersicum) cultivars

The aim of this study was to investigate the impact of application of calcium silicate and salinity singly, on plant growth and nutritional behavior and photosynthetic pigments of tomato. Application of sodium chloride (NaCl) induced significant reduction in plant development and growth parameters. Salt stress also led to an accumulation of sodium (Na+) and a decrease in potassium (K+) concentration. Reduction of chlorophyll and carotenoid in leaves were amongst other symptoms in salt-affected plants in 2 cultivars. Rio Grande was qualified as salt sensitive and Moneymaker as the salt tolerant genotype. Application of Silicon (Si) only improved plant behaviour as compared to control. Furthermore, Si induced ameliorative effects on the growth potential of NaCl stressed plants. This Si-ameliorative effect on plant varied depending on the considered cultivar and Si concentration. Based on these results, application of calcium silicate was suggested as an alternative way to ameliorate the harmful effects of salinity on tomato

Characterization of transgenic Arabidopsis and tomato plants antisensed for the ethylene receptor gene <i>CcEIN4</i> under NaCl stress

<div><p>The plant hormone ethylene (C₂H₄) plays important roles in plant growth and development. Here, we report physiological response of transgenic Arabidopsis and tomato plants, antisensed for the ethylene receptor gene <i>CcEIN4</i> from coffee trees (<i>Coffea canephora</i>), under salinity stress. Results showed that the germination rate was higher in seeds collected from transgenic plants than that seeds from wild plants under salt stress condition. Growth of transgenic Arabidopsis and tomato plants was less sensitive to salt stress than wild type. Some transgenic plants showed a stimulation of radicle length and root system growth. The better salt tolerance observed in transgenic tomatoes lines can be explained by: ability to control the accumulation of Na⁺ and Cl⁻ in shoots and better K⁺ and Ca^{2 +} uptake, resulting in higher K⁺:Na⁺ and Ca^{2 +}:Na⁺ ratios. These results suggest that ethylene perception is involved in the plant response to saline stress and plays a pivotal role in the plant salt tolerance.</p></div

Superoxide dismutase isozyme activity and antioxidant responses of hydroponically cultured Lepidium sativum

The present study was focused to assess the physiological behavior and antioxidant responses of the medicinal plant Lepidium sativum L. (commonly called Garden cress) subjected hydroponically to NaCl stress during its vegetative growth stage. The results showed that the addition of NaCl to growth medium significantly reduced plant growth. The magnitude of the response was also linked to the plant organ considered and NaCl concentration supplemented to the medium. Tissue hydration seemed unaffected by salinity. Reduction in dry weight (DW) production was associated with a high accumulation of Na+ and Cl- and a significant reduction of K+ content in shoots. The accumulation of osmoregulatory compounds (proline and total sugars) in shoots and roots was greatly increased by NaCl. Activity staining of antioxidants after a native polyacrylamide gel electrophores (PAGE) showed four superoxide dismutase (SOD) isozymes in the extract of leaf-soluble proteins (one Mn-SOD, two Fe-SODs, and one CuZn-SOD), and three isoforms in roots (Mn-SOD, Fe-SOD, and CuZn-SOD). Four peroxidase (POD) isozymes in the roots and only one isozyme in the leaves were detected. The work demonstrated that activities of antioxidant defense enzymes changed in parallel with the increased salinity. In summary, these findings proved that L. sativum can be classified as a moderately tolerant plant to salinity. © 2013 Taylor &amp; Francis