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Biomolecular carbon dots (CDs) have immense potential for various industries due to exceptional bioactivity, biocompatibility, low toxicity, and biodegradability. In the present work xylitol (Xlt), a natural sweetener produced by microbial fermentation of sugarcane bagasse (71.98% conversion) has been used for CDs preparation by microwave‐assisted carbonization in the presence of ethylene diamine (EDA). The resultant xylitol carbon dots (XCDs) were irregular shaped, rough with an average size of 8.88 nm and exhibiting fluorescence between 400 and 450 nm. The presence of EDA preserves the native chemical structure of Xlt even after exposure to microwaves. Purified XCDs were conjugated (AM‐XCD) with ketoconazole and tetracycline for fungi and bacteria, respectively. In comparison to Xlt, XCDs have higher inhibitory potential and reduced dosage size of antimicrobials against Cryptococcus neoformans, Candida albicans, Streptococcus pyogenes, and Escherichia coli by 75%, 75%, 87.50%, and 50%, respectively. For Listeria monocytogenes and Salmonella typhi also inhibitory potential was increased by 14.68% and 21.38%. Increased efficacy advocated the improved drug delivery in the presence of XCDs. However, no inhibitory effect was recorded against DU145 (human prostate cancer) and HCT‐15 (human colon adenocarcinoma) cell lines. The findings of the current work suggested the possible use of Xlt as an important antimicrobial agent besides an efficient drug carrier in healthcare. [ABSTRACT FROM AUTHOR]

Species that can germinate under low water potential are likely to have greater utility for fodder production and restoration in arid habitats. We investigated seed germination response of four native grass species (Panicum acuminatum, Panicum turgidum, Pennisetum divisum and Polypogon monspeliensis) to five osmotic potentials (0, −0.3, −0.6, −0.9 and −1.2 MPa) using polyethylene glycol‐6000 and two light treatments (0, 12 h light per day). All the studied species exhibited high germination (> 77%) at ψ = 0 MPa except P. turgidum (42%). Polypogon monspeliensis seeds did not show any significant reduction in germination from ψ = 0 to −0.3 MPa (90–83%), but all other species did, averaging from 75.8 to 60.5%. At ψ = −0.6 MPa seed germination was reduced to around 20%. Germination of most species was unaffected by light, but P. divisum seeds that germinated in darkness were more tolerant to water deficit. Reduction of water potential to −0.3 MPa inhibited the germination timing for P. acuminatum (ca 1.69 days difference to 50% germination [t50]), P. divisum (ca 1.56 day) and P. monspeliensis (ca 1.14 days). Germination of P. acuminatum and P. monspeliensis were similar after stressful exposure to all osmotic potentials, while for P. divisum there was reduced germination (85% at −0.6 MPa to 58% −1.2 MPa), indicating a dormancy induction. Tolerance to low water potentials, and response after release from these low potentials, indicates the species are adapted to survive in drier environments. [ABSTRACT FROM AUTHOR]

The new diorganotin (IV) complexes of composition [Me2SnCl(3,5‐(NO2)2C6H2(OH)CONHO)] (I) and [n‐Bu2SnCl(3,5‐(NO2)2C6H2(OH)CONHO)] (II) have been synthesized by the reactions of Me2SnCl2 and n‐Bu2SnCl2 with potassium 3,5‐dinitrosalicylhydroxamate [3,5‐(NO2)2C6H2(OH)CONHOK]‐ a ligand of biological significance bearing –NO2 and –OH substituents presumed to yield complexes with efficient bioactivity. The complexes have been characterized by elemental analyses, IR, 1H, 13C and 119Sn NMR and mass spectrometry in order to study the ligational behavior and probale geometry around tin as the ligand might show different bonding modes and geometry in complexes. The geometries of (I) and (II) have been computed using B3LYP/6–31 + G(d,p) set by DFT method and the vibrational frequencies, 1H and 13C NMR spectra compared with the experimental data. A comparison of computed bond lengths (C=O, C‐N, and N‐O) of (I) and (II) with that of free ligand, the Sn‐O bond lengths, bond angles coupled with 119Sn NMR and IR spectral data have suggested coordination through carbonyl and hydroxamic oxygens (O, O coordination) displaying five‐coordinate distorted trigonal‐bipyramidal geometry around tin. The thermal behavior of (I) and (II) has been studied by thermogravimetric techniques (TGA, DTG, DTA) and various kinetic parameters have been calculated. The electrochemical behavior of ligand, (I) and (II) studied by cyclic voltammetric technique has shown ligand centered redection. The HOMO‐LUMO energies and orbitals, global reactivity descriptors, various thermodynamic parameters and dipole moment (μ) have been computed to determin the molecular properties of complexes. The in vitro antimicrobial activity assay against bacteria and fungi by MIC method has indicated higher potency of (I) than (II). The in vitro cytotoxicity on human muscle rhabdomyosarcoma (RD) by MTT method and the antioxidant potential by DPPH free radical scavenging showed higher inhibitory effect of complexes than ligand. [ABSTRACT FROM AUTHOR]

Abstract: The effect of photoperiod, thermoperiod and their interaction on seed germination and its rate was studied for nine grasses growing in the Arabian desert. Germination tests were conducted under two photoperiods and three thermoperiods. Germination of light‐incubated seeds of Hyparrhenia hirta, Pennisetum divisum, Stipacapensis, Centropodia forsskaolii, Stipagrostis plumosa, Cymbopogon parkeri and Panicum turgidum was significantly higher than that detected in the darkness. Photoperiod did not influence the seed germination of Aristida adscensionis and Imperata cylindrica. Seeds of all species, except P. divisum, C. parkeri and I. cylindrica, germinated indepen dently of the tested temperature. Our results indicate that species belonging to the same family and growing in the same hyper‐arid desert habitat may influence and act in different ways during the seed germination phase, causing species‐specific effects, and therefore might affect the ecology of each taxon in this harsh environment. [ABSTRACT FROM AUTHOR]

Haloxylon salicornicum and Salsola vermiculata (Amaranthaceae) are two perennial shrubs producing fruits with differently coloured perianths (yellow vs pink) on separate individuals. To test the impact of different storage periods (four, eight and twelve months) and temperature conditions (freezing, room temperature and natural field temperatures) on the seed germination of the two seed categories, germination tests were carried out on both species. For both species, collected from wild plants in the Arabian desert (Qatar), seed germination was tested under two photoperiods (light 12/12; dark 24 hours) at 20/30°C for winged (intact) and de‐winged seeds. For each species, all the considered factors (perianth colour, wing presence, photoperiod, storage period and storage conditions) had significant effects on seed germination (p < 0.001), while the interactions among factors varied in their level of significance depending on the species. In both species, yellow seeds germinated considerably better than the pink ones, the presence of wings slowed the germination, and both storage period and temperature conditions highly influenced their germination ability. Our results indicate that seeds from different perianth colours have different germination strategies to delay their germination and distribute the species through time by escaping germination time by imposing some kind of after‐ripening or seed dormancy. The variation in storage time and storage conditions might help in extending their germination period, where one set of seeds germinate immediately, and the other set of seeds becomes dormant and thus contributes to the formation of a soil seed bank for the long‐term recruitment of seedlings. This study highlights an ecological advantageous strategy for these two species growing in the unpredictable desert habitat. [ABSTRACT FROM AUTHOR]

We investigated the dimorphic perianth colour of Salsola vermiculata and its association with seed germination percentage, interactions with temperature, light, salinity and recovery from prior salinity exposure. Seeds with and without pink and yellow perianth were incubated at three thermal regimes, two photoperiods, and five salinity levels. Germination recovery after salinity exposure was observed on seeds that failed to germinate during the salinity study. The germination percentage and rate were significantly related to the perianth colour, the presence of perianth wings, thermal regimes and photoperiod. The presence of a perianth wing significantly reduced germination percentage and germination rate in both the pink and the yellow morph, but the yellow morph exhibited a higher germination percentage. Perianth wing removal increased germination in saline conditions. With the perianth removed, germination recovery was higher for the pink morph than for the yellow one. We suggest that by providing two different strategies for balancing germination with dormancy during favourable conditions, the presence of two morphs makes S. vermiculata more successful in highly unpredictable desert environments. [ABSTRACT FROM AUTHOR]

Haloxylon salicornicum is a perennial shrub that grows in sandy and stony desert areas. This species produces two types of dispersal unit with yellow and pink winged perianths that are wind dispersed. This species has been considered as an excellent sand binder and can tolerate extreme temperature, drought and salinity. We compared the germination characteristics of both colored dispersal units (with and without a wing) under various light, temperature and salinity treatments. It was found that wing color, presence of wings, temperature and light have a significant effect on germination percentage and germination rate. The presence of a winged perianth significantly reduced the germination percentage and germination rate in both yellow and pink dispersal units. De-winged yellow dispersal units were able to tolerate higher salinity and, therefore, their germination was higher in all the tested concentrations of NaCl compared with pink de-winged dispersal units. However, salinity tolerance in both pink and yellow dispersal units decreased with increasing salinity concentration. The germination-recovery percentage was also higher for yellow compared with pink dispersal units. The present study has demonstrated that both morphological and physiological differences exist in different colored dispersal units, which might represent the combination of different complementary adaptive strategies and have ecological significance for Haloxylon salicornicum's successful survival in harsh desert environmental conditions. [ABSTRACT FROM AUTHOR]

Suaeda aegyptiaca is a facultative halophyte found in saline and non-saline habitats of the Arab Gulf desert, which produces small-sized undispersible seeds. The interactive effects of maternal salinity and other environmental conditions, such as salinity, light and temperatures, that are prevailing during seed germination have received little attention for a facultative halophyte. This study tested the effects of maternal salinity on salt tolerance during seed germination of S. aegyptiaca under different light and temperature regimes. Seeds collected from both saline and non-saline habitats of the United Arab Emirates ( UAE) were germinated in 0, 50, 100, 200 and 400 mM NaCl, and incubated at 15/25°C, 20/30°C and 25/35°C in both 12-h light/12-h dark regimes and continuous darkness. Generally, seeds of the non-saline habitat were 56% heavier and attained greater germination at the lower temperatures than seeds of the saline habitat. Seeds of the saline habitat germinated better in saline solutions at higher temperatures and in light. Germination was faster for seeds of the saline habitat than for seeds of non-saline habitats. Germination recovery after transfer to distilled water was significantly greater for seeds from the non-saline habitat, compared with seeds from saline habitats. Recovery was greater at lower and/or moderate temperatures, compared with at higher temperatures. Germination was significantly faster during recovery, compared with in the saline solutions. The study indicates that the maternal effect of salinity was confounded with the seed-size effect and it cannot be conclusively confirmed. [ABSTRACT FROM AUTHOR]

Bienertia cycloptera (Chenopodiaceae) produces two types of leaf foliage colour (reddish and yellowish). In order to determine the role of leaf colour variation in regulating the germination characteristics and salinity tolerance during germination, a study was conducted on seeds collected from plants of both colours. Seeds with and without pulp were germinated under two illumination conditions (12-h light photoperiod and continuous dark), three alternating temperature regimes (15/25°C, 20/30°C and 25/35°C), and several salinity levels at 20/30°C. Germination percentage was significantly higher for seeds without pulp as compared to the seeds with pulp. The response of B. cycloptera seeds to salinity depended on the leaf colour. Thus, the seeds collected from reddish coloured plants were able to tolerate higher salinity compared to those of yellowish coloured plant. The germination recovery results indicate that the seeds from both coloured plants could remain viable in saline condition and they will be able to germinate once the salinity level are decreased by rain. The production of different foliage colours by B. cycloptera seems to be an adaptative strategy which increases the possibility for establishment in unpredictable environments by producing seeds with different germination requirements and salinity tolerance. [ABSTRACT FROM AUTHOR]

Increased air pollution in a number of developing African countries, together with the reports of vegetation damage typically associated with acid precipitation in commercial forests in South Africa, has raised concerns over the potential impacts of acid rain on natural vegetation in these countries. Recalcitrant (i.e. desiccation sensitive) seeds of many indigenous African species, e.g. must germinate shortly after shedding and hence, may not be able to avoid exposure to acid rain in polluted areas. This study investigated the effects of simulated acid rain (rainwater with pH adjusted to pH 3.0 and 4.5 with 70:30, H2SO4: HNO3) on germination, seedling growth and oxidative metabolism in a recalcitrant-seeded African tree species Trichilia dregeana Sond., growing in its natural seed bank. The results suggest that acid rain did not compromise T. dregeana seed germination and seedling establishment significantly, relative to the control (non-acidified rainwater). However, pH 3.0 treated seedlings exhibited signs of stress typically associated with acid rain: leaf tip necrosis, abnormal bilobed leaf tips, leaf necrotic spots and chlorosis, reduced leaf chlorophyll concentration, increased stomatal density and indications of oxidative stress. This may explain why total and root biomass of pH 3.0 treated seedlings were significantly lower than the control. Acid rain also induced changes in the species composition and relative abundance of the different life forms emerging from T. dregeana's natural seed bank and in this way could indirectly impact on T. dregeana seedling establishment success. [ABSTRACT FROM AUTHOR]

The article focuses on the ecological features of a critically rare medicinal plant known as Swertia chirayita in Himalaya Mountains Region. It identifies Swertia as an important genus in the family of Gentianaceae. There are over 32 species of Swertia in the Indian Himalayan region and 16 species in the northwest Himalaya in which 11 of species contain medicinal properties. It considers Swertia chirayita as a critically rare and virtually endemic to Himalaya.