Photosynthetic Activity Parameters Research Articles

Analysis of the variability of morphometric and physiological parameters of grain crops when using biofertilizers

Currently, solving the problem of improving agricultural crops’ productivity is of great relevance. The parameters of photosynthetic activity play an important role in photosynthesis and ensure the efficient functioning of plants under various conditions. Understanding of these processes helps better understand the mechanisms of plant growth and development, as well as develop methods to increase productivity and resistance to stress conditions. The purpose of the current study was to estimate the effect of biofertilizers on the functioning of the photosynthetic apparatus and the variability of the area of leaf blades of agricultural grain crops (durum wheat, spring barley), and to establish the dependence of productivity on the ameliorant used. The objects of study were the spring barley variety ‘Anna’ and the durum wheat variety ‘Orenburgskaya’. The area of the leaf blade was measured by scanning using the APFill Ink&Toner Coverage Meter program. To determine the chlorophyll content, there was used a portable N-tester. There has been reliably established positive correlation between productivity increase and the size of the leaf blade of the experimental plants. The application of the studied biofertilizer has had a positive effect on chlorophyll increase in the barley leaf blades. This explains the possibility of changing the studied parameters by agricultural methods (fertilizer application). There has been found a significant correlation (at p˂0.05) between the height parameters with a number of seeds in a head (r = 0.63) and a leaf blade area (r = 0,69), a number of seeds in a head and productivity (r = 0.86). As a result of the study, there has been established a relationship between some quantitative parameters of the seed material (head length – number of seeds in a head), and a positive correlation was identified between a leaf area and a head length (r = 0.69). There has been obtained a significant dependence of barley productivity on the ameliorant used. At the same time, the productivity increase when using fertilizer compared to the control was 58.9 %.

Understanding boron toxicity in aquatic plants (Salvinia natans and Lemna minor) in the presence and absence of EDTA

Even though boron is a widely used element in various industries and a contributor to water pollution worldwide, few studies have examined the toxicity of boron in aquatic plants. EDTA is used to maintain aquatic plants cultures, however it is possible to modify the toxicity of metals. The objective of this study is to assess the toxicity of boron in aquatic plants and explore the impact of EDTA presence on the resulting toxic responses. Floating watermoss Salvinia natans and duckweed Lemna minor were exposed to concentrations ranging from 5 to 100 mg/L for 7 days and 1 to 60 mg/L for 3 days, respectively. Growth and photosynthetic activity parameters were investigated in the presence and absence of EDTA. Growth inhibitions in both aquatic plants were observed in a concentration-dependent manner, irrespective of the presence or absence of EDTA. For instance, based on the specific growth rate (leaves coverage), EC10 values for S. natans were calculated as 12.7 (9.9–15.3) mg/L and 8.0 (5.8–10.3) mg/L with and without EDTA, respectively. In the case of L. minor, EC10 values were calculated as 1.3 (0.8–1.89) mg/L and 2.0 (0.4–4.3) mg/L with EDTA without EDTA, respectively. Significant effects were also observed on the photosynthetic capacity, however there was no change in the increase of boron concentration. Generally, negligible effects of EDTA to the toxicity of boron were observed in the present study. By comparing toxicity results based on the presence and absence of EDTA, which is an essential element in the test medium, the results of this study are expected to be utilized for the ecological risk assessment of boron in aquatic ecosystems.

Prediction of biomass accumulation and tolerance of wheat seedlings to drought and elevated temperatures using hyperspectral imaging.

Early prediction of important agricultural traits in wheat opens up broad prospects for the development of approaches to accelerate the selection of genotypes for further breeding trials. This study is devoted to the search for predictors of biomass accumulation and tolerance of wheat to abiotic stressors. Hyperspectral (HS) and chlorophyll fluorescence (ChlF) parameters were analyzed as predictors under laboratory conditions. The predictive ability of reflectance and normalized difference indices (NDIs), as well as their relationship with parameters of photosynthetic activity, which is a key process influencing organic matter production and crop yields, were analyzed. HS parameters calculated using the wavelengths in Red (R) band and the spectral range next to the red edge (FR-NIR) were found to be correlated with biomass accumulation. The same ranges showed potential for predicting wheat tolerance to elevated temperatures. The relationship of HS predictors with biomass accumulation and heat tolerance were of opposite sign. A number of ChlF parameters also showed statistically significant correlation with biomass accumulation and heat tolerance. A correlation between HS and ChlF parameters, that demonstrated potential for predicting biomass accumulation and tolerance, has been shown. No predictors of drought tolerance were found among the HS and ChlF parameters analyzed.

Defoliation tolerance of soybean cultivars commercially released in different decades

Breeding programs have increased the precocity and yield potential of modern soybean cultivars. Such changes may have altered the crop tolerance to defoliation due to the smaller leaf area of modern cultivars. The objective of this study was to determine the tolerance to defoliation of soybean cultivars commercialized in Brazil in different decades, their photosynthetic efficiency and the relationship between photosynthetic efficiency and tolerance to defoliation in the reproductive phase. The experiment was set in a greenhouse with controlled humidity and temperature, in the municipality of Lages, Santa Catarina State, South of Brazil, during the growing season of 2018/2019. A randomized block design was used, with treatments arranged in a 5×5 factorial scheme. The first factor was composed of five soybean cultivars released in different years: Davis (1968), Paraná (1974), BR-16 (1985), FT Abyara (1991), and Brasmax Elite IPRO (2014). The second factor consisted of five levels of defoliation applied in stage R3: 0, 16.6, 33.3, 50.0, and 66.6%. Leaf area, photosynthetic activity parameters, grain yield and its components were determined. Brasmax Elite IPRO had the lowest grain yield per plant and did not increase yield compared to older cultivars, regardless of defoliation level. There were no significant differences in photosynthetic efficiency or defoliation tolerance between the modern cultivar Brasmax Elite IPRO and the old cultivars Davis, Paraná, BR-16, and FT Abyara.

The Treatment of Aquaculture Wastewater with Biological Aerated Filters: From the Treatment Process to the Microbial Mechanism

Algal cell proliferation has posed significant problems for traditional water treatment facilities; these problems are attributed to surface hydrophilicity and electrostatic repulsion. Biological aerated filters (BAFs) have been extensively used in wastewater treatment to remove pollutants such as algal cells by utilizing the adsorption and separation capabilities of the filter media. In this study, a BAF was supplemented with biological filter medium (Marchantia polymorpha) to assess its effectiveness of pretreating aquaculture wastewater. In terms of process performance, steady and consistent treatment was achieved by the BAF with M. polymorpha (BAF2) under an algal cell density as high as 1.65 × 108 cell/L, with average removal rates for NH4+-N and algae cells of 74.4% and 81.9%, respectively. The photosynthetic activity parameters (rETRmax, α, Fv/Fm, and Ik) of the influent and effluent were quantitatively assessed, and M. polymorpha was found to remove algae by disrupting the photosynthetic system of the algal cells. Furthermore, the addition of the M. polymorpha filter medium enhanced the community structure of the functional microbes in the BAF system. The highest microbial community richness and diversity were observed in the BAF2. Meanwhile, M. polymorpha promoted an increase in the abundance of denitrifying bacteria, including Bdellovibrio and Pseudomonas. Overall, this work offers a unique perspective on the aquaculture wastewater pretreatment process and BAF design.

Attenuating the toxicity of isoproturon to maize by priming in ascorbate, glutathione or thiourea

Maize grains were primed in ascorbate (AsA), glutathione (GSH) or thiourea (TU) for 24 h, sown in pots for 10 days and then treated with Ipu whose residues persisted in shoots from the next day and increased over 8 days and then decreased continuously. The herbicide significantly reduced growth parameters, pigments, photosynthetic activity parameters, AsA, GSH and GSH/oxidized glutathione (GSSG) ratio and inhibited the activities of δ-aminolevulinate dehydratase (ALA-D), ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEP-C), malate dehydrogenase (MDH), pyruvate phosphate dikinase (PPDK), superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) but significantly increased malondialdehyde (MDA), H 2 O 2 , superoxide radicals (O 2 ∙−) and GSSG. The priming mostly improved the tested parameters and overcame the deficiency in enzymatic and non-enzymatic antioxidants as well as in the photosynthetic parameters and enzyme activities; AsA or GSH were more efficient than TU. Besides, in vitro tests showed that the inhibition constant (IC50) for Ipu was lowest for CAT but highest for PPDK indicating that CAT was the most inhibited but PPDK was the least while the others were moderate. Furthermore, calculations showed that Ipu competitively inhibited ALA-D, Rubisco, APX, PEP-C, MDH and PPDK but caused non-competitive inhibition of APX, CAT and SOD. These findings reveal that maize was prone to suffering from Ipu; however, priming attenuated the toxicity of Ipu and overcame the herbicide impacts by repairing, maintaining and improving antioxidants and photosynthetic activities .

Photosynthetic activity of wheat - wheatgrass hybrids and winter wheat under salinization

Wheat is considered to be one the most important crop on Earth. Wheat-wheatgrass hybrids are the promising gene donors for further breedingprocrss. The parameters of photosynthetic activity are the key factor of crop yield formation. Based on the parameters of photosynthetic activity, the most resistant to salinization hybrids of PPG and wheat were identified. The structure of the photosynthetic apparatus of wheat plants and wheat-wheatgrass hybrids under the salinization is described.

Technology of effective microorganisms for the growth of agricultural plants of the Fabaceae family

This article presents the results of studies reflecting the influence of the technology of effective microorganisms (TEM) on the development of plants of the Fabaceae family (Pisum sativum L.). The assessment of the real effectiveness of EM agents in the mild climate of the Central Black Earth region and their influence on field germination and morphophysiological parameters of plants is given. The theoretical foundations of the use of EM agents, their role in the formation of soil microbiological communities and the assessment of their impact as a factor influencing the efficiency of legume-rhizobium symbiosis are presented. The exogenous treatment with biological products significantly increased the number and mass of active nodules on experimental plants, which contributed to the increase in nitrogen-fixing activity, which was an important component for legumes. The authors pay due attention to the assessment of the parameters of photosynthetic activity of plants under the conditions of increased inoculation with microorganisms. Not only an increase in leaf area was noted, but also a longer functioning of the photosynthetic apparatus, which led to an increase in the intensity of the work of the green surface of plants during the entire growing season. The combination of stimulating factors provided a better increase in dry biomass, which was reflected in a significant increase in the value of plant yield. The most intense accumulation of dry matter was observed in the flowering phase, which was also characterized by more intensive inoculation of plants. At the end of the growing season, this was reflected in an increase in the number of beans per plant and seeds in one bean, which had a positive effect on the crop yield indicators. The research results indicate the prospects of the use of the technology of effective microorganisms in plant growing and agriculture for the production of environmentally friendly food products and soil fertility recovery.

ФОТОСИНТЕТИЧНІ ПАРАМЕТРИ ПОСІВІВ ПШЕНИЦІ ТВЕРДОЇ ОЗИМОЇ ЗАЛЕЖНО ВІД СОРТУ

Under different weather conditions, not all plant varieties successfully adapt to agro-ecosystems. Given that, wheat is the most important food crop It is important to study the possibility of its adaptation to climatic conditions. The choice of plant variety is the first, most important and most difficult stage for wheat producers. Aim. To study the parameters of photosynthetic activity of durum winter wheat plantings depending on the variety. Methods. Laboratory, mathematical and statistical, physical. Results. The article presents the formation of photosynthetic parameters (length, leaf width, number of leaves on one stem, area of one leaf, area of one stem, leaf surface area, apical leaf parameters) of durum winter wheat plantings depending on the variety. The length and width of durum winter wheat leaves varied significantly depending on the variety and stage of plant growth. On the average for three years of researches the number of leaves on one stem in the tillering stage was 4.1–4.5 pieces depending on the variety. In the booting stage, this indicator was the lowest – 3.1–3.3 pieces, and in the earing stage of all varieties was at the level of 4.0 pieces. The number of leaves on the stem almost did not change during the milk stage of grain – 3.9–4.0 pieces. The parameters of the apical leaf also varied significantly with weather conditions. The area of apical leaves in 2013 in the standard and studied varieties was 5.9 and 5.5–7.3 thousand m2/ha, respectively. In the following 2014, the leaf area indicator was higher than in 2013 by 51–60%. The increase in leaf area in durum winter wheat in 2014 is due to the formation of a higher number of stems compared to 2013. Conclusions. Photosynthetic parameters of durum winter wheat plantings have features. The number of leaves on one stem changed the least depending on the year of study, as the variation coefficient was insignificant (V = 1.7–3.6 %). The length and width of durum wheat leaf varied in a wide range - V = 3.7–53.0 %. In the more favourable 2014, the leaf surface area was 40.1–71.0 thousand m2/ha in the earing stage, and in the less favourable – 15.9–29.0 thousand m2/ha in the earing and milk stages of grain depending on the variety. The area of apical leaves varies from 5.7–7.3 to 8.8–14.2 thousand m2/ha depending on the weather conditions of the season

The nuclear GUCT domain-containing DEAD-box RNA helicases govern gametophytic and sporophytic development in Physcomitrium patens

Key messageIn Physcomitrium patens, PpRH1/PpRH2 are GUCT-domain-containing DEAD-BOX RNA helicases localize to the nucleus. They are implicated in cell and tissue development in all stages of the moss life cycle.The DEAD-box-containing RNA helicase family encompasses a large and functionally important group of enzymes involved in cellular processes committed to the metabolism of RNA, including its transcription, processing, transport, translation and decay. Studies indicate this protein family has implied roles in plant vegetative and reproductive developmental processes as well as response to environmental stresses such has cold and high salinity. We focus here on a small conserved sub-group of GUCT domain-containing RNA helicase in the moss Physcomitrium patens. Phylogenetic analysis shows that RNA helicases containing the GUCT domain form a distinct conserved clade across the green lineage. In this clade, the P. patens genome possesses two closely related paralogues RNA helicases predicted to be nuclear, PpRH1 and PpRH2. Using in-locus gene fluorescent tagging we show that PpRH1 is localized to the nucleus in protonema. Analysis of PpRH1 and PpRH2 deletions, individually and together, indicates their potential roles in protonema, gametophore and sporophyte cellular and tissue development in P. patens. Additionally, the ultrastructural analysis of phyllid chloroplasts in Δrh2 and Δrh1/2 shows distinct starch granule accumulation under standard growth conditions associated with changes in photosynthetic activity parameters. We could not detect effects of either temperature or stress on protonema growth or PpRH1 and PpRH2 expression. Together, these results suggest that nuclear GUCT-containing RNA helicases play a role primarily in developmental processes directly or indirectly linked to photosynthesis activity in the moss P. patens.

Assessment of photosynthetic productivity of new perennial forage crops in forest-steppe conditions of Western Siberia

The article presents the results of six years of experience in comparative evaluation of perennial forage crops (Sida hermaphrodita Rusby., Silphium perfoliatum L., Polygonum divaricatun L., Polygonum weyrichii Fr. Schmidt, Helianthus tuberosus L., Rhaponticum carthamoides (Willd.), Symphytum asperum Lep., Urtica dioica L., Isatis tinctoria L., Rumex tianschanicus L. × Rumex patientia L.) on parameters of photosynthetic activity and dry matter yield in the forest-steppe conditions of Western Siberia. These crops are characterized by environmental plasticity, longevity (up to 25 years), high productivity (30-100 t/ha of green mass). And they have a versatile economic use. The experiment’s purpose is to assess the potential of crop cultivation and recommend species for inclusion in the regional cropping system. It was found that the largest area indicators of the assimilable apparatus (131.4-149.3 thousand m2 / ha) and photosynthetic potential (4.5–4.6 million m2 day/ha) were in S. hermaphrodita and S. perfoliatum crops, which exceeded the maize values by 1.2–2.4 times. A significant increase in leaf area in these crops contributed to a 23% decrease in net photosynthesis productivity compared to maize. By collecting dry matter for two mowings, these crops surpassed maize by 65-85% with a relatively high indicator of EER PAR (1.2 - 1.4%).

Accumulation of Airborne Toxic Elements and Photosynthetic Performance of Lolium multiflorum L. Leaves

In this study, we aimed to investigate the accumulation of airborne trace elements in Lolium multiflorum leaves concerning photosynthetic activity parameters. Five sites for four 28-day series of plant exposition were selected. The concentration of trace elements in leaves was measured after each series, while photosynthetic activity parameters were measured three times during each series. Net photosynthesis rate (PN) and stomatal conductance (gs) were mostly negatively associated with all analyzed trace elements, unlike to CO2 concentrations (Ci). Arsenic was found with opposite trend in two exposure series. The high accumulation of Cd and Pb in plants recorded at two sites was mostly related to lowest PN and gs. Similar tendency for PN was found at sites and series with the highest Cr and Ni content in plants. L. multiflorum revealed a medium-level accumulation of trace elements and a low tolerance of the photosynthetic process to the presence of trace elements in ambient air.

Photosynthesis parameters of oil crops (Brassicaceae family)

The results of studying the parameters of photosynthetic activity of oilseeds (false flax, Abyssinian crumbe and white mustard) are presented. So, in the phase of the rosette, the assimilation surface was 11.2-21.8 thousand m2 per hectare. The smallest leaf area of 11.2 thousand m2 per hectare was formed in the Abyssinian crambe agrocenosis. During the budding phase, the leaf area of the crambe doubled and amounted to 22.3 thousand m2 per hectare. The leaf surface of all studied oilseeds reaches its maximum value in the flowering phase - 42.4-52.1 thousand m2 per hectare. In white mustard, the minimum leaf area was in the rosette phase - 21.8 thousand m2 per hectare, the maximum - in the flowering phase - 44.2 thousand m2 per hectare. Then the total assimilation surface decreased by 29.5% and amounted to 31.2 thousand m2 per hectare. The value of photosynthetic potential ranged from 1594 to 1964 thousand m2 × day per hectare. The maximum value of photosynthetic potential was in Abyssinian crambe - 1964 thousand m2 × day per hectare, the minimum one - in false flax - 1594 thousand m2 × day per hectare. The high productivity of photosynthesis was in Abyssinian crambe (2.52 g / m2 × day). White mustard and false flax are characterized by slightly lower parameters of the net productivity of photosynthesis - 2.07 and 1.98 g / m2 × day, respectively. A longer period of the assimilation surface of false flax, white mustard and Abyssinian crambe plants provides high net photosynthesis productivity - 1.98-2.52 g / m2 × day and, as a result, high potential productivity up to 2.11-3.05 t / ha.

Nitrogen alleviates NaCl toxicity in maize seedlings by regulating photosynthetic activity and ROS homeostasis

Seven-day-old maize seedlings were subjected to NaCl (150 mM) without or with the presence of equimolar concentrations of urea, potassium nitrate or ammonium sulfate (at 60 kg N ha−1) for the subsequent 15 days. The results show that NaCl significantly decreased photosynthetic activity parameters (Hill reaction, Pn, Ci and Gs), shoot fresh and dry weights, chlorophylls, protein, GSH and AsA. The activities of ALA-D, Rubisco, PEP-C, MDH, PPDK, SOD, CAT and APX were significantly inhibited. On the contrary, NaCl significantly elevated MDA, O 2 ∙− , H2O2, soluble sugars and proline. The application of the nitrogenous sources mostly ameliorated the photosynthetic activity synchronous with counterbalancing the decreases in growth, protein and pigments. The activities of ALA-D, Rubisco, PEP-C, MDH and PPDK enhanced remarkably with N applied under salinity. Furthermore, enhancements were detected in GSH and AsA contents and SOD, CAT and APX activities, which decreased free radicals, soluble sugars and proline. These effects reveal that maize was vulnerable to NaCl stress; however, N overcame the stress status and ameliorated the plant tolerance to salinity concomitant with repairing photosynthetic activity and maintaining higher antioxidants and ROS homeostasis; urea seemed to be the most efficient. Taken together, these findings conclude that N enhanced the capability of maize to tolerate NaCl via protecting photosynthetic apparatus for normal photochemical functioning and improving antioxidants and ROS homeostasis as effective salt tolerance mechanisms.

Вплив густоти рослин і доз добрив на фотосинтетичну діяль­ність і врожайність сої середньостиглого сорту Святогор в умовах зрошення

Goal. To establish the optimal parameters of photosynthetic activity of crops of mid-season soybean variety Sviatogor in conditions of irrigation in the South of Ukraine depending on plant density and doses of nitrogen fertilizers. Methods. The field — for determination of yield; calculation — for optimization of doses of mineral fertilizers, plant density; measurement-weighe — for fixation of plant height, leaf area, and photosynthetic indices. Results. The density of sowing significantly influenced the leaf area of soybean plants, its indices varied in the range of 23.5–47.38 thousand m2/ha at the density of 300 thousand plants/ha; 26.19–52.42 thousand m2/ha at the density of 600 thousand plants/ha; 50.56–49.92 thousand m2/ha at the density of 900 thousand plants/ha. It was fixed that the leaf area of plants in the plots with the introduction of N30 and N60 was 50% and 49% more than in the variant without fertilizers. High yield was provided by the density of plants 600 t/ha on the background of fertilizers N30 and N60. Conclusions. For the first time for the South of Ukraine, features are determined of the formation of the photosynthetic activity of soybean crops of mid-season variety Sviatohor depending on plant density and doses of nitrogen fertilizers, providing the yield at the level of 4.32–4,47 t/ha. The best performance of interfacial photosynthetic capacity (beginning of flowering — beginning of seed ripening) — 1.38–1.23 million m2 of days/ha, and over the vegetation period — 3.45–3.19 million m2 of days/ha were formed in areas where the plant density was 600 thousand plants/ha on the background of N30 and N60 respectively. Correlation is determined between the yield level and the studied factors. It is found that the maximum leaf area in the ripening phase of the seeds is 52.42 thousand m2/ha at a plant density of 600 thousand plants/ha, and the rate application of nitrogen fertilizer involves a dose of N30.

Formation and productivity of photosynthetic apparatus of maize plants for the action of Polimiksobakteryn – a plant growth stimulator

Currently, the introduction of new techniques for corn growing technology, which involves the use of microbial drugs – growth stimulators and the study of their effects on the process of photosynthesis is relevant. In the conditions of field experiment on black soil, the effect of microbial preparation Polimiksobakteryn – a growth stimulator of plants on various methods of its application on the formation and productivity of the photosynthetic apparatus of maize plants of hybrid Dniprovsky 181 SV was studied. It was determined that the bacterialisation of seeds with subsequent surface treatment of vegetable corn plants with Polymiksobacteryn in the phase of 3–5 or 7–9 leaves – agroprimus, which provides activation of the process of photosynthesis. In particular, for the combination of bacteritisation and surface treatment of vegetative plants, the area of the leaf surface increases to 5315 cm2/plant in the flowering phase, which is 40.0% more relative to the control variant, this indicates an improvement in the conditions of growth and development of maize due to the growth-stimulating properties of the microbial preparation. The index of chlorophyll content (a + b) increases, and among all the experimental variants, the highest value of 146.7 mg/100 g of leaves installed with the combined use of Polimyksobacteryn – the bacteritisation of seeds and surface treatment by vegetation, which is 36.2% higher than the benchmark 107.7 mg/100 g of leaves. The increase in area of the leaf surface was accompanied by raising in the net photosynthesis efficiency of 6.34 g/m2 per day in the control version to 10.39 g/m2 per day (or 63.8%) as a result of bacteritisation and surface treatment of corn vegetable plants, indicating about formation of the optimum structure and productivity of the paper machine. It should be noted that according to the data, the method of using microbial preparation, which included seeding bacteria and superficial treatment of vegetative plants, better than taking bacteria or seed treatment separately. Therefore, in the cultivation of maize, the use of the microbial preparation Polymiksobacteryn, the growth stimulator of plants, by bacterialization of seeds in combination with surface treatment of plants in vegetation, increases the quantitative and improves qualitative parameters of photosynthetic activity of plants, which is essentially of practical importance for increasing the productivity of this culture.

Effect of Light Quality and Microbiological Inoculum on Geranium (Pelargonium zonale L.) Gas Exchange Parameters

Geranium plants were cultivated in a growth chamber with different light quality and microorganism inoculation conditions. The long-term effect of irradiance quality (LED and fluorescent) as well as two types of microorganism treatments on photosynthetic activity parameters was examined. The maximum reached values of net photosynthesis rate (PN), stomatal conductance (gs), transpiration rate (E) and intercellular CO2 concentration (Ci) were afterwards measured in plants cultivated under six colours of light – white, white-blue, blue, red, red-blue and green – emitted by two types of lamp: LED and fluorescent. Two types of microorganism treatments were used: BAF1 created in the Department of General and Environmental Microbiology and the commonly used Effective Microorganisms (EM) biopreparation. A highest level of PN were found in plants after cultivation under white-blue light (both – fluorescent and LED) and treated by BAF1. The positive effect of EM was only noted in the case of plants cultivated under blue-red fluorescent light. Considering plants without microbial inoculation the highest levels were recorded in plants under red and blue light. The comparison of the effect of light quality revealed that in all colours a higher or similar level of net photosynthetic rate was noted in plants under LEDs. Mostly the higher photosynthetic activity was connected with higher stomatal opening as well as with higher transpiration rate, which is especially true for plants cultivated under red and blue LED light.

Relations Between Mn Concentration and Yield, Nutrient, Water Status, and Gas Exchange Parameters of Tomato

Abstract 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 lycoper-sicum L.). Mn supplementation significantly modified the nutrient content of leaves. Macronutrient content var-ied 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 PN (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. PN and gs (stomatal con-ductance) also increased, while Ci (intercellular CO2 concentration) decreased, indicating proper CO2 consumption during the assimilation process.

Involvement of nitrogen in salt resistance of Atriplex portulacoides is supported by split‐root experiment data and exogenous application of N‐rich compounds

AbstractUsing a split‐root system, we aimed to identify the limiting factors for the growth of the halophyte Atriplex portulacoides L. under extreme salinity (800 mM NaCl) conditions. One half of the root system was immersed in complete nutrient solution at 0 or 800 mM NaCl and the other half was immersed in NaCl‐free medium, containing all nutrients or deprived of potassium (K+) or calcium (Ca2+) or nitrogen (N). Data indicate that at high salinity levels A. portulacoides growth is limited by the restrictions imposed by NaCl on N uptake. Next, the alleviation of the adverse impact by salt stress (800 mM NaCl) on plant growth was investigated through urea (U) and/or thiourea (TU) external addition through foliar application. Whether separately or supplied together, both components mitigated the negative impact of salinity on the plant growth by significantly improving the photosynthetic activity parameters [CO2 assimilation rate, stomatal conductance and maximum quantum efficiency of PSII photochemistry (Fv/Fm)], as well as shoot N concentration and the photosynthetic nitrogen‐use efficiency (PNUE). A concomitant increase of protein and free amino acid concentrations was also observed. As a whole, the present study highlights the significance of N in A. portulacoides response to high salinity and suggests that combined application of U and TU could promote the growth of this halophyte potentially useful for saline soil reclamation and revegetation purposes.

Brassica napus L. cultivars show a broad variability in their morphology, physiology and metabolite levels in response to sulfur limitations and to pathogen attack

Under adequate sulfur supply, plants accumulate sulfate in the vacuoles and use sulfur-containing metabolites as storage compounds. Under sulfur-limiting conditions, these pools of stored sulfur-compounds are depleted in order to balance the nitrogen to sulfur ratio for protein synthesis. Stress conditions like sulfur limitation and/or pathogen attack induce changes in the sulfate pool and the levels of sulfur-containing metabolites, which often depend on the ecotypes or cultivars. We are interested in investigating the influence of the genetic background of canola (Brassica napus) cultivars in sulfur-limiting conditions on the resistance against Verticillium longisporum. Therefore, four commercially available B. napus cultivars were analyzed. These high-performing cultivars differ in some characteristics described in their cultivar pass, such as several agronomic traits, differences in the size of the root system, and resistance to certain pathogens, such as Phoma and Verticillium. The objectives of the study were to examine and explore the patterns of morphological, physiological and metabolic diversity in these B. napus cultivars at different sulfur concentrations and in the context of plant defense. Results indicate that the root systems are influenced differently by sulfur deficiency in the cultivars. Total root dry mass and length of root hairs differ not only among the cultivars but also vary in their reaction to sulfur limitation and pathogen attack. As a sensitive indicator of stress, several parameters of photosynthetic activity determined by PAM imaging showed a broad variability among the treatments. These results were supported by thermographic analysis. Levels of sulfur-containing metabolites also showed large variations. The data were interrelated to predict the specific behavior during sulfur limitation and/or pathogen attack. Advice for farming are discussed.