Special Issue "Response and Tolerance of Agricultural Crops to Salinity Stress"

A special issue of Agriculture (ISSN 2077-0472).

Deadline for manuscript submissions: closed (31 October 2018)

Special Issue Editor

Guest Editor
Dr. Jorge Ferreira

US Salinity Laboratory, 450 W. Big Springs Rd., Riverside, CA 92507, USA
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Special Issue Information

Dear Colleagues,

Abiotic stresses affect mineral nutrient balance, physiological, biochemical, and morphological responses, and gene expression of plants growing in saline soils or under irrigation with saline waters. The literature is abundant in the uptake and accumulation of salts (mainly NaCl), the accumulation of aminoacids such as proline and glycine betaine, physiological aspects such as stomatal conductance and photosynthetic activity, and on the expression of genes that are important to salt tolerance mechanisms in model crops. However, we lack information in several aspects that will help us understand plant response to salinity.  These include, but are not restricted to, reactive oxygen species (ROS), biochemical markers such as antioxidant flavonoids that accumulate inside of vacuoles (as salts do), sugars, aminoacids besides proline and betaine, root and shoot morphology, plant hormones and growth regulators, and secondary metabolites (such as flavonoids, polyamines, etc.) that, besides protecting the plant from stress, may also increase the nutritional value of the crop.  Understanding the interaction between stress and nutrition is also highly relevant for modern agriculture in order to ensure high yields and high quality of plant products produced under saline environments. Combinations of stresses such as drought and salinity and salinity and nutrition, are more complex to understand than individual stress and should also be considered. Although we understand the importance of the several aspects related to plant response and tolerance to salinity, we should also urge colleagues to submit their work related to the involvement of microorganisms (e.g., endophytes), chemical primers (e.g., H2O2, salicylic acid, etc.), new potential agricultural, horticultural, and forage crops that may be alternatives to cultivation under salinity (including their respective postulated mechanisms of salinity tolerance) and that will allow irrigated agriculture to continue providing food and animal feed to sustain a fast growing world population.

This Special Issue intends to highlight the recent progress in the efforts to understand response and tolerance mechanisms of plants to saline stress and alternatives to minimize salinity effects, maintaining plant growth and development to assure commercially-feasible crop yields. All types of articles, original research, opinions and reviews that provide new insights into the effects of salinity stress and the mechanisms involved in the stress responses are welcome. Experimental studies and theoretical approaches referring to the molecular, cellular, organ or whole plant level may also be considered. The following list gives some examples, but is not exhaustive:

  • Mechanisms of salt tolerance (tissue tolerance, exclusion, sequestration into vacuoles, etc.)
  • Morphological aspects (shoot and root architecture and morphology)
  • Alternative salt-tolerant species with agronomical/horticultural potential
  • Biochemical markers (aminoacids, sugars, hormones, secondary metabolites, antioxidants, etc.)
  • Chemical primers (H2O2, salicylic acid, jasmonic acid, growth regulators, salts, etc.)
  • Symbiotic microbes (e.g., endophytes)
  • Gene expression associated with salt-tolerance mechanisms
  • New data on economic aspects of the effects of salinity on global agricultural production



Dr. Jorge Ferreira
Guest Editor

Manuscript Submission Information

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Keywords

  • Mechanisms of salt tolerance (tissue tolerance, exclusion, sequestration into vacuoles, etc.) 
  • Morphological aspects (shoot and root architecture and morphology) 
  • Alternative salt-tolerant species with agronomical/horticultural potential 
  • Biochemical markers (aminoacids, sugars, hormones, secondary metabolites, antioxidants, etc.) 
  • Chemical primers (H2O2, salicylic acid, jasmonic acid, growth regulators, salts, etc.) 
  • Symbiotic microbes (e.g., endophytes) 
  • Gene expression associated with salt-tolerance mechanisms 
  • New data on economic aspects of the effects of salinity on global agricultural production

Published Papers (5 papers)

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Research

Open AccessArticle Relationship of Salinity Tolerance to Na+ Exclusion, Proline Accumulation, and Antioxidant Enzyme Activity in Rice Seedlings
Agriculture 2018, 8(11), 166; https://doi.org/10.3390/agriculture8110166
Received: 31 August 2018 / Revised: 17 October 2018 / Accepted: 18 October 2018 / Published: 23 October 2018
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Abstract
Rice is a staple crop for over 50% of the world’s population, but its sensitivity to salinity poses a threat to meeting the worldwide demand. This study investigated the correlation of salinity tolerance to Na+ exclusion, proline accumulation, and the activity of
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Rice is a staple crop for over 50% of the world’s population, but its sensitivity to salinity poses a threat to meeting the worldwide demand. This study investigated the correlation of salinity tolerance to Na+ exclusion, proline accumulation, and the activity of antioxidant enzymes in some rice cultivars originating from Egypt. Giza 182 was shown to be the most tolerant of the five cultivars, as judged by visual symptoms of salt injury, growth parameters, and patterns of Na+ accumulation, while Sakha 105 appeared to be highly susceptible. In detail, Giza 182 accumulated the lowest Na+ concentration and maintained a much lower Na+/K+ ratio in all plant organs in comparison to Sakha 105. The salinity-tolerant varieties had higher accumulation of proline than the salinity-susceptible cultivars. The salinity-tolerant Giza 182 accumulated a higher concentration of proline, but the lipid peroxidation (MDA) level was significantly reduced compared to in the salinity-susceptible Sakha 105. In addition, Giza 182 had stronger activity of both catalase (CAT) and ascorbate peroxidase (APX) compared to Sakha 105. The findings of this study reveal that the salinity tolerance in rice is primarily attributable to Na+ exclusion, the accumulation of proline in rice organs, a low Na+/K+ ratio, and a low level of lipid peroxidation. The levels of the antioxidant enzymes CAT and APX and the accumulation of proline may play important roles in salinity tolerance in rice. However, the comparative involvement of individual antioxidant enzymes in salinity stress in rice should be further investigated. Giza 182 has the potential to be cultivated in salinity-affected areas, although the effects of salinity stress on its grain yield and quality should be evaluated during the full crop cycle. Full article
(This article belongs to the Special Issue Response and Tolerance of Agricultural Crops to Salinity Stress)
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Open AccessArticle Effect of Saline Irrigation on Accumulation of Na+, K+, Ca2+, and Mg2+ Ions in Rice Plants
Agriculture 2018, 8(10), 164; https://doi.org/10.3390/agriculture8100164
Received: 9 September 2018 / Revised: 13 October 2018 / Accepted: 17 October 2018 / Published: 19 October 2018
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Abstract
Salinity is an abiotic stress that curtails rice production in many parts of the world. Although Koshihikari and Nikomaru are high-yielding japonica rice cultivars, their salinity-tolerance levels are not well known. This experiment was conducted in Ehime, Japan to assess the effect of
[...] Read more.
Salinity is an abiotic stress that curtails rice production in many parts of the world. Although Koshihikari and Nikomaru are high-yielding japonica rice cultivars, their salinity-tolerance levels are not well known. This experiment was conducted in Ehime, Japan to assess the effect of salinity on ion accumulation and dry mass production of Koshihikari and Nikomaru compared with a salinity-tolerant indica rice cultivar (Pokkali). Control (0.16 dS/m), 6 dS/m and 12 dS/m irrigation treatments were conducted during the tillering stage (1st phase of experiment), and later only control and 6 dS/m irrigations were applied during the reproductive stage (2nd phase of experiment). Excessive Na+ accumulation in plants hampers the uptake of the macronutrients K+, Ca2+, and Mg2+, which consequently retards growth and yield. Because salinity-tolerant plants can avoid this stress, minimal Na+ was found in Pokkali during the tillering stage (under 6 dS/m salinity). Additionally, Nikomaru showed better growth and dry mass than Koshihikari. Moreover, the Koshihikari leaves contained more Na+ than Nikomaru and Pokkali. The japonica cultivars had higher Na+/K+ in their leaves than Pokkali. In the reproductive stage, the two japonica cultivars accumulated almost the same amount of Na+ under 6 dS/m salinity. However, under 6 dS/m salinity, the grain yield of Nikomaru was higher than control, whereas that of Koshihikari decreased because of salinity. Meanwhile, Pokkali had the lowest Na+/K+ in the whole plant, and most parts of Nikomaru showed lower Na+/K+ than Koshihikari. Koshihikari was relatively less tolerant than Nikomaru under 6 dS/m salinity during both stages, while both failed to withstand 12 dS/m. Full article
(This article belongs to the Special Issue Response and Tolerance of Agricultural Crops to Salinity Stress)
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Open AccessArticle Spinach (Spinacea oleracea L.) Response to Salinity: Nutritional Value, Physiological Parameters, Antioxidant Capacity, and Gene Expression
Agriculture 2018, 8(10), 163; https://doi.org/10.3390/agriculture8100163
Received: 28 September 2018 / Revised: 11 October 2018 / Accepted: 13 October 2018 / Published: 17 October 2018
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Abstract
Scarcity of good-quality irrigation water is a major impediment to meet food demand for a growing world population. Recycled waters may be available locally more affordably, but their higher salinity is a concern. Salinity effects on spinach mineral composition, antioxidant capacity, photosynthesis, and
[...] Read more.
Scarcity of good-quality irrigation water is a major impediment to meet food demand for a growing world population. Recycled waters may be available locally more affordably, but their higher salinity is a concern. Salinity effects on spinach mineral composition, antioxidant capacity, photosynthesis, and gene expression have not been established. Spinach cv. Raccoon was greenhouse-grown and irrigated with four levels of water salinity of electrical conductivities (ECiw) of 1.4 (control) or ranging from 3.6 to 9.4 dS m−1, combined with three levels of K (3, 5, and 7 meq L−1). Irrigation waters had 2, 20, 40, and 80 meq L−1 of NaCl. After 23 treatment days, plants significantly accumulated Na and Cl in shoots and roots with increasing salinity, regardless of the K concentration in the irrigation water. Plants exhibited no visual symptoms of salt toxicity and there were no differences in shoot growth. Plants maintained their overall concentrations of mineral nutrients, physiological parameters, and oxalic acid across salinity treatments. Leaves retained all their antioxidant capacity at 20 meq L−1 NaCl, and 74% to 66% at 40 and 80 meq L−1 NaCl, respectively. Expression analyses of ten genes, that play important role in salt tolerance, indicated that although some genes were upregulated in plants under salinity, compared to the control, there was no association between Na or K tissue concentrations and gene expression. Results clearly show that spinach maintains its growth, mineral composition, and antioxidant capacity up to ECiw = 9.4 dS m−1. As this salinity is equivalent to a soil salinity of 4.5 dS m−1, spinach can tolerate over two-fold its previously-considered salinity threshold. Thus, growers can cultivate spinach using recycled, saline, waters without detriment to shoot biomass accumulation, and nutritional value. Full article
(This article belongs to the Special Issue Response and Tolerance of Agricultural Crops to Salinity Stress)
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Open AccessArticle Growth, Phenolics, Photosynthetic Pigments, and Antioxidant Response of Two New Genotypes of Sea Asparagus (Salicornia neei Lag.) to Salinity under Greenhouse and Field Conditions
Agriculture 2018, 8(7), 115; https://doi.org/10.3390/agriculture8070115
Received: 17 June 2018 / Revised: 17 July 2018 / Accepted: 18 July 2018 / Published: 23 July 2018
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Abstract
Small succulent halophytic shrubs of the genera Salicornia and Sarcocornia (Salicornioideae, Amaranthaceae) are commonly named sea asparagus and consumed worldwide as green salad in gourmet food, as conserves, and beverages. Their shoots are rich in bioactive compounds and plants show high yields in
[...] Read more.
Small succulent halophytic shrubs of the genera Salicornia and Sarcocornia (Salicornioideae, Amaranthaceae) are commonly named sea asparagus and consumed worldwide as green salad in gourmet food, as conserves, and beverages. Their shoots are rich in bioactive compounds and plants show high yields in a wide range of salinities, but little is known about how salt cultivation conditions affect their chemical composition. Two genotypes (BTH1 and BTH2) of the Brazilian sea asparagus Salicornia neei Lag. were evaluated for salt tolerance and changes in shoot concentrations of organic metabolites and antioxidant activity under different salt exposure in both greenhouse and field conditions. All greenhouse plants received full strength modified Hoagland solution in deionized water with a basic electrical conductivity (EC) of 1.7 dS m−1, and with NaCl concentrations (in mM) of ~0.1 (control), 34, 86, 171, 513, and 769. After fifty days of cultivation, both S. neei genotypes showed high salt tolerance and grew better under low salinities (34–86 mM NaCl) than under control salinity. Shoots of BTH1 genotype appeared to be undergoing lignification and used their high carotenoid content to dissipate the oxidative power, and the zeaxanthin content and de-epoxidation state of xanthophylls (DES) were positively affected by salinity. Under increasing salinity, BTH2 genotype had higher relative content of chlorophyll b, which may have lowered the plant photo-oxidation rate, and increased shoot concentration of the flavonoid quercetin (up to 11.6 μg g−1 dw at 769 mM NaCl), leading to higher antioxidant capacity. In the field experiment, after 154 days of irrigation with saline (213 mM NaCl) shrimp farm effluent, BTH2 plants grew taller, produced more metabolites (e.g., total phenolics, total free flavonoids, quercetin, and protocatechuic acid) and had a greater antioxidant capacity of shoots than that of BTH1 plants and that of traditional crops irrigated with fresh water. Yield and bioactive compound composition of S. neei genotypes’ shoots can be enhanced by cultivation under moderate saline conditions. Full article
(This article belongs to the Special Issue Response and Tolerance of Agricultural Crops to Salinity Stress)
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Open AccessArticle Salt Tolerance of Six Switchgrass Cultivars
Agriculture 2018, 8(5), 66; https://doi.org/10.3390/agriculture8050066
Received: 5 April 2018 / Revised: 26 April 2018 / Accepted: 28 April 2018 / Published: 29 April 2018
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Abstract
Panicum virgatum L. (switchgrass) cultivars (‘Alamo’, ‘Cimarron’, ‘Kanlow’, ‘NL 94C2-3’, ‘NSL 2009-1’, and ‘NSL 2009-2’) were evaluated for salt tolerance in two separate greenhouse experiments. In experiment (Expt.) 1, switchgrass seedlings were irrigated with a nutrient solution at an electrical conductivity (EC) of
[...] Read more.
Panicum virgatum L. (switchgrass) cultivars (‘Alamo’, ‘Cimarron’, ‘Kanlow’, ‘NL 94C2-3’, ‘NSL 2009-1’, and ‘NSL 2009-2’) were evaluated for salt tolerance in two separate greenhouse experiments. In experiment (Expt.) 1, switchgrass seedlings were irrigated with a nutrient solution at an electrical conductivity (EC) of 1.2 dS·m−1 (control) or a saline solution (spiked with salts) at an EC of 5.0 dS·m−1 (EC 5) or 10.0 dS·m−1 (EC 10) for four weeks, once a week. Treatment EC 10 reduced the tiller number by 32% to 37% for all switchgrass cultivars except ‘Kanlow’. All switchgrass cultivars under EC 10 had a significant reduction of 50% to 63% in dry weight. In Expt. 2, switchgrass was seeded in substrates moistened with either a nutrient solution of EC 1.2 dS·m−1 (control) or a saline solution of EC of 5.0, 10.0, or 20.0 dS·m−1 (EC 5, EC 10, or EC 20). Treatment EC 5 did not affect the seedling emergence, regardless of cultivar. Compared to the control, EC 10 reduced the seedling emergence of switchgrass ‘Alamo’, ‘Cimarron’, and ‘NL 94C2-3’ by 44%, 33%, and 82%, respectively. All switchgrass cultivars under EC 10 had a 46% to 88% reduction in the seedling emergence index except ‘NSL 2009-2’. No switchgrass seedlings emerged under EC 20. In summary, high salinity negatively affected switchgrass seedling emergence and growth. Dendrogram and cluster of six switchgrass cultivars indicated that ‘Alamo’ was the most tolerant cultivar, while ‘NSL 2009-2’ was the least tolerant cultivar at both seedling emergence and growth stages. A growth-stage dependent response to salinity was observed for the remaining switchgrass cultivars. ‘NSL 2009-1’ and ‘NL 94C2-3’ were more tolerant to salinity than ‘Cimarron’ and ‘Kanlow’ at the seedling emergence stage; however, ‘Kanlow’ and ‘Cimarron’ were more tolerant to salinity than ‘NSL 2009-1’ and ‘NL 94C2-3’ at the seedling growth stage. Full article
(This article belongs to the Special Issue Response and Tolerance of Agricultural Crops to Salinity Stress)
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