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Purpose Olive oil mill wastewater (OMW) is a major waste stream from the olive oil industry. It is highly polluted due to phenolic compounds. The present study focused on the physicochemical properties of OMW as well as the quantitative and qualitative effects of two methods of extraction (maceration and liquid-liquid extraction) of phenolic compounds. Methods Liquid-liquid extraction and maceration methods were used for the extraction of phenolics. Spectrophotometry and High-Performance Liquid Chromatography-Electrospray Ionization–Mass Spectrometry (HPLC-ESI-MS) were adopted to quantify the phytochemical contents and the phenolic compounds. The antioxidant potentials were evaluated using three assays DPPH, ABTS + and FRAP radical scavenging activities. Results The findings showed that the OMW was an acidic effluent (pH = 5.05) loaded with mineral and organic matter expressed in terms of a high value of electrical conductivity (EC = 13.51 mS/cm). Indeed, the OMW showed high dry matter, chemical oxygen demand (COD) and biological oxygen demand (BOD5). The extract obtained by the maceration method showed the highest yields of total polyphenol, flavonoid, and tannins contents than the liquid-liquid extraction method. The LC-MS results revealed the presence of 16 phenolic compounds in the extract obtained by the maceration method and only 12 phenolic compounds were found in the extract obtained by the second method. Quinic acid was identified as the most abundant compound. Moreover, the macerated extracts possessed the highest antioxidant potential as evidenced by their strong DPPH, ABTS and FRAP radical scavenging activities compared to the liquid-liquid extracts. Conclusions The maceration methods seemed to be the most effective method for extracting phenolic compounds from OMW than liquid-liquid extraction. The OMW constitute a rich source of natural phenolic compounds that could be used as a potential source of natural antioxidants.

Chromium (Cr) is a serious environmental contaminant that drastically limited the crop yields. Nitric oxide (NO) and spermine (Spm) portrayal significance in improving the plant tolerance against abiotic stresses. Therefore, we investigate the protective efficacy of seed priming with NO (100 μM) and/or Spm (0.01 mM) in minimising the Cr-induced toxic effects in rice (Oryza sativa L.) plants. Our outcomes revealed that Cr alone treatments (100 μM) notably reduced the seed germination rate, plant growth, photosynthetic apparatus, nutrients uptake and antioxidant defence system, but extra generation of reactive oxygen species (ROS). Interestingly, the combine applications of NO and Spm significantly reversed the Cr-induced toxic effects by reducing the Cr-accumulation, maintaining the nutrient balance, improving the germination indices, levels of photosynthetic pigments (chl a by 24.6%, chl b by 36.3%, chl (a + b) by 57.2% and carotenoids by 79.4%), PSII, photosynthesis gas exchange parameters and total soluble sugar (74.9%) by improving antioxidative enzyme activities. As a result, NO + Spm lowered the accumulation of oxidative markers (H2O2 by 93.9/70.4%, O2˙− by 86.3/69.9% and MDA by 97.2/73.7% in leaves/roots), electrolyte leakage (71.4% in leaves) and improved the plant growth traits. Based on these findings, it can be concluded that NO triggers Spm to minimise the Cr-accumulation and its adverse effects on rice plants. Additionally, combined treatments (NO + Spm) were more effective in minimising the Cr-induced toxic effects in comparison to NO and Spm alone treatments. Thus, co-exposure of NO and Spm may be utilised to boost rice tolerance under Cr stress conditions.

Trace metal pollution is increasing worldwide due to human activities. In this study, we investigated the physiological and biochemical effects of heavy metals on henna plants (Lawsonia inermis L.) grown in oases situated at various distances from an industrial complex in arid southern Tunisia. Our results showed that leaves had higher mean Zn and Cu concentrations than roots, while the reverse was true for Pb and Cd. Such metal immobilization in root cells is related to an exclusion strategy. The biological concentration factor (BCF) of Cu was > 1 at all studied sites, indicating the potential of henna plants to accumulate Cu from the soil. Heavy metals affected various physiological parameters of henna, including water status, macronutrient content, and photosynthetic activity, and increased the rate of hydrogen peroxide (H2O2) production and lipid peroxidation in leaves and roots, indicating oxidative stress. Deleterious heavy metal effects induced biochemical mechanisms in henna plants by accumulating proline and soluble sugars and activated the antioxidant system by enhancing the activities of superoxide dismutase, catalase, and glutathione peroxidase. The magnitude of accumulation and activation was proportional to the concentration of heavy metals in the plant tissues. The stimulation of enzymatic and non-enzymatic antioxidant systems reflects the ability of henna plants to survive in highly polluted environments.

The aim of this research was to investigate the variation regarding the chemical composition and biological activities of needles essential oils (EOs) of P. halepensis. Chemical profiles demonstrated a significant (P

The design of the current study was to determine the functional properties of P. maritimum seeds by evaluating their mineral content, fatty acid composition, and biactive compounds. Results showed that seeds contained remarkable amounts of Na, K, Ca, Mg, Cu, Zn, and Fe. The oil yield was found to be 4.58% and contained higher unsaturated fatty acids predominated by linoleic and oleic acids. The colorimetric investigation revealed high total polyphenol (33.56 mg gallic acid equivalent/g), flavonoid (46.3 mg quercetin equivalent/g), and condensed tannin (22.3 mg catechin equivalent/g) contents. Furthermore, the LC-ESI/MS analysis revealed the presence of 13 phenolics mostly predominated by (+) catechin, quercetin-3-O-galactoside, gallic acid, and quinic acid. The seeds possessed strong antioxidant potential evidenced by ABTS and DPPH radical scavenging activities, total antioxidant capacity, and reducing power. The present findings suggest that P. maritimum seeds may be used as a potential source of biologically active natural products.

Cross-tolerance to abiotic stresses is a typical phenomenon in plants which occurs when exposure to one form of stress confers tolerance to a variety of stresses. Our study aims at investigating whether salinity priming could induce, after a recovery period (2 months), drought tolerance in olive cv. Chétoui. Here, our results revealed that this method of cross-adaptation had further enhanced the olive’s subsequent response to drought. In fact, relative to the non-pretreated plants, the salt-pretreated ones displayed an enhancement in terms of shoot biomass accumulation, photosynthetic performance, water-use efficiency, and hydration status. Furthermore, the attenuation of oxidative stress and the maintenance of structural lipid contents, as well as their fatty acid composition in salt-pretreated plants, also supported the beneficial effect of this method. From our results, it seems that salt priming substantially modulated the physiological and biochemical responses of olive plants to subsequent drought. Accordingly, metabolite adjustments (soluble sugars and proline), the enzymatic antioxidant system (superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (GP) activities) as well as the nonenzymatic one (phenols), and the increase in leaf density together with the raise of structural lipids content, to a lesser extent, seemed to perform a major role in the development of this improved tolerance to drought. The ameliorative response found in salt-primed olive plants, when subsequently exposed to drought, indicates an efficient cross-tolerance reaction. This could be particularly important in the Mediterranean area, where olive orchards are mainly cultivated under dry-land farming management.

Six varieties of Tunisian durum wheat, barley and oat cultivars namely Maali, Karim, Rihane, Manel, Meliane and Ghzella were analyzed for their physicochemical properties, antioxidant activities and phenolic acids profile. Results showed that there are significant (p < 0.05) differences in moisture (11.8-12.8%), proteins (10.98-12.09%), neutral detergent fibre (NDF) (47.67-67.39%), ash (2.4-3.93%), fat (2.6- 6.75%), and carbohydrates (64.78-70.95%) contents between all studied varieties. Cereal grains were also a good source of potassium, sodium, calcium, zinc and iron. The results revealed that oat Meliane (5.9%) and barley Rihane (5.4%) varieties are good sources of dietary fiber β-glucan compared to the other varieties. Rihane, Meliane and Maali varieties had the highest total phenolic, total flavonoids and total condensed tannin contents. Antioxidant activity of whole grain extracts was performed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test and revealed that barley Rihane had the best radical scavenging activity compared to oat and durum wheat varieties. The RP-HPLC analysis revealed that Tunisian barley, oat and durum wheat varieties are a good source of phenolic components and natural antioxidants.

The genus Brachypodium is generally considered taxonomically difficult because of the high levels of phenotypic variation and frequent hybridization between its species. In this study, the patterns of genetic variation of 180 lines of B. distachyon (B. distachyon, B Stacei and B. hybridum) collected from diverse regions in Tunisia were investigated using 18 morpho-phenological traits and 15 SSR markers. Our results showed that the polyploid species B. hybridum is the most abundant in Tunisia. Moreover, considerable morphological variation was revealed for the majority of analyzed traits. The variation was found to be more pronounced within B. hybridum, than its two progenitors. Importantly, we found that B. distachyon was characterized by early maturity, B. stacei differed from the two other species by plant height, whereas the allotetraploid species was mainly characterized by traits related to biomass production. At the molecular level, the fifteen SSR marker were found to be very informative in terms of polymorphism and allelic diversity (P = 100%, Na = 20.3 and Ne = 10.8). B. hybridum was found to be much variable than B. stacei and B. distachyon (He = 0.86, He = 0.78 and He = 0.58, respectively). FCA and Bayesian clustering showed a clear separation between the three species, which suggests the high usefulness of SSR markers used in our study in the delimitation between B. distachyon, B. stacei and B. hybridum.

Highlights • Salt stress effects agronomic traits and uptake of minerals. • Salt stress also enhanced the oxidative stress biomarkers like hydrogen peroxide (H2O2). • Supplementation of Mycorrhiza enhances the agronomical traits and alleviates slat stress. • Silicon application also mitigates the salt stress through modulating antioxidant enzymes. • The combination of Mycorrhiza and Silicon were more effective than their individual effect., Citrullus lanatus L. is critical vegetable for salinity stress. Arbuscular mycorrhizal fungi (AMF) and silicon treatments are known to help as bio-ameliorator of saline soils that can improve salinity tolerance in plants. But their combined effect has never been examined on watermelon therefore, present study investigated the effect of inoculation with the Arbuscular mycorrhizal fungi (AMF) along with silicon on the growth and yield parameters, antioxidant enzyme activities, pigment and mineral content of Citrullus lanatus L. plants grown during salt stress conditions. Outcomes from the study point out that salt stressed watermelon plants showed the best morphological and biochemical values when inoculated with Silicon (4 mM) + Glomus mosseae + Gigaspora gigantean. In addition, the plants inoculated by similar treatment demonstrated less osmotic activity, electrolyte leakage, as well as peroxide content. Treatments comprising Silicon (4 mM) with either Glomus mosseae and Gigaspora gigantean also performed significantly similar for most of the traits studied in the present investigation and better than the treatment only with either one of Glomus mosseae and Gigaspora gigantean. Antioxidant efficiency of melon was certainly appreciably enhanced after incubation with AMF and Si combination in salinity stress. Overall, the application of mycorrhiza and silicon can be considered to overcome the salinity stress in watermelon.

In the present study, ameliorative capabilities of wuxal amino (bio stimulant) under salt stress has been investigated through adaptive mechanisms and antioxidant potential in tomato plants. In the experiment, two different concentrations (2 cm L-1 and 3 cm L-1) of wuxal amino through foliar application and soil irrigation were applied to the salt (150 mM) treated tomato plants and then morphological traits, photosynthetic pigments, osmolytes, secondary metabolites, oxidative stress and antioxidant enzymes activity were assessed at 60 days after planting. The results revealed that salt stress decreased the growth parameters, photosynthetic pigments, soluble sugars and soluble protein whereas, content of proline, ascorbic acid, total phenols, malondialdehyde, hydrogen peroxide and the activity of antioxidant enzymes activity increased under salt stress. Moreover, Wuxal amino application through foliar or soil to salt stressed plants improved morphological traits, photosynthetic pigments, osmolytes, total phenol and antioxidant enzymes activity. Interestingly, the deleterious impact of salinity on tomato plants were significantly reduced and it can be evident from reduced MDA and H2O2 levels. These responses varied with the mode (foliar or soil) of application of Wuxal amino under different concentrations (2 cm L-1 and 3 cm L-1). It was concluded that application of Wuxal amino (2 cm L-1, foliar) and (3 cm L-1; soil) proved best and could be commercially used as eco-friendly tool for the protection of tomato plants grown under salinity stress.

Despite the fact that damask rose (Rosa damascena Mill. var. trigintipetala Dieck) is an economically important aromatic plant, its growth and development has been severely suppressed by salt stress. Reports show that moringa leaf extract (MLE) or salicylic acid (SA) are involved in salt-stress tolerance. Nevertheless, scarce information is available about MLE or SA impacts on aromatic plants, especially damask rose under salinity. This investigation was, therefore, conducted to investigate the effects of MLE and (or) SA on salt-stress mitigation in damask rose. Rose plants were treated with 200 mmol·L−1 sodium chloride, and foliar applied with MLE at 1:30 (v:v) and (or) 0.2 mmol·L−1 SA. Foliar spraying with MLE and (or) SA enhanced the growth attributes, chlorophyll content, relative water content, proline content, and membrane stability index under salinity. Less accumulation of malondialdehyde and H2O2 was also observed when MLE and (or) SA were applied. Furthermore, MLE and (or) SA applications considerably increased the radical scavenging activity, total phenols, and antioxidant enzyme activity (catalase and superoxide dismutase) under stress. The mitigative effect of MLE or SA was more pronounced when they were applied in combination. Collectively, MLE and (or) SA had efficient antioxidant defense system that scavenged reactive oxygen species, and thus afforded considerable protection against salt-induced oxidative damage.

Crude oil contamination is a serious environmental threat to soil and plants growing in it. Biochar has the potential of biostimulation for remediation of crude oil-contaminated soil. Therefore, the current research was designed to analyze the bio-stimulatory impact of biochar for remediating the crude oil contaminated soil (10%, and 15%), and growth of maize under glasshouse conditions. Biochar was produced by pyrolysis of Australian pines at 350 °C. Soil incubations were done for 20 days. The results of soil analysis showed that the crude oil degradation efficiency of biochar was 34%. The soil enzymatic activities had shown 38.5% increase in fluorescein diacetate (FDA) hydrolysis and 55.6% increase in dehydrogenase activity in soil incubated with biochar in comparison to control. The soil microbial diversity was improved to 41% in biochar treated soil with respect to untreated one, while microbial respiration rate had shown a 33.67% increase in soil incubated with biochar with respect to control under oil stress. Gas Chromatography Mass spectrometry (GC-MS) analysis had shown the high content of low molecular weight hydrocarbons (C9-C13) in the soil incubated with biochar in comparison to untreated soil. Biochar showed a significant increase in fresh and dry biomass (25%, 14.61%), leaf area (10%), total chlorophyll (11%), water potential (21.6%), osmotic potential (21%), and membrane stability index (12.7%). Moreover, biochar treatment showed a higher increase in the contents of proline (29%), total amino acids (18%), soluble sugars (30.4%), and antioxidant enzymes like superoxide dismutase (16.5%), catalase (11%), and peroxidase (12%). Overall, the results of the present study suggest the bio-stimulating potential of biochar for degradation of hydrocarbons in crude oil contaminated soil and their growth-stimulating effects on maize.

The aim of this comparative research was to determine the chemical composition, antioxidant and antibacterial activities of the methanolic extracts and essential oils (EOs) of Artemisia absinthium aerial parts from five different regions (Bizerte, Zaghouan, Kasserine, Gabes and Tozeur). The polyphenol and flavonoid contents significantly varied (P < 0.05) among the studied regions with maximal contents observed in Zaghouan. Based on the High Performance Liquid Chromatography results, quercetin and isorhamnetin were the main compounds and their percentages were region dependent. The methanolic extract of Zaghouan showed the highest scavenging ability of DPPH (IC50 = 31.46 ± 1.42 µg/mL). A. absinthium EOs from of the different regions were found to interestingly inhibit the growth of both Gram-negative and Gram-positive bacteria strains. The antibacterial effect was strongly related to the organoleptic EO quality. The EO of Zaghouan exhibited an important inhibitory effect with an inhibition zone estimated at 31 mm against Escherichia coli strain. The EO composition was obtained by GC-MS analysis showing the presence of thirty-five compounds. Camphor (49.70 ± 2.34 %) and chamazulene (25.41 ± 0.61 %) were the main constituents. These results suggested that the north regions have a high potential for selecting varieties rich on bioactive volatile and phenolic compounds. Resumen. El objetivo de esta investigación fue determinar y comparar la composición química, las actividades antioxidantes y antibacterianas de los extractos metanólicos y de los aceites esenciales (AE) de las partes aéreas de Artemisia absinthium de cinco regiones (Bizerta, Zaghouan, Kasserine, Gabes y Tozeur). Los contenidos de polifenoles y flavonoides variaron significativamente (P < 0,05) entre las regiones estudiadas con contenidos máximos observados en Zaghouan. De acuerdo con los resultados de la cromatografía líquida de alta resolución, la quercetina y la isorhamnetina fueron los compuestos principales y sus porcentajes dependieron de la región. El extracto metanólico de Zaghouan mostró la mayor capacidad secuestrante de DPPH (IC50 = 31.46 ± 1.42 µg mL-1). Se descubrió que los aceites esenciales de A. absinthium de las diferentes regiones inhibían de manera interesante el crecimiento de cepas de bacterias Gram-negativas y Gram-positivas. El efecto antibacteriano estuvo fuertemente relacionado con la calidad organoléptica del AE. El AE de Zaghouan exhibió un importante efecto inhibidor con un halo de inhibición estimado en 31 mm frente a una cepa de Escherichia coli. La composición de AE se obtuvo mediante análisis GC-MS y mostró la presencia de treinta y cinco compuestos. El alcanfor (49.70 ± 2.34 %) y el camazuleno (25.41 ± 0.61 %) fueron los principales constituyentes. Estos resultados sugirieron que las regiones del norte tienen un alto potencial para seleccionar variedades ricas en compuestos bioactivos volátiles y fenólicos.

The response of Damask rose to drought and the underlying mechanisms involved are not known. In this study, vegetative, propagated rose plants were grown under control and water-deficit conditions in a greenhouse at Taif University, south-west of Saudi Arabia. Control plants were irrigated to field capacity (FC), while water-stressed plants were irrigated to either 50% FC (mild stress) or 25% FC (severe stress). After 60 days, leaf, stem and root fresh and dry weights (g plant−1), photosynthetic activity, leaf water potential (Ψw), leaf water content (WC), apoplastic water fraction (AWF), osmotic potential at full turgor (Ψs100) and turgor loss point (Ψs0), cell wall elasticity, osmotic adjustment (OA), and some solutes (K+, Ca2+, Cl−, proline and soluble carbohydrates) were evaluated. Water stress significantly decreased fresh and dry weights of R. damascena and all photosynthetic parameters, apart from leaf temperature, which increased. Severe water stress (25% FC) resulted in more negative Ψs100 and Ψs0 values than the mild water stress and control. The AWF did not significantly change in response to water stress. The leaf bulk modulus of elasticity (e) increased from 2.5 MPa under well-watered conditions to 2.82 and 3.5 MPa under mild and severe water stress, respectively. R. damascena experienced OA in response to water stress, which was due to the active accumulation of soluble carbohydrates and, to a lesser degree, proline under mild stress, along with tissue dehydration (passive OA) under severe stress. Overall, we identified two important mechanisms of drought tolerance in R. damascena—osmotic and elastic adjustment—but they could not offer resistance to water stress beyond 25% FC.

Depending on the geochemical forms, heavy metal (HM) accumulation is one of the most serious environmental problems in the world and poses negative impacts on soil, plants, animals, and humans. Although the use of biochar to remediate contaminated soils is well known, the huge quantities of waste used and its recycling technique to sustain soil in addition to its use conditions are determinant factors for its characteristics and uses. A pot experiment was conducted in a completely randomized block design to evaluate metal forms and their availability under the application of garden waste biochar (GB) pyrolyzed at different temperatures, and a sequential extraction procedure was designed to fractionate Pb, Cd, Zn, and Cu of the contaminated soil. The results show that the TCLP-extractable Pb, Cd, Zn, and Cu were significantly decreased depending on the biochar addition rate, pyrolysis temperature, and tested metal. The acid extractable fraction was significantly decreased by 51.54, 26.42, 16.01, and 74.13% for Pb, Cd, Zn, and Cu, respectively, at the highest application level of GB400 compared to untreated pots. On the other hand, the organic matter bound fraction increased by 76.10, 54.69, 23.72, and 43.87% for the corresponding metals. The Fe/Mn oxide bound fraction was the predominant portion of lead (57.25–62.84%), whereas the acid fraction was major in the case of Cd (58.06–77.05%). The availability of these metals varied according to the application rate, pyrolysis temperature, and examined metals. Therefore, the GB is a nominee as a promising practice to reduce HM risks, especially pyrolyzed at 400 °C by converting the available fraction into unavailable ones.

This research aimed to study the chemical composition of Aloysia citrodora methanolic extract and its biological activities as an antioxidant, and its antibacterial, antifungal and anti-inflammatory activities based on four bioclimatic collection stages. The contents of total phenols, total flavonoids and total tannins were determined. Nine phenolic compounds were identified by LC-DAD–ESI-MS/MS. The major compound was acteoside, a phenylpropanoid which represented about 80% of the methanolic fraction in the various regions. The antioxidant activities of different locations were measured by different analytical assays, such as DPPH, ABTS and iron reducing power. The results showed that phenolic compounds and antioxidant activities varied with climatic and environmental factors. Moreover, there was a significant dependency between regions and biological activities. The use of a principal component analysis showed that there was a close relationship among phenylpropanoids, phenolic compounds and the studied biological activities.

Chromium (Cr) is a serious environmental contaminant that drastically limited the crop yields. Nitric oxide (NO) and spermine (Spm) portrayal significance in improving the plant tolerance against abiotic stresses. Therefore, we investigate the protective efficacy of seed priming with NO (100μM) and/or Spm (0.01mM) in minimising the Cr-induced toxic effects in rice (Oryza sativa L.) plants. Our outcomes revealed that Cr alone treatments (100μM) notably reduced the seed germination rate, plant growth, photosynthetic apparatus, nutrients uptake and antioxidant defence system, but extra generation of reactive oxygen species (ROS). Interestingly, the combine applications of NO and Spm significantly reversed the Cr-induced toxic effects by reducing the Cr-accumulation, maintaining the nutrient balance, improving the germination indices, levels of photosynthetic pigments (chl a by 24.6%, chl b by 36.3%, chl (a+b) by 57.2% and carotenoids by 79.4%), PSII, photosynthesis gas exchange parameters and total soluble sugar (74.9%) by improving antioxidative enzyme activities. As a result, NO+Spm lowered the accumulation of oxidative markers (H2O2 by 93.9/70.4%, O2˙- by 86.3/69.9% and MDA by 97.2/73.7% in leaves/roots), electrolyte leakage (71.4% in leaves) and improved the plant growth traits. Based on these findings, it can be concluded that NO triggers Spm to minimise the Cr-accumulation and its adverse effects on rice plants. Additionally, combined treatments (NO+Spm) were more effective in minimising the Cr-induced toxic effects in comparison to NO and Spm alone treatments. Thus, co-exposure of NO and Spm may be utilised to boost rice tolerance under Cr stress conditions.

This study aimed to rigorously investigate and integrate the underlying hypothesis that an enhancing effect of gibberellic acid (GA(3), 3 µM) with increased growth actually leads to a modification of the physiological role of polyamines during salinity stress (NaCl, 100 mM) in fennel. These analyses concern both reserve tissues (cotyledons) and embryonic axes in growth. Physiological results indicate a restriction of germination, growth, mineral nutrition and damages to membranes of salt-treated seedlings. This was partially attenuated in seedlings treated with an interaction effect of GA(3) and NaCl. Peroxidase and catalase activities showed a reduction or an augmentation according to the treatments and organs. The three main polyamines (PA): putrescine, spermidine and spermine were elevated in the salt-treated seedlings. Meanwhile, GA(3) seed priming was extremely efficient in reducing PA levels in salt-stressed seedlings compared to the control. Response of PA genes to salinity was variable. Up-regulation was noted for SPMS1, ODC1, and ADC1 in hypocotyls and cotyledons (H + C) and down-regulation for SAMDC1 in the radicle. Interaction of salt/GA(3) treatment showed different responses, only ODC1 in (H + C) and ADC1 in both radicle and (H + C) were overexpressed. Concerning other genes, no change in mRNA abundance was observed in both organs compared to the salt-treated seedlings. From these results, it could be inferred that the fennel seedlings were NaCl sensitive. This sensitivity was mitigated when GA3 applied for seed priming and applied in combination with NaCl, which resulted in a reduction of the PA content. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-022-01140-4.

Nitrogen (N) is an indispensable mineral nutrient for plant growth and development. Proper nitrogen (N) management, in terms of quality and availability, can increase plant productivity and reduce soil N losses. This study investigated the impact of N availability (form and dose) on the growth, water relations, and nitrogen status and assimilation of smooth cordgrass (Spartina alterniflora) in the presence of 200 mM NaCl. At the optimal N concentration, ammonium (NH4+) application improved biomass production and total leaf area more than nitrate (NO3–) application—the leaves-free NH4+ contents remained very low and did not reach the plant toxicity threshold, while those of NO3− were low, regardless of N form. Compared to NO3−, the use of NH4+ as the sole N source increased water economy. However, at low N concentration, S. alterniflora was sensitive to NH4+ deficiency. Media containing 0.25 or 0.5 mM N as NH4+ inhibited plant growth, causing general chlorosis and cell death, particularly on the lower leaves. In contrast, the response of S. alterniflora to NO3− dose did not significantly differ, indicating their preference for NH4+. The lower glutamine synthetase activity in NH4+-fed plants also suggests NH4+ tolerance. Our findings question the use of NO3−-based fertilizers for species that prefer NH4+ as an N source in salt-affected soil.

Drought and salinity are the most serious environmental factors affecting crop productivity worldwide; hence, it is important to select and develop both salt- and drought-tolerant crops. The perennial smooth cordgrass Spartina alterniflora Loisel is unusual in that it is highly salt-tolerant and seems to prefer ammonium (NH4 + ) over nitrate (NO3 - ) as an inorganic N source. In this study, we determined whether Spartina's unique preference for NH4 + enhances performance under salt and drought stress. Greenhouse experiments were conducted to compare the interactive effects of N source, salinity, and low water availability on plant performance (growth and antioxidant metabolism). Drought significantly reduced growth and photosynthetic activity in S. alterniflora, more so with NH4 + than NO3 - ; in contrast, NH4 + enhanced growth under high salinity. The increased tolerance of S. alterniflora to salt stress in the presence of NH4 + was linked to a high level of antioxidant enzyme activity, combined with low MDA content, EL, and H2 O2 production. In contrast, drought stress negated the growth advantages for S. alterniflora exposed to salt stress in the presence of NH4 + . The susceptibility of S. alterniflora to drought was partly due to reduced antioxidant enzyme activities, thereby reducing the defense against the oxidative damages induced by osmotic stress. In conclusion, in contrast to salt stress, drought stress negates the beneficial effects of ammonium as an N source in the C4 plant Spartina alterniflora.

Water scarcity is a major concern for sunflower production in the semi-arid and arid regions of the world. Potassium (K) application has been found effective to alleviate the influence of drought stress; however, the impact of drought stress on seed quality of sunflower has not been reported frequently. Therefore, a field experiment was performed to determine the optimum K requirement for mitigating the adverse effects of water stress and improving growth and seed quality of spring-planted sunflower. Sunflower plants were exposed to water stress at different growth stages, i.e., Io = no stress (normal irrigation), I1 = pre-anthesisi stress (irrigation skipped at pre-anthesis stage), I2 = anthesis stress (irrigation skipped at anthesis stage) and I3 = post-anthesis stress (irrigation skipped at post-anthesis stage). Potassium was applied at four different rates, i.e., Ko = 0, K1 = 50, K2 = 100 and K3 = 150 kg ha-1. The results revealed that water stress at pre- and post-anthesis stages significantly reduced plant height, head diameter, number of achenes, oleic acid contents, and phosphorus (P) uptake. However, pre-anthesis stress improved linoleic acid contents. Treatment IoK3 (stress-free with 150 kg ha-1 K) was optimum combination for 1000-achene weight, biological and achene yields, oil contents, protein contents, and N and P uptake. Results indicated that a higher amount of K and irrigation resulted in higher yield, whereas yield and yield components decreased with early-stage water stress. Nevertheless, potassium application lowered the impacts of waters stress compared to no application. Keeping in view these results, it is recommended that sunflower must be supplied 150 kg ha-1 K in arid and semi-arid regions to achieve higher yield and better seed quality.

Mismanagement of crop straw and coal gas residue threatens the atmosphere and the economy. Nevertheless, thermal-pyrolysis is an option for management that turns bio-waste into biochar; its viability and adoption by the public as soil amendments is dependent on the agronomic and environmental values compared between biochar and the raw materials. We undertook a 60-day short-term analysis to assess the impact of various wastes and biochars, as well as inorganic nutrients (N), on carbon dioxide (CO2) fluxes, soil enzyme activities, soil fertility status, and microbial activities. There were eight treatments of soil amendments: without an amendment (CK), Nutrients (N), straw + nutrients (S+N), straw biochar + nutrients (SB+N), coal gas residue + nutrients (C+N), coal gas residue biochar + nutrients (CB+N), straw + straw biochar + nutrients (S+SB+N) and coal gas residue waste + coal gas residue biochar + nutrients (C+ CB +N). The results indicated that soil EC, pH, nitrate N (NO3–- N), SOC, TN and available K were significantly (p

GETTING the highest flower yield with high-quality volatile oil of Rosa damascena Miller var. trigintipetala Dieck through good agricultural practices is one of the main challenges for oil production. Despite the critical role of pruning and P-fertilizer which strongly improve the flower productivity, their impacts on growth, flower yield, volatile oil and some physiological and biochemical processes are still poorly investigated on damask rose. Thus, in this experiment, two pruning levels i.e. 80 and 100cm from ground level and three rates of P-fertilizer (0, 15 and 30kg P2O5 ha-1, respectively) were examined. The tallest plants were observed in response to the combined treatment of pruning level at 100 cm and P-fertilizer at 30kg ha-1. However application of the same P-fertlizer level with pruning at 80 cm resulted in the highest new shoots number/hill, flower yield components, oil content, relative water content, chlorophyll content, stomatal conductance, total soluble sugars, and N, P and K percentages relative to the other treatments. The flower yield was increased by 23.52% when plants pruned at 80cm and fertilized with P at 30kg ha-1 compared to the pruning at 100cm withought P addition. Decreasing pruning level and increasing P-fertilizer enhanced the protein content while reduced the free amino acids content. Conclusevelly, to obtain higher flower yield and volatile oil productivity, pruning damask rose plants at 80cm and P-fetilizet at 30kg ha-1 is recommended.

Mismanagement of crop straw and coal gas residue threatens the atmosphere and the economy. Nevertheless, thermal-pyrolysis is an option for management that turns bio-waste into biochar; its viability and adoption by the public as soil amendments is dependent on the agronomic and environmental values compared between biochar and the raw materials. We undertook a 60-day short-term analysis to assess the impact of various wastes and biochars, as well as inorganic nutrients (N), on carbon dioxide (CO2) fluxes, soil enzyme activities, soil fertility status, and microbial activities. There were eight treatments of soil amendments: without an amendment (CK), Nutrients (N), straw + nutrients (S+N), straw biochar + nutrients (SB+N), coal gas residue + nutrients (C+N), coal gas residue biochar + nutrients (CB+N), straw + straw biochar + nutrients (S+SB+N) and coal gas residue waste + coal gas residue biochar + nutrients (C+ CB +N). The results indicated that soil EC, pH, nitrate N (NO3–- N), SOC, TN and available K were significantly (p