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Copper (Cu) is an essential element involved in various metabolic processes in plants, but at concentrations above the threshold level, it becomes a potential stress factor. The effects of two different cytokinins, kinetin (KIN) and 6-benzylaminopurine (BAP), on chlorophyll a fluorescence parameters, stomatal responses and antioxidation mechanisms in castor (Ricinus communis L.) under Cu2+ toxicity was investigated. Ricinus communis plants were exposed to 80 and 160 μM CuSO4 added to the growth medium. Foliar spraying of 15 μM KIN and BAP was carried out on these seedlings. The application of these cytokinins enhanced the tissue water status, chlorophyll contents, stomatal opening and photosynthetic efficiency in the castor plants subjected to Cu2+ stress. The fluorescence parameters, such as Fm, Fv/Fo, Sm, photochemical and non-photochemical quantum yields, energy absorbed, energy trapped and electron transport per cross-sections, were more efficiently modulated by BAP application than KIN under Cu2+ toxicity. There was also effective alleviation of reactive oxygen species by enzymatic and non-enzymatic antioxidation systems, reducing the membrane lipid peroxidation, which brought about a relative enhancement in the membrane stability index. Of the various treatments, 80 µM CuSO4 + BAP recorded the highest increase in photosynthetic efficiency compared to other cytokinin treatments. Therefore, it can be concluded that BAP could effectively alleviate the detrimental effects of Cu2+toxicity in cotyledonary leaves of R. communis by effectively modulating stomatal responses and antioxidation mechanisms, thereby enhancing the photosynthetic apparatus’ functioning.

Satureja khuzistanica Jamzad is a valuable and endemic medicinal plant. Boron and zinc are essential elements for the vegetative and reproductive growth of plants and have significant effects on yield, essential oil composition and the seed production of plants. To investigate the effects of the foliar application of zinc and boron on the growth, yield, seed production and phytochemical properties of S. khuzistanica, a study was conducted in a factorial experiment with three replicates in two consecutive years based on a randomized complete block design. The foliar application of boron (B) at three concentrations (control or distilled water, 0.4% and 0.8% as H3BO3) and zinc (Zn) at three concentrations (control or distilled water, 0.3% and 0.6% as ZnSO4) was carried out. Our results showed that the foliar application of B resulted in a significant increase in the fresh and dry weights of plants, the dry weight of stems, drug yield, seed yield, seed germination and 1000-seed weight. At the same time, the application of B resulted in a significant decrease in seed emptiness. The fresh and dry weights of plants, drug yield, seed yield, 1000-seed weight and seed germination were also significantly improved by Zn foliar spraying compared to the control. Application of 0.8% B resulted in a significant decrease in seed emptiness by 14.16% and 22.37%, as compared to the control. The foliar spraying of B and Zn improved the total phenolic content, the essential oil content and the yield and antioxidant activity of S. khuzistanica. Moreover, B application generally concentrated more carvacrol in the essential oil (in the first experimental year). In contrast, no significant differences were observed between Zn treatments in carvacrol content and total flavonoids. The use of several microelements, such as B and Zn, could improve both the quantity and quality of S. khuzistanica. Additionally, improvement of seed set and seed quality by the foliar spraying of Zn and B may be useful for growing plants in arid and semi-arid areas.

GABA (gamma-aminobutyric acid) and melatonin are endogenous compounds that enhance plant responses to abiotic stresses. The response of Vicia faba to different stressors (salinity (NaCl), poly ethylene glycol (PEG), and sulfur dioxide (SO2)) was studied after priming with sole application of GABA and melatonin or their co-application (GABA + melatonin). Both melatonin and GABA and their co-application increased leaf area, number of flowers, shoot dry and fresh weight, and total biomass. Plants treated with GABA, melatonin, and GABA + melatonin developed larger stomata with wider aperture compared to the stomata of control plants. The functionality of the photosynthetic system was improved in primed plants. To investigate the photosynthetic functionality in details, the leaf samples of primed plants were exposed to different stressors, including SO2, PEG, and NaCl. The maximum quantum yield of photosystem II (PS II) was higher in the leaf samples of primed plants, while the non-photochemical quenching (NPQ) of primed plants was decreased when leaf samples were exposed to the stressors. Correlation analysis showed the association of initial PIabs with post-stress FV/FM and NPQ. Stressors attenuated the association of initial PIabs with both FV/FM and NPQ, while priming plants with GABA, melatonin, or GABA + melatonin minimized the effect of stressors by attenuating these correlations. In conclusion, priming plants with both GABA and melatonin improved growth and photosynthetic performance of Vicia faba and mitigated the effects of abiotic stressors on the photosynthetic performance.

The beneficial role of fungi from the Trichoderma genus and its secondary metabolites in promoting plant growth, uptake and use efficiency of macronutrients and oligo/micro-nutrients, activation of plant secondary metabolism and plant protection from diseases makes it interesting for application in environmentally friendly agriculture. However, the literature data on the effect of Trichoderma inoculation on tomato fruit quality is scarce. Commercially used tomato cultivars were chosen in combination with indigenous Trichodrema species previously characterized on molecular and biochemical level, to investigate the effect of Trichoderma on photosynthetic characteristics and fruit quality of plants grown in organic system of production. Examined cultivars differed in the majority of examined parameters. Response of cultivar Gružanski zlatni to Trichoderma application was more significant. As a consequence of increased epidermal flavonols and decreased chlorophyll, the nitrogen balance index in leaves has decreased, indicating a shift from primary to secondary metabolism. The quality of its fruit was altered in the sense of increased total flavonoids content, decreased starch, increased Bioaccumulation Index (BI) for Fe and Cr, and decreased BI for heavy metals Ni and Pb. Higher expression of swolenin gene in tomato roots of more responsive tomato cultivar indicates better root colonization, which correlates with observed positive effects of Trichodrema.

Copper (Cu) is an essential element involved in various metabolic processes in plants, but at concentrations above the threshold level, it becomes a potential stress factor. The effects of two different cytokinins, kinetin (KIN) and 6-benzylaminopurine (BAP), on chlorophyll a fluorescence parameters, stomatal responses and antioxidation mechanisms in castor (Ricinus communis L.) under Cu2+ toxicity was investigated. Ricinus communis plants were exposed to 80 and 160 μM CuSO4 added to the growth medium. Foliar spraying of 15 μM KIN and BAP was carried out on these seedlings. The application of these cytokinins enhanced the tissue water status, chlorophyll contents, stomatal opening and photosynthetic efficiency in the castor plants subjected to Cu2+ stress. The fluorescence parameters, such as Fm, Fv/Fo, Sm, photochemical and non-photochemical quantum yields, energy absorbed, energy trapped and electron transport per cross-sections, were more efficiently modulated by BAP application than KIN under Cu2+ toxicity. There was also effective alleviation of reactive oxygen species by enzymatic and non-enzymatic antioxidation systems, reducing the membrane lipid peroxidation, which brought about a relative enhancement in the membrane stability index. Of the various treatments, 80 µM CuSO4 + BAP recorded the highest increase in photosynthetic efficiency compared to other cytokinin treatments. Therefore, it can be concluded that BAP could effectively alleviate the detrimental effects of Cu2+toxicity in cotyledonary leaves of R. communis by effectively modulating stomatal responses and antioxidation mechanisms, thereby enhancing the photosynthetic apparatus’ functioning.

The natural mineral resources (hard coal, sands, dolomites, lead and zinc ores) found in the Silesia and the excavation of them led to significant transformation or even degradation of the environment. The landscape of Upper Silesia was dominated by heaps created as a result of the accumulation of post-mining coal waste. These post-industrial sites are characterised by difficult conditions for the development of plant communities. Nevertheless, the heaps are spontaneously overgrowing and over time, a separate ecosystem can be observed (for heaps). The article analyzes the enzymatic activity of the substrate in relation to the selected dominant grass (Monocots) and herbaceous (Dicots) plant species. The aim of this study was to compare the activity of particular enzymes in soil substratum of the vegetation patches dominated by grass and herbaceous plants.

Vascular plants are able to conduct biomineralization processes and collect synthesized compounds in their internal tissues or to deposit them on their epidermal surfaces. This mechanism protects the plant from fluctuations of nutrient levels caused by different levels of supply and demand for them. The biominerals reflect both the metabolic characteristics of a vascular plant species and the environmental conditions of the plant habitat. The SEM/EDX method was used to examine the surface and cross-sections of the Calamagrostis epigejos and Phragmites australis leaves from post-industrial habitats (coal and zinc spoil heaps). The results from this study have showed the presence of mineral objects on the surfaces of leaves of both grass species. The calcium oxalate crystals, amorphous calcium carbonate spheres, and different silica forms were also found in the inner tissues. The high variety of mineral forms in the individual plants of both species was shown. The waxes observed on the leaves of the studied plants might be the initializing factor for the crystalline forms and structures that are present. For the first time, wide range of crystal forms is presented for C. epigejos. The leaf samples of P. australis from the post-industrial areas showed an increased amount of mineral forms with the presence of sulfur.