Negative Effects Of Salinity Stress Research Articles

CO2 enrichment changed N metabolism of tomatoes under salinity stress

• Elevated CO 2 reduced the negative effect of salinity stress in tomato. • Photosynthesis and transpiration improved in 50/50 v/v NO 3 : NH 4 but growth parameter was improved in 100/0 NO 3 : NH 4 in salinity stress in tomato. • The rate of reduction of vegetative traits due to salinity stress was significantly reduced by increasing the nitrate in the ratio of NO 3 : NH 4 in salinity stress in tomato. • Carbon dioxide enrichment was significant on protein and nitrate concentration. Salinity is a worldwide concern. The effects of CO 2 enrichment and N sources under salinity on the vegetative, photosynthetic, and biochemical parameters of tomato was explored. The tomato plants are cultivated in two climate-controlled greenhouses with two CO 2 levels: 300 (C1) and 700 (C2) ppm. Five NO 3 :NH 4 ratios (25/75(N1), 50/50(N2), 75/25(N3), and 100/0 (N4)) were used to fertilize plants in two salinity conditions (0 (S1) and 50 mM (S2)). When NH4 was raised, vegetative, yield and biochemical characteristics were seen to decline. By increasing nitrate, yield, and desirable tomato characteristics such as fresh weight of shoot, root, and fruit, dry weight of shoot and fruit, and the number of fruits per plant, photosynthesis, and water content of shoot were enhanced. Increased CO 2 mitigated the detrimental effects of salt stress. By increasing the nitrate in the ratio of NO 3 :NH 4 , notably in the S2N4 treatment, the rate of decrease of vegetative characteristics caused by salinity stress was greatly slowed. Under the detrimental influence of salinity stress, photosynthesis and transpiration improved in NO 3 :NH 4 , 50/50 (S2N2 treatment). In general, when the amount of ammonium was greater than nitrate (NO 3 :NH 4 ratio of 25/75) in both saline and non-saline conditions, the examined attributes did not demonstrate a favorable influence on all features.

Biochemical and molecular responses of Rosa damascena mill. cv. Kashan to salicylic acid under salinity stress

BackgroundToday, salinity stress is one of the most important abiotic stresses in the world, because it causes damage to many agricultural products and reduces their yields. Oxidative stress causes tissue damages in plants, which occurs with the production of reactive oxygen species (ROS) when plants are exposed to environmental stresses such as salinity. Today, it is recommended to use compounds that increase the resistance of plants to environmental stresses and improve plant metabolic activities. Salicylic acid (SA), as an intracellular and extracellular regulator of the plant response, is known as one of these effective compounds. Damask rose (Rosa damascena Mill.) is a medicinal plant from the Rosaceae, and its essential oils and aromatic compounds are used widely in the cosmetic and food industries in the world. Therefore, considering the importance of this plant from both medicinal and ornamental aspects, for the first time, we investigated one of the native cultivars of Iran (Kashan). Since one of the most important problems in Damask rose cultivation is the occurrence of salinity stress, for the first time, we investigated the interaction of several levels of NaCl salinity (0, 4, 8, and 12 ds m− 1) with SA (0, 0.5, 1, and 2 mM) as a stress reducer.ResultsSince salinity stress reduces plant growth and yield, in this experiment, the results showed that the increase in NaCl concentration caused a gradual decrease in photosynthetic and morphological parameters and an increase in ion leakage. Also, increasing the level of salinity stress up to 12 ds m− 1 affected the amount of chlorophyll, root length and leaf total area, all of which reduced significantly compared to plants under no stress. However, many studies have highlighted the application of compounds that reduce the negative effects of stress and increase plant resistance and tolerance against stresses. In this study, the application of SA even at low concentration (0.5 mM) could neutralize the negative effects of salinity stress in the Rosa damascena. In this regard, the results showed that salinity increases the activity of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) and the concentration of proline, protein and glycine betaine (GB). Overexpression of antioxidant genes (Ascorbate Peroxidase (APX), CAT, Peroxidase (POD), Fe-SOD and Cu-SOD) showed an important role in salt tolerance in Damascus rose. In addition, 0.5 mm SA increased the activity of enzymatic and non-enzymatic systems and increased salinity tolerance.ConclusionsThe change in weather conditions due to global warming and increased dryness contributes to the salinization of the earth’s surface soils. Therefore, it is of particular importance to measure the threshold of tolerance of roses to salinity stress and the effect of stress-reducing substances in plants. In this context, SA has various roles such as increasing the content of pigments, preventing ethylene biosynthesis, increasing growth, and activating genes involved in stress, which modifies the negative effects of salinity stress. Also, according to the results of this research, even in the concentration of low values, positive results can be obtained from SA, so it can be recommended as a relatively cheap and available material to improve production in saline lands.

Mitigation of Salinity-Induced Oxidative Damage, Growth, and Yield Reduction in Fine Rice by Sugarcane Press Mud Application.

Salinity stress is one of the major global problems that negatively affect crop growth and productivity. Therefore, ecofriendly and sustainable strategies for mitigating salinity stress in agricultural production and global food security are highly demandable. Sugarcane press mud (PM) is an excellent source of the organic amendment, and the role of PM in mitigating salinity stress is not well understood. Therefore, this study was aimed to investigate how the PM mitigates salinity stress through the regulation of rice growth, yield, physiological properties, and antioxidant enzyme activities in fine rice grown under different salinity stress conditions. In this study, different levels of salinity (6 and 12 dS m–1) with or without different levels of 3, 6, and 9% of SPM, respectively were tested. Salinity stress significantly increased malondialdehyde (MDA, 38%), hydrogen peroxide (H2O2, 74.39%), Na+ (61.5%), electrolyte leakage (40.32%), decreased chlorophyll content (32.64%), leaf water content (107.77%), total soluble protein (TSP, 72.28%), and free amino acids (FAA, 75.27%). However, these negative effects of salinity stress were reversed mainly in rice plants after PM application. PM application (9%) remained the most effective and significantly increased growth, yield, TSP, FAA, accumulation of soluble sugars, proline, K+, and activity of antioxidant enzymes, namely, ascorbate peroxidase (APX), catalase (CAT), and peroxidase (POD). Thus, these findings suggest a PM-mediated eco-friendly strategy for salinity alleviation in agricultural soil could be useful for plant growth and productivity in saline soils.

Elucidating the Effects of Combined Treatments of Salicylic Acid and l-Proline on Greenhouse-Grown Cucumber Under Saline Drip Irrigation

Salinity is one of the major abiotic stress factors that threaten crop development and sustainable food production. As a mitigation strategy, several plant growth regulators and osmoprotectants have been applied to ameliorate the negative effects of salinity stress in plants. Therefore, the current study aimed to investigate the effect of foliar applications of different concentrations of salicylic acid and proline on the growth, yield, fruit quality, and nutritional composition of cucumber crops grown under saline conditions. The three main irrigation salinity variations included electrical conductivity (EC) of 0.5 dS/m (control), EC 6.0 dS/m, and EC 12.0 dS/m. Foliar spray treatments were as follows: T1 (distilled water), T2 (1.0 mM salicylic acid), T3 (1.0 mM salicylic acid + 5.0 mM proline), and T4 (1.0 mM salicylic acid + 10 mM proline). Our results showed that foliar application of salicylic acid alone or in combination with proline under non-saline conditions improved the growth and yield of cucumber, with T4 recording the highest values. Irrigating plants with saline water (EC 6.0 and 12.0 dS/m) severely compromised cucumber's growth performance and yield, with the lowest values recorded at EC 12.0 dS/m. However, under EC 6.0 dS/m, T2 and T3 slightly ameliorated salinity stress effects regarding fruit yield, for T2, and nutritive composition of fruits, for T2 and T3. Overall, this study demonstrated that cucumber (Cucumis sativa L.) could tolerate irrigation salinity levels of up to EC 6.0 dS/m without significant detrimental effects on the growth performance, yield, and nutritional composition of fruits.

Enhancing Irrigation Salinity Stress Tolerance and Increasing Yield in Tomato Using a Precision Engineered Protein Hydrolysate and Ascophyllum nodosum-Derived Biostimulant

Most vegetable crops are salt sensitive, growing inadequately in salinised soils due to the accumulation of toxic ions from prolonged irrigation regimes. Plant biostimulants are a potential tool that can be used to counteract salinity stress and increase crop yield. The aim of this study was to investigate the ability of the proprietary protein hydrolysate and Ascophyllum nodosum-derived biostimulant PSI-475 to activate salinity stress tolerance responses in plants. After characterising PSI-475 composition, initial biostimulant activity screening was performed using Arabidopsis thaliana. PSI-475 stimulated primary root growth (+5.5–20.0%) and photosynthetic pigments content (18.8–63.0%) under unstressed and salinity stressed conditions. Subsequently, PSI-475 was assessed by foliar application on tomato plants (cv. Micro-Tom) that received a saline irrigation water program, which caused a significant decrease in fruit yield (−37.5%). Stressed plants treated with PSI-475 increased this parameter by 31.8% versus the stressed control. Experimental data suggest that PSI-475 can alleviate the negative effects of saline irrigation by improving osmotic adjustment and ion homeostasis markers. PSI-475 was also able to provide significant yield benefits in unstressed plants (+16.9%) that were associated with improved leaf biochemical markers. The data presented support the use of this precision biostimulant to target the negative effects of salinity stress from irrigation.

ارزیابی تأثیر بیوچار حاصل از دماهای مختلف پیرولیز بر رشد گیاه همیشه بهار تحت تنش شوری

ارزیابی تأثیر بیوچار حاصل از دماهای مختلف پیرولیز بر رشد گیاه همیشه بهار تحت تنش شوری

Methyl jasmonate promotes salinity adaptation responses in two grapevine (Vitis vinifera L.) cultivars differing in salt tolerance

The effects of foliar spray of methyl jasmonate (MJ; 0, 50 and 100 µM) on phytochemical changes and nutritional balance of two grapevine (Vitis vinifera L.) cultivars [‘Sultana’ (as moderately salt-tolerant) and ‘Rishbaba’ (as a least salt-tolerant)] were evaluated under different saline conditions (NaCl; 0 and 75 mM). To explore optimum concentration of MJ treatment, grapevine plants were sprayed with MJ twice a day at 12-h intervals during the second week of salinity stress. The results showed that foliar spray of MJ especially at 100 µM was effective in alleviating deleterious effects of NaCl-induced salinity stress on both cultivars. The MJ at 50 and 100 µM significantly decreased ion leakage and production of malondialdehyde and hydrogen peroxide, but increased photosynthetic pigments, soluble carbohydrate, proline, and total phenol and flavonoid contents, especially in ‘Sultana’ compared with ‘Rishbaba’. Moreover, application of 100 µM MJ was associated with enhanced the activities of catalase, guaiacol peroxidase, and ascorbate peroxidase, resulting in greater leaf cell biomembranes stability in vines under saline condition compared with control plants (no treatment). The MJ was also associated with decreased accumulation of sodium and chlorine in leaves, but increased leaf minerals and trace elements compared with control vines. These findings suggest that foliar application of MJ, especially at 100 µM, might be useful to reduce negative effects of salinity stress in vineyards and nurseries.

Plants Saline Environment in Perception with Rhizosphere Bacteria Containing 1-Aminocyclopropane-1-Carboxylate Deaminase.

Soil salinity stress has become a serious roadblock for food production worldwide since it is one of the key factors affecting agricultural productivity. Salinity and drought are predicted to cause considerable loss of crops. To deal with this difficult situation, a variety of strategies have been developed, including plant breeding, plant genetic engineering, and a wide range of agricultural practices, including the use of plant growth-promoting rhizobacteria (PGPR) and seed biopriming techniques, to improve the plants’ defenses against salinity stress, resulting in higher crop yields to meet future human food demand. In the present review, we updated and discussed the negative effects of salinity stress on plant morphological parameters and physio-biochemical attributes via various mechanisms and the beneficial roles of PGPR with 1-Aminocyclopropane-1-Carboxylate(ACC) deaminase activity as green bio-inoculants in reducing the impact of saline conditions. Furthermore, the applications of ACC deaminase-producing PGPR as a beneficial tool in seed biopriming techniques are updated and explored. This strategy shows promise in boosting quick seed germination, seedling vigor and plant growth uniformity. In addition, the contentious findings of the variation of antioxidants and osmolytes in ACC deaminase-producing PGPR treated plants are examined.

Effects of using humic acid and selenium on some morphophysiological characteristics of Calendula officinalis L. under salinity stress

Salinity stress is one of the most important factors in reducing the crop yield in the world. The application of humic acid along with selenium can improve the plant yield under salinity stress conditions by increasing the antioxidant capacity. To evaluate the effects of humic acid and selenium application under salinity stress conditions in Calendula officinalis L., a factorial greenhouse experiment was conducted in a completely randomized design with three replications in Islamshahr city in 2018. The experimental treatments included sodium chloride (0, 50, and 100 mg l-1), humic acid (0, 100, and 200 mg l-1), and selenium (0, 5, and 10 mg l-1) and their combined effects. The results showed that increasing the salinity significantly reduced the fresh and dry weight of shoots and roots and number of flowers per plant. The foliar application of 200 mg l-1 humic acid and 10 mg l-1 selenium improved carotenoids content of the petals and total chlorophyll of the leaves at all salinity levels. Also, with increasing the sodium chloride level up to 100 mg l-1, the amount of proline increased significantly. Meanwhile, the interaction treatments of humic acid and selenium had significant effects (P≤0.0.1) on improving the activity of superoxide dismutase and peroxidase enzymes at different salinity levels. The highest amount of essential oil (1.37%) was obtained in the interaction treatment of 200 mg l-1 humic acid and 10 mg l-1 selenium under salinity stress of 50 mg l-1 sodium chloride. In general, the results of this study showed that the foliar application of 200 mg l-1 humic acid and 10 mg l-1 selenium could be effective in reducing the negative effects of salinity stress on C. officinalis.

Response of physiological traits, antioxidant enzymes and nutrient uptake of soybean to Azotobacter Chroococcum and zinc sulfate under salinity

Globally, one of the key restrictions on agricultural production is salinity and its impact is expected to increase. As a result, it is necessary to improve crop salinity tolerance. One promising approach is the use of plant nutrition technologies such as the application of zinc sulfate (Zn) and Azotobacter chroococcum (Az) which may improve plant survival under environmental stresses. A greenhouse experiment was conducted with three replications and included four levels of salinity (0, 40, 60 and 80 mM NaCl) in combination with four treatments [control, 2 mM zinc sulfate foliar application (Zn), inoculation with Azotobacter chroococcum (Az) and co-application of Az and Zn (Az+Zn)]. The results indicate that exposure to salinity increased soybean contents of anthocyanin, malondialdehyde (MDA), osmolytes, sodium ion (Na+), and the activities of antioxidant enzymes However, the amount of chlorophyll and carotenoid, relative water content (RWC), maximum quantum yield of photosystem II (PSII; Fv/Fm), membrane stability index (MSI), and ion contents decreased. Application of Zn and inoculation with Az enhanced the chlorophyll (a, b and a+b), carotenoid, RWC, Fv/Fm, MSI, anthocyanin, osmolytes, N, K+, P contents, and K+/Na+; the activities of CAT, SOD, POX, and APX as well as MDA and Na+ contents were reduced. Overall our results reveal that combined Zn and Az application was the most effective treatment for alleviating the negative effects of salinity stress in soybean.

Attenuation of negative effects of saline stress in wheat plant by chitosan and calcium carbonate

BackgroundChitosan and Ca+ are natural signal molecules that can be used in agriculture as biostimulants and elicitors. They enhance different physiological responses and mitigate the negative effects of salinity. So, this investigation was done to study the effect of soaking wheat grains in chitosan and CaCO3 (20 and 40 mg/L) on alleviating the adverse effect of salinity stress (0.0 and 5000 mg/L) on growth, some biochemical and physiological and yields of wheat plant.ResultsShoot length (cm), leaves no/tiller, shoot dry weight (g), root fresh weight (g) and root dry weight (g) were significantly decreased as a result of salt stress. Soaking wheat grains in Chitosan or CaCO3 significantly promoted plant growth under normal and stressed conditions. Irrigation of wheat plants with saline water significantly decreased photosynthetic pigments (Chlo-a, Chlo-b, carotenoids and total pigments) in addition to Chlo-a/Chlo-b ratio, indole acetic acid content in the plant leaves. Meanwhile, saline water significantly increased phenolics, total soluble sugars (TSS) and proline content. H2O2 and lipid peroxidation expressed by malondialdehyde (MDA) content clearly showed significant increases under salinity stress compared with untreated control. Soaking wheat grains in chitosan or CaCO3 before sawing significantly increased the accumulation of H2O2 and MDA in the leaves of wheat plants. Treatment of wheat grains with chitosan or CaCO3 significantly promoted the activity of various antioxidant enzymes (SOD and POX) as compared to the control. CAT activity was significantly decreased as a result of chitosan or CaCO3 treatments. The highest CAT activity was recorded in plants irrigated with 5000 mg/L saline water followed by control plants which recoded 36.40 and 24.82 U/min/g FW, respectively. On the other hand, irrigation of wheat plants with 5000 mg/L saline water significantly decreased spike length (cm), spikelets no/spike, grains wt/plant (g), 1000-grains wt (g), yield and biomass/plant (g) as well as, carbohydrate % and protein % compared with the control. However, treating wheat plants either with Chitosan or calcium carbonate resulted in obvious significant increases in carbohydrates and protein contents, especially in plants treated with 40 mg/L chitosan followed by 40 mg/L calcium carbonate. Soaking wheat grains in chitosan, especially at 40 mg/L, exhibited the strongest scavenging potential (2,2-diphenyl-1-picryl-hydrazyl-hydrate assay (DPPH%) followed by treatment with 40 mg/L CaCO3.ConclusionIn conclusion, the used treatment enhanced the protective parameters such as antioxidant enzymes, total phenols and free radical scavengers and consequently helped the plants to decrease lipid peroxidation, increased their tolerance and improved yield and spike quality. Application of 40 mg/L chitosan recorded the highest increment in the scavenging ability of the natural antioxidants of the plant extract toward the stable free radical DPPH.

Sodium nitroprusside application improves morphological and physiological attributes of soybean (Glycine max L.) under salinity stress.

Salinity is among the major abiotic stresses negatively affecting the growth and productivity of crop plants. Sodium nitroprusside (SNP) -an external nitric oxide (NO) donor- has been found effective to impart salinity tolerance to plants. Soybean (Glycine max L.) is widely cultivated around the world; however, salinity stress hampers its growth and productivity. Therefore, the current study evaluated the role of SNP in improving morphological, physiological and biochemical attributes of soybean under salinity stress. Data relating to biomass, chlorophyll and malondialdehyde (MDA) contents, activities of various antioxidant enzymes, ion content and ultrastructural analysis were collected. The SNP application ameliorated the negative effects of salinity stress to significant extent by regulating antioxidant mechanism. Root and shoot length, fresh and dry weight, chlorophyll contents, activities of various antioxidant enzymes, i.e., catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX) were improved with SNP application under salinity stress compared to control treatment. Similarly, plants treated with SNP observed less damage to cell organelles of roots and leaves under salinity stress. The results revealed pivotal functions of SNP in salinity tolerance of soybean, including cell wall repair, sequestration of sodium ion in the vacuole and maintenance of normal chloroplasts with no swelling of thylakoids. Minor distortions of cell membrane and large number of starch grains indicates an increase in the photosynthetic activity. Therefore, SNP can be used as a regulator to improve the salinity tolerance of soybean in salt affected soils.

The effect of silicate fertilizer on the root development of rice and its tolerance to salinity stress

The problem of salinity stress in agricultural land is increasing rapidly, mainly due to climate change. Salinity in the soil has a detrimental effect on the root growth of rice and reduces the ability of the plant to absorb water and other nutrients from the soil resulting in stunted growth. The application of silicate fertilizers is an effort to reduce the negative effects of salinity stress. Absorption of beneficial element silicon (Si) by rice plants can reduce salinity stress. The objective of this research is to analyze the effect of calcium silicate on rice root growth and its tolerance to salinity stress. This research was conducted with the addition of silicate fertilizer consisting of three levels of CaSiO3 (0 mM, 2 mM, 4 mM) in red rice (Oryza sativa L. ‘Sembada Merah’) under salinity stress treatment at the level of 0 dS m-1(control), 3 dS m-1 (low), 7 dS m-1 (moderate) and 10 dS m-1 (high). The treatment with a salinity level of 10 dS m-1 reduced root length, fresh and dry weight of the root. The addition of calcium silicate in salinity stress conditions was able to improve the root anatomical characteristics of rice ‘Sembada Merah’ by increasing the epidermis thickness, cortex thickness, stele diameter and root diameter. Silicate fertilizer is indicated to play a role in increasing suberin and lignin to form apoplast defenses in order to prevent the entry of Na+ ions into the stele.

Investigation of yield, phytochemical composition, and photosynthetic pigments in different mint ecotypes under salinity stress.

Salinity stress is one of the main limiting factors of medicinal plant growth and may affect their characteristics and chemical composition. In order to evaluate the response of different species of Iranian mint to salinity stress, an experiment was designed in greenhouse conditions. In this experiment, six Iranian mint species were cultivated in pots under different salinity stress including 0, 2.5, 5, and 7.5 dS/m. The chlorophyll indices (a, b, total, and a/b ratio), carotenoids, total anthocyanin, total phenolic and flavonoid content, antioxidant activity, dry matter yield, and essential oil content were measured in two different harvest stages. Salinity stress affected various measured traits. The results showed that despite the negative effect of salinity stress on photosynthetic pigments, in some ecotypes and species, photosynthetic pigments were not affected by salinity stress. The amount of total phenolic content, total flavonoid content, and total anthocyanin increased in response to salinity stress. The dry matter decreased under salinity stress, but the content of essential oil increased as a result of salinity stress increment. The results of PCA biplot showed that the E16 and E18 ecotypes were separated by a large distance. Among the various ecotypes, E18 had the most desirable traits which can be recognized as a salt‐tolerant ecotype. Also, piperita species was the best among the species in all salinity stress levels.

Effects of silicon on some morphological and physiological traits of rose (Rosa chinensis var. minima) plants grown under salinity stress

Miniature rose (Rosa chinensis) is an ornamental and commercial plant having many applications, especially in green space design. One of the major environmental factors limiting the cultivation of this plant is salinity. This study investigated the effect of silicon application on the morphological and physiological responses of miniature rose under the salinity stress conditions in 2018. A factorial experiment was conducted in a completely randomized design with three replications. Experimental factors were including the salinity (0, 3 and 6 m mos/m) and silicone fertilizer (0, 250, 500 and 1000 mg/L nano silicon, 250, 500 and 1000 mg/L potassium silicate). The results indicated that salinity stress leads to a significant reduction in the plant height, leaf area, vase life, fresh weight of the plant, number of flowers, stem diameter, peduncle, open flower diameter, flower life on plants and chlorophyll a and b concentrations. Under the salinity of 6 dS/m without applying silicon, the activity of glutathione reductase and superoxide dismutase enzymes was 2.44 and 2.25 fold with respect to the control, respectively. Upon applying the silicon treatment, the concentration decrement of potassium, phosphorous, iron and zinc was reduced in the shoots of rose. Application of potassium silicate and nano silicon at concentrations of 1000 mg/L had the greatest effect on the improvement of studied traits. Therefore, adding the silicate fertilizers to saline soils can reduce the negative effects of salinity stress on the miniature rose plant var. minima.

Growth and biochemical responses of sorghum genotypes to nitrogen fertilizer under salinity stress conditions

This study was carried out to assess the efficiency of nitrogen (N) fertilizer in mitigating the harmful effects of salinity stress on growth and biochemical traits in sorghum genotypes. The experiment was conducted as a factorial trial based on the completely randomized design with four replications under the greenhouse conditions. The factors included four sorghum genotypes (KDFGS1, KDFGS23, KDFGS29 lines, and KFS2 cultivar), two salinity levels (3 and 12 dS m−1) and three nitrogen levels (0, 75 and 150 mg N kg−1soil). The results showed that application of nitrogen fertilizer increased photosynthetic pigments and K+/Na+ ratio in leaf sheath and root. Also, nitrogen dramatically decreased malondialdehyde (MDA) content. This was an indication of the reduced detrimental effects of salinity stress found in all genotypes. In addition, it was found that upon 150 mg N kg−1 treatments, proline (Pro) and antioxidant enzymes markedly decreased in all sorghum genotypes. The highest impact of nitrogen fertilizer for reducing the negative effect of salinity stress was observed in KFS2 (known as tolerant genotype). Due to the highest Pro accumulation in KDFGS23 (known as sensitive genotype), it did not appear to be a suitable criterion for the selection of the tolerant lines/cultivars. In general, the results suggested that using a reasonable N fertilizer level could be used as an efficient tool to improve the growth of the sorghum genotypes subjected to salinity stress and this effect was more pronounced in the tolerant genotype.

Physiological Response and Productivity of Alfalfa to Potassium Foliar and Soil Applications under Saline Calcareous Soil Conditions

A field experiment was conducted at Nubaria Agricultural Research Station, El-Behira Government, Egypt along the duration of 2015 to 2017 to study the physiological response and productivity of alfalfa (cv., Nubaria1) to seven potassium fertilization treatment of 0, 28.6, 57.14Kg/ha as soil dressing, spraying with 1%K2O and 2% K2O alone or in combination with adding 28.6Kg K2O/ha under saline calcareous soil conditions. Experimental design was Randomized Complete Block design with four replications. Eighteen successive cuts were taken (Nine cuts /year), to estimate growth and physiological parameters, and alfalfa productivity. Potassium fertilization treatments had significant effects on all studied traits in individual cuts except the 1st and 9th cuts in the first year and 2nd cut in the second year for plant height, the 2nd and 7th cuts in the two years for dry matter%, the 2nd cut in the second year for dry forage Kg/m2 and 1st, 4th and 5th cuts for protein content in the first year. In general, plant height, leaf steam ratio, green forage yield Kg/m2, dry matter%, dry forage yield Kg/m2, relative water content, K+ content, K+/Na+ ratio and protein content increased significantly when plants received 28.6 K2O/ha + 2%K2O and 57Kg K2O/ ha with insignificant difference as compared with other potassium treatments. Also, a significant increase was recorded in Na+ content in leaves under control K+ treatment (0 K2O/ha). Linear relationship was found between potassium fertilization rates (soil dressing, foliar application as well as 28.6KgK2O/ha +foliar1 and 2% applications) and fresh forage weight t/ha. The linear regression equation showed that as potassium fertilizer rate (soil dressing) increased by one unite/ha, fresh forage weight/ha increased by 1.139t/ha and as potassium fertilizer rate (foliar application) increased by one unite/ha, fresh forage weight/ha increased by 3.112t/ha. In addition, the highest fresh forage weight/ha (125.850 t/ha) was produced under treatment of 28.6KgK2O/ha + 2%K2O. Highly positive significant correlation coefficients were found for all traits except the relation between Na+ content and other traits which was a highly significant negative relationship. Profitability assessment results revealed that addition of 28.6KgK2O/ha with foliar application of 2%K2O as potassin 30%K2O followed by addition of 57.14KgK2O/ha markedly obtained the highest values of alfalfa yield with insignificant difference. These results were incorporated with the highest values of output, net income and the investment ratio. Results indicated that controlling soil fertility, especially K+ as soil application, in addition to foliar application under saline calcareous soil condition is considered to be one of the most important factors to overcome the negative effects of salinity stress.

Silicon Supplementation Induces Physiological and Biochemical Changes That Assist Lettuce Salinity Tolerance

Little is known abou the effects of silicon on the physiological and biochemical characteristics of vegetables under salt stress. Our aim was to evaluate Silicon’s role as attenuator of negative effects of saline stress in lettuce plants. The experiment was carried out in a completely randomized design with four replicates in a a 3 × 2 factorial arrangement, three salinity levels (1.65, 3.65, 7.65 dS m− 1) with and without silicon (0 and 2 mM). Gas exchange, chlorophyll ‘a’ fluorescence, photosynthetic pigments, lipid peroxidation, hydrogen peroxide (H2O2) levels, enzymatic and non-enzymatic mechanisms and accumulation of inorganic ions were evaluated. Salinity increased the total chlorophyll and maintained a high Fv/Fm ratio (above 0.80). Silicon reduced gas exchange at severe salt stress. The activity of ascorbate peroxidase enzymes and guaiacol increased in high-salinity stress, which resulted in a lower content of H2O2 and lipid peroxidation. Si induced the reduction of antioxidant enzymes activity in severe stress. Na+ and Cl− ions increased with the saline water, while K+ and the K+/Na+ ratio decreased. The limited accumulation of silicon in lettuce leaf tissues has not been sufficient to induce physiological responses that lead to increased production under high-salinity conditions.

Morphophysiology of yellow passion fruit seedlings under application of nitrogen and potassium and irrigation with high-salinity water

Salinity is one of the most problematic abiotic stresses in agriculture globally, especially in semi-arid regions. Thus, the application of nutrients, such as nitrogen and potassium to improve plant nutritional conditions may be a viable alternative to minimize the negative effects of saline stress. Therefore, the aim of this study was to evaluate the morphophysiological behavior of yellow passion fruit seedlings under varying nitrogen and potassium doses and irrigation with salt water. The experimental design was a randomized complete block with a 5 x 5 incomplete factorial scheme, generated from the Central Composite Design with five electrical conductivities of irrigation water (0.5, 0.98, 2.15, 3.32, and 3. 80 dS m-1) and five increasing doses of nitrogen and potassium (0.0, 29.08, 100.0, 170.92, and 200.0%). Leaf, stem, and root dry phytomass and gas exchange were evaluated 75 days after sowing. The increase in salinity had negative effects on the morphological and physiological characteristics of yellow passion fruit seedlings. The application of nitrogen and potassium positively influenced photosynthetic rate and leaf and root dry phytomasses. The application of nitrogen and potassium increased intercellular CO2 concentration and transpiration in yellow passion fruit seedlings under saline stress.

Effect of titanium foliar applications on tomato fruits from plants grown under salt stress conditions

Salt stress affects plant metabolism, while beneficial elements such as titanium (Ti) may stimulate adaptive responses to mitigate salt stress. Here we evaluated the main effects of sodium chloride (NaCl 0, 50 and 100 mM) in the nutrient solution, and of titanium foliar spray (Ti 0.75 and 150 mg L-1), as well as the interaction of these study factors, on tomato cv. ‘Rio Supremo’ performance in greenhouse. Plants were treated with NaCl during 80 d through automated drip irrigation; while eight Ti foliar sprayings were applied with a manual sprayer, at intervals of 10 d each. Yield and quality parameters of fruits were evaluated in the second cluster. NaCl reduced yield parameters, pH value and increased the titratable acidity (TA), electrical conductivity (EC), and total soluble solids (TSS), as well as the TSS/TA ration in the fruits. Ti did not affect yield parameters, though it reduced the pH and increased the TSS/TA ratio of fruits. NaCl and Ti have differential effects on fruit quality as separate factors, while the interaction of both factors revealed that Ti effects dependent on the presence of NaCl and its level in the nutrient solution. In conclusion, Ti did not mitigate the negative effects of saline stress on the evaluated yield parameters, but importantly, with moderate levels of NaCl in the nutrient solution (50 mM), Ti increased EC, TA and TSS of fruits.