Salinity Stress Treatments Research Articles

Comprehensive Selection Criteria for High-Yielding Bread Wheat (Triticum aestivum L.) Hybrids under Salinity Stress

THE MOST important aspect of this investigation was evaluating a set of wheat genotypes with different responses to salt stress while conducting the selection process on the number of spikes/plant, the number of filled grains/spike, 1000-grain weight, and grain yield/plant traits besides, some physiological attributes and related to salinity tolerance such as Na+, K+ contents, Na+/K+ ratio, osmotic adjustment, proline, and glycine betaine contents under control and salinity conditions. The wheat genotypes were divided into two groups according to half diallel analysis. Where, the first one included parents, namely; Sakha 8, Shandweel 1, Masr 1, Giza 171, Sakha 94, Gimeaza 11, and Gimeaza 12, respectively. While the second group was 21 F1 wheat crosses obtained from half diallel crossing among the seven wheat genotypes. Heterosis over better-parent, general, and specific combining ability effects was the most important measurements for all studied traits for both experiments. Further, the seven wheat genotypes and the highest 5 F1 crosses were evaluated for the salinity tolerance indices test using grain yield/plant trait depending on all data estimated for all studied attributes under salt-stress treatment compared to the control experiment. The final results revealed that; parents 1, 2, and 3 besides, the crosses; P1 X P2, P1 X P3, P2 X P3, P2 X P4, and P3 X P4 exhibited a high trend in salinity tolerance under salinity stress treatment compared to the control experiment. Further, the previous wheat genotypes recorded high levels of salinity tolerance indices. SCoT markers determined the hybrids with the highest salinity tolerance indices. Out of nine primers used, only six generated polymorphic bands with 43 polymorphic bands. Therefore, identifying genetic evidence at the molecular level could be used in the future as a taxonomic tool to tolerate salinity in promising wheat genotypes.

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.

Efeito atenuador do silício no desenvolvimento inicial de amendoim submetido ao estresse por alumínio e salinidade

Peanut (Arachis hypogea L.) is an oleaginous crop with great potential for human consumption, production of biofuels and forage, and may expand to new cultivation areas that present limitations to its growth, such as high concentration of aluminum (Al) and salinity. This work was carried out with the objective of verifying if silicon (Si) linked to seed treatment attenuates the effects of salinity and Al toxicity in the initial development of peanut plants. Two experiments were carried out in a completely randomized design, in a 3x2 factorial scheme, with three concentrations of Al3+ (0; 54 and 216 mg.L-1) or three concentrations of salinity (0, 30 and 60 µM of NaCl), in the absence and presence of calcium silicate (0.0 and 200 µM) in the seed treatment, and the seeds were immersed for 40 min in a 1.0 mmol.L-1 calcium silicate solution, with four repetitions per treatment. While the seeds were immersed for 40 min. controls were immersed in distilled water, with four replications per treatment. After the imbibition process, one seed was sown per pot (300 mL), which were filled with coconut powder substrate. Plants were cultivated in nutrient solution for 30 days containing the appropriate treatments. At the end of this period, the growth parameters were verified through the evaluations of height, root length, number of leaflets and shoot and root dry mass. Young peanut plants showed sensitivity to salinity and Al toxicity, with a deleterious effect on growth, evidenced by the drop in plant development, highlighting the results of roots and leaves in the saline stress treatments. Thus, seed treatment with Si contributed to the attenuation of stressors.

Contrasting response of two Lotus corniculatus L. accessions to combined waterlogging-saline stress.

Waterlogging and salinity impair crop growth and productivity worldwide, with their combined effects being larger than the additive effects of the two stresses separately. Here, a common forage tetraploid Lotus corniculatus (cv. San Gabriel) and a diploid L. corniculatus accession, collected from a coastal area with high frequency of waterlogging-saline stress events, were evaluated for tolerance to waterlogging, salinity and these two stresses combined. We hypothesize that, due to its environmental niche, the diploid accession would show better adaptation to combined waterlogging-saline stress compared to the tetraploid L. corniculatus. Plants were evaluated under control conditions, waterlogging, salinity and a combined waterlogging-saline treatment for 33 days. Shoot and root growth were assessed, together with chlorophyll fluorescence and gas exchange measurements. Results showed that salinity and waterlogging effects were more severe for the tetraploid accession, with a larger effect being observed under the combined stress condition. Concentrations of Na+ , Cl- and K+ were measured in apical and basal leaves, and in roots. A larger accumulation of Na+ and Cl- was observed under both saline and combined stress treatments for the tetraploid L. corniculatus, for which ion toxicity effects were evident. The expression of CLC gene, coding for a Cl- transporter, was only increased in diploid L. corniculatus plants in response to the combined stress condition, suggesting that ion compartmentalization mechanisms were induced in this accession. Thus, this recently characterized L. corniculatus could be used for the introduction of new tolerance traits in other Lotus species used as forage.

Respons of Early Growth Vetiver (Vetiveria Zizanioides L.) Seedling on Salt Stress Condition

Vetiver (Vetiveria zizanioides) is one of the essential oil-producing plants which is commonly called vetiver oil. Agricultural land in Indonesia has a salinity problem estimated at 0.44 million ha, the increase in salinity of agricultural land threatens the stability of agricultural production. This study aims to determine the respons of early growth vetiver (Vetiveria zizanioides L.) seedlings on salt stress condition. This research was conducted in a greenhouse, Faculty of Agriculture, University of North Sumatra, Medan. This study used a non-factorial randomized block design (RBD), namely the salinity (S) which consisted of 3 factors: the EC salinity levels were 0 (distilled water), 4 and 8 ds / m. The salinity stress treatment showed a significant effect of reducing the growth parameters of leaf dry weight, number of stomata and cuticle thickness but did not significantly affect the specific leaf area parameters at 8 WAP. The salinity stress treatment gave significantly better effect in conditions without salinity stress and partly showed better results in the salinity stress condition at the level of 8 dsm-1.

Antioxidative metabolism in sugarcane (Poaceae) varieties subjected to water and saline stress

ABSTRACT This study aimed to identify the antioxidant responses of sugarcane (Saccharum spp.) varieties subjected to water and saline stress. Sugarcane seedlings of six different varieties obtained through micropropagation were subjected to either water or saline stress, or a combination of water + saline stress. The study was carried out in May 2012, in a greenhouse at the Universidade Federal Rural de Pernambuco (UFRPE). The experimental design was randomized, with treatments arranged in a 6 × 4 factorial scheme (six varieties and four treatments), and four replicates. Lipid peroxidation, hydrogen peroxide (H2O2) concentrations, and relative water content (RWC) were evaluated. Furthermore, we evaluated the plants’ antioxidative defense systems by measuring the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT). The sugarcane varieties had higher lipid peroxidation and/or higher H2O2 concentrations when subjected to the combined water + saline stress. The antioxidant enzymes responded to the water and saline stress treatments differently depending on the sugarcane variety. However, under combined saline + water stress conditions, the enzymes may have become inactivated, which indicates that the response to the combined water + saline stress was different from the sum of the responses to only water stress or only saline stress. High concentrations of malondialdehyde (MDA) associated with low RWC may be an effective indicator of multiple stress sensitivity in sugarcane varieties. The RB99395 and RB867515 sugarcane varieties responded more efficiently to environmental stress, and maintained their cell water content when subjected to either water or saline stress.

Genome-wide analysis of PHD finger gene family and identification of potential miRNA and their PHD finger gene specific targets in Oryza sativa indica.

Rice (Oryza sativa L.) is one of the most important cereal crops for one third of the world population. However, the grain quality as well as yield of rice is severely affected by various abiotic stresses. Environmental stresses affect the expression of various microRNAs (miRNAs) which in turn negatively regulate gene expression at the post-transcriptional level either by degrading the target mRNA genes or suppressing translation in plants. Plant homeo-domain (PHD) finger proteins are known to be involved in the plant response to salinity stress. In the present study, we identified 44 putative OsPHD finger genes in Oryza sativa Indica, using Ensembl Plants Database. Using computational approach, potential miRNAs that target OsPHD finger genes were identified. Out of the 44 OsPHD finger genes only three OsPHD finger genes i.e., OsPHD2, OsPHD35 and OsPHD11, were found to be targeted by five newly identified putative miRNAs i.e., ath-miRf10010-akr, ath-miRf10110-akr, osa-miR1857–3p, osa-miRf10863-akr, and osa-miRf11806-akr. This is the first report of these five identified miRNAs on targeting PHD finger in Oryza sativa Indica. Further, expression analysis of 44 PHD finger genes under salinity was also performed using quantitative Real-Time PCR. The expression profile of 8 genes were found to be differentially regulated, among them two genes were significantly up regulated i.e., OsPHD6 and OsPHD12. In silico protein-protein interaction analysis using STRING database showed interaction of the OsPHD finger proteins with other protein partners that are directly or indirectly involved in development and abiotic stress tolerance.

TiO2 nanoparticles effects on morphology and physiology of Artemisia absinthium L. under salinity stress

Providing strategies for coping and managing NaCl salinity stress is the goal of many researches. Titanium dioxide nanoparticles (TiO2 NPs) are widely used as photo-catalytic agents due to their strong oxidative properties, optical stability, lack of toxicity, cheapness and availability. Here, the effects of various concentrations of NaCl salinity and titanium dioxide nanoparticles on certain growth factors of the shoot and root, the protein content, activities of catalase, guaiacol peroxidase, superoxide dismutase and polyphenol oxidase enzymes in Artemisia absinthium L were studied. SDS–PAGE was used to analyze the protein expression of A. absinthium at different levels of NaCl salinity stress and TiO2 nanoparticles treatment. All the experiments were performed as a factorial in a completely randomized design in three replications. Data were analyzed using SPSS software. We found that the increase in the concentration of TiO2 NPs up to 20 mg L−1 leads to the enhancement in the length and dry/fresh weights of roots, while there is a reverse pattern for all the traits with the concentration of 30 mg L−1 of nanoparticles. Moreover, the results showed a significant enhancement in the antioxidant activity of catalase, peroxidase, superoxide dismutase, polyphenol oxidase and guaiacol peroxidase enzymes and also protein content in some salinity-stressed plants and those were treated with various concentrations of titanium dioxide nanoparticles in comparison with the control group. According to protein molecular weight in NCBI and SDS–PAGE, some isoenzymes were found for each of the evaluated antioxidant enzymes, and their expression highly differed among the evaluated samples. The increase in isoenzymes’ band intensity was related to the increase in their protein expression, isoenzymes accumulation in the cells or both of them. In some cases, enzymes’ activities were increased, but there was no change in the related band intensity in the SDS–PAGE. It seems that the increase in enzymes activities could be due to the effect of nanoparticles on the enzyme’s active site. Therefore, the increase in antioxidant enzymes activities was related to increase in gene expression, enzyme activity or both processes. In this study, the highest concentrations of the nanoparticles (30 mg L−1) had the negative effects on the NaCl salinity-treated samples and in several cases decreased growth of the shoot and root, proteins content and enzymes activities.

Effect of Chitosan on Growth, Yield and Certain Salinity Stress-Related Metabolites in Two Barley Cultivars Contrasting in Salt Tolerance تأثیر الکیتوزان على النمو، المحصول و بعض المحتویات البیوکیماویة ذات العلاقة بالاجهاد الملحى فى صنفین من الشعیر یتمایزان فى قدرتهما على تحمل الملوحة

The present study aimed to elucidate the effect of chitosan on germination, growth, yield and certain salinity stress-related metabolites in two barley cultivars contrasting in salt tolerance namely cvs. Giza 129 (salt susceptible) and Giza 136 (salt tolerant). Salinity stress treatments were commenced 30 days after sowing via soil irrigation with either NaCl or CaCl2 each at three levels 0, 3000 mgL-1 (4.6875 dS m-1) and 6000 mgL-1 (9.375 dS m-1). The obtained results indicated that both types of salinity at 6000 mgL-1 decreased germination percentage, growth parameters, total chlorophylls, relative water content and yield whereas increased mean germination time as well as carotenoids, proline and total soluble sugars (TSS). Chitosan (CHS) treatment at 200 mgL-1 increased yield and its components in plants growing under normal conditions, and alleviated the negative effects of salinity on characters that were negatively-affected in salinity-stressed plants. On the other hand, there was an additive effect between salinity and CHS on inducing the content of carotenoids, proline and TSS. The damaging effect of salinity was more pronounced in case of NaCl compared with CaCl2, and the alleviative effects of CHS was more pronounced at 200 mgL-1. Salinity tolerance of cv G 136 may be attributed to higher seed germination potential along with higher intrinsic contents from proline and TSS.

Genome-wide analysis of mitogen-activated protein (MAP) kinase gene family expression in response to biotic and abiotic stresses in sugarcane.

To systematically analyze mitogen-activated protein (MAP) kinase gene families and their expression profiles in sugarcane (Saccharum spp. hybrids; Sh) under diverse biotic and abiotic stresses, we identified 15 ShMAPKs, 6 ShMAPKKs and 16 ShMAPKKKs genes in the sugarcane cultivar R570 genome. These were also confirmed in one S. spontaneum genome and two transcriptome datasets of sugarcane trigged by Acidovorax avenae subsp. avenae (Aaa) and Xanthomonas albilineans (Xa) infections. Phylogenetic analysis revealed that four subgroups were present in each ShMAPK and ShMAPKK family and three sub-families (RAF, MEKK and ZIK) presented in the ShMAPKKK family. Conserved protein motif and gene structure analyses supported the evolutionary relationships of the three families inferred from the phylogenetic analysis. All of the ShMAPK, ShMAPKK and ShMAPKKK genes identified in Saccharum spp. R570 were distributed on chromosomes 1-7 and 9-10. RNA-seq and qRT-PCR analyses indicated that ShMAPK07 and ShMAPKKK02 were defense-responsive genes in sugarcane challenged by both Aaa and Xa stimuli, while some genes were upregulated specifically by Aaa and Xa infection. Additionally, ShMAPK05 acted as a negative regulator under drought and salinity stress, but served as a positive regulator under salicylic acid (SA) treatment. ShMAPK07 plays a positive role under drought stress, but a negative role under SA treatment. ShMAPKKK01 was negatively modulated by both salinity stress and SA treatment, whereas ShMAPKKK06 was positively regulated by both of the two stress stimuli. Our results suggest that members of MAPK cascade gene families regulate adverse stress responses through multiple signal transduction pathways in sugarcane.

Physiological and molecular responses of golden pompano Trachinotus ovatus subjected to the acute salinity stress

Golden pompano (Trachinotus ovatus) is a commercially important marine fish and is widely cultured in the coastal area of South China. Salinity is one of the most important environmental factors influencing aquatic organisms. In this study, T. ovatus was subjected to the acute salinity stress treatments using four salinity levels of 0‰, 10‰, 20‰, and 40‰ to investigate its physiological and molecular responses. Our results revealed that serum osmolality, Na+, and Cl– concentrations showed a similar decreasing trend after salinity stress at the first 2 h and then increased after 8 h. In particular, the Na+/K+-ATPase alpha 1-isoform (Tonka α1) rapidly responded to changes in salinity levels. In the gills, the expression of Tonka α1 was markedly upregulated at 2 h in all the experimental groups (0‰, 10‰, 20‰, and 40‰). In the kidney, Tonka α1 expression in these experimental groups tended first to increase but then decreased, with its values peaking at 2 h, 4 h, and 8 h, respectively. In the intestine, Tonka α1 responded rapidly to salinity changes and then changed dramatically within 4 h under salinity stress. The Na+/K+-ATPase activity was also affected by the acute salinity stress, and it was higher in the 10‰ and 40‰ groups than in the control group (0 h). Interestingly, Na+/K+-ATPase activity was lowest in the 20‰ group. Our results show the various physiological response of T. ovatus under acute salinity stress and demonstrate that under such conditions, Na+/K+-ATPase is primarily involved in the osmoregulation required to maintain homeostasis in this species.

Effects of acute salinity stress on the survival and prophenoloxidase system of Exopalaemon carinicauda

The ridgetail white prawn Exopalaemon carinicauda is a euryhaline shrimp species in the estuarine and coastal areas of China. In this study, survival rates, transcription levels of two prophenoloxidase system-related genes (EcLGBP and EcproPO) and PO activity were determined quantitatively in juvenile and adult E. carinicauda under different salinity levels. The results showed that E. carinicauda juveniles could survive in a wider range of salinity conditions than adults. For juvenile E. carinicauda, the expression levels of EcLGBP and EcProPO were up-regulated in low salinities and showed no significant difference at 20–40, while PO activities in low salinities were higher compared to those in high salinities. For adult E. carinicauda, the expression profiles of EcLGBP and EcproPO had a different trend of up-regulation in salinity stress treatments and no obvious difference was observed in the gene expression levels and PO activity between 30 and 40. The salinity tolerance range of immunity for juvenile and adult E. carinicauda is 20–40 and 30–40, respectively.

Effect of stocking density and water exchange on performance and stress tolerance to low and high salinity by Litopenaeus vannamei postlarvae reared with biofloc in intensive nursery phase

The effect of stocking density and water exchange was evaluated on growth performance of Litopenaeus vannamei postlarvae (PL), reared in a biofloc-based system at the nursery level and exposed to short-term low-high salinity stress. A bioassay was conducted with four treatments in triplicate: T1 = 8500 postlarvae/m3 without water exchange, T2 = 16,500 postlarvae/m3 without water exchange, T3 = 8500 postlarvae/m3 with 50% water exchange per week, and T4 = 16,500 postlarvae/m3 with 50% water exchange per week. At 0 (PL′22), 15 (PL′37), 30 (PL′52), and 45 (PL′67) days of culture, a group of shrimp from each treatment was exposed to acute stress by low (27 to 2‰) and high (27 to 60‰) salinity. After 45 days, the water exchange rate and water exchange rate × stocking density interaction affected shrimp survival, but shrimp growth was affected only by stocking density. The mean weight of shrimp in the treatments with the lowest stocking density was higher than that with the highest stocking density, independently from the water exchange rate. In the salinity stress tests, shrimp survival was affected by the interaction between the salinity stress tests and treatments. Generally, shrimp showed a greater tolerance when subjected to low salinity (27 to 2‰). In the culture with biofloc at the nursery level, it was confirmed that L. vannamei shrimp improve their tolerance to a sudden low salinity endpoint; a directly proportional relationship of survival with ontogenetic development in low and high salinity was determined.

Response of Different Cultivars of Wheat Plants (Triticum aestivum L.) to Inoculation by Azotobacter sp. under Salinity Stress Conditions

Salinity is one of the key restraints to agricultural productivity worldwide and is expected to increase further. Therefore, cope with this problem we should be develop strategies to enhance salinity tolerance in different crops. One of these modern strategies is to use plant growth promoting rhizobacteria (PGPR) which can help plants to withstand under harsh environmental conditions. The present study was evaluated six isolates of Azotobacter sp. (Az1-Az6) which tested in vitro for growth, PGPR traits such as indole-3 acetic acid (IAA) production and nitrogen fixation, germination indicators for different wheat cultivars i.e. Misr 1, Gemmiza 12 and Sakha 95 under different levels of NaCl. Also, the efficacy of inoculation with two superior isolates in different wheat cultivars in a Gnotobiotic Sand System and greenhouse experiment for improving growth dynamics, physiological attributes, nutrient uptake and antioxidant enzymes under different levels salinity of sandy soil (0, 4, 8 and 12 dS m-1).
 Out of 6 isolates, two isolates (Az2 and Az6) could show salinity tolerance and exhibited PGPR traits as well as improvement germination tests. Both the bacteria could promote growth in 3 cultivars of wheat tested in terms of increase in fresh weight, dry weight, root and shoot length as well as root colonization compared to uninoculated control under Gnotobiotic Sand System experiment. 
 Under greenhouse experiment conditions, inoculation treatment with Az6 showed a significant increase of vegetative growth, physiological and biochemical parameters of different wheat cultivars under different salinity stress treatments. Also, Az6 treatment recorded the highest N% from wheat plants attained 2.64, 2.51 and 2.43% at 4 dS m-1 for Misr1, Sakha 95 and Gemmiza 12 cultivars, respectively but the highest K+, K+/Na+% and the lowest Na+% were obtained from plants that grown in soil salinized with 8 and 12 dS m-1. The same trend was observed for antioxidant enzymes. Thus, inoculation with Azotobacter isolates Az2 and Az6 could be efficiently used to partially or completely eliminate the effects of salt stress on growth of different wheat cultivars.

Enhanced lipid productivity of Chlamydomonas reinhardtii with combination of NaCl and CaCl2 stresses.

Salinity (NaCl) stress treatment is a strategy to induce lipid accumulation in microalgae. This study aimed to investigate the effect of a combination of two salts (NaCl/CaCl2) on lipid productivity of Chlamydomonas reinhardtii. C. reinhardtii was cultured in a two-stage culture comprising 9-day active growth in C medium followed by 3-day salt stress in C medium with various concentrations of NaCl (50‒200mM)/CaCl2 (100mM). In salt stress stage, NaCl (200mM), CaCl2 (100mM), and the NaCl/CaCl2 mixture inhibited growth but increased the lipid content in C. reinhardtii in comparison with NaCl (0, 50, and 100mM) conditions. Combinatorial treatment with 100mM NaCl/100mM CaCl2 resulted in the highest lipid content (73.4%) and lipid productivity (10.9mg/L/days), being 3.5- and 2.1-fold, respectively, in salt-free control conditions, and 1.8- and 1.5-folds, respectively, with 200mM NaCl. Furthermore, 100mM NaCl/100mM CaCl2 treatment markedly upregulated glycerol-3-phosphate dehydrogenase (GPDH), lysophosphatidic acid acyltransferase (LPAAT), and diacylglycerol acyltransferase (DAGAT), which are involved in lipid accumulation in C. reinhardtii. The upregulation of these genes with 100mM NaCl/100mM CaCl2 resulted in the highest lipid content in C. reinhardtii. Therefore, stress treatment using two salts, 100mM NaCl/100mM CaCl2, is a potentially promising strategy to enhance lipid productivity in microalgae.

ANALISIS KETAHANAN 10 GENOTIPE KACANG HIJAU (Vigna radiata L.) ASAL PROVINSI RIAU TERHADAP CEKAMAN SALINITAS

Mung bean (Vigna radiata L.) is one of the important because it has a high nutritional value, so many Indonesia consumption its crop. The production of mung beans is still relatively low due to the reduced availability of land, so it is necessary to use marginal land such as saline land. Therefore, this study aims to analyze the resistance of 10 mung bean genotypes (Vignaradiata L.) from Riau Province on salinity stress. Mung beans seeds of 10 genotypes were grown in polybags with treatments including Control and Treatment saline 7 g/L NaCl of Dolphin salt with 7 replications for 66 HST. The interval of watering saline treatment was five days on time the plant begins to bloom. All genotypes showed different morphological responses to salinity stress. Characteristic of 10 genotypes of mung beans from Riau Province based on salinity stress treatment was obtained a significantly different result on the character of productive branch number, plant height, flowering period, number of pods, pod length, seed number, 100 seed weight, and root length. The tolerant genotype of the salinity of Rohul origin 1 (RU1) was superior to plant height, flowering period, number of pods, number of seeds, and root volume. Genotypes from Pelalawan (P) for branch character, Inhu (IU) genotype was for long pods and 100 seeds, and Rohul 2 (RU2) genotype was for long root characters.

Interaction between hydrogen peroxide and sodium nitroprusside following chemical priming of Ocimum basilicum L. against salt stress.

Sodium nitroprusside (SNP) and hydrogen peroxide (H2 O2 ), as priming agents, have the well-recorded property to increase plant tolerance against a range of different abiotic stresses such as salinity. In this regard, the present study was conducted to evaluate the effect of different levels of SNP (100 and 200 µM) and H2 O2 (2.5 and 5 mM) as well as their combinations under salt stress (0 and 50 mM NaCl) on key physiological and biochemical attributes of the economically important aromatic plant basil (Ocimum basilicum L.) grown under hydroponic culture. Results revealed that morphological parameters such as plant height, root length, leaf fresh and dry weights (FW and DW) were significantly decreased by salinity stress, while SNP and H2 O2 treatments, alone or combined, increased FW and DW thus enhancing plant tolerance to salt stress. Furthermore, 200 µM SNP + 2.5 mM H2 O2 appeared to be the most effective treatment by causing significant increase in chlorophyll a and b, anthocyanin content and guaiacol peroxidase and ascorbate peroxidase enzymes activities under saline condition. In addition, analytical measurements showed that essential oil profile (concentration of main components) under salt stress was mostly affected by SNP and H2 O2 treatments. The highest increase was observed for methyl chavicol (43.09-69.91%), linalool (4.8-17.9%), cadinol (1.5-3.2%) and epi-α-cadinol (0.18-10.75%) compounds. In conclusion, current findings demonstrated a positive crosstalk between SNP and H2 O2 toward improved basil plant tolerance to salt stress, linked with regulation of essential oil composition.

Novel Miscanthus genotypes selected for different drought tolerance phenotypes show enhanced tolerance across combinations of salinity and drought treatments.

Background and AimsWater deficit and salinity stresses are often experienced by plants concurrently; however, knowledge is limited about the effects of combined salinity and water deficit stress in plants, and especially in C4 bioenergy crops. Here we aim to understand how diverse drought tolerance traits may deliver tolerance to combinations of drought and salinity in C4 crops, and identify key traits that influence the productivity and biomass composition of novel Miscanthus genotypes under such conditions.MethodsNovel genotypes used included M. sinensis and M. floridulus species, pre-screened for different drought responses, plus the commercial accession Miscanthus × giganteus (M×g.). Plants were grown under control treatments, single stress or combinations of water deficit and moderate salinity stress. Morphophysiological responses, including growth, yield, gas exchange and leaf water relations and contents of proline, soluble sugars, ash and lignin were tested for significant genotypic and treatment effects.Key ResultsThe results indicated that plants subjected to combined stresses showed more severe responses compared with single stresses. All novel drought-tolerant genotypes and M×g. were tolerant to moderate salinity stress. Biomass production in M. sinensis genotypes was more resilient to co-occurring stresses than that in M×g. and M. floridulus, which, despite the yield penalty produced more biomass overall. A stay-green M. sinensis genotype adopted a conservative growth strategy with few significant treatment effects. Proline biosynthesis was species-specific and was triggered by salinity and co-occurring stress treatments, mainly in M. floridulus. The ash content was compartmentalized differently in leaves and stems in the novel genotypes, indicating different mechanisms of ion accumulation.ConclusionsThis study highlights the potential to select novel drought-tolerant Miscanthus genotypes that are resilient to combinations of stress and is expected to contribute to a deeper fundamental knowledge of different mechanistic responses identified for further exploitation in developing resilient Miscanthus crops.

Ecophysiological Responses of Carpinus turczaninowii L. to Various Salinity Treatments

Carpinus turczaninowii L., commonly known as hornbeam, has significant economic and ornamental importance and is largely distributed in the northern hemisphere, including parts of China and Korea, with high adaptation to harsh conditions in very unfertile soils. In this study, the ecophysiological responses of C. turczaninowii seedlings to various salinity stress treatments (NaCl: 0, 17, 34, 51, 68, and 85 mM) were studied for 42 days by determining stress-induced changes in growth parameters and biochemical markers. Salinity stress affected the values of all the examined parameters, both morphological and physiological, and caused the inhibition of plant growth, the degradation of photosynthetic capacity and stomatal behavior, a decrease in the photosynthetic pigments contents and relative water content, an increase in the Malondialdehyde (MDA) content and relative electrolytic conductivity, and the accumulation of Na+ and Cl− content. The presence of relatively high concentrations of organic osmolytes, the activation of antioxidant enzymes, and the ionic transport capacity from the root to shoots may represent a constitutive mechanism of defence against stress in C. turczaninowii seedlings. Our results suggest that C. turczaninowii can tolerate salinity at low and moderate concentrations (17–51 mM) under nursery conditions and can be widely used in roadsides, gardens, parks, and other urban areas.

Biochemical, physiological and phenological genetic analysis in common bean (Phaseolus vulgaris L.) under salt stress

Salinity is one of the most important abiotic stresses affecting agricultural productivity. The present study investigated combining abilities, heterosis and heritability estimates of common bean under salinity conditions for biochemical, physiological and phenological traits using a half-diallel cross. The salinity stress treatments were applied during all the vegetative cycle. Genetic analysis revealed highly significant genotypic variations between the four parents and their six hybrids, indicating a genetic variability and possibility of genetic improvement using such genetic material of common bean for salinity tolerance. Both general (GCA) and specific (SCA) combining abilities were highly significant for all the studied traits under all conditions, revealing the important role of both additive and dominant gene effects in the inheritance of these traits. The ratio GCA/SCA indicated preponderance of the additive effects for all the studied characters. The parental genotypes Améliore Roza and Coco nain proved to be the best combiners for salinity tolerance; on the other hand the crosses namely Amina × Améliore Roza; MGT × Améliore Roza and Coco nain × Amina recorded significant heterosis percentage relative to mid-parent (MP) and better parent (BP) for almost all the traits, the same crosses recorded significantly positive SCA effects. Diallel analysis revealed high heritability in broad-sense for salinity tolerance, while moderate to high narrow-sense heritability suggests a large breeding population and possible selection for salt tolerance. The results of this study confirmed that salinity tolerance is expressed by a different set of genes that could be pyramided using different genotypes to enhance salinity tolerance.