Intensity Of Photosynthesis Research Articles

Анатомо-морфологические адаптации равноспорового папоротника Crepidomanes latealatum (Hymenophyllaceae) к специфическим условиям среды

In the course of the study, adaptations of the homosporous fern Crepidomanes latealatum (Bosch) Copel. to the petrophytic and epiphytic mode of life at the organismic and cell-tissue levels were revealed. These are the following: long rhizomatous creeping biomorphs growing both on flat surfaces of stones and on the bases of trunks with a small amount of humus applied to them; openwork and evergreen fronds, providing the maximum surface of contact with the environment and allowing photosynthesis year-round in conditions of extremely shaded microbiotopes; multifunctional trichomes, which are a protective device, preventing excessive evaporation, contributing to the absorption and retention of moisture and consolidation of the plant in the soil; the ability to flow into cryptobiosis and dwelling in moss sinuses for solving the problem of dehydration for a short period in the conditions of extreme hydration of the environment; reduction of mesophyll to one layer, as well as the apostrophic and epistrophic position of chloroplasts for effectively absorbing light of low intensity. The low intensity of photosynthesis under shading conditions is compensated by the equally low intensity of respiration, resulting in a positive balance of photosynthesis, allowing the fern to accumulate biomass. In the course of adaptationgenesis Crepidomanes latealatum was able to rise to a high level of morphological and ecological specialization. As a result of the reduction, structures were formed to compensate for poor lighting and increased hydration, there was a blurring of the boundaries between the organs and their transformation into new structures with the change of functions. The tactics of drought avoidance was effective because this fern is quite rare in seasonal climate azonal habitats in the moss synusia – rocks and stones near water sources, specific microniches on the butt of the trunks and etc. In conditions of water stress it is able to fall into cryptobiosis and to restore hydrature of cells under favorable conditions.

Influence of Aquatic Plant Photosynthesis on the Reservoir Effect of Genggahai Lake, Northeastern Qinghai-Tibetan Plateau

AbstractTerrestrial plant remains in the sediments of lakes from semi-arid and arid regions are rare and therefore the establishment of a sediment chronology depends on accurate assessment of the reservoir effect of the lake water. In a study of Genggahai Lake in the Gonghe Basin, northeastern Qinghai-Tibetan Plateau, we used accelerator mass spectrometry radiocarbon (AMS 14C) dating to determine the age of (1) dissolved inorganic carbon in the water (DICLW), (2) macrophyte remains in the uppermost samples of core sediments, (3) living P. pectinatus in the lake, and (4) dissolved inorganic carbon of spring water in the catchment. The results show that the ages of the DICLW (910 14C yr BP on average) were much younger than the ages of the groundwater (6330 14C yr BP on average), which may result mainly from CO2 exchange between the lake water and the atmosphere. In addition, the 14C ages of DICLW and macrophyte remains in the uppermost core sediments varied from site to site within the lake, which we ascribe to the different photosynthesis rates of Chara spp. and vascular plants. The higher photosynthesis rate of Chara spp. decreases lake-water pCO2, which leads to more atmospheric CO2 being absorbed by the lake water, and thereby greatly reducing the age of carbon species in areas dominated by Chara spp. Although Genggahai Lake is well mixed, the differences between the apparent ages of the lake water are significantly modulated by the photosynthesis intensity of submerged plants.

Mechanisms of oat (Avena sativa L.) acclimation to phosphate deficiency.

BackgroundDeficiency of available forms of phosphorus is common in most soils and causes reduction of crop plants growth and yield. Recently, model plants responses to phosphate (Pi) deficiency have been intensively studied. However, acclimation mechanisms of cereals like oat (Avena sativa L.), to low Pi stress remains not fully understood. Oat plants have been usually cultured on poor soils, with a low nutrient content, but their responses to such conditions are not well known, therefore the main goal of the study was to investigate the mechanisms that enable oat plants to grow under low Pi conditions.MethodsFour oat cultivars (A. sativa, cv. Arab, Krezus, Rajtar and Szakal) were grown for three weeks in a nutrient media with various P sources: inorganic—KH2PO4 (control), organic—phytate (PA) and with no phosphate (−P). The effects of Pi deficiency on the level of P, oat growth parameters, intensity of photosynthesis, plant productivity, root exudation ability, localization, activity and isoforms of acid phosphatases, enzymes involved in Pi mobilization, were estimated. In addition, the effect of mycorrhization on plant growth was also observed.ResultsAll studied oat cultivars grown on Pi-deficient media had significantly decreased Pi content in the tissues. Pi deficiency caused inhibition of shoot growth, but generally it did not affect root elongation; root diameter was decreased, root/shoot ratios increased, whereas PA plants showed a similar growth to control. Photosynthesis rate and productivity parameters decreased under low Pi nutrition, however, sugar content generally increased. Studied oat cultivars did not respond to low Pi via increased exudation of carboxylates from the roots, as pH changes in the growth media were not observed. Pi starvation significantly increased the activity of extracellular and intracellular acid phosphatases (APases) in comparison to the control plants. Three major APase isoforms were detected in oat tissues and the isoform pattern was similar in all studied conditions, usually with a higher level of one of the isoforms under Pi starvation. Generally no significant effects of mycorrhizal colonization on growth of oat cultivars were observed.DiscussionWe postulated that acid phosphatases played the most important role in oat cultivars acclimation to Pi deficiency, especially extracellular enzymes involved in Pi acquisition from soil organic P esters. These APases are mainly located in the epidermis of young roots, and may be released to the rhizosphere. On the other hand, intracellular APases could be involved in fast Pi remobilization from internal sources. Our study showed that oat, in contrast to other plants, can use phytates as the sole source of P. The studied oat cultivars demonstrated similar acclimation mechanisms to Pi deficiency, however, depending on stress level, they can use different pools of acid phosphatases.

Influence of abiotic factors on photosynthesis and production process of different winter wheat varieties

Aim. The investigation of photosynthesis and production process in winter wheat varieties, different in their grain productivity, its connection to the active surface area of the root system in optimal conditions, under drought and mineral nutrition defi ciency. Methods. Physiological, biochemical, gas exchange analysis, statisti- cal methods. Results. It was demonstrated that different conditions of mineral nutrition and soil drought have impact on the intensity of photosynthesis, photo- and dark respiration, the content of pigments in the fl ag leaf of winter wheat plants; the results obtained testify to the interrelation of these indices to the active surface area of the root system and grain productivity of winter wheat varieties, different in potential grain productivity. Conclusions. It was determined that under drought the photosynthetic apparatus of a highly productive winter wheat variety Smuhlianka demonstrated higher stability compared to the photosynthetic apparatus of the vari- ety Myronivska 808, moderately resistant to drought conditions. At the same time, highly intensive varieties of winter wheat, Favorytka and Smuhlianka, had a larger active surface area of the root system and chlorophyll content in leaves, compared to Myronivska 808 plants, notable for their lower grain productivity. It was deter- mined that there was considerable reliable correlation between the intensity of fl ag leaf photorespiration and the active surface area of the root system in winter wheat plants of varieties Myronivska 808 and Smuhlianka (r = 0.805). Considerable correlation (r = 0.878) was found between the intensity of fl ag leaf photorespiration in the heading-blossoming phase and the sum of chlorophylls in these leaves. It was determined that the index S r act × chlorophyll may be used to estimate the active surface area of the root system with the error of up to 3.8 % for fi ve winter wheat varieties.

Carbon dioxide exchange in the needles of the common spruce in southern taiga spruce forests

Dynamics of carbon dioxide exchange in the Common Spruce (Picea abies L.) in relation to environmental factors was monitored during several seasons. Direct linear dependence of photosynthesis rate from the levels of air temperature and illumination was found, and correlation coefficients were 0.860 (p < 0.001) and 0.704 (p < 0.001). It was found that seasonal maximum of net photosynthesis production was attained at temperatures of 23–25°C. A decrease in temperature optimum was associated with reduction of the CO2 assimilation intensity level. The impact of environmental factors on photosynthesis intensity is discussed in terms of the developed model. Using this model, we demonstrated that temperature and illumination dynamics in toto accounts for 82% of changes in photosynthesis rate. It is the air temperature that exerts the strongest influence on the process of photosynthesis. According to our calculations, the net photosynthesis level was three times higher than the level of respiration. This is indicative of a positive carbon dioxide balance in the needles of the Common Spruce.

Effectiveness of cyanobacteria and green algae in enhancing the photosynthetic performance and growth of willow (Salix viminalis L.) plants under limited synthetic fertilizers application

The physiological response of plants to triple foliar biofertilization with cyanobacteria and green algae under the conditions of limited use of chemical fertilizers was investigated. Triple foliar biofertilization with intact cells of Microcystis aeruginosa MKR 0105, Anabaena sp. PCC 7120, and Chlorella sp. significantly enhanced physiological performance and growth of plants fertilized with a synthetic fertilizer YaraMila Complex (1.0, 0.5, and 0.0 g per plant). This biofertilization increased the stability of cytomembranes, chlorophyll content, intensity of net photosynthesis, transpiration, stomatal conductance, and decreased intercellular CO2 concentration. Applied monocultures augmented the quantity of N, P, K in plants, the activity of enzymes, such as dehydrogenases, RNase, acid or alkaline phosphatase and nitrate reductase. They also improved the growth of willow plants. This study revealed that the applied nontoxic cyanobacteria and green algae monocultures have a very useful potential to increase production of willow, and needed doses of chemical fertilizers can be reduced.

Operation of an enclosed aquatic ecosystem in the Shenzhou-8 mission

Long- term spaceflight needs reliable Biological life support systems (BLSS) to supply astronauts with enough food, fresh air and recycle wasters, but the knowledge about the operation pattern and controlling strategy is rear. For this purpose, a miniaturized enclosed aquatic ecosystem was developed and flown on the Chinese spaceship Shenzhou-8. The system with a total volume of about 60mL was separated into two chambers by means of a gas transparent membrane. The lower chamber was inoculated with Euglena gracilis cells, and the upper chamber was cultured with Chlorella cells and three snails. After 17.5 days flight, the samples were analyzed. It was found that all snails in the ground module (GM) were alive, while in the flight module (FM) only one snail survived. The total cell numbers, assimilation of nutrients like nitrogen and phosphorus, soluble proteins and carbohydrate contents showed a decrease in FM than in GM. The correlation analysis showed upper chambers of both FM and GM had the same positive and negative correlation factors, while differential correlation was found in lower chambers. These results suggested primary productivity in the enclosed system decreased in microgravity, accompanied with nutrients assimilation. The FM chamber endured lacking of domination species to sustain the system development and GM chamber endured richness in population abundance. These results implied photosynthesis intensity should be reduced to keep the system healthy. More Chlorella but less Euglena might be a useful strategy to sustain system stability. It is the first systematic analysis of enclosed systems in microgravity.

ЗАВИСИМОСТЬ ИНТЕНСИВНОСТИ ФОТОСИНТЕЗА LAURUS NOBILIS L. ОТ ФАКТОРОВ ВНЕШНЕЙ СРЕДЫ (ТВ, I-ФАР, DВОЗ.), ТЕМПЕРАТУРЫ ЛИСТЬЕВ, ТРАНСПИРАЦИИ И ИХ ИЗМЕНЕНИЕ В ХОДЕ ВЕГЕТАЦИИ В УСЛОВИЯХ ЮБК

ЗАВИСИМОСТЬ ИНТЕНСИВНОСТИ ФОТОСИНТЕЗА LAURUS NOBILIS L. ОТ ФАКТОРОВ ВНЕШНЕЙ СРЕДЫ (ТВ, I-ФАР, DВОЗ.), ТЕМПЕРАТУРЫ ЛИСТЬЕВ, ТРАНСПИРАЦИИ И ИХ ИЗМЕНЕНИЕ В ХОДЕ ВЕГЕТАЦИИ В УСЛОВИЯХ ЮБК

Scientific study of 13C/12C carbon and 18O/16O oxygen stable isotopes biological fractionation in grapes in the Black Sea, Don Basin and the Western Caspian regions

The report presents the results of a study of carbon and oxygen stable isotopes in carbohydrates and intracellular water of red and white grapes of 2016 wine-growing season in the Crimean peninsula areas, South-west coast of the Greater Caucasus, the Don basin and the Western Caspian region. The mass concentration of reducing sugars in the studied grape samples has been from 17.5 to 25.0 g/100 ml, titrated acids concentration (based on tartaric acid) – from 6.0 to 9.1 g/l, the buffer capacity 34.1–63.2 mg-Eq/l. Red and white wine made from respective grapes contained from 0.5 to 3.6 g/l of residual sugar; from 11.1 to 14.5% ethanol by volume; buffer capacity was 35.2–52.6 mg-Eq/l. It has been found that the δ13 CVPDB values for carbohydrates of red and white grape varieties as a result of biological fractionation of carbon isotopes in the agro-climatic conditions of plant growth for the studied geographical areas are ranging from − 26.74 to − 20.74‰ (the Crimean peninsula); from − 27.31 to − 21.58‰ (South West Coast of the Greater Caucasus), from − 27.33 to − 24.73‰ (Don Basin) and from − 26.64 to − 23.17‰ (West Caspian). The δ13 CVPDB values for ethanol of the red and white dry wines range from − 28.52 to − 24.26‰ (the Crimean peninsula); from − 29.23 to − 24.52‰ (South West Coast of the Greater Caucasus); from − 28.97 to − 26.22‰ (Don Basin); from − 29.14 to − 25.22‰ (Western Caspian). Compared with the surface water and groundwater (averages from δ18 OVSMOW − 13.90 to − 6.38‰) and with precipitation (averages from δ18 OVSMOW − 10.30 to − 9.04‰) the δ18 OVSMOW values in intracellular water of grapes are the following: for the Crimean peninsula grapes, from 0.40 to 4.97‰; the South West Coast of the Greater Caucasus, from -2.11 to 6.29‰; the Don Basin, from − 2.21 to 6.26‰; the Western Caspian, from − 0.24 to 1.44‰. It has been noted that in conditions of water shortage caused by low rainfall or lack of rainfall and irrigation, grapes are prone to the accumulation of “heavy” 13 C carbon isotope due to changes in isotopic exchange with the environment through a partial reduction in the intensity of transpiration and photosynthesis.

ИНТЕНСИВНОСТЬ ФОТОСИНТЕЗА ЛИСТЬЕВ РАСТЕНИЙ ГРЕЧИХИ В СВЯЗИ С СЕЛЕКЦИЕЙ НА ВЫСОКУЮ И СТАБИЛЬНУЮ УРОЖАЙНОСТЬ

ИНТЕНСИВНОСТЬ ФОТОСИНТЕЗА ЛИСТЬЕВ РАСТЕНИЙ ГРЕЧИХИ В СВЯЗИ С СЕЛЕКЦИЕЙ НА ВЫСОКУЮ И СТАБИЛЬНУЮ УРОЖАЙНОСТЬ

Role of photosynthetic potential in identifying the regularities of functioning of the bioproductivity of agrobiocenoses

It is shown that the optimal value of the photosynthetic potential determining the level of productivity of agricultural crops is achieved mainly by selecting varieties and hybrids that are adapted for every growing area and taking into account the time of their physiological activity and the high intensity of photosynthesis. A model of photosynthetic potential in irrigated light-brown soils in the system of forest belts is given. The regularity of the functioning of agroforestry systems in the form of exponential dependence has been revealed for forecasting maize bioproductivity.

The Effect of Different Doses of Blue Light on the Biometric Traits and Photosynthesis of Dill Plants

The supplementation of blue light to red light enhanced plant growth compared with the use of red alone. The aim of thestudy was to determine the effect of different doses of blue light on the biometric traits and photosynthesis of dill plants. Theplants were grown in pots in a growth chamber. They were grown in red light (100 μmol m-2 s-1) and blue light (from 10 to 50μmol m-2 s-1) in five combinations. Light emitting diode modules were the source of light. The plants were evaluated every 7days during vegetation, for the first time - seven days after germination and later on the 14th, 21st and 28th day aftergermination. The share of blue light in the spectrum significantly influenced the biometric traits of the dill plants. Itsignificantly inhibited the elongation growth of the plants and negatively affected the increase in fresh weight. A small dose ofblue light (20%) had positive effect on the plants’ area. The research did not reveal a simple relationship between the amountof blue light and dry weight yield. The value of physiological indexes depended both on the combination and measurementtime. The plants from the combination with 30% blue light were characterised by the greatest photosynthesis intensity. Aneffective share of blue light in the spectrum may range from 10 to 30% in relation to red light and depends on the plant’sdevelopment phase and on the result we want to achieve in the cultivation of plants.

The Effect of Different Doses of Blue Light on the Biometric Traits and Photosynthesis of Dill Plants

The supplementation of blue light to red light enhanced plant growth compared with the use of red alone. The aim of thestudy was to determine the effect of different doses of blue light on the biometric traits and photosynthesis of dill plants. Theplants were grown in pots in a growth chamber. They were grown in red light (100 μmol m-2 s-1) and blue light (from 10 to 50μmol m-2 s-1) in five combinations. Light emitting diode modules were the source of light. The plants were evaluated every 7days during vegetation, for the first time - seven days after germination and later on the 14th, 21st and 28th day aftergermination. The share of blue light in the spectrum significantly influenced the biometric traits of the dill plants. Itsignificantly inhibited the elongation growth of the plants and negatively affected the increase in fresh weight. A small dose ofblue light (20%) had positive effect on the plants’ area. The research did not reveal a simple relationship between the amountof blue light and dry weight yield. The value of physiological indexes depended both on the combination and measurementtime. The plants from the combination with 30% blue light were characterised by the greatest photosynthesis intensity. Aneffective share of blue light in the spectrum may range from 10 to 30% in relation to red light and depends on the plant’sdevelopment phase and on the result we want to achieve in the cultivation of plants.

Different responses of two ecotypes of C3–C4 xero-halophyte Bassia sedoides to osmotic and ionic factors of salt stress

The effects of low and moderate salinity (100 and 200 mM NaCl, respectively) and iso-osmotic stress generated by polyethylene glycol PEG (1) (–0.3 MPa) and PEG (2) (–0.6 MPa) on maximum quantum yield of photosystem II (PSII), growth, photosynthesis, transpiration, dark respiration, water use efficiency (WUE), water content, chlorophyll, proline, Na+ and K+ concentrations were investigated in shoots of two ecotypes С3–С4 xero-halophyte Bassia sedoides (Pall.) Aschers. Plants were grown from seeds of two Southern Urals populations (Makan and Podolsk) differing in their bioproductivity. Aboveground biomass of the Makan plants was approximately 10-fold higher than that of the Podolsk ecotype. The plants of both ecotypes were sensitive to water deficit. They showed similar decrease in biomass, water content, net photosynthesis and transpiration intensity under both low and moderate osmotic stress (PEG). However, the content of сhlorophyll and free proline in shoots of the Podolsk plants increased under moderate osmotic stress (PEG(2)). Under salinity the differences between transpiration, F v/F m, WUE, water content, chlorophyll and proline concentrations in shoots of two ecotypes were no found. But, the Podolsk plants showed decrease in the growth parameters (1.5-fold), increase in the dark respiration intensity (2-fold) and the Na+/K+ ratio (1.2-fold) under moderate salinity (200 mM NaCl). Thus, the reduction of bioproductivity of the Podolsk ecotype under salinity was the result of ionic rather than osmotic factor of salinity. In the Podolsk plants the additional transpiration costs and consumption of assimilates (correspondingly) increased with the toxic sodium ion accumulation under salinity. This led to decrease in the growth parameters. Thus, two B. sedoides ecotypes have different adaptive strategies of tolerance to the ionic factor of salt stress at the level of the physiological processes associated with the dark CO2 gas exchange. Moreover, in less tolerant and productive Podolsk ecotype the increase in proline content in shoots characterized comparatively low adaptation to osmotic factor, and the increase in dark respiration and the Na+/K+ ratio pointed to relatively low resistance to ion factor of salinity as compared with the Makan ecotype.

Toxic effects of high copper content on physiological processes in Pinus sylvestris L.

The aim of this study was to determine the impact of increased copper contents on selected physiological processes in oneyear-old Pinus sylvestris L. needles from a former German timber storage area in Warcino Forest District, a subject to an environmental quality survey. Samples were collected from the area with the high copper content in the soil. The control area was a nearby pine tree stand showing unimpeded growth. The significant growth inhibition was found in dwarf shoots and whole needles, increased water content, and reduced dry mass were also observed. The chlorophyll content was lowered, while 20% higher electrolyte leakage was found. Chlorophyll a fluorescence indicated only higher values of the nonphotochemical quenching in P. sylvestris from the Cu-site. Significant differences were shown in the rate of gas exchange measured by changes in carbon dioxide or oxygen concentration. The intensity of photosynthesis in needles of P. sylvestris from the Cu-site measured by CO2 uptake was considerably higher than that of oxygen production. The rate of respiration in the needles from the Cu-site measured by the amount of released CO2 was higher only by 15%, while according to O2 consumed, the rate increased by 30% in relation to the control. Our results suggest that the copper accumulation in P. sylvestris needles affected the morphology and physiology of the studied organs.

Research Concerning the Influence of Fertilization on Some Physiological Processes and Biochemical Composition of Lavender (Lavandula Angustifolia L.)

Abstract The aim of the research was to study the influence of phosphorus (P) and potassium (K) fertilization on the main physiological processes in lavender and biochemical characterization of essential oil obtained by steam distillation. Physiological processes studied were the photosynthesis and transpiration intensity. The material used for herbal purposes includes commercial genotype of lavender (Lavandula angustifolia L.). Experiment was carried out under controlled conditions and fertilization was performed with a modified Hoagland nutrient solutions. For biochemical analysis were used average samples of lavender leaf, stem and flowers. Separation and analysis of compounds was performed by gas chromatography analysis coupled with mass spectrometry (GC-MS). Transpiration intensity was performed by successive mass determinations from leaves and resulted values were reported per unit leaf area. The rate of photosynthesis was measured by Qubit Systems CO 2 analysis package. Researches were performed in the laboratory of Plant Physiology within the Faculty of Horticulture and Forestry and Plant extracts laboratory, Faculty of Food Processing Technology, from Banat University of Agricultural Sciences and Veterinary Medicine Timisoara. Following the experiment, it was found that potassium fertilization has a positive effect both on the photosynthesis and transpiration. Linalool (30.398%), lynalil acetate (23.609%), camphor (8.844%), borneol (5.49%) and eucalyptol (3.964%), were determined as the main compounds from over 50 identified through biochemical analysis of the essential oil.

State, ecological-coenotic characteristics, and prospects of the silver birch (Betula pendula Roth, Betulaceae, Dicotyledones) forest cultures in steppe afforestation

In the summer of 2010, thermal damages to birch in cultures reached 4.2–4.8 points according to the authors’ five-point scale. In 2011, the stands of birch trees were weakened to variable degrees, but some healthy stands remained. High-density forest massifs and birch forest belts are more drought-resistant. The grass cover is weakly developed therein. Thinned birch cultures become overgrown with herbs and die out after droughts. The root exudates of shrubs depress the intensity of photosynthesis of steppe plants by 10–25%. In vegetation experiments, various species of shrubs stimulate or slow down the growth of shoots and roots and the intensity of photosynthesis of the birch by 10–30%, on average. It is recommended to cultivate birch trees in forest belts using shrubby borders with high allelopathic activity for biological defense of the soil from overgrowth with weedy and steppe plants.

Photosynthetic parameters and physiological indexes of Paris polyphylla var. yunnanensis influenced by arbuscular mycorrhizal fungi

Through potted inoculation test at room temperature and indoor analysis, the photosynthetic parameters and physiological and biochemical indexes of Paris polyphylla var. yunnanensis were observed after 28 arbuscular mycorrhizal (AM) fungi were injected into the P. polyphylla var. yunnanensis growing in a sterile soil environment. The results showed that AM fungi established a good symbiosis with P. polyphylla var. yunnanensis. The AM fungi influenced the photosynthetic parameters and physiological and biochemical indexes of P. polyphylla var. yunnanensis. And the influences were varied depending on different AM fungi. The application of AM fungi improved photosynthesis intensity of P. polyphylla var. yunnanensis mesophyll cells, the contents of soluble protein and soluble sugar, protective enzyme activity of P. polyphylla var. yunnanensis leaf, which was beneficial to resist the adverse environment and promote the growth of P. polyphylla var. yunnanensis. Otherwise, there was a certain mutual selectivity between P. polyphylla var. yunnanensis and AM fungi. From the comprehensive effect of inoculation, Racocetra coralloidea, Scutellospora calospora, Claroideoglomus claroideum, S. pellucida and Rhizophagus clarus were the most suitable AM fungi to P. polyphylla var. yunnanensis when P. polyphylla var. yunnanensis was planted in the field.

Discrepancies between the stable isotope compositions of water, macrophyte carbonates and organics, and mollusc shells in the littoral zone of a charophyte-dominated lake (Lake Lednica, Poland)

The aim of this study was to better understand the relations between carbon and oxygen stable isotope values of ambient water, mollusc shells, macrophytes and their carbonate encrustations, commonly used in palaeolimnological studies. Water, molluscs and macrophytes were sampled from the littoral zone in Lake Lednica, NW Poland. The influence of carbon species assimilated during photosynthesis and the net intensity of photosynthesis resulting from the size of charophyte species and the density of their stands were postulated to be the most important factors causing the species-specific δ13C values of charophyte thalli and encrustations. It was suggested that photosynthetic activity of charophytes affected not only the δ13C values of charophyte encrustations but also mollusc shells by changing δ13C values of DIC within charophyte stands. In addition, incorporation of metabolic carbon into the shell was proposed as the main cause of both the 13C depletion of mollusc shells relative to δ13C values of DIC and the species-specific δ13C values of shells. Mollusc shells were precipitated at the isotope equilibrium or close to the equilibrium with δ18O values of lake water. Charophyte encrustations were found to be 18O depleted due to the kinetic isotope effects during intense photosynthesis and thus fast precipitation of the calcite.

Research on the Effect of Electrical Signals on Growth of Sansevieria under Light-Emitting Diode (LED) Lighting Environment.

The plant electrical signal has some features, e.g. weak, low-frequency and time-varying. To detect changes in plant electrical signals, LED light source was used to create a controllable light environment in this study. The electrical signal data were collected from Sansevieria leaves under the different illumination conditions, and the data was analyzed in time domain, frequency domain and time–frequency domain, respectively. These analyses are helpful to explore the relationship between changes in the light environment and electrical signals in Sansevieria leaves. The changes in the plant electrical signal reflected the changes in the intensity of photosynthesis. In this study, we proposed a new method to express plant photosynthetic intensity as a function of the electrical signal. That is, the plant electrical signal can be used to describe the state of plant growth.