Acta Botanica Croatica

Abstract Bryophytes, a group of terrestrial plants widely used in biomonitoring, are reviewed for their relation to heavy metals. In the present article, we summarized the knowledge on heavy metals pollution and accumulation effects on bryophytes. Mechanisms of tolerance and resistance are given as well.

Abstract Centric diatoms of 107 different Hungarian running waters were investigated. Among them the largest was the River Danube, from which more than one hundred plankton samples were analysed by scanning electron microscopy (SEM). Only one sample was analysed from creeks, which were the smallest running waters analysed in this study. There were also channels with slow currents flowing out of rivers or connecting different rivers. In total, 41 centric taxa belonging to 11 genera were found during this study. The average number of taxa found in a single watercourse was 7, the maximum 40 and the minimum 1.Cyclotella meneghinianawas the most frequently encountered species (present in 60% of sites). Twelve taxa were found in more than 20% of sites, 7 taxa between 5-10% and 6 taxa only in one site.

Abstract The physiological response of crop plants againstTrichoderma harzianum(Th-6) in a saline habitat was studied.Trichoderma harzianum(Th-6) is an endophytic fungus that shows salt tolerance and establishes a symbiotic relationship with a host plant. To evaluate the role ofTrichoderma harzianum(Th-6) in mitigating the consequences of salinity stress on crop plants, seeds of maize and rice were coated withTrichodermabefore sowing and salt treatment. Later, after germination, twenty-one day old seedlings were subjected to NaCl concentrations (50, 100 and 150 mM). Salinity negatively affected all investigated physiological parameters in both crops. Treatment of seeds withTrichodermaimproved plant growth andTh-treated plants exhibited substantial physiological adjustment in a saline environment compared toTh-untreated plants. TheTh-treated plants under salt stress showed higher relative water content and stomatal conductance, better photosynthetic performance and higher pigment concentrations, as well as higher catalase and superoxide dismutase activities. Moreover, proline content in salt stress environment was higher inTh-treated plants, while H2O2content declined. The physiological role ofTrichoderma harzianumin mitigating the salt related consequences of both crop plants is discussed.

Abstract Seeds of chickpea inoculated with Rhizobium were sown in pots supplemented with different doses of cadmium (0, 25, 50 or 100 mg per kg of soil). At the stage of 30 days after sowing (DAS), the plants were sprayed with 20 mM solution of proline and were sampled at 90 DAS to assess the various parameters. The foliar treatment of proline resulted in the alleviation of the adverse effects generated by metal exposure, which was expressed in terms of the increase in plant growth. The activity of carbonic anhydrase in the cadmium-fed plants sprayed with proline was higher than that of control. The proline applied as foliar spray increased the photosynthetic attributes and yield characteristics in the cadmium-stressed plants. The activity of antioxidative enzymes increased with increasing concentration of cadmium. Maximum values were recorded in the plants exposed to 100 mg cadmium per kg of soil.

Licorice (Glycyrrhiza glabra L.) is known as an important medicinal plant throughout the world. Glycyrrhizin is one of the most important specialized metabolites produced by licorice. In order to study the effect of TiO2 nanoparticles (TiO2 NPs) and spermine on physiological and biochemical traits of licorice under cold stress conditions, a factorial experiment was conducted in a completely randomized design with three replications. Plants were exposed to optimum temperature (26 ºC) as control and low temperature (4 ºC) as cold stress conditions and also treated with TiO2 NPs (2 and 5 ppm) and spermine (1 mM), separately. Results from physiological and biochemical analyses of the aerial parts of licorice seedlings showed that the growth parameters and the content of photosynthetic pigments decreased in response to low temperature. TiO2 NPs and spermine treatments increased plant resistance to cold stress and decreased the level of oxidative damage by reduction of malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents. In other hand, TiO2 NPs and spermine caused increase of phenolics, total protein and osmolytes contents under cold stress conditions. An increase in glycyrrhizin content was significantly induced by low temperature, TiO2 NPs and spermine.

Abstract Arsenic (As)-toxicity is a major constraint for crop production. The present study was intended to examine the comparative ameliorative effects of diphenyleneiodonium (DPI), 24-epibrassinolide (EBL) and proline (Pro) on As-stress inGlycine maxL. Seeds ofGlycine maxL. were subjected to As (100 µM) singly, and together with DPI (10 µM), EBL (0.5 µM) or Pro (10 mM), for five days, and were then analyzed. Experimental results showed that As treatment caused a substantial fall in growth traits like germination percentage, radicle length and dry mass, which was accompanied by As accumulation. Additionally, As application also revealed reduced viability, total protein content and activities of antioxidative enzymes (superoxide dismutase, catalase and ascorbate peroxidase), while it increased the levels of total sugar, proline and oxidative stress markers such as electrolyte leakage, reactive oxygen species, lipid oxidized products, protein carbonyls and hydroperoxides, Amadori and Maillard reaction products, malondialdehyde-/4-hydroxy-2-nonenal-protein adducts, protease and proteasome. Isozymes of antioxidative enzymes were also observed to be altered considerably under As-stress. Impressively, DPI, EBL and Pro played their role as protective agents, hence caused enhanced growth and reduced As accumulation. These protective chemicals also improved the viability, accruals of total protein, total sugar and endogenous proline, and activities of antioxidants, while they reduced the levels of oxidative stress markers. Our findings demonstrated the involvement of DPI, EBL and Pro in As-stress tolerance inGlycine maxL. Further, Pro appears to be superior to DPI and EBL, in alleviating As-induced responses inGlycine maxL.

Abstract The physiological performance of some sunflower genotypes (S.28111, SF0049, Hysun-33, Hysun-39) under salt, drought stress separately and in combination was examined. Salt, drought and a combination of these stresses were applied to plants by gradual increments. The plants were exposed to stress for two weeks. Relative water content, osmotic potential, stomatal conductance, performance index, dark adapted quantum yield and chlorophyll contents were reduced upon salinity and drought stresses. However, when plants were subjected to a combination of these stresses, a greater reduction in all tested attributes was observed. Proline and carotenoid contents in drought stress were elevated compared to salt stress. Superoxide dismutase (SOD) and catalase (CAT) showed the highest activity in individual salt and drought stress with less accumulation of H2O2. Combined stress reduced the activity of antioxidant enzymes which ultimately decreased the physiological performance of sunflower plants. However, among the tested genotypes, S.28111 and SF0049 were found to be more tolerant to drought, salt and combined stress than both Hysun genotypes. The physiological performance of genotypes against salinity and drought individually and in combination is discussed in detail.

Abstract Croatia is among the most ecologically diverse and floristically rich countries in Europe, with a great variety of communities. The vegetation elaboration according to the standard central European method was initiated in Croatia at the beginning of the 20thcentury. In previous overviews of Croatian vegetation, the number of classes and alliances was underrepresented in relation to the country’s floristic richness. Furthermore, the level of knowledge and the amount of available data varied greatly among the various types of vegetation. The aims of this paper are mainly to compile a stabile syntaxonomic list of classes, orders and alliances dominated by vascular plants in Croatia and to adjust Croatian vegetation to the new European syntaxonomic system (EuroVegChecklist). It introduces a consistent description of high-rank syntaxa in Croatian. In conclusion, the vegetation of Croatia comprises 66 classes, 121 orders and 201 alliances. The number of syntaxa shows vegetation diversity that is rather high compared to most other European countries; this is related to the high floristic richness and endemism. The list points out the obvious problems and gaps in our knowledge of vegetation in Croatia and can serve as a baseline for the future vegetation studies.

Abstract Phenotyping of rice (Oryza sativa L. cv. Donggin) in salt stress environment using infrared imaging was conducted. Results were correlated with the most frequently used physiological parameters such as stomatal conductance, relative water content and photosynthetic parameters. It was observed that stomatal conductance (R2 = -0.618) and relative water content (R2 = -0.852) were significantly negatively correlated with average plant temperature (thermal images), while dark-adapted quantum yield (Fv/Fm, R2 = -0.325) and performance index (R2 = -0.315) were not consistent with plant temperature. Advantages of infrared thermography and utilization of this technology for the selection of stress tolerance physiotypes are discussed in detail.

Abstract Lettuce production in the winter on the Adriatic coast, especially in a non-heated plastic tunnel, requires longer cultivation and is characterised by lower head mass and yield. In these conditions, the effect of biostimulant Bio-algeen S-90 and fertilizer Megagreen on the production of the traditional winter lettuce cultivar ‘Four Seasons’ was tested. Both treatments showed a positive effect on the growth and total yield of winter lettuce, and decreased the share of non-marketable yield. Bio-algeen S-90 treatment increased the plant height by 61.5%, and foliar treatment with Megagreen by 60.9%, as compared to the control treatment. Equally, both treatments resulted in higher leaf numbers (47.7% for Bio-algeen S-90 and 37.2% for Megagreen). The head mass of lettuce treated with Bio-algeen S-90 and Megagreen was 30.3% and 25.0% higher than in the control treatment, respectively. Megagreen contributed more to chlorophyll and carotenoid content, while Bio-algeen S-90 elevated the amount of vitamin C and dry matter. The pH value of lettuce juice decreased after Bio-algeen S-90, while the mineral content (N, P and K) did not differ between the tested treatments. Lower nitrate content was detected after both treatments. The obtained results elucidate the effect of Bio-algeen S-90 and Megagreen on “low input” lettuce production.

This study investigated the physiological and molecular responses of two common bean ( Phaseolus vulgari s L.) genotypes, “Balkız” and “Local Genotype”, which differ in their relative heat tolerance, with the “Local Genotype” being more tolerant than “Balkız”, to high-temperature stress during the seedling stage, aiming to identify genotype-specific physiological and biochemical responses and to determine reliable indicators of thermotolerance. Leaf relative water content (RWC), turgor loss, membrane damage, proline levels, total soluble protein (TSP), and the expression of heat shock proteins HSP23 and HSP60 were examined. The “Local Genotype” exhibited greater thermotolerance, with lower membrane damage while the temperature at which 50% injury occurs (LT50) was higher, despite the accumulation of less proline than “Balkız”. Genotype-specific variations detected in protein expression indicate distinct biochemical responses to heat stress. HSP23 showed a rapid, transient increase at moderate temperature (40 °C) in both genotypes, suggesting it has a role in early heat stress response. HSP60 levels were maintained near LT50 temperatures, supporting sustained stress adaptation, but declined at 48 °C, reflecting extreme stress rather than genotype-specific differences. These findings emphasize LT50 and HSP dynamics as key indicators of thermotolerance and provide insights for understanding heat stress responses in common bean seedlings.

In the flora of Ukraine, 48 findings of the spontaneous spread of the alien species Nepeta racemosa Lam. were recorded: 30 records within the introduction centers and 18 outside the boundaries of cultivation. A brief morphological description of the plants is provided, and their ecological and biological features are investigated. It was found that all the habitats of this species in Ukraine were confined to synanthropic biotopes: decorative cultivated biotopes (parks, squares, lawns, flower gardens), residential and technotopes (biotope complexes of built-up areas, garbage and solid waste landfills). Most often, the plants grow in cracks in sidewalks and asphalt. According to time of introduction, N. racemosa belongs to neophytes, and according to method of introduction to ergasiophytes. The species requires further monitoring to assess the likelihood of its further spread within and beyond urban environments.

During light and scanning electron microscope observations of marine benthic diatoms on various substrates in the eastern Adriatic Sea and the western Black Sea, we discovered a peculiarly structured amphoroid diatom species. The species was characterised by semi-elliptic to semi-lanceolate valves with distinctly protracted capitate to occasionally rostrate apices, a dorsal valve side crossed by transapical slits, a wide dorsal marginal ridge, biseriate dorsal striae internally, and usually lacking ventral striae externally, except for one or two poroids at the apices. Following a search in the literature, this taxon could only be identified as Halamphora yundangensis, a recently described species from the southeastern coasts of China. Here we present the first verified observation of this species in the Mediterranean Region. After thorough analyses of the observed populations in scanning electron microscopy and a literature overview, we provide an emended description of the species, and additional information enabling/justifying its separation from similar taxa occurring in the Mediterranean Region. Notes on the ecology and distribution of the species based on the new observations are also given.

A conspicuous wetland species, Lathyrus palustris L. with Holarctic distribution has been discovered as new for the flora of Slovenia, although the wetland flora and vegetation of the country is relatively well studied. We recorded the species in the area of the intermittent Lake Cerknica, growing in different herbaceous wetland plant communities. The ecology fits the data from the surrounding regions. Our finding fills an important gap in the distribution area between Southeastern and Central Europe, where the species’ rarity has resulted in it being declared endangered and accordingly protected.

This study reports the first discovery of Sisyrinchium micranthum in Tunisia, marking the species' inaugural record on the African mainland and along the southern Mediterranean coast. The paper provides a concise morphological description of the species, an account of its phenology, and detailed information on its distribution, habitat, and ecological context in Tunisia. Additionally, we present original photographs of this diminutive annual species. An updated key to the diversity of the Iridaceae family in North Africa is also included.

In this study, the cypsela features of eight Senecio species in Türkiye ( Senecio olympicus Boiss., S. paludosus L., S. tauricolus VA. Matthews, S. salsuginea H. Duman & Vural, S. castagneanus DC., S. fluviatilis Wallr., S. pseudo-orientalis Schischk., and S. racemosus (M. Bieb.) DC.) were investigated in detail using light microscopy (LM) and transmission electron microscopy (TEM). A very thick and darkly stained cuticle layer was observed on the epidermal cells of all the species examined. Papillae were observed only in epidermal cells of S. olympicus Boiss, and sclerenchyma cells were less developed in the cypsela. In the other seven species, well-developed sclerenchyma tissue was found along the pericarp wall in the form of a semicircle, in bundles, or around the secretory ducts. Although secretion ducts were observed along the cypsela wall in the mid-layer cells of S. olympicus , S. tauricolus , S. castagneanus , and S. fluviatilis , no secretion ducts were observed in the other four species. Although prismatic calcium oxalate crystals were observed in the intermediate (mid) layer of S. tauricolus, S. castagneanus , and S. pseudo-orientalis , no crystals were found in the other five species. Phytomelanin accumulation was found in the schizogenic spaces between the outer and intermediate layers of S. olympicus , S. paludosus , S. tauricolus , S. castagneanus , S. pseudo-orientalis , and S. racemosus , but not in S. salsuginea and S. fluviatilis .

Acalypha is a genus native to tropical and subtropical regions of the world and eastern North America and Asia, with some species considered as aliens in Eurasia. The European flora is reported to include four species, all occurring in Italy according to Plant of the World Online database. As part of the ongoing studies of the flora of Treviso Province (Veneto region, north-eastern Italy), we came across to a population of A. rhomboidea Raf. which represents not only the first record for Veneto and the second one for the Italian flora, but also the fifth discovery of the species out of its native range; a description of the species (the first one for Italy), ecological remarks, and a map of the European occurrences are provided.

This study reports the isolation of two natural compounds, zearalenone and hyrtiosulawesine, from the endophytic fungus Penicillium chrysogenum isolate SR192 which is associated with the invasive plant species Solanum rostratum . In general, both isolated compounds exhibited a dose-dependent stimulatory effect on the growth of four weed species when concentrations ranging from 5 to 100 µg mL-1 were tested. However, suppressive effects were observed when the concentration was increased to 500 µg mL-1, suggesting a biphasic response. Our findings indicate that these compounds have the potential to be further investigated as environment-friendly plant growth regulatory agents.

This study presents the first records of Potamogeton compressus L. and P. friesii Rupr. in the Caucasus, where both are confined to Lake Tabatskuri, Georgia. Potamogeton compressus was identified from 1965 herbarium specimens found in TGM, while P. friesii was documented in 2023. These findings extend their known southern ranges, highlighting the importance of high-altitude lakes in preserving boreal aquatic flora in the South Caucasus.

Silver nanoparticles (AgNPs) are widely used due to their specific physico-chemical properties, but their release in wastewater poses a threat to aquatic ecosystems. The microalga Chlorella vulgaris is often used as a model organism in toxicological research. Since this alga can switch from an autotrophic to a mixotrophic mode of life, we investigated whether glucose as an additional energy source can mitigate AgNP phytotoxic effects. Algae were cultivated in a nutrient medium with and without glucose and treated with a concentration of AgNPs allowing 60% cell survival. The effects were studied by monitoring oxidative stress and photosynthesis parameters. In the absence of glucose, AgNPs caused significant accumulation of reactive oxygen species, increased lipid peroxidation and carotenoid content with weak activation of antioxidant enzymes. In addition, reduced photosynthetic efficiency and ultrastructural damage were observed. The addition of glucose to AgNP treatments attenuated all negative effects by reducing oxidative stress and increasing the activity of antioxidant enzymes. Furthermore, C. vulgaris cells exposed in glucose-enriched media showed recovered photosynthesis by exhibiting the photosynthetic rate and chlorophyll fluorescence parameters of control algae. Ultrastructural analysis showed greater synthesis of lipid droplets and less structural damage. The study shows that glucose supplementation effectively mitigates the phytotoxic effects of AgNPs on C. vulgaris . By reducing oxidative stress, enhancing antioxidant enzyme activity and restoring photosynthetic function, glucose helps maintain cellular integrity and overall algal health in the presence of AgNPs, which suggests that mixotrophic cultivation may represent a protective strategy against nanoparticle-induced toxicity in aquatic microalgae.