Higher Photosynthetic Potential Research Articles

Moderate alternate wetting and drying irrigation enhances drought-resistance abilities by improving structural mesophyll conductance of water-saving and drought-resistant rice under severe drought.

Water-saving and drought-resistant rice (WDR) coupled with alternate wetting and drying irrigation (AWDI) possesses a high photosynthetic potential due to higher mesophyll conductance (gm) under drought conditions. However, the physiological and structural contributions to the gm of leaves and their mechanisms in WDR under AWDI are still unclear. In this study, WDR (Hanyou 73) and drought-sensitive rice (Huiliangyou 898) were selected as materials. Three irrigation patterns were established from transplanting to the heading stage, including conventional flooding irrigation (W1), moderate AWDI (W2), and severe AWDI (W3). A severe drought with a soil water potential of -50 kPa was applied for a week at the heading stage across all treatments and cultivars. The results revealed that severe drought reduced gas exchange parameters and gm but enhanced antioxidant enzyme activities and malondialdehyde content in the three treatments and both cultivars. The maximal photosynthetic rate (Amax) of HY73 in the W2 treatment was greater than that in the other combinations of cultivars and irrigation patterns. The contribution of leaf structure (54%) to gm (gm-S, structural gm) was higher than that of leaf physiology (46%) to gm (gm-P, physiological gm) in the W2 treatment of Hanyou 73. Additionally, gm-S was significantly and linearly positively correlated with gm under severe drought. Moreover, both the initial and apparent quantum efficiencies were significantly and positively with gm in rice plants (p < 0.05). These results suggest that the improvements in photosynthesis and yield in the WDR combined with moderate AWDI can mainly be attributed to the enhancement of gm-S under severe drought conditions. Quantum efficiency may be a potential factor in regulating photosynthesis by cooperating with the gm of rice plants under severe drought conditions.

Photosynthetic adaptation mechanisms of waterlogged wheat (Triticum aestivum) at flowering under exogenous nitric oxide donor application

AbstractThe effects of nitric oxide (NO) on the photosynthetic adaptation mechanisms of wheat plants in waterlogging during the flowering stage are poorly understood. Field and pot experiments using two cultivars were conducted with three treatments: waterlogging (WL), waterlogging plus NO donor sodium nitroprusside (WLsnp), and adequate water (CK). The results indicated that the WLsnp and CK treatments exhibited significantly higher 1000‐kernel weight and yield than the WL treatment because of high photosynthetic potential(P&lt;0.05). We found that the photosynthetic performance, including photosynthetic rate (Pn), stomatal conductance (gs), mesophyll conductance (gm), carbon dioxide concentration at the carboxylation site (Cc), maximum carboxylation rate (Vcmax), maximum electron transfer rate (Jmax), actual electron transfer rate (J), actual PSII efficiency (ΦPSII) and potential maximum efficiency in PSII (Fv/Fm), was significantly improved in the WLsnp treatment compared to the WL treatment, both during waterlogging and after de‐waterlogging. Little difference was observed in the photosynthetic performance between the WLsnp and CK treatments during waterlogging for cultivar YM15 and after de‐waterlogging for cultivar YM24. Further analysis indicated that gs, gm and J were identified as key physiological indicators that synergistically regulate Pn of waterlogged wheat plants. Overall, the improvement of wheat's waterlogging resistance capacity after spraying NO is mainly related to high gs, great gm, and high J.

Salt-Induced Modulation of Ion Transport and PSII Photoprotection Determine the Salinity Tolerance of Amphidiploid Brassicas.

Brassica species show varying levels of resistance to salt stress. To understand the genetics underlying these differential stress tolerance patterns in Brassicas, we exposed two widely cultivated amphidiploid Brassica species having different genomes, Brassica juncea (AABB, n = 18) and Brassica napus (AACC, n = 19), to elevated levels of NaCl concentration (300 mM, half the salinity of seawater). B. juncea produced more biomass, an increased chlorophyll content, and fewer accumulated sodium (Na+) and chloride (Cl-) ions in its photosynthesizing tissues. Chlorophyll fluorescence assays revealed that the reaction centers of PSII of B. juncea were more photoprotected and hence more active than those of B. napus under NaCl stress, which, in turn, resulted in a better PSII quantum efficiency, better utilization of photochemical energy with significantly reduced energy loss, and higher electron transport rates, even under stressful conditions. The expression of key genes responsible for salt tolerance (NHX1 and AVP1, which are nuclear-encoded) and photosynthesis (psbA, psaA, petB, and rbcL, which are chloroplast-encoded) were monitored for their genetic differences underlying stress tolerance. Under NaCl stress, the expression of NHX1, D1, and Rubisco increased several folds in B. juncea plants compared to B. napus, highlighting differences in genetics between these two Brassicas. The higher photosynthetic potential under stress suggests that B. juncea is a promising candidate for genetic modifications and its cultivation on marginal lands.

Exploring key physiological attributes of grapevine cultivars under the influence of seasonal environmental variability

Seasonal climatic variability is a key challenge in many grape-growing regions across the globe, affecting phenology, growth, physiological responses, and yield at harvest. Unfavourable climatic conditions impair the plant's physiological processes, such as chlorophyll accumulation, gas exchange and photosynthesis in grapevine leaves. It is critical to unlock the complex physiological behaviour of grapevine cultivars at key phenological stages and under varying environmental conditions. The present study was designed to evaluate the key physiological processes, such as gas exchange, chlorophyll contents and water use efficiency (WUE), of four table grape cultivars at key growth stages under varying environmental conditions of the Pothwar region, in a factorial experimental set up (Location× Year × Cultivar × Phenological stage). The physiological responses of the table grape cultivars were recorded at the 5-leaf stage, full bloom, berry set, veraison and harvest during two consecutive vintages (2019 and 2020) in two locations (Islamabad and Chakwal). The results show that the mean photosynthetic activity in colder Islamabad was 30.7 % higher than in Chakwal, and the transpiration rate and WUE were 10.4 % and 28.6 % higher. Similarly, 12 % higher photosynthetic activity, with 13 % more WUE, was observed in the colder vintage of 2020 compared to that of 2019. The vine physiological activity also varied among cultivars; for example, cv. Sugraone was found to have 12 % more chlorophyll and 30 % higher photosynthetic activity than cv. Kings Ruby. Similarly, higher photosynthetic activity and transpiration rates were recorded at the berry set stage, while WUE peaked near blooming. The biplot analysis for the first two principal components also showed cv. Sugraone to be a highly responsive and physiologically efficient cultivar. The findings of the present research will help to better assess the effect of seasonal variability on vine physiological performance and to identify genotypes with higher photosynthetic potential and WUE. It could also assist in devising vineyard management strategies to better adapt to varying environmental conditions.

Comparisons of the stomatal conductance and electron transport rate of three Japanese rice cultivars including Himenorin in Ehime Prefecture

This study focused on stomatal conductance (gs) and electron transport rate (ETR) as one possible approach to the mechanisms of controlling canopy temperature and photosynthetic traits in rice. Three Japanese rice cultivars, Koshihikari (KH), Nikomaru (NM), and the new cultivar Himenorin (HR) developed in Ehime Prefecture were selected for the experiment. From the uppermost to the fifth leaves of five or more rice plants of each cultivar, gs and ETR were measured in situ using a handheld porometer/fluorometer. The results revealed the highest gs in HR among the three cultivars in all leaf positions from before the flag leaf extension until the maturity stage, which could be regarded as one of the advantageous mechanisms for moderating the thermal condition of the canopy with larger transpiration and supporting a higher photosynthetic level. The ETR of HR was highest among the three cultivars in most leaf positions from the heading stage to the maturity stage, which could be expected to maintain a higher photosynthetic level. These traits of gs and ETR in HR compared with NM and KH could be assessed as possible synergistic mechanisms for higher production and quality of rice with higher photosynthetic potential.

ФОТОСИНТЕТИЧНІ ПІДВАЛИНИ ПРОДУКТИВНОГО ПРОЦЕСУ СОРТІВ ЯБЛУНІ

The research was conducted in 2017-2020 in apple orchards, which were located in the garden of FG "Neophytes" - a branch of the Department of Horticulture and Viticulture Uman National University of Horticulture. The objects were apple varieties: Golden Delicious (control), Fuji, Red Chief, Florina and Jonagold, grafted on rootstock M.9 and planted in 2014 according to the scheme 3.5 x 1 m. The high photosynthetic potential of the studied phytocenosis has been established. The highest parameters of leaf area were in the varieties Red Chief (18399 m2 / ha) and Jonagold (19485 m2 / ha), other pomological varieties accumulated from 14971 m2 / ha (Fuji) to 17199 m2 / ha (Florina) of leaf cover. At the age of three, the largest phytomass - 4,394 kg / tree was produced by Jonagold plants, and the smallest - 2,088 kg / tree - Red Chief. As the age of plantations increased, the phytomass of Jonagold trees increased to 20.4 kg / tree and Golden Delicious plants to 14.9 kg / tree. The actual yield of apple phytocenosis was the highest in the four-year period and the leader was the Jonagold variety, which 3.1 kg of fruit from the tree exceeded the Golden Delicious variety and 5.3 - Florina. The Red Chief and Fuji varieties produced 5.1 and 5.8 kg / tree of fruit during this period. The analysis of the obtained indicators indicates a rather high - from 68.1 to 80.5% share of fruits at the age of three. The pomological variety Red Chief prevailed, and the strongest results were grown by the vigorous Jonagold variety. As the age of plantations increased to six years, the share of fruits in the total phytomass of trees decreased to 32.4 (Jonagold) - 44.1% (Florina). The final analysis of the productive potential of new apple varieties gives reason to believe that the intensive phytocenosis of apple trees, depending on age can realize from 29.8% to 80.5% of the accumulated phytomass on the economically valuable part - the fruit. Preference should be given to new varieties of Red Chief, Fuji and Florina.

Influence of growth regulators on the formation of main indicators of photosynthetic activity in amaranth (Amaranthus tricolor) varieties

Three year field experiments were carried out at a location with a temperate semi-arid climate condition on the comparative productivity of Amaranth cultivars Kizlyarets (standard variety), Valentina, Iriston on moderately saline meadow-chestnut soils of the Terek-Sulak sub-province of Dagestan, against the background of presowing treatment with growth regulators Albit and Potassium Humate. The studied cultivars provided sufficiently high indicators of the leaf surface area and net productivity of photosynthesis in the variant with the Albit-regulator, 47.6, 49.6 and 51.4 thousand m2/ha and 1.91, 1.97 and 2.01 g/m2 per day, respectively. Compared with the control data and the variant with the potassium humate regulator, they increased the productivity of photosynthesis by 2.6, 4.2, 4.0, 0.8, 1.0, 1.4 and 29.9, 31.3, 32.2, 1.0, 1.5, 1.0%, respectively. The maximum data of photosynthetic activity were observed on crops of the Iriston variety. So on an average, according to the variants with growth regulators, the leaf area was at the level of 50.5 thousand m2/ha, with 47.1 and 48.8 thousand m 2 /ha in plots with varieties Kizlyarets and Valentina, respectively. The net productivity of the Iriston variety was 1.52 g/m2 per day, in the control (non treated), 2.01 g/m 2 per day - against the background of the use of the regulator Albit and 1.99 g/m2 per day -when treated with the potassium humate regulator. Low values, in the range of 1.47 to 1.91 g/m2 per day, were recorded for the standard variety. The data for Valentina occupies an intermediate position. Higher photosynthetic potential was attained by the Iriston variety when the growth regulator Albit was applied.

Photosynthetic Potential Of Spring Barley Plants In The Steppe Zone

Today, an increase in the real potential of grain crops, including spring barley, is a necessary condition for elements of crop cultivation technologies. Therefore, given the limited resource potential of spring barley crops, their fastidiousness to the soil, considerable attention should be paid to the photosynthetic potential of plants and the standardised application of mineral fertilisers. The aim of the study was to improve the elements of the technology of growing promising varieties of spring barley by establishing the mineral nutrition effect on the photosynthetic activity of plants in the conditions of the Luhanska Oblast. This study provides examples of improving some technologies for growing promising varieties of spring barley and determines the optimal norms for applying mineral nutrition to ensure the high photosynthetic potential of these plants in the climatic conditions of the steppe zone of Ukraine. It was found that the use of ammonium nitrate had a positive effect on the leaf area, increasing it by 1-2.2 thousand m2 /ha compared to the control for all varieties studied. The combined use of diammonium phosphate and ammonium nitrate contributed to an increase in the leaf area by 2-4. 4 thousand m2 /ha compared to the control variant. Simultaneous application of ActiBION increased the total leaf area for all samples studied by 3.8-6.4 thousand m2 /ha. The best indicators among the studied varieties were observed on the six-row variety Helios and the double-row variety Stalker. The six-row variety Vakula and the two-row variety Adapt showed slightly lower results. Further research implies the study of the influence of photosynthetic activity of promising varieties of spring barley on crop productivity in the steppe zone of Ukraine. The findings can be recommended for production as one of the elements in the technology of growing spring barley in the climatic conditions of the Luhanska Oblast

Формування продуктивності рослин аґрусу (Grossularia uva-crispa (L.) Mill.) залежно від функціонального стану фотосинтетичного апарату

The authors present the results of determining the functional state of the four gooseberry cultivars (Izumrud, Bezshypnyi, Neslukhivskyi and Krasen) plants leaves indices dynamics during the vegetation period applying the chlorophyll fluorescence induction and establishment of the correlations between the photosynthesis intensity and primary crop. Researched cvs differ concerning the genetic origin, usage, are characterized with different ripening rates, resistance to diseases and negative environmental factors. The laboratory study of the chlorophyll fluorescence induction change in the leaves was carried out in the Laboratory of Plant Physiology and Microbiology of the Institute of Horticulture of NAAS of Ukraine using the portable fluorometer "Floratest". The data of the investigation prove that the plants of the varieties Neslukhivskyi and Izumrud have higher photosynthetic potential and are more adaptive to the negative environmental conditions. The high primary fluorescence intensity level as well as higher indexes of the maximum fluorescence and stationary level indicate greater energy losses when it migrates to the reactionary centres. This means that the pigment complex includes more chlorophyll molecules which are not connected with the reactionary centres and do not take part in the charge division. These indices indicate the high potential productivity of the plants of the cultivars Neslukhivskyi and Izumrud that reflect themselves on the Kautsky induction curve. Suppose, those cvs can be potential source of the higher photosynthetic apparatus productivity. Under the similar soil and climatic conditions the Neslukhivskyi plants prove to be more productive as compared to the rest of the studied varieties. The correlation analysis has proved that the productivity of the explored cultivars is effected most considerably by the fluorescence background level indicator and coefficient of correlation between the rising and variable fluorescence. The photosynthetic activity determines the biological productivity and shows the crop potential abilities as regards the harvest formation, therefore the correlation between the leaves chlorophyll fluorescence induction indices and gooseberry yield which we have revealed enables to recommend ‘Izumrud’ and ‘Neslukhivskyi’ for the wide use in the industrial small fruit growing.

Features of energy willow biomass accumulation on floodplain soils of Polissia (Ukraine)

Purpose. To determine the parameters of the main factors affecting the productivity of energy plantations of willow on the floodplain soils of Polissya (Ukraine).Methods. The experimet with energy willow plantations were created using annual cuttings of the varieties ‘Zbruch’, ‘Ternopilska’ and a Salix triandra willow clone, planted in double rows with a distance of 0.75 m between them and with a row spacing of 1.5 m. Planting cuttings density: 10, 15 and 20 thousand pcs/ha.Results. After the first growing season in the 'Ternopilska' variety, the survival rate of cuttings on peat-bog soil ranged from 48.6 to 54.8 %, in the 'Zbruch' variety from 72.8 to 86.6 %, and in Salix triandra from 71.0 to 82.3 %. During the second growing season there was a significant decline in plants, especially in denser stands. On sandy soil, after the second year of vegetation, from 74.1 to 87.5 % of plants remained. Biomass productivity in the first 3 years on peat-bog soil was 0.58–1.10 t/ha/year in ‘Ternopilska’ variety, 0.80 to 3.28 t/ha/year in ‘Zbruch’ variety, and from 0.62 to 0.96 t/ha/year. At the same time, the density of plantations and edaphic conditions significantly affected the productivity of the dry mass of plants. In particular, on sandy loam soil, 'Ternopilska' variety in the first 2 years had productivity from 0.77 to 3.21 t/ha/year, which is significantly higher than on rich of organic substainces moistened peat-bog soils. The largest leaf area was in 'Ternopilska' variety on sandy loam soil, from 22.0 to 31.3 thousand m2/ha, and in 'Zbruch' variety (from 17.2 to 27.5 thousand m2/ha). The average photosynthetic potential according to the experimental options ranged from 1.67 to 5.06 million m2·day/ha, increasing with increasing planting density and leaf area. The highest net productivity of photosynthesis indicators are observed in 'Ternopilska' variety on sandy soil, from 0.98 to 1.62 g/m2 per day and in ‘Zbruch’ variety (0.70–1.16 g/m2 per day). At the same time, these indicators were maximum with a density of 15 thousand plants./ha.Conclusions. In floodplains of the Polissia, sandy loamy soils are more suitable for growing the willow energy biomass compared to peat-bog soils. Willow energy plantations have a large leaf surface area, high photosynthetic potential and net photosynthesis productivity, which provides relatively high biomass productivity indicators. On peat-bog soils from the studied varieties, it is advisable to use ‘Zbruch’ variety, which is characterized by high biomass productivity (3.28 t/ha/year), to create willow energy plantations.

ФИТОМЕТРИЧЕСКИЕ ПОКАЗАТЕЛИ ПРОДУКТИВНОСТИ ОЗИМОЙ РЖИ

The article presents the results of field studies on the assessment of methods of presowing seeds treatment on different nutritional backgrounds. The experiments were conducted on the experimental field of Agrochemistry and Soil Science Department of Kazan State Agrarian University in 2015-2018 on gray forest medium loam granulometric composition of the soil with a humus content according to Tyurin 3.4%, absorbed bases 18.4 mmol/100 g, hydrolytic acidity 3.9 mmol/100 g, P2O5 and K2O according to Kirsanov, respectively 179 and 151 mg per kg soil, salt pH 5.6. Experiment design: Factor A - Presowing treatment of seeds: 1. VialTT- disinfectant (2 kg/t); 2. Extremely high frequency therapy - 15 minutes; 3. Extremely high frequency therapy - 30 min .; 4. Extremely high frequency therapy - 15 m. + VialTT; 5. Extremely high frequency therapy - 30 m. + VialTT. The options for pre-sowing seed treatment in the tables will be indicated by numbers from 1 to 5. Factor B - Nutrition backgrounds: 1. Without fertilizers; 2. NRK at 4.0 tons per hectare. The results of studies showed that the maximum accumulation of dry plant biomass (6.79 tons per hectare), an increase in leaf surface area (49 thousand m2 ha), high photosynthetic potential (3017 thousand m2 x day/ha), better control over the spread and development of root rot (P - 23%, R - 9.3%) and the maximum yield of winter rye grain (3.88 tons) from 1 ha occurred against the background with the introduction of mineral fertilizers calculated at 4.0 tons per hectare and application of electromagnetic processing “Extremely high frequency therapy - 30 min. + VialTT disinfectant - 0.5 litre per ton "for pre-sowing seed treatment.

Agronomic and physiological evaluation of eight cassava clones under water deficit conditions.

Cassava (Manihot esculenta Crantz) is an important crop in Africa, Asia, Latin America, and the Caribbean. This species grows adequately in drought conditions and is ideal to ensure food safety in marginal environments, such as soils with low fertility and low rainfall conditions. Complementary irrigation practices can be used, or genotypes with good yield potential can be identified against these conditions to enhance productivity in those environments. For this reason, this research aimed to study several physiological mechanisms and agronomical characteristics in eight cassava clones under prolonged water deficit. The experimental design was a split-plot where the principal plot was composed of three irrigation treatments (7, 15, and 21 days without irrigation, DWI) and the secondary plot by the eight clones. The results showed that cassava plants against drought conditions (21 DWI) decreased their growth, foliar expansion, and partially closed the stomata, avoiding water losses through transpiration. The variables of the net assimilation rate of CO2, yield, and biomass accumulation were not affected by the maximum drought period. The best clones under drought were Guajira, Guajira 3, Guajira 4, Concha Rosada, and MeVen 77-1. The frequency of irrigation 15 DWI increased the variables of gas exchange and vegetative growth. This behavior is due to the ability to tolerate complex conditions through morphological and physiological mechanisms, among them, long life leaf, stomatal control, and high photosynthetic potential.

Size matters – Microalgae production and nutrient removal in wastewater treatment high rate algal ponds of three different sizes

High rate algal ponds for coupled wastewater treatment and resource recovery have been the focus of much international research over the last 15 years. Microalgal biomass productivity reported in full-scale studies (1-ha or greater) have often been substantially lower than that reported from smaller scale ponds in similar climates, regardless of the season or the dominant microalgal species used. The disconnect between smaller-scale and full-scale productivity is unclear and uncertainty remains regarding the applicability of smaller scale studies to full-scale systems. In order to better understand the differences in reported productivity, the performance of three different size wastewater treatment high rate algal ponds (5 m2, 330 m2 and 1-ha) were assessed with respect to nutrient removal and microalgal productivity over three seasons. Both daily areal nutrient removal and biomass production were affected by the size of the pond. NH4-N removal via nitrification/denitrification decreased with increasing pond size, with the highest removal rate in the 5 m2 pond and the lowest in the 1-ha. Microalgal areal productivity was maximal in the 330 m2 pond, suggesting that a combination of mixing frequency and higher photosynthetic potential under low light conditions were the main drivers of enhanced productivity in this pond compared to the 5 m2 (mesocosm) and 1-ha (full-scale) ponds. The lowest daily nutrient removal and biomass production occurred in the 1-ha (full-scale) pond. Our results suggest that, based on the current design and operation of high rate algal ponds, the optimum size for maximum productivity is considerably smaller than the current full-scale systems. This has implications for commercial scale systems, with respect to capital and operational costs.

Effects of simulated N deposition on photosynthesis and productivity of key plants from different functional groups of alpine meadow on Qinghai-Tibetan plateau

Nitrogen (N) deposition may alter physiological process of plants in grassland ecosystem. However, little is known about the response mechanism of individual plants in alpine regions to N deposition. We conducted a field experiment, and three treatments including 0 kg Nha-1year-1 (CK), 8 kgNha-1year-1 (Low N), and 72 kg N ha-1 year-1 (High N) were established to simulate N deposition in alpine meadow of Qinghai-Tibetan plateau. Our objectives were to determine the influence of N deposition on photosynthesis of different functional types of herbage species in alpine meadow, and finally characterize the links of plant productivity and photosynthesis with soil nutrients. The results showed that responses of alpine plants were species-specific under N deposition. Compared with grass species Agropyron cristatum and forb species Thalictrum aquilegifolium, the sedge species Carex melanantha was much more sensitive to N deposition; a lower N load (8 kgNha-1year-1) can cause a negative effect on its photosynthesis and productivity. Additionally, N deposition can promote plant N uptake and significantly decreased the C (carbon)/N (nitrogen) ratio. Compared with CK and low N deposition, high N deposition inhibited the photosynthesis and growth of the forb species Thalictrum aquilegifolium and sedge species Carex melanantha. In all three functional types of herbage species, the grass species A.cristatum tended to show a much higher photosynthetic capacity and better growth potential; thus, suggesting that grass species A.cristatum will be a more adaptative alpine plants under N deposition. Our findings suggested that plant photosynthetic responses to N deposition were species-specific, low N deposition was not beneficial for all the herbage species, and N deposition may change plant composition by the differential photosynthetic responses among species in alpine grassland. Plant composition shift to grass-dorminant in alpine regions might be attributed to a much higher photosynthetic potential and N use efficiency of grass species.

Physiological bases of biomass accumulation of willow energy under the conditions of the Central Forest-Steppe

Purpose. To establish the parameters of the main physiological factors influencing the growth and productivity of energy plantations of Salix viminalis varieties depending on the technologies used during their establishment under the conditions of the Central Forest-Steppe of Ukraine. Methods. Experimental energy plantations of willow were created with annual cuttings of clones ‘Tora’ and ‘Ternopilska’, planted in paired rows with a distance of 0,75 m between them and 1,5 and 2,5 m spacings. The density of cutting was 12, 15 and 18 thousand pcs/ha. Soil in the experiment was leached loamy chernozem. Results. At the end of the first year, the survivability of ‘Tora’ plants ranged 88% to 93% and ‘Ternopilska’ 89% to 95%. The average plant height for the first three years in all variants of the experiment was greater in variety ‘Tora’. In particular, at the end of the third year of vegetation, it was 524–604 cm vs. 414–557 cm in the ‘Ternopilska’ variety. In both cultivars, the plants were higher at the 1.5 m spacing. The average diameter of the shoots in all variants of the experiment correlated with plant height and, accordingly, were larger in ‘Tora’. The yield of dry biomass of this variety was 14.8–22.5 t/ha, and of ‘Ternopilska’ 6.2–14.8 t/ha per year. The largest leaf surface of ‘Tora’ variety (46,0 thousand m2/ha) was formed according to the planting scheme 0.75–2.50–0.75 m and the density of 18 thousand plants per hectare, and in the variety ‘Ternopilska’ (40,200 m2/ha), for planting scheme of 0.75–1.50–0.75. Maximum indices of the net productivity of photosynthesis (10.5 g of dry matter per m2 of leaf surface per day) were observed in the ‘Tora’ variety for planting scheme 0.75–1.50–0.75 m and density of plantings of 15 thousand plants per hectare. Conclusions. In the chernothems of the Central Forest-Steppe, the optimal scheme of cutting is the formation of coupled rows with a distance of 0.75 cm between them, 1.5 m spacing and a density of 12–15 thousand pieces/ha. Significantly higher rates of dry biomass productivity – from 14.8 to 22.5 t/ha per year – marked ‘Tora’ variety, while in ‘Ternopilska’ this indicator ranged from 6.2 to 14.8 t/ha per year. The higher productivity of ‘Tora’ variety, compared with ‘Ternopilska’, provided a larger leaf surface (up to 46.0 thousand m2/ha), higher photosynthetic potential (1.75–4.40 million m2∙days/ha), and the net productivity of photosynthesis (up to 10.5 g/m2 per day).

Localization of Chromosome Regions Controlling High Photosynthetic Potential in Russian Rice Cultivars

Breeding practice defined the main ways to increase crop yield: morphotype change, exploitation of heterosis, and increase in photosynthesis effectiveness. We identified donors and sources of high photosynthetic potential genetic system and polymorphic loci controlling photosynthetic efficiency in Russian rice cultivars. Thirty-two Russian rice cultivars were used as material. The content of chlorophyll a and b and carotenoids was measured at the beginning of tillering, heading, and flowering stages by a Genesys 8 spectrophotometer. Twenty plants of each cultivar in two replications were used for measurement. SSR markers were used. DNA was extracted by the STAB method. Polymerase chain reaction (PCR) and visualization of amplification products were performed under the International Rice Research Institute (IRRI) protocol. Donors of high contents of each pigment were found. A high level of polymorphism for the loci connected with photosynthesis effectiveness in Russian rice cultivars will allow us to create new cultivars with improved characters by hybridization. Six markers significantly divided cultivar groups with different photosynthetic rate, three of them (RM154, RM600, RM5508) were related to the content of carotenoids, two markers (RM347, RM240) were related to specific leaf weight (SLW) control, and two others (RM154, RM509) were related to the chlorophyll a content.

Dependency of a Photosynthesis Rate in Nerium oleander L. on Environmental Factors, Leaf Temperature, Transpiration, and Their Change During Vegetation in Subtropics

Dependence of net photosynthesis rate in Nerium oleander L. on environmental factors, leaf temperature, transpiration, and also on the changes of these factors during vegetation has been studied under conditions of the Southern Coast of Crimea. The mapping of a photosynthesis response function onto environmental factors in a three-dimensional coordinate system represents a convex surface with the maximum at the top point. This fact makes it possible to obtain numerical coefficients for nonlinear regression equations (simulators) describing interrelations between the net photosynthesis and the main environmental factors, leaf temperature, and transpiration. The data obtained provide a possibility to interpret a photosynthesis rate as a potential ecophysiological characteristic of this species that makes it possible to compare different plant species growing under similar conditions using parameters measured by the same method. Nerium oleander L. has a high photosynthetic potential for acclimatization to high temperatures. If air temperature exceeds the optimum value, photosynthetic intensity sharply decreases. The threshold temperature for leaves is 36.5°С. After the termination of the active growth phase, the maximum net photosynthesis rate decreased during August–October by 51.73%, while transpiration intensity and leaf temperature decreased by 78 and 28.58%, respectively. Compared to August, the optimums of the air temperature, air humidity deficit, and PAR illumination in October shifted to lower values by 17, 89.14, and 31.58%, respectively.

Формування продуктивності сорго цукрового під впливом строків сівби

The scientifically based choice of sowing terms for sorghum depends on the climatic conditions, type, state and humidity of the soil, biological characteristics of varieties and hybrids, the economic purpose of sowing, rate of positive temperatures growth. The purpose of the research was to determine the effect of sowing terms on the growth, development and the yield of green mass of sugar sorghum. In the experiment, the variety of sugar sorghum Silosne 42 and the hybrid Dovista were sown in three terms when the soil temperatures at the depth of seeding were: І – 6–8 °С, ІІ – 8–10 °С, ІІІ – 10–12 °С. Biometric indexes of sugar sorghum depended both on sowing terms and varietal characteristics. The plants most intensively developed and formed the above-ground mass in a variant where the soil temperature at the depth of seeding was 10–12 °С, and plants height was 151.7 and 193.7 cm in the period of flowering – respectively in the Silosne 42 variety and the Dovista hybrid. The highest indexes of the leaf area (51.87 and 57.25 thousand m2/ha), photosynthetic potential (4.26 and 4.32 million m2×days/ha) and the net productivity of photosynthesis (3.50 and 3.54 g/m2 per day) of sugar sorghum were on varieties, sown when the soil temperature at the depth of seeding was 10–12 °С, respectively in the Silosne 42 variety and the Dovista hybrid. It was noted that the increase in the surface of leaf area and the duration of vegetation result in higher photosynthetic potential and, consequently, the growth of the green mass yield. Maximum indexes of pure productivity of photosynthesis are observed in the flowering period, that is, during the period of the most intense growth of the above-ground mass and the leaf surface of sugar sorghum. From the flag leaf stage until flowering stage there is an intense growth in sugar sorghum, and increment of green mass is 57.3-78.6% compared with the growing point differentiation stage. The sorghum biomass indexes had the highest values at all stages of the third sowing term. Increment of the green mass continues to the hard dough stage, while dry matter grows throughout the growing period. The highest yield of the green and dry mass of the Silosne 42 variety and the Dovista hybrid is observed in the hard dough stage, when the soil temperature at the depth of seeding was 10–12 °С – 74.8 and 17.4 t/ha and 83.7 and 20.2 t/ha. The Dovista hybrid prevailed on the yield of the green mass on 9.8–12.7% and dry matter on 4.5–7.8% than the Siloshne 42 variety.

Leaf ontogeny and meristem activity of Typha domingensis Pers. (Typhaceae) under different phosphate concentrations

Phosphorus eutrophication may promote increased growth, photosynthesis, and shoot investment in cattail (Typha domingensis). However, its influence in early leaf development and meristem traits remains unclear. Therefore, this work aimed to evaluate the effects of phosphate levels on meristem structure and activity as well as tissue differentiation during the leaf development of T. domingensis. Plants were subjected to modified nutrient solutions containing three phosphate concentrations. The leaves were collected daily for 7days, and were used to evaluate growth, meristem characteristics and tissue differentiation. In addition, phosphorus content was measured in roots and rhizomes exposed to phosphate treatments. The leaf primordia cultured in 0.4 and 0.8mM phosphate levels showed a larger proportion of ground meristem than those grown in 0.1mM. The procambium proportion was higher under 0.8mM phosphate when compared to other concentrations. However, the proportion of protodermis was greater in 0.1mM phosphate when compared to 0.4 and 0.8mM. In addition, leaf primordia submitted to 0.4 and 0.8mM phosphate increased meristem cell production. These primordia also showed fewer dividing cells and shorter cell cycle as compared to 0.1mM phosphate. The development of aerenchyma and palisade parenchyma was promoted by greater phosphate concentrations. Higher aerenchyma proportion was found in plants from 0.8mM phosphate treatment. Phosphorus content was higher in root than rhizomes for plants grown at 0.4 and 0.8mM of phosphate. Likewise, the higher phosphate concentrations increased P levels in both roots and rhizomes. Therefore, optimal phosphorus levels promote the development of leaves with a higher photosynthetic potential, which may contribute to the uncontrolled growth of cattail under phosphorus eutrophication.

Assessing the effects of ultraviolet radiation on the photosynthetic potential in Archean marine environments

AbstractIn this work, the photosynthesis model presented by Avilaet al. in 2013 is extended and more scenarios inhabited by ancient cyanobacteria are investigated to quantify the effects of ultraviolet (UV) radiation on their photosynthetic potential in marine environments of the Archean eon. We consider ferrous ions as blockers of UV during the Early Archean, while the absorption spectrum of chlorophyllais used to quantify the fraction of photosynthetically active radiation absorbed by photosynthetic organisms. UV could have induced photoinhibition at the water surface, thereby strongly affecting the species with low light use efficiency. A higher photosynthetic potential in early marine environments was shown than in the Late Archean as a consequence of the attenuation of UVC and UVB by iron ions, which probably played an important role in the protection of ancient free-floating bacteria from high-intensity UV radiation. Photosynthetic organisms in Archean coastal and ocean environments were probably abundant in the first 5 and 25 m of the water column, respectively. However, species with a relatively high efficiency in the use of light could have inhabited ocean waters up to a depth of 200 m and show a Deep Chlorophyll Maximum near 60 m depth. We show that the electromagnetic radiation from the Sun, both UV and visible light, could have determined the vertical distribution of Archean marine photosynthetic organisms.