The aim of experiments was to assess the efficiency of choline-stabilized orthosilicic acid (ch-OSA; complex of orthosilicic acid with choline and a bioavailable source of silicon) application under increasing manganese (Mn) stress on the micronutritional composition and yielding of tomato (Solanum lycopersicum L. cvs. 'Alboney F1' and 'Emotion F1'). Plants were grown in rockwool with the application of a nutrient solution varied the Mn concentrations (in mg dm(-3)): 9.6 and 19.2 which cause strong oxidative stress of plants comparing with optimal concentration of that microelement in nutrient solution. The effect of ch-OSA application (at Si concentration of 0.3 mg dm(-3) nutrient solution) was investigated at both Mn-levels. Increasing Mn stress modified the concentration of microelements and silicon (Si) in tomato leaves. Application of ch-OSA also influenced the concentration of nutrients, but the determined changes were generally multidirectional and varied depending on Mn-level and cultivar. Under the increasing Mn stress a significant downward trend was observed for the mean concentration of Fe (in both cultivars) in fruits--but changes of Mn, Zn and Cu were varied depend on cultivar. In the case of cv. 'Alboney F1' ch-OSA application caused an increase the mean concentrations of Fe, Zn and Cu, while in the case of cv. 'Emotion F1' the reduction of mean concentrations of Zn and Cu was recorded. Ch-OSA treatment did not influence on the Mn concentrations in fruits. A beneficial role of ch-OSA was also found in photosynthesis activity. This was especially valid for lower levels of Mn. Application of ch-OSA improved significantly the marketable yield of tomato under stress by a low Mn level.
We measured cadmium and lead concentrations in two littoral plants (Phragmites australis Cav. Trin ex. Steudel and Typha angustifolia L.) collected in June and September 2007 from five selected lakes in the Poznan city area, and also in sediment and water samples from the same places. We determined the metal concentrations in rhizomes and leaves, and in sediment and water from the littoral and near the bank zone. Only low levels of the heavy metals were found. Pb and Cd concentrations were higher in water collected from the bank zone than from the littoral zone. Pb and Cd accumulation was noted in sediments. Heavy metal levels were higher in rhizomes than in stems and leaves. The studied aquatic macrophytes may be bioaccumulators and bioindicators of Pb and Cd in freshwater in natural conditions, even when concentrations are low.K Ke ey y w wo or rd ds s: : Cadmium, lead, accumulation, Phragmites australis, Typha angustifolia.ACTA BIOLOGICA CRACOVIENSIA Series Botanica 52
Nutrition is one of the most important factors influencing quantitative and qualitative plant yield. This study examined the effect of manganese (Mn) in nutrient solution on photosynthetic activity parameters, and the relations between photosynthetic activity parameters, yield and plant nutrient status in tomato (Solanum lycopersicum L.). Mn supplementation significantly modified the nutrient content of leaves. Macronutrient content varied less than micronutrient content. The optimal Mn concentration differed between the studied cultivars. Both Mn deficit and Mn excess caused a decrease of tomato yield. Gas exchange parameters, relative water content (RWC) and specific leaf area (SLA) were measured in fully expanded tomato leaves. Certain levels of Mn were found to be needed for proper plant function and future yield, and toxic effects of excess Mn were noted. Changes in P N (net photosynthetic rate) were found to be the first signal of plant response to higher Mn supply, while yield was as for optimal Mn concentrations. Under Mn treatment, uptake of some nutrients increased. A higher level of absorbed Mg led to a higher photosynthesis rate and increased stomatal opening. P N and g s (stomatal conductance) also increased, while C i (intercellular CO 2 concentration) decreased, indicating proper CO 2 consumption during the assimilation process.K Ke ey y w wo or rd ds s: : Macroelement, microelement, Solanum lycopersicum L., photosynthetic activity, manganese stress.
Key message Zn caused an increase of photosynthesis activity, carbohydrates and chlorophyll at the level 1-2.5 mM, while phenols revealed a continuous increase together with Zn increase in the medium. Abstract The aim of the present study was to determine the effect of various Zn application levels on some physiological, morphological and biochemical parameters of a hybrid Salix purpurea 9 triandra 9 viminalis 2. Plants were cultivated under control conditions with application of Zn in the range 0-5 mM. The effects on net photosynthesis rate (P N ), stomatal conductance (g s ), transpiration rate (E), intercellular CO 2 (C i ), chlorophyll a and b, carotenoids, growth, sugars and phenols were analysed. Our investigations confirmed a dual role of Zn, with benefits at the level 1-2.5 mM, and a decrease of measured photosynthesis activity, carbohydrates and chlorophyll below and above this range. Moreover, the decrease of these parameters at the highest Zn application did not reach the level of control plants. This means that this species may have further potential as an accumulator in polluted areas. However, phenols revealed a continuous increase together with Zn increase in the medium.
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