Nonsaline Nutrient Solutions Research Articles

Growing Salicornia europaea L. with Saline Hydroponic or Aquaculture Wastewater

Among halophyte plants, Salicornia species (also known as glasswort or sea asparagus) are increasingly grown in open fields and greenhouses for edible or non-edible purposes. Their salinity tolerance makes it possible to irrigate Salicornia plants with saline waters and even seawater, which cannot be used by other crop species. In this work, S. europaea (L.) was cultivated in pots under the typical climatic conditions of the fall season in the Mediterranean region and irrigated with non-saline standard nutrient solution (SNS) or saline wastewater discharged from a greenhouse semi-closed hydroponic (substrate) culture of tomato or a saltwater recirculating aquaculture system (RAS) with Gilthead sea bream (Spaurus aurata L., which was used as such or after dilution (50:50) with SNS. Plant growth was not significantly affected by the composition of irrigation water, while higher antioxidant capacity (measured using the DPPH assay) and concentration of photosynthetic pigments, phenols, flavonoids, and ascorbic acid were found in the shoots of SNS plants than in those of plants irrigated with wastewater. The level of lipid peroxidation and H2O2 production significantly increased in the SNS plants, which also showed higher activity of superoxide dismutase and lower activity of catalase. These results suggest that S. europaea can be cultivated using wastewater with moderate to high salinity discharged from greenhouse hydroponic crops or RASs, and that salt is not strictly required for the growth of this species. Using non-saline nutrient solution can result in moderate oxidative stress that improves the shoot quality of S. europaea.

Post-stress restorative response of two quinoa genotypes differing in their salt resistance after salinity release

Soil salinity is one of the most important environmental factors that adversely affect plant growth and productivity. Quinoa emerges as a good food candidate due to its exceptional nutritive value, and its adaptability to various abiotic stresses. This high quinoa potential was investigated in the present study by evaluating the impact of salinity and post-stress restorative processes, in order to test how a pulse of saline water affects the growth and survival of two quinoa genotypes differing in salt resistance, Kcoito (salt sensitive) and UDEC-5 (salt resistant). Plants established in non-saline nutrient solution (hydroponic system) were exposed to a pulse of 0, 100 and 300 mM NaCl salinity for three weeks followed by four weeks in nutrient solution. Both genotypes survived exposure to salinity pulses. After stress removal, only the salt resistant variety UDEC-5 presented a significant stimulation of growth above the level of the non-pulsed treatment. Furthermore, the two varieties showed different responses in physiological, biochemical and antioxidant parameters. Again, the salinity release was highly controlled in pulsed UDEC-5 and more targeted as in Kcoito. In a win-win situation, the NaCl remaining in the tissues was used from UDEC-5 to optimize water uptake (osmotic force), to release vacuolar nutrients to enhance indirectly photosynthesis and to reduce ionic burden. This straightforward adjustment was accompanied by priming-effects such as a high proline accumulation and a balanced oxidative stress defense to scavenge remaining toxic reactive oxygen species (ROS), to stabilize enzymes and to be poised and to reduce lipid peroxidation and membrane damage. It can be concluded, that both species can tolerate short periods of exposure to saline conditions and this gives some flexibility of transient or permanent irrigation with saline water. However, taken together all of these markers indicate that only UDEC-5 quinoa can utilize salinity pulses in the applied range to enhance, growth, their antioxidant defense and water relations even above the level of non-pulsed plants.

Physiological and Phytochemical Responses of Spinach Baby Leaves Grown in a PFAL System with LEDs and Saline Nutrient Solution

Spinach is a leafy vegetable containing a plethora of bioactive compounds. Our study aimed to evaluate the physiological (i.e., JIP-test) and phytochemical response of spinach baby leaves grown with regular or mildly saline (40 mM NaCl) nutrient solution and irradiated by four light-emitting diodes (LEDs) with broad spectra. T1 (highest red and far-red, low blue) and T3 (high red, balanced blue, green and far-red) led to a better developed photosynthetic apparatus compared to T2 (red peak in 631 nm) and T4 (highest blue and green), highlighted by PIABS and its structural components: RC/ABS, φP0, ψE0, and ΔVIP. Elevated salinity only affected the latter parameter. T1 induced the maximum yield production but also the highest nitrate content which was far below the maximum level permitted by European legislation. Regardless of salinity level, T3 enhanced total phenol, chlorophyll, and carotenoid content. T2 and T4 led to inferior nutritional quality. Non-saline nutrient solution promoted the chlorophyll and carotenoid contents and the antioxidant potential, regardless of light treatment. By contrast, soluble sugar content was enhanced by saline nutrient solution. Our study shows that physiology and nutritional quality of spinach baby leaves can be manipulated by small interplays in the light spectra and salinity level.

Salt sensitivity in chickpea: Growth, photosynthesis, seed yield components and tissue ion regulation in contrasting genotypes

Chickpea is a relatively salt sensitive species but shows genotypic variation for salt tolerance, measured as grain yield per plant in mild-to-moderately saline soil. This experiment was designed to evaluate some physiological responses to salinity in three contrasting genotypes. One tolerant (Genesis836), one moderately tolerant (JG11) and one sensitive (Rupali) genotype were grown for 108d in non-saline nutrient solution (controls) and two levels of salinity treatment (30 and 60mM NaCl). No plants survived to maturity in the 60mM NaCl treatment; however, Genesis836 survived longer (87d) than JG11 (67d) while Rupali died after 27d; only Genesis836 flowered, but no pods were filled. At 30mM NaCl, Genesis836 produced a few filled pods, whereas JG11 and Rupali did not. Genotypic differences in plant dry mass at the vegetative stage were evident only at 60mM NaCl, while at maturity differences were evident at 30mM NaCl. Photosynthesis was maintained to different degrees by the three genotypes (e.g. at 30mM NaCl, 35–81% of controls; highest in Genesis836); photosynthesis was restricted predominately due to non-stomatal limitations as the intercellular CO2 concentration was only modestly affected (94–99% of controls). Photosystem II damage was evident in the less tolerant genotypes (e.g. at 30mM NaCl, actual quantum efficiency of photosystem II values were 63–96% of controls). Across treatments, shoot dry mass was negatively correlated with both Na+ and Cl− shoot concentrations. However, the sensitive genotype (Rupali) had equal or lower concentrations of these ions in green leaves, stems or roots compared to tolerant genotypes (JG11 and Genesis836); ion ‘exclusion’ does not explain variation for salt tolerance among these three chickpea genotypes. The large difference between Rupali (sensitive) and Genesis836 (tolerant) in the salt-induced reduction in net photosynthesis via non-stomatal limitations and the assessed damage to photosystem II, but with similar leaf ion concentrations, provides evidence that variation in ‘tissue tolerance’ of Na+ and/or Cl− in leaves contributes to the differential salt tolerance of these chickpea genotypes.

The influence of rootstock on growth and ion concentrations in pepper (Capsicum annuum L.) under saline conditions

SUMMARYA study was conducted to evaluate the influence of rootstock on the growth and ion concentrations in pepper (Capsicum annuum L.) plants under salt stress. Pepper plants (‘Ibleor’) were grafted onto three different rootstocks (‘Atlante’, ‘Galaxy’, and ‘Robusto’). Non-grafted ‘Ibleor’ plants were also studied as controls. Treatments consisted of a non-saline nutrient solution or two iso-osmotic saline plus nutrient treatments (30 mM NaCl and 20.5 mM Na2SO4).Grafting did not enhance the growth of pepper plants under non-saline conditions, whereas reductions in growth due to salinity were attenuated in grafted plants compared to non-grafted plants. The different levels of tolerance of the three rootstocks to salinity did not appear to be related to the capacity of each genotype to maintain leaf turgor by osmotic adjustments, but did appear to be associated primarily with a reduced uptake of toxic ions and, therefore, to a lower concentration of these ions in the grafted plants. The nutritional status of plants exposed to either saline treatment was influenced only slightly by grafting.

Comparison of the subirrigation and drip-irrigation systems for greenhouse zucchini squash production using saline and non-saline nutrient solutions

Soilless cultivation is a method that permits the achievement of high yields, good control of plant growth and development, and is currently in practice all over the world. Several irrigation systems have been developed for containerized-crops (drip-irrigation and subirrigation). Irrigation system can significantly impact the effect of irrigation water salinity on crop performance. Comparing the subirrigation and drip-irrigation systems using saline and non-saline nutrient solutions can be useful for developing optimal management strategies in semiarid regions which are characterized by the shortage of good quality water. A greenhouse experiment was carried out during the spring-summer season to determine the influence two irrigation systems (drip and subirrigation) and two nutrient solution concentrations (2.0 and 4.1 dS m −1) on substrate electrical conductivity (EC e), growth, yield, fruit quality (dry matter, carbohydrates, protein, Vitamin C), yield water use efficiency (WUE y) and tissue mineral composition of zucchini squash ( Cucurbita pepo L.). At the mid and at the end of the trial, plants grown with the subirrigation system resulted in a higher EC e in the upper and lower parts of the substrate in comparison to the drip-irrigation system, especially at an EC of 4.1 dS m −1. At an EC of 2.0 dS m −1, zucchini yield (total and marketable) was 13% lower with the subirrigation than with the drip-irrigation systems but offered several benefits: higher fruit quality (dry matter, glucose, fructose, starch and total carbohydrates content) and WUE y. The yield reduction with subirrigation was more pronounced at an EC 4.1 dS m −1, where the zucchini production with subirrigation was lower by 36% than with drip-irrigation. Increasing salinity from 2.0 to 4.1 dS m −1 improved fruit quality (high content of dry matter, reduced sugars, starch, total carbohydrates, and Vitamin C) in both irrigation systems. The results indicate that the choice of the irrigation system appears to be of foremost importance especially when using low quality irrigation water. Unlike subirrigation, using drip-irrigation with saline solution (4.1 dS m −1) would be an attractive strategy in limiting yield reduction, taking advantage of the quality effect of saline water and improving the WUE y.

Exogenous ascorbic acid (vitamin C) increases resistance to salt stress and reduces lipid peroxidation.

The transition from reversible to permanent wilting, in whole tomato seedlings (Lycopersicon esculentum Mill. cv. M82) following severe salt-stress by root exposure to 300 mM NaCl, was investigated. Salinized seedlings wilted rapidly but recovered if returned to non-saline nutrient solution within 6 h. However, after 9 h of salt-treatment 100% of the seedlings remained wilted and died. Remarkably, the addition of an anti-oxidant (0.5 mM ascorbic acid) to the root medium, prior to and during salt-treatment for 9 h, facilitated the subsequent recovery and long-term survival of c. 50% of the wilted seedlings. Other organic solutes without known anti-oxidant activity were not effective. Salt-stress increased the accumulation in roots, stems and leaves, of lipid peroxidation products produced by interactions with damaging active oxygen species. Additional ascorbic acid partially inhibited this response but did not significantly reduce sodium uptake or plasma membrane leakiness.

Kernel Distributions in Main Spikes of Salt‐Stressed Wheat: A Probabilistic Modeling Approach

Grain development in wheat (Triticum aestivum L.) is a complex process that responds to interactions among primary genotypic factors and the environment. This study was conducted to determine the effects of salinity stress on kernel occurrence and kernel mass distributions within the main spike. Mexican semidwarf wheat cuitivars Yecora Rojo and Anza were grown in sand tanks in the greenhouse with saline and nonsaline nutrient solutions. At harvest, each spikelet position and grain position was identified and the weight of every kernel was determined. Hierarchical multiple linear regression models were derived and fit to the kernel mass patterns. In a similar manner, logistic regression models were derived and fit to the kernel occurrence patterns. Kernel mass was shown to be highly dependent on spikelet location long the spike, kernel position within the spikelet, and salinity stress. Results from the logistic regression models confirm that these same factors affect kernel occurrence. Both types of statistical analysis are advantageous, since the changes in kernel occurrence and kernel mass distributions due to each of the above factors can be easily detected and studied.

Combined effects of KNO3 and salinity on yield and chemical composition of lettuce and Chinese cabbage

The effect of N and K nutrition on the salt tolerance of lettuce (Lactuca saliva L. cv. ‘Saunas’) and Chinese cabbage (Brassica campestris L., Pekinensis cv. Kazumi) was evaluated in three greenhouse experiments under a controlled aero-hydroponic system of cultivation. Three levels of KNO3 (1, 5 and 10 mM) were tested in all the experiments with rapidly circulated saline and nonsaline nutrient solutions. Two experiments, carried out between January and March 1989, with lettuce (Exp. I) and Chinese cabbage plants (Exp. III), consisted of two salinity levels, EC = 1.75 and 6.0 dS m−1, the former representing a nonsaline nutrient solution. In the third experiment with lettuce (Exp. II., conducted between March and May 1989), three saline nutrient solutions having EC levels of 4.7, 7.75 and 10.75 dS m−1 were compared to the nonsaline solution. The nutrient solutions were salinized with NaCl and CaCl2, in a 4:1 molar ratio. The highest yields of fresh weight of both crops were obtained from the 5 mM KNO3 under both saline and non-saline conditions. The 10 mM treatment caused yield reduction in Chinese cabbage, probably due to a severe tipburn disorder. The relatively high fresh weight yield obtained at the lowest (1 mM) KNO3 level can be explained by the positive effect of circulation velocity on nutrient uptake. The threshold salinity damage value for the vegetative yield of lettuce plants fed by 5 or 10 mM KNO3 was approximately 5 dSm−1 and the yield decreased by 6.5% per unit dS m−1 above the threshold. No yield improvement due to the addition of KNO3 occurred under highly saline conditions (Exp. II). The fresh weight of Chinese cabbage obtained from the ‘saline’ 1 and 5 mM KNO3 treatments was approximately 15% lower than the ‘non-saline’-treatment (Exp. III). Salinity increased tipburn and the effect was not altered by the addition of KNO3. No significant interaction between nutrition (KNO3 level) and salinity was found. The application of salts increased the concentration of Na and Cl in plant tissue and reduced the levels of N and K; the opposite occurred in plants fed by the medium and high levels of KNO3.

Foliar salt accumulation and injury in crops sprinkled with saline water

Many crops accumulate salts through the leaves when they are wetted by sprinkler irrigation. This accumulation may cause foliar injury and decrease crop yield. This study was conducted to test the salt sensitivity of sprinkled alfalfa, barley, cauliflower, cotton, potato, safflower, sesame, sorghum, sugarbeet, sunflower and tomato. Plants were grown in a greenhouse in covered sand cultures that were trickle-irrigated with nonsaline nutrient solutions. Sprinkling with 15 and 30, and in the case of cotton and sunflower, 30 and 60 meq/l waters (9:1 NaCl:CaSO4) was begun when plants were 1 to 3 months old and was continued for 4 to 7 weeks at a frequency of 1 h/day, 5 days/week. Except for sorghum, Na+ and Cl− absorption through the leaves was essentially a linear function of salt concentration and duration of sprinkling. Most species absorbed Nat at approximately the same rate as Cl−; however, in potato and sugarbeet Nat absorption exceeded Cl−; and in barley and sesame Cl−; exceeded Na1. The mean rates of Na+ and Cl−; absorption among species increased in the order: sorghum ≪ cotton = sunflower < cauliflower < sesame = alfalfa = sugarbeet < barley = tomato < potato = safflower. Susceptibility to leaf injury among species did not vary in strict relation to rates of salt absorption from 30 meq/l water. Potato and tomato readily absorbed Na+ and Cl−; and quickly exhibited symptoms of leaf tip and margin necrosis. On the other hand, safflower, with one of the highest rates of salt absorption was only slightly injured by sprinkling. Barley readily absorbed salt, particularly Cl−; and exhibited minor injury symptoms; whereas sesame and alfalfa had intermediate absorption rates but were somewhat more susceptible to injury. Sugarbeet was uninjured by sprinkling but absorbed appreciable amounts of Nat; whereas sorghum developed some necrosis along leaf edges but absorbed very little salt. Cauliflower, cotton, and sunflower absorbed salt slowly and exhibited almost no injury.

Interaction between Light Intensity and NaCl Salinity and Their Effects on Growth, CO2 Assimilation, and Photosynthate Conversion in Young Broad Beans

Seedings of Vicia faba were grown for four weeks at two different light intensities (55 and 105 watts per square meter) in a saline (50 millimolar NaCl) and nonsaline nutrient solution. NaCl salinity depressed growth and restricted protein formation, CO(2) assimilation, and especially the incorporation of photosynthates into the lipid fraction. Conversion of photosynthates in leaves was much more affected by salinity than was photosynthate turnover in roots. The detrimental effect of NaCl salinity on growth, protein formation, and CO(2) assimilation was greater under low than under high light conditions. Plants of the high light intensity treatment were more capable of excluding Na(+) and Cl(-) and accumulating nutrient cation species (Ca(2+), K(+), Mg(2+)) than plants grown under low light intensity. It is suggested that the improved ionic status provided better conditions for protein synthesis, CO(2) assimilation, and especially for the conversion of photosynthates into lipids.