Growth and pigment content of wheat as influenced by the combined effects of salinity and growth regulators

A field experiment was conducted to investigate the effects of presoaking the wheat grains (Triticum aestivum L.) in different levels of salinity (33 or 66 mM) and in growth regulators (indolyl-3-acetic acid, IAA at SO g m^-3, gibberellic acid, GA₃ at 100 g m^-3, or kinetin at 100 g m_-3) on the shoot growth and pigment content of the developing wheat flag leaf. Salinity at 33 or 66 mM led to an insignificant increase in the fresh and dry masses as well as in the shoot diameter and shoot length, but it attenuated the flag leaf area. In the majority of cases, salinity increased the chlorophyll (Chla, Chlb) and carotenoid contents as well as the number of chloroplasts per a mesophyll cell. The growth in the wheat shoot of the saline-treated plants was, in general, stimulated in response to presoaking the grains in kinetin or GA₃. On the other hand, IAA + salinity led to a negligible effect on the growth in the wheat plants particularly at the early stages of growth. The presoaking of grains in NaCl at 33 mM + IAA or 66 mM + kinetin induced a marked increase in the pigment content of the wheat flag leaf particularly at the early stages of growth. The interaction between salinity and phytohormones increased the number of chloroplasts; kinetin was the most effective.     

Influence of saline irrigation on growth,ion accumulation and partitioning,and leaf gas exchange of carrot (Daucus carota L.)

Like those of many horticultural crop species, the growth and leaf gas exchange responses of carrot (Daucus carota L.) to salinity are poorly understood. In this study ion accumulation in root tissues (periderm, xylem and phloem tissues) and in leaves of different ages was assessed for carrot plants grown in the field with a low level of salinity (5.8 mM Na(+) and 7.5 mM Cl(-)) and in a glasshouse with salinity ranging from 1-80 mM. At low levels of salinity (1-7.5 mM), in both the field and glasshouse, carrot leaves accumulated high concentrations of Cl(-) (140-200 mM); these appear to be the result of a high affinity for Cl(-) uptake and a low retention of Cl(-) in the root system. However, Cl(-) uptake is under tight control, with an 80-fold increase in external salinity resulting in only a 1.5-fold change in the Cl(-) concentration of the shoot and no increase in the Cl(-) concentration of the root xylem tissue. In contrast to Cl(-), shoot Na(+) concentrations were comparatively low (30-40 mM) but increased by seven-fold when salinity was increased by 80-fold. Growth over the 56-d treatment period in the glasshouse was insensitive to salinity less than 20 mM, but at higher concentrations the yield of carrot tap roots declined by 7 % for each 10 mM increase in salinity. At low levels of salinity the accumulation of high concentrations of Cl(-) (150 mM) in carrot laminae did not appear to limit leaf gas exchange. However, photosynthesis and stomatal conductance were reduced by 38 and 53 %, respectively, for plants grown at a salinity of 80 mM compared with those grown at 1 mM. Salinity-induced reductions in both p(i) and carbon isotope discrimination (delta) were small (2.5 Pa and 1.4 per thousand, respectively, at 80 mM) indicating that the reduction in photosynthesis was only marginally influenced by CO(2) supply. At a salinity of 80 mM the photosynthetic capacity was reduced, with a 30 % reduction in the CO(2)-saturated rate of photosynthesis (A(max)) and a 40 % reduction in both the apparent rate of RuBP-carboxylase-limited CO(2) fixation (V(cmax)) and the electron transport rate limiting RuBP regeneration (J(max)). This study has shown that carrot growth and leaf gas exchange are insensitive to the high leaf Cl(-) concentrations that occur at low levels (1-7 mM) of salinity. However, growth is limited at salinity levels above 20 mM and leaf gas exchange is limited at salinity levels above 8 mM.     

Effects of short- and long-term salinity on leaf water relations, gas exchange, and growth in Ipomoea pes-caprae

Ipomoea pes-caprae is widespread in pantropical coastal areas along the beach. The aim of this study was to investigate the salinity tolerance level and physiological mechanisms that allow I. pes-caprae to endure abrupt increases in salinity under brief or prolonged exposure to salinity variations. Xylem sap osmolality (X_osm), leaf water relations, gas exchange, and number of produced and dead leaves were measured at short- (1-7 d) and long- (22-46 d) term after a sudden increase in soil salinity of 0, 85, 170, and 255 mM NaCl. In the short-term, X_osm was not affected by salinity, but in the long-term there was a significant increase in plants grown in presence of salt compared with control plants. After salt addition, the plants showed osmotic stress with temporal cell turgor loss. However, the water potential gradient for water uptake was re-established at 4, 7 and 22 d after salt addition, at 85, 170 and 255 mM NaCl, respectively. In the short-term I. pes-caprae was able to tolerate salinities of up to 255 mM NaCl without significant reduction in carbon assimilation or growth. With the duration of stress, leaf ion concentration continued to increase and reached toxic levels at high salinity with a progressive decrease in photosynthetic rate, reduced leaf formation and accelerated senescence. Then, if high levels of soil salts from tidal inundation occur for short periods, the survival of I. pes-caprae is possible, but prolonged exposure to salinity may induce metabolic damage and reduce drastically the plant growth.     

Inductive responses of some organic metabolites for osmotic homeostasis in peanut (Arachis hypogaea L.) seedlings during salt stress

The salt tolerance of peanut (Arachis hypogaea L.) seedlings was evaluated by analyzing growth, nutrient uptake, electrolyte leakage, lipid peroxidation and alterations in levels of some organic metabolites under NaCl stress. The plant height, leaf area and plant biomass decreased significantly in salt-treated seedlings as compared with control. The relative water content (RWC %) of leaf decreased by 16 % at high concentrations of NaCl. There was an increase in the lipid peroxidation level and decrease in the electrolyte leakage at high concentrations of NaCl. The total free amino acid and proline contents of leaf increased by 5.5- and 43-folds, respectively in 150 mM NaCl-treated plants as compared with control. Total sugar and starch content increased significantly at high concentrations of NaCl. Chl a, Chl b, total chlorophyll and carotenoid contents decreased significantly at high salinity. Na⁺ contents of leaf, stem and root increased in dose-dependent manner. K⁺ content remained unaffected in leaf and root and decreased in stem by salinity. The results from present study reveal that the peanut plants have an efficient adaptive mechanism to tolerate high salinity by maintaining adequate leaf water status associated with growth restriction. In order to circumvent the stress resulting from high salinity, the levels of some organic metabolites such as total free amino acids, proline, total sugars and starch were elevated. The elevated levels of the organic metabolites may possibly have some role in maintenance of osmotic homeostasis, nutrient uptake and adequate tissue water status in peanut seedlings under high-salinity conditions.     

Physiological and Biochemical Mechanisms of Salinity Tolerance in <i>Carex morrowii</i> Boott

Carex species are widely used in many parts of the world and contain a large number of ecologically diverse species. Among the Carex species, some of them are known to be glycophytes, while others are halophytes. Carex morrowii Boott (Cyperaceae) is resistant to trample through their root structure and has an essential ornamental value in the landscape with their leaves. However, no information was found about the level of salinity tolerance/ sensitivity of the Carex morrowii among these species. In the present study, changes in trace element contents (Na, K, Ca, Cu, Mn, Mg, Ni, Fe, P, Zn, and N) and their transport from roots to leaves, osmotic regulation, alterations in chlorophyll and carotenoid contents, nitrogen assimilation (nitrate reductase activity; NRA) and total soluble protein content in both roots and leaves of Carex morrowii under different salinity concentrations (50 mM, 100 mM, 200 mM and 300 mM NaCl) were examined in detail. Our study provides the first detailed data concerning the responses of leaves and roots and the determination of the level of salinity tolerance/sensitivity of the Carex morrowii. The K+ /Na+ ratio was preserved up to 200 mM NaCl, and accordingly, the element uptake and transport ratios showed that they could control moderate NaCl levels. Ca homeostasis that is maintained even in 200 mM NaCl concentration can be effective in maintaining the structural integrity and selective permeability of the cell membranes, while 300 mM NaCl concentration caused decreased photosynthetic pigments, and deterioration in element content and compartmentation. Moreover, these data suggest that plant parts of Carex morrowii respond differently against varied levels of salinity stress. Although the decrease in NR activity at 200 mM and 300 mM NaCl concentrations in the leaves, NR activity was maintained in the roots. Consequently, Carex morrowii is moderately tolerant to salinity and the carotenoid content and osmotic regulation of Carex morrowii appears to be instrumental in its survival at different salinity levels. Especially the roots of Carex morrowii have a remarkable role in salinity tolerance.     

Photosynthetic activity and leaf antioxidative responses of Atriplex portulacoides subjected to extreme salinity

Responses of Atriplex portulacoides upon 40-day-long exposure to salinity (0?C1,000?mM NaCl) were investigated. Mother plants originated from a sabkha located in a semi-arid region of Tunisia. The plant relative growth rate and leaf expansion increased significantly at 200?mM NaCl but decreased at higher salinities. Interestingly, the plants survived salinity as high as 1,000?mM NaCl without displaying salt-induced toxicity symptoms. Despite significant increase in leaf Na⁺ and Cl^? concentrations upon salt treatment, no significant effect on leaf relative water content was registered. Chlorophyll contents and the gas exchange parameters showed a significant stimulation at the optimal salinity (200?mM NaCl) followed by a decline at higher salinities. Extreme salinity hardly impacted the maximal efficiency of photosystem II photochemistry (F _v/F _m), but a marked decrease in the relative quantum yield of photosystem II (??_PSII) was observed, along with a significant increase in non-photochemical quenching (NPQ). Leaf malondialdehyde and carotenoid contents were generally unaffected following salt exposure, whereas those of anthocyanins, polyphenols, and proline increased significantly, being maximal at 1,000?mM NaCl. Leaf superoxide dismutase (EC 1.15.1.1), ascorbate peroxidase (EC 1.11.1.11), and glutathione reductase (EC 1.6.4.2) activities were significantly stimulated by salinity, whereas catalase (EC 1.11.1.6) activity was maximal in the 0?C400?mM NaCl range. As a whole, protecting the photosynthetic machinery from salt-induced photodamage together with the sustained antioxidant activity may account for the performance of A. portulacoides under high salinity.     

Growth and Fatty Acid Composition of Borage (Borago officinalis L.) Leaves and Seeds Cultivated in Saline Medium

The effects of salinity on growth and fatty acid composition of borage (Borago officinalis L.) leaves and seeds grown in hydroponic medium were investigated. Three different levels of NaCl (25, 50, and 75 mM) were applied. The first results showed that salinity significantly reduced plant growth by 56.5 % at 75 mM compared with the control, suppressed seed yield at 50 and 75 mM, and increased lipid peroxidation. Raising NaCl concentrations led to an important decrease in total fatty acid (TFA) content by 77 % at 75 mM NaCl. Moreover, the polyunsaturated fatty acid (PUFA) content decreased, whereas the saturated fatty acids increased with respect to increasing salinity. The 25 mM NaCl level did not modify the fatty acid composition of seeds and their contents.     

Salicylic acid induced changes on some physiological parameters symptomatic for oxidative stress and mineral nutrition in maize (Zea mays L.) grown under salinity

It has been proposed that salicylic acid (SA) acts as an endogenous signal molecule responsible for inducing abiotic stress tolerance in plants. The effect of varying salicylic acid (SA) supply (0, 0.1, 0.5 and 1.0mM) on growth, mineral uptake, membrane permeability, lipid peroxidation, H(2)O(2) concentration, UV-absorbing substances, chlorophyll and carotenoid concentrations of NaCl (40 mM) stressed maize (Zea mays L.) was investigated. Exogenously applied SA increased plant growth significantly both in saline and non-saline conditions. As a consequence of salinity stress, lipid peroxidation, measured in terms of malondialdehyde (MDA) content and membrane permeability was decreased by SA. UV-absorbing substances (UVAS) and H(2)O(2) concentration were increased by increasing levels of SA. SA also strongly inhibited Na(+) and Cl(-) accumulation, but stimulated N, Mg, Fe, Mn and Cu concentrations of salt stressed maize plants. These results suggest that SA could be used as a potential growth regulator to improve plant salinity stress resistance.     

Physio-Biochemical Composition and Untargeted Metabolomics of Cumin (Cuminum cyminum L.) Make It Promising Functional Food and Help in Mitigating Salinity Stress

Cumin is an annual, aromatic, herbaceous, medicinal, spice plant, most widely used as a food additive and flavoring agent in different cuisines. The study is intended to comprehensively analyse physiological parameters, biochemical composition and metabolites under salinity stress. Seed germination index, rate of seed emergence, rate of seed germination, mean germination time, plant biomass, total chlorophyll and carotenoid contents decreased concomitantly with salinity. In contrast, total antioxidant activity, H₂O_2, proline and MDA contents increased concurrently with stress treatments. Total phenolic and flavonoid contents were decreased initially about 1.4-fold at 50 mM, and thereafter increased about 1.2-fold at 100 mM NaCl stress. Relative water content remained unchanged up to 50 mM NaCl stress, and thereafter decreased significantly. About 2.8-fold electrolyte leakage was found in 50 mM, which increases further 4-fold at 100 mM NaCl stress. Saturated fatty acids (FAs) increased gradually with salinity, whereas unsaturation index and degree of unsaturation change arbitrarily along with the percent quantity of unsaturated FAs. Total lipid and fatty acid composition were significantly influenced by salinity stress. A total of 45 differentially expressed metabolites were identified, including luteolin, salvianolic acid, kaempferol and quercetin, which are phenolic, flavonoid or alkaloids in nature and contain antioxidant activities. Additionally, metabolites with bioactivity such as anticancerous (docetaxel) and antimicrobial (megalomicin) properties were also identified. The study evidenced that plant shoots are a rich source of metabolites, essential amino acids, phenolic compounds and fatty acids, which unveil the medicinal potential of this plant, and also provide useful insight about metabolic responses under salinity stress.     

Inhibition of carotenoid accumulation and abscisic acid biosynthesis in fluridone-treated dark-grown barley

Treatment of dark-grown barley with 0.1 mM fluridone inhibited carotenoid accumulation but did not alter plastid biogenesis. Plastids isolated from dark-grown control and dark-grown fluridone-treated plants were similar in size and protein compositions. Dehydration of dark-grown control barley caused abscisic acid levels to increase 30-40-fold in 4 h, while plants treated with 0.1 mM fluridone accumulated very little abscisic acid in response to dehydration. These results suggest that fluridone-treated plants do not accumulate abscisic acid because of carotenoid deficiency rather than plastid dysfunction. Dark-grown barley plants treated with 0.31 microM fluridone accumulated low levels of carotenoids. Dehydration of these plants resulted in a 4-8-fold increase in abscisic acid and a decrease in antheraxanthin, violaxanthin and neoxanthin, but no change in beta-carotene or lutein plus zeaxanthin levels. This result is consistent with the suggestion that xanthophylls are precursors to abscisic acid in dehydrated plants.     

Auxin and Sodium Nitroprusside Effects on Wheat Antioxidants in Salinity

The effect of indole butyric acid (IBA) as auxin hormone and sodium nitroprusside (SNP) on total antioxidant, carotenoid, total phenolic compounds, catalase activity and shoot dry weight in wheat (Triticum aestivum L. cv. Chamran) under 50 and 100 mM NaCl as salt stress were studied. These two experiments were done separately and in a completely randomized design, in three replications. Indole butyric acid in three levels and sodium nitroprusside in one level were used as spray on the plant to compare their effects. According to the results, the amount of carotenoid, total phenolic compounds, antioxidants and catalase activity have increased but shoot dry weight have decreased by either salinity alone and/or combined with IBA and SNP in our experiments, comparison to the control but with different level. None of the carotenoid, total phenolic compounds, antioxidants, catalase activity and shoot dry weight showed significant changes when indole butyric acid or sodium nitroprusside treatment were induced alone that shows their nontoxicity for seedlings. In connection with indole butyric acid or sodium nitroprusside treatment, these compounds appears to alleviate the stress conditions by showing significant decreasing of carotenoid, total phenolic compounds, antioxidants and catalase activity and significant increasing of shoot dry weight. Our results showed that IBA and SNP had the same effects in salt stress, so in salt stress conditions it is recommended to use IBA for crop and non-crop plants and SNP for only not edible plants.     

Effect of soil type, salinity, and allelochemicals on germination and seedling growth of a medicinal plant Lepidium sativum L.

The present work was conducted to elucidate the effect of soil type, salinity stress and allelochemicals from alfalfa on the germination efficiency, seedling growth and photosynthetic pigments of Medicago sativa L. The highest germination rate (69.9%) was recorded for seeds cultivated in sandy soil followed by that of clay soil (42%) and then loamy soil (19%). The maximum germination rate was attained at 50 mM NaCl concentration level, after that the values were decreased as the salinity levels increased. The maximum lengths (cm) of plumule and radicle and their growth rates (cm/day) were obtained at control level and found to decline significantly as the salinity increased. Aqueous extracts of alfalfa reduced the germination rate, radicle and plumule growth and seedling dry weight of L. sativum. However, chlorophyll and carotenoid content was increased, their maxima were recorded at 50% concentration level. The chlorophyll a/b ratio attained its maximum at the full strength concentration level.     

Changes in Growth and Nitrogen Assimilation in Maize Plants Induced by NaCl and Growth Regulators

Experiments were conducted to determine the interactive effects of salinity and certain growth regulators on growth and nitrogen assimilation in maize (Zea mays L. cv. GS-2). 100 mM NaCl inhibited the biomass accumulation, chlorophyll and carotenoid contents in leaves, nitrate content and uptake and nitrate reductase activity. The application of kinetin, ascorbic acid and 10 and 50 μM abscisic acid in the first experiment and 50 and 100 μM abscisic acid in the second experiment induced a substantial increase in the above parameters, the effect was highest with abscisic acid in salinized as well as non-salinized plants. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of NaCI stress on nitrogen and phosphorous metabolism in a true mangrove Bruguiera parviflora grown under hydroponic culture

The influence of varying levels of salinity (0, 100, 200 and 400 mM) on the activities of nitrate reductase (NR, E.C. 1.6.6.1), acid phosphatase (ACP, E.C. 3.1.3.2), and alkaline phosphatase (ALP, EC 3.1. 3.1) as well as on nitrate and phosphate uptake and total nitrogen levels in leaves of a true mangrove Bruguiera parviflora was investigated under hydroponic culture conditions. NR activity increased in 100 mM NaCl treated plants, whereas it decreased gradually in 200 and 400 mM treated plants, relative to the controls. Decreased activity of NR by NaCl stress was also accompanied by a decrease in total nitrogen level and nitrate uptake. Decreases in NR activity, nitrate (NO₃⁻), and total nitrogen level due to high salinity may be responsible for a decrease in growth and biomass production in this plant. However, salinity caused an increase in both ACP and ALP activity. Activity staining of ACP by native polyacrylamide gel electrophoresis revealed three isoforms: ACP-1, ACP-2, and ACP-3. We observed a preferential enhancement in the ACP-3 isoform by salinity. In order to understand whether the salinity-induced increase in phosphatase activity was due to inhibition in phosphate uptake, we monitored phosphate (Pi) levels in leaves and noted that phosphate levels decreased significantly under salinity. These results suggest that the induction of acid and ALP under salt stress may be due to a phosphorous deficiency.     

Citrate, a possible precursor of astaxanthin in Phaffia rhodozyma: influence of varying levels of ammonium, phosphate and citrate in a chemically defined medium.

The influence of ammonium, phosphate and citrate on astaxanthin production by the yeast Phaffia rhodozyma was investigated. The astaxanthin content in cells and the final astaxanthin concentration increased upon reduction of ammonium from 61 mM to 12.9 mM (from 140 microg/g to 230 microg/g and 1.2 microg/ml to 2.3 microg/ml, respectively). Similarly, both the astaxanthin content and astaxanthin concentration increased by reducing phosphate from 4.8 mM to 0.65 mM (160 microg/g to 215 microg/g and 1.7 microg/ml to 2.4 microg/ml, respectively). Low concentrations of ammonium or phosphate also increased the fatty acid content in cells. By analogy with lipid synthesis in other oleaginous yeasts, an examination of the data for varying nitrogen and phosphate levels suggested that citrate could be the source of carbon for fatty acids and carotenoid synthesis. Supporting this possibility was the fact that supplementation of citrate in the medium at levels of 28 mM or higher notably increased the final pigment concentration and pigment content in cells. Increased carotenoid synthesis at low ammonium or phosphate levels, and stimulation by citrate were both paralleled by decreased protein synthesis. This suggested that restriction of protein synthesis could play an important role in carotenoid synthesis by P. rhodozyma.     

Salinity effects on CO2 assimilation and diffusive conductance of cowpea leaves

The effect of NaCl salinity at concentrations of 43–173 mM in nutrient solution on net gas exchange of attached cowpea [Vigna unguiculata (L.) Walp cv. California Black-eye No. 5 (CB5)] leaves was investigated under both greenhouse and growth chamber conditions.
There was a marked decrease in leaf conductance to water vapor after exposure to low salinity levels and a slighter decrease when salinity levels were higher. The decrease in net assimilation was much more gradual throughout the entire salinity range. The altered responses of net assimilation and leaf conductance to salinity were more evident at a high light intensity. A decrease in intercellular partial CO₂ pressure [p(CO₂)] was found at the low and intermediate salinity levels but not at the high level. These findings suggest that CO, assimilation was mainly controlled by stomatal conductance and the fixation of CO, might have been increased due to stimulated biochemical activity or to higher chlorophyll concentration per unit leaf area. A decrease in assimilation was already found one day after salinization and pro-ceeded up to 4 days when it was inhibited by 50% at 43 mM NaCl and up to 85% at 173 mM. The decrease in transpiration was larger than the decrease in net assimila-tion, and both were attributed to osmotic stress. Partial recovery was found thereaf-ter and new steady-state rates, in the range of 55 to 100% of the control, were then obtained for salinity levels between 43 and 130 mM. Inhibition of net CO, assimila-tion at this stage was attributed partly to a specific sodium effect and partly to plant water status. A linear relationship between leaf sodium content and net photosynthe-sis was also evident at this stage. Net CO, assimilation recovered more completely than transpiration when salt stress was removed, but at 173 mM NaCl recovery was neglible.     

Germination inhibitory constituents from Erigeron annuus

(5-Butyl-3-oxo-2,3-dihydrofuran-2-yl)-acetic acid was isolated from the flowers of Erigeron annuus as one of four germination inhibitory constituents. Its structure was determined by analysis of MS and NMR spectroscopic data. Three known compounds, 3-hydroxy-pyran-4-one, 4-hydroxycinnamic acid, and 3,4-dihydroxycinnamic acid methyl ester were also identified as active constituents. These compounds showed 50% inhibitory effects (IC(50)) on the germination of lettuce seed at concentrations of 2.13+/-0.03, 12.85+/-0.56, 4.97+/-0.24, and 4.87+/-0.25 mM, respectively. 4-Hydroxybenzoic acid was used as a positive control, displaying an IC(50) value of 4.02+/-0.39 mM.     

Ameliorating effect of triacontanol on salt stressederythrina variegata seedlings. Changes in growth,biomass, pigments and solute accumulation

Erythrina variegata Lam. seedlings were grown under low (100 mM NaCl) and high (250 mM NaCl) salinity. Seedlings exposed to high salinity for 10 d showed significant reduction in growth rate and biomass production while the root/shoot ratio increased. In contrast to pigment and protein contents, starch and saccharide contents increased in salt stressed seedlings. When the seedlings were subsequently sprayed with triacontanol (1 mg kg^-1) the salinity effect was partially ameliorated and growth, biomass, chlorophyll and carotenoid contents increased.     

Antioxidative Defense Potential to Salinity in the Euhalophyte Salicornia brachiata

The antioxidative defense mechanism to salinity was assessed by monitoring the activities of some antioxidative enzymes and levels of antioxidants in an obligate halophyte, Salicornia brachiata, subjected to varying levels of NaCl (0, 200, 400, and 600 mM) under hydroponic culture. In the shoots of S. brachiata, salt treatment preferentially enhanced the activities of ascorbate peroxidase (APX), guaiacol peroxidase (POX), glutathione reductase (GR), and superoxide dismutase (SOD), whereas it induced the decrease of catalase (CAT) activity. Similarly, salinity caused an increase in total glutathione content (GSH + GSSG) and a decrease in total ascorbate content. Growth of S. brachiata was optimum at 200 mM NaCl and decreased with further increase in salinity. Salinity caused an increase in Na⁺ content and a decrease in K⁺ content of shoots. Proline levels did not change at low (0-200 mM NaCl) or moderate (400 mM NaCl) salinities, whereas a significant increase in proline level was observed at high salinity (600 mM NaCl). Accumulation of Na⁺ may have a certain role in osmotic homeostasis under low and moderate salinities in S. brachiata. Parameters of oxidative stress such as malondialdehyde (MDA), a product of lipid peroxidation, and H₂O₂ concentrations decreased at low salinity (200 mM NaCl) and increased at moderate (400 mM NaCl) and high salinities (600 mM NaCl). As a whole, our results suggest that the capacity to limit ionic and oxidative damage by the elevated levels of certain antioxidative enzymes and antioxidant molecules is important for salt tolerance of S. brachiata.     

Salinity-induced changes in essential oil,pigments and salts accumulation in sweet basil (Ocimum basilicum) in relation to alterations of morphological development

The objective of the project was to study salinity-induced effects on essential oil, pigments and salts accumulation in sweet basil (Ocimum basilicum, the cultivar Perrie) in relation to the alteration of plant morphological development and yield production. Hydroponically grown plants were exposed to one of six NaCl concentrations (1, 25, 50, 75, 100 and 130 mM NaCl). Inhibitory effects of salinity on biomass production of the shoot and the root, and area of individual leaves were apparent already under cultivation with 25 mM NaCl. Elevation of salinity from 1 to 100 mM NaCl induced 63% and 61% reductions in fresh and dry herb biomass production, respectively. The stress-induced reduction of foliage biomass sourced mainly from inhibition of leaf area development rather than reduction of internode and leaf number. Cl and Na concentrations in the leaves, stems and roots increased with elevation of NaCl concentration in the cultivation solution. While the extent of Cl accumulation was leaves>stems>roots, Na was largely excluded from the leaves and was preferentially accumulated in roots and the stems, potentially accounting for the moderate sensitivity of the leaf tissue to salinity. Salt stress increased the contents of essential oil and carotenoids in the leaves that may further account for the moderate sensitivity of sweet basil to salinity and suggest a potential for agro-industrial production. A twofold increase in both carotenoid concentration and the percent of essential oil in the fresh tissue was observed by elevation of the salinity from 1 to 130 mM NaCl. Overall, the stress induced increase of the percent of essential oil in the tissue in the salinity range 1–75 mM NaCl was about 50%, and thereby compensated for the similar reduction of biomass production in this salinity range, so that oil production on per plant basis was not reduced by salinity.