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In the present study, an eco-friendly process was made for the rapid synthesis of silver nanoparticles using aqueous leaf extract of Hibiscus sabdariffa . The process was characterized by Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible and X-ray diffraction (XRD). These green silver nanoparticles (NPs) were used for mitigating the adverse effects of salinity on seed germination and growth parameters in plants. Accordingly, two experiments were conducted. In the first experiment, seven concentrations of green silver NPs and nine levels of NaCl:CaCl were apptoed on seeds for germination, and their effects were evaluated. In the second experiment, three concentrations of green silver NPs and NaCl were hypothesized to affect plant growth parameters. Seed germination, plant height, leaf, and root fresh and dry weights, as well as relative water content (RWC), decreased significantly under salt stress. However, green silver NPs intervened by alleviating the adverse effects of stress. Accordingly, green silver NPs were beneficial due to (1) activation of the antioxidant system by enhancing antioxidant enzymes such as catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), and superoxide dismutase (SOD); (2) increase in the amounts of proline, soluble sugars and carbohydrates for osmoprotection; (3) improvements in flavonoid and anthocyanin contents. Real-time PCR showed that flavonoid and anthocyanin contents increased because of higher expressions in chalcone synthase ( CHS ), flavanone 3‐hydroxylase ( F3H ), and anthocyanidin synthase ( ANS ) genes. In conclusion, green silver NPs offered an eco-friendly application for further research on agricultural development.

Improving marketability and extension of vase life of cut flowers has practical significance for the development of the cut flower industry. Although considerable efforts have been made over many years to improve the vase life of cut flowers through controlling the immediate environment and through post-harvest use of floral preservatives, the impact of lighting environment on vase life has been largely overlooked. In the current study, the effect of three LED light spectra [white (400–730 nm), blue (peak at 460 nm), and red (peak at 660 nm)] at 150 μmol m–2 s–1 on vase life and on physiological and biochemical characteristics of carnation cut flowers was investigated. Exposure to blue light (BL) considerably delayed senescence and improved vase life over that of flowers exposed to red light (RL) and white light (WL). H2O2 and malondialdehyde (MDA) contents in petals gradually increased during vase life; the increase was lowest in BL-exposed flowers. As a consequence, BL-exposed flowers maintained a higher membrane stability index (MSI) compared to RL- and WL-exposed flowers. A higher activity of antioxidant enzymes [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)] was detected in petals of BL-exposed flowers, compared to their activities in RL- and WL-exposed flowers. In BL-exposed flowers, the decline in petal carotenoid contents was delayed in comparison to RL- and WL-exposed flowers. Maximum quantum efficiency of photosystem II (Fv/Fm) and a higher percentage of open stomata were observed in leaves of BL-exposed flowers. Sucrose and glucose contents accumulated in petals during vase life; sugar concentrations were higher in BL-exposed flowers than in RL- and WL-exposed flowers. It is concluded that BL exposure improves the vase life of carnation cut flowers through its effect on the antioxidant defense system in petals and on photosynthetic performance in the leaves.

Carnation is an important cut flower with industrial and medicinal applications. To establish an efficient protocol without somaclonal variation for micropropagation of Dianthus caryophyllus , direct and indirect somatic embryogenesis (DSE and ISE) were investigated under six different light spectra (white, red, green, blue, red + blue and far red + red) and four combinations of different plant growth regulators (PGRs) never tested so far for carnation. The best results were achieved with 2,4-dichlorophenoxyacetic acid (2,4-D) + N-(2-chloro-4-pyridyl)-N′-phenylurea (4-CPPU) for ISE and picloram + 4-CPPU or naphthoxyacetic acid (NOA) + 6-benzylaminopurine (BAP) for DSE. The DSE method was faster (3 weeks compared to 8 weeks) and easier (no subculturing compared to two rounds of subculture with ISE methods) but the percentage of somatic embryos in the ISE method was higher compared to the DSE method. Our results showed that the highest DSE, formation of embryogenic callus, embryo maturation (generation of globular, heart and torpedo shapes) and ISE rate was observed in carnation explants exposed to blue light (450–495 nm). In contrast, green (495–570 nm), red (610–700) and far red (710–730 nm) lights caused negative effects on embryogenesis compared to white light controls (380–750 nm). For the first time, genetic stability of regenerated carnation plants was estimated using inter-simple sequence repeat (ISSR) markers. The amplified products showed 75 distinct and scorable bands, and regenerants [plants obtained by primary (PSE) and secondary SE (SSE)] were completely identical to the mother plant. Similarly, flow cytometric analysis confirmed that somatic embryo-derived plants had on average 1.53 pg nuclear DNA (2C), and all plants maintained their ploidy. In conclusion, obtained embryos under blue light were big in size and torpedo-shaped and their germination was highest compared to other light spectra. Moreover, blue light was effective for direct and indirect somatic embryogenesis in carnation without induction of somaclonal variation. Key message An effective protocol through application of phytohormones is introduced. Blue light can be used to improve in vitro propagation of carnation by somatic embryogenesis. Genetic stability of regenerated carnation plants was confirmed using inter-simple sequence repeat (ISSR) markers.