Exploring the Use of Cold Atmospheric Plasma for Sound and Vibration Generation.

In this study, we investigate the potential of cold atmospheric plasma (CAP) as a non-contact excitation device, comparing its performance with an ultrasound transmitter. Utilizing a scanning Laser Doppler Vibrometer (LDV), we visualize the acoustic wavefront generated by a CAP probe and an ultrasound sensor within a designated 50 mm × 50 mm area in front of each probe. Our focus lies in assessing the applicability of a CAP probe for exciting a small polymethyl methacrylate (PMMA) sample. By adjusting the dimensions of the sample to resonate at the excitation frequency of the probe, we can achieve high vibrational velocities, enabling further mechanical analysis. In contrast with traditional vibration excitation techniques such as electrodynamical shakers and hammer impact excitation, a plasma probe can offer distinct advantages without altering the structure's dynamics since it is contactless. Furthermore, in comparison with laser excitation, plasma excitation provides a higher power level. Additionally, while pressurized air systems are applicable for limited low frequencies, plasma probes can perform at higher frequencies. Our findings in this study suggest that CAP is comparable with acoustic excitation, indicating its potential as an effective mechanical excitation method.

Change in antioxidant enzymes activity and some morpho-physiological characteristics of strawberry under long-term salt stress.

The effects of long term salinity on some morpho-physiological characteristics were studied in strawberry Kurdistan and Queen elisa cultivars. Vegetative and biochemical traits were measured in strawberry cultivars subjected to three levels of salinity including 0, 40 and 80 mM at 20, 40 and 60th days after NaCl addition. Results showed that in both cultivars the dry weight of plant organs decreased in response to NaCl, except of crown weight in cv. Kurdistan. Root to shoot ratio increased due to a greater reduction in above ground biomass under salinity. Strawberry cultivars tended to decrease their stomatal conductance, RWC, proline, soluble carbohydrates and proteins during the different evaluation periods. Compared to the 20th day, peroxidase activity decreased at 80 mM during 40 and 60 days in cv. Queen elisa. On the contrary, ascorbate peroxidase activity elevated until the 40th day and decreased afterwards, in addition application of 40 and 80 mM NaCl increased the ascorbate peroxidase activity of both studied cultivars. Catalase activity increased from 20th until 60th days in cv. Queen elisa, while showed increase in cv. Kurdistan until day 40 and then decreased again at day 60. Application of 40 and 80 mM NaCl resulted in an increase in peroxidase, ascorbate peroxidase and catalase activities of both cultivars. The Queen elisa cv. showed lower tolerance index (45.88%) compared with cv. Kurdistan (67.97%). Finally, higher salinity resistance of cv. Kurdistan is probably associated with its ability to maintain higher RWC and higher activity of antioxidant enzymes.

Grape response to salinity stress and role of iron nanoparticle and potassium silicate to mitigate salt induced damage under in vitro conditions.

Grape softwood cuttings of Khoshnaw cultivar were cultured using tissue-culture methods to study the effect of iron nanoparticles and potassium silicate under salinity conditions during the 2015-2016 growing season. The treatments consisted of salinity stress (0, 50, and 100 mM NaCl), nanoparticles of iron (0, 0.08, and 0.8 ppm), and potassium silicate (0, 1, 2 mM). The results also showed that the application of iron nanoparticles and potassium silicate significantly increased the total protein content and reduced proline, enzymatic antioxidant activity and hydrogen peroxide. Salinity stress reduced membrane stability index while increased malondialdehyde content. Increase of membrane stability index and reduction of malondialdehyde content were obtained for 2 mM potassium silicate and 0.8 ppm iron nanoparticle. Iron and potassium silicate were shown to lower the sodium content and increase the potassium content under salinity-stress conditions. The highest ratio of sodium to potassium was observed in plants under salinity conditions (100 mM) treated with neither iron nanoparticles nor potassium silicate; conversely, the lowest ratio was achieved in plants treated with both 0.8 ppm iron nanoparticles with 1 mM and 2 mM potassium silicate under non-stress conditions. These results indicate that the application of micronutrients in stressful conditions is a suitable method to compensate for the negative effects of salinity stress. Tissue culture in this study was shown to be an economically efficient and applicable technique for producing grape softwood cuttings to be used in experiments.

Mitigation by sodium nitroprusside of the effects of salinity on the morpho-physiological and biochemical characteristics of Rubus idaeus under in vitro conditions.

This study examined the changes brought about by sodium nitroprusside (SNP) in the effects of salinity on the morpho-physiological and biochemical characteristics of Rubus idaeus var. Danehdrosht. Raspberry shoot-tip explants were cultured on Murashige and Skoog medium supplemented with a growth regulator that combined benzyleadenine (1 mg/l), indol-3-butyric acetic acid (0.2 mg/l), SNP (0, 50 and 100 µM) and sodium chloride (0, 50 and 100 mM). The results showed that salinity stress significantly decreased morpho-physiological and biochemical characteristics such as RWC, MSI and total protein content in regenerated explants and significantly increased the total soluble sugar, proline contents, peroxidase and superoxide dismutase activity in compared to the control. However, SNP treatments mitigated the impacts of salinity on morphological and physiological characteristics in raspberry shoot-tip explants by increasing the accumulation of proline content, total protein content and total soluble sugar in line with increasing antioxidant enzyme activity under salinity conditions.

Light-emitting diode combined with humic acid improve the nutritional quality and enzyme activities of nitrate assimilation in rocket (Eruca sativa (Mill.) Thell.).

Belonging to the Brassicaceae family, rocket (Eruca sativa (Mill.) Thell.), is considered to be a nitrate-accumulating leafy vegetable. Many studies show that light-emitting diode (LED) lights can be a suitable tool to decrease anti-nutritional compounds (e.g., nitrate (and enhance antioxidant and nutritional quality for phytochemical-rich vegetable production. The positive influence of humic acid on health-promoting compounds in different crops is also well documented. This study aimed to investigate the effects of supplemental LED lights of various spectral compositions, namely 25-100% red, 25-100% blue, and 100% white, as well as their combination with humic acid on the physiological and biochemical responses of rocket plants. ANOVA results showed that almost all the measured traits were significantly affected by LED and humic acid treatments. Generally, LED combined with humic acid improved the accumulation of nutritional compounds (e.g., polyphenols, flavonoid, ascorbic acid, carbohydrate, tannin), increased the activity of key enzymes involved in nitrogen metabolism (e.g., nitrate reductase, nitrite reductase, and glutamine synthetase), and lowered nitrate and ammonium concentrations. The results of principal component analysis indicated that the combination of LED lights, regardless of the spectra, with humic acid was the most effective treatment to enhance the nutritional value and activity of enzymes involved in nitrate assimilation. In sum, these findings may be used as a reference in rocket production for supplemental LED light optimization and its combination with humic acid.

Stomatal and non-stomatal limitations are responsible in down-regulation of photosynthesis in melon plants grown under the saline condition: Application of carbon isotope discrimination as a reliable proxy.

Salinity is one of the most severe environmental stresses limiting agricultural crop production worldwide. Photosynthesis is one of the main biochemical processes getting affected by such stress conditions. Here we investigated the stomatal and non-stomatal factors during photosynthesis in two Iranian melon genotypes "Ghobadlu" and "Suski-e-Sabz", as well as the "Galia" F1 cultivar, with an insight into better understanding the physiological mechanisms involved in the response of melon plants to increasing salinity. After plants were established in the greenhouse, they were supplied with nutrient solutions containing three salinity levels (0, 50, or 100 mM NaCl) for 15 and 30 days. With increasing salinity, almost all of the measured traits (e.g. stomatal conductance, transpiration rate, internal to ambient CO2 concentration ratio (Ci/Ca), Rubisco and nitrate reductase activity, carbon isotope discrimination (Δ13C), chlorophyll content, relative water content (RWC), etc.) significantly decreased after 15 and 30 days of treatments. In contrast, the overall mean of water use efficiency (intrinsic and instantaneous WUE), leaf abscisic acid (ABA) and flavonol contents, as well as osmotic potential (ΨS), all increased remarkably with increasing stress, across all genotypes. In addition, notable correlations were found between Δ13C and leaf gas exchange parameters as well as most of the measured traits (e.g. leaf area, biomass, RWC, ΨS, etc.), encouraging the possibility of using Δ13C as an important proxy for indirect selection of melon genotypes with higher photosynthetic capacity and higher salinity tolerance. The overall results suggest that both stomatal and non-stomatal limitations play an important role in reduced photosynthesis rate in melon genotypes studied under NaCl stress. This conclusion is supported by the concurrently increased resistance to CO2 diffusion, and lower Rubisco activity under NaCl treatments at the two sampling dates, and this was revealed by the appearance of lower Ci/Ca ratios and lower Δ13C in the leaves of salt-treated plants.

Genotypic differences in physiological and biochemical responses to salinity stress in melon (Cucumis melo L.) plants: Prospects for selection of salt tolerant landraces.

Melon (Cucumis melo L.) is one of the most important horticultural crops in Iran often cultivated in arid and semiarid regions of the country with salinity problems. The objective of this work was to better understand the mechanisms of physiological and biochemical responses to salinity stress of five Iranian melon landraces "Samsuri", "Kashan", "Khatouni", "Suski-e-Sabz", and "Ghobadlu" from different geographical origins, and "Galia" F1 cultivar. Plants were grown under greenhouse conditions and irrigated with half-strength Hoagland solution containing 0, 30, 60, or 90 mM NaCl for 60 days. Increase in the external salt concentration was accompanied by an obvious depression in leaf relative water content, membrane stability index, chlorophyll a and b and carotenoid contents, stomata and trichome density, leaf area, specific leaf area, biomass, leaf and stem K+ concentrations as well as leaf and stem K+/Na+ ratios in all landraces studied. In contrast, hydrogen peroxide, lipid peroxidation, proline and soluble carbohydrate contents, activity of antioxidant enzymes as well as leaf and stem Na+ and Cl- concentrations, all increased significantly with increasing stress over all plants. Moreover, carbon isotope discrimination (Δ13C), determined on leaf organic matter, was found to be associated with evaluated traits. For example, a highly positive correlation between Δ13C and both biomass production and salt tolerance index was notable when all saline treatments were averaged (r = 0.998 and 0.998, respectively). Also, scatter plot and clustering analysis showed that "Suski-e-Sabz" and "Ghobadlu" were placed close to "Galia" F1, a salt tolerant cultivar, indicating that their similar behavior under salinity. Overall, the present results indicated a significant genetic variability for most of the traits studied, suggesting that "Suski-e-Sabz" and "Ghobadlu" could be introduced as the superior landraces and the most promising tolerant parents in the future melon breeding programs due to their suitable performance, in terms of responses to salt stress as compared with other landraces. Also, Δ13C can be used as a powerful criterion in melon breeding programs aimed at selection of salt tolerant landraces.