Shoot Growth Rate Research Articles

Isolation, Characterization and Identification of Contaminant Bacteria from Sugarcane (Saccharum officinarum L.) in vitro Culture in Tigray Biotechnology Center, Mekelle, Ethiopia

Plant tissue cultures can be contaminated by extensive diversity of bacteria and the contaminations are species specific. The contamination can reduce growth rate of shoot and root, multiplication factor, and even cause plant death. The study was conducted at Mekelle University, College of Veterinary Medicine and Tigray Biotechnology center and contaminated in vitro sugarcane culture obtained from laboratory of plant tissue culture. The objective of the study was to isolate, characterize, and identify bacteria from contaminated in vitro Sugarcane culture and to test the sensitivity of the isolates to the most commonly used antibiotics. Morphological, Gram stain, Endospore stain and Biochemical test method were used to isolate and identify the contaminates and disk diffusion method was used for the drug susceptibility test. Commonly available antibiotics were used for susceptibility testing. In the present study Escherichia, Bacillus and Micrococcus were isolated and identified as the major contaminant bacteria from in vitro sugarcane cultures. In antibacterial susceptibility test the isolates of Bacillus and Micrococcus were susceptible to Gentamicin, Chloramphenicol, Ciprofloxaciline, Tetracycline, Vancomycine, Streptomycin, Penicillin G and Kanamycine demonstrating the efficacy of these antimicrobials for the treatment of sugarcane in vitro culture contamination by incorporating in to the sugarcane media formulation while, the third isolate Escherichia were resistance to all antibiotic agents.

Citrus Leafminer Management: Jasmonic Acid versus Efficient Pesticides

The citrus leafminer (Phyllocnistis citrella Stainton) is a significant pest for Citrus spp. worldwide. Hence, the effectiveness of jasmonic acid (JA) was compared to three pesticides, abamectin, thiamethoxam, and acetamiprid, against P. citrella infesting mandarin (Citrus reticulata L.) and lime (C. aurantifolia L.) seedlings. Mortality rate was significantly different due to JA and other pesticides treatments. Moreover, on the 3rd day after treatment, JA demonstrated the highest reduction percentage of leafminer (77.08 and 33.33%) on mandarin and lime, respectively. By the 10th day after treatment, JA and abamectin displayed 100% reduction in both plant species. Furthermore, the foliar application of JA enhanced the most vegetative characteristics in the treated seedlings, including growth rate (shoot length/root length), fresh and dry weights of shoot and root as well as the number of leaves/seedling. Moreover, soluble protein content was increased significantly under JA treatment in the two Citrus spp. Jasmonic acid showed a good biological activity, which gives a practical reason to recommend it to be integrated in pest management programs as an alternative product for controlling P. citrella.

Acquisition of Virus Eliminated Apple Plants by Thermotherapy and the Factors Influenced the Eliminating Efficiency

The aim of this study was to establish reliable and efficient detection and elimination methods for five apple viruses and viroids, including Apple chlorotic leaf spot virus (ACLSV), Apple stem grooving virus (ASGV), Apple stem pitting virus (ASPV), Prunus necrotic ringspot virus (PNRSV) and Apple scar skin viroid (ASSVd) from infected apple plants using thermotherapy. Based on multiple alignments of available virus or viroid characteristic genes, compatible degenerate primer pairs were designed and an efficient and sensitive detection method was developed using quantitative real-time PCR (qPCR) and was further verified by short interfering RNA (siRNA) deep sequencing. Coupled with root protecting and shoot growth promoting measures, six cultivars of potted apple plants were subjected to thermotherapy for 30 days, followed by virus detection of new emerged shoots and shoot tip grafting. The results showed that the virus elimination efficiency was over 30% for the five viruses tested for ‘Kudowu’, ‘Fuji 2001’, and ‘Devil Gala’, but only 10% for ‘Red Jonathan’ and ‘Shizuka’, while no virus-free plants were detected for ‘Shinano Gold’. Correlation analysis of the factors influencing the virus elimination showed that the elimination efficiency and the virus free plant number were significantly related to the shoot growth rate, implying a vital role of the shoot growth rate in virus elimination using thermotherapy. This study provides a new qPCR assay for five apple viruses and stresses the importance of cultivar characteristic in virus thermotherapy elimination.

Multi-Scale Landscape Influences on Genetic Diversity and Adaptive Traits in a Neotropical Savanna Tree.

Changes in landscape structure can affect essential population ecological features, such as dispersal and recruitment, and thus genetic processes. Here, we analyze the effects of landscape metrics on adaptive quantitative traits variation, evolutionary potential, and on neutral genetic diversity in populations of the Neotropical savanna tree Tabebuia aurea. Using a multi-scale approach, we sampled five landscapes with two sites of savanna in each. To obtain neutral genetic variation, we genotyped 60 adult individuals from each site using 10 microsatellite loci. We measured seed size and mass. Seeds were grown in nursery in completely randomized experimental design and 17 traits were measured in seedlings to obtain the average, additive genetic variance (Va) and coefficient of variation (CVa%), which measures evolvability, for each trait. We found that habitat loss increased genetic diversity (He) and allelic richness (AR), and decreased genetic differentiation among populations (FST), most likely due to longer dispersal distance of pollen in landscapes with lower density of flowering individuals. Habitat amount positively influenced seed size. Seeds of T. aurea are wind-dispersed and larger seeds may be dispersed to short distance, increasing genetic differentiation and decreasing genetic diversity and allelic richness. Evolvability (CVa%) in root length decreased with habitat amount. Savanna trees have higher root than shoot growth rate in the initial stages, allowing seedlings to obtain water from water tables. Landscapes with lower habitat amount may be more stressful for plant species, due to the lower plant density, edge effects and the negative impacts of agroecosystems. In these landscapes, larger roots may provide higher ability to obtain water, increasing survival and avoiding dying back because of fire. Despite the very recent agriculture expansion in Central Brazil, landscape changes are affecting neutral and adaptive variation in T. aurea. Several populations have low additive genetic variation for some traits and thus, may have limited evolvability, which may jeopardize species long-term persistence. The effect of habitat loss on highly variable neutral loci may only be detected after a certain threshold of population size is attained, that could become dangerously small masking important losses of heterozygosity endangering species conservation.

INFLUENCE OF NUTRITION COMPOSITIONS ON MICROCLONAL PROPAGATION DIFFERENT GENOTYPES OF THE WALNUT JUGLANS REGIA L.

Walnut is one of the most common nuts in many countries of the world. It is used in cooking and in traditional medicine. Walnut cultivation on an industrial scale in Kazakhstan began only in 2016-2017, so Kazakhstan scientists in this field do not yet have any scientific experience. The article presents the results of studies on the influence of the nutrient medium compositions Murashige-Skoog and Driver-Kunzhuki on the microclonal propagation of different genotypes of the walnut Juglans regia L. Two varieties were selected as mother plants: the Uzbek variety Ideal and the Chinese variety Liaohe-1, adapted in the southeast Kazakhstan. In the course of work, we compared the growth rate of walnut shoots of two varieties on nutrient media Murasige-Skoog (MS) and Driver-Kunzhuki (DKW) with a concentration of 6-benzylaminopurine (BAP) of 1 and 1.5 mg / l. After a month of cultivation of shoots, positive growth dynamics was observed only on MS medium. On plants of both varieties, the growth rate was slow on DKW medium, the plants had yellow leaves, some shoots blackened and perished. To obtain high-quality material, as well as to increase the growth rate of shoots, DKW medium was supplemented with FeEDDHA (119 mg / L) and phloroglucinol (50 mg / L). As a result of phenological observations: the height of the main shoot, the number of internodes, the formation of additional shoots, and the state of the plants, it was found that the best nutrient medium for microclonal propagation of walnut Ideal and Liaohe-1 is a modified DKW medium. MS can only be used at the initial stage - an introduction to in vitro culture.

Tomorrow Never Dies: biodegradation and subsequent viability of invasive macrophytes following exposure to aquatic disinfectants

Aquatic invasive alien species (IAS) negatively impact freshwater ecosystems worldwide. As suppression and eradication of established invader populations are often complex, costly and resource-intensive, the prevention of further invader spread is considered a key aspect of proactive management measures. Although broad-spectrum aquatic disinfectants have been suggested as a suitable decontamination mechanism to enhance invader spread-prevention strategies, inconsistencies concerning their effectiveness are reported within the literature. Here, we examine the use of two aquatic disinfectants, which were developed to kill damaging microbes, to induce substantial degradation of the apical fragmentary propagules of five invasive macrophytes: Crassula helmsii (Kirk) Cockayne; Egeria densa Planchon; Elodea canadensis Michx; Hydrocotyle ranunculoides Linnaeus; Lagarosiphon major (Ridley) Moss. Apical fragments were exposed to 0% (0 g L-1), 2% (20 g L-1) or 4% (40 g L-1) solutions of Virkon® Aquatic and Virasure® Aquatic, for submergence treatments of five, fifteen, thirty or sixty minutes. After 28 days, degradation of treated fragments was significantly greater than that of control groups, particularly for 4% solutions and longer exposure times. Despite this, sustained viability in relation to shoot and/or root regrowth was exhibited by almost all plant species. However, new shoot growth rates were significantly reduced following exposure to all treatments. At matched concentrations, there was no significant difference between the two disinfectants. Overall, it appears that the examined aquatic disinfectants will not curtail the spread of these invasive macrophytes. Yet, longer submergence times, multiple applications and synergistic effects of different biosecurity treatments may enhance preventative measures against further spread and this requires investigation.

The effectiveness of a complex microbial preparation when used in the vineyards of the Crimean Peninsula

A multicenter study of the application of the microbiological preparation Embiko® in vineyards with its introduction with drip irrigation in the Western foothill-seaside viticultural zone of Crimea was carried out. Granulometric analysis of the soil showed that in the experimental version with the use of Embiko®, the specific content of its fine fractions increased by 5%, i.e. the soil became looser. The introduction of Embico® in liquid form with drip irrigation gave an increase in yield by 1.3 kg per bush, while the sugar content of the berry juice improved by at least 8%. An antistress effect on plants under the influence of treatment with a biological preparation was also revealed, which manifests itself in a significant functional improvement of the leaf apparatus and an increase in the growth rates of grape shoots. When using the biological preparation Embico®, the profit or net income at the pilot site increased compared with the control option (without application) and, accordingly, the profitability of production increased by 79%.

Stabilising Urea Amine Nitrogen Increases Potato Tuber Yield by Increasing Chlorophyll Content, Reducing Shoot Growth Rate and Increasing Biomass Partitioning to Roots and Tubers

Much of the nitrogen in crop fertiliser is degraded before acquisition. Technologies that stabilise urea-nitrogen minimise this. Degradation also specifically reduces the amount of ureic amine that many fertilisers initially contain, which is important because this nitrogen form has unique beneficial effects on plants. To investigate mechanisms whereby urea stabilisation increases potato tuber yield, we compare effects of foliar applications of chemically stabilised and non-stabilised urea against industry-standard fertiliser, on the physiology, form and yield of greenhouse-grown Casablanca under identical nitrogen supply. Stabilised urea is tested on Rooster and Shelford yields in Irish and British field trials. Stabilised amine nitrogen (SAN) increases Casablanca leaf relative chlorophyll content and initially reduces shoot growth rate. When harvested shortly after tuber initiation, SAN-treated plants have increased root to shoot weight ratios and we find tight negative correlations between shoot growth rate and root weight: large roots and slow shoot extension occur predominantly in SAN-treated plants. SAN increases ratios between initiation-stage tuber weight and (a) shoot length and (b) shoot growth rate. At a second harvest at mid-bulking, SAN increases high-grade Casablanca tuber yielding. At this later stage, yield correlates positively with shoot weight. In the field, SAN increases Rooster canopy greenness and marketable yields of both Rooster and Shelford. Yield improvements specific to this N form when stabilised are suggested to occur through increased photosynthesis and early-stage increases in root to shoot weight ratio. This phenotype then supports increased bulking-stage shoot growth and shoot-sourced resource for tuber growth. Stabilising urea amine induces high-yielding phenotypes with improved internal nitrogen utilisation efficiencies.

Analysis of Cold-Developed vs. Cold-Acclimated Leaves Reveals Various Strategies of Cold Acclimation of Field Pea Cultivars

Peas (Pisum sativum L.) belong among the world’s oldest domesticated crops, serving as a source of proteins, complex carbohydrates, vitamins and minerals. Autumn sowing allows a higher biomass production as well as the avoidance of the drought and heat stresses of late spring. However, the character of European continental winters limits plant growth and development through cold stress. This work sought parameters that reflect the cold tolerance of pea plants and consequently to suggest an afila-type pea cultivar with resilience to European continental winters. For this purpose, we employed indoor remote sensing technology and compared the 22-day-long acclimation to 5 °C of four pea cultivars: Arkta, with normal leaves and the known highest cold resistance to European continental winters, and Enduro, Terno and CDC Le Roy, all of the afila type. Besides evaluation of shoot growth rate and quenching analysis of chlorophyll fluorescence (ChlF) by imaging methods, we measured the chlorophyll content and ChlF induction with a nonimaging fluorometer. Here we show that the acclimation to cold of the Arkta exhibits a different pattern than the other cultivars. Arkta showed the fastest retardation of photosynthesis and shoot growth, which might be part of its winter survival strategy. Terno, on the other hand, showed sustained photosynthetic performance and growth, which might be an advantageous strategy for spring. Surprisingly, Enduro showed sustained photosynthesis in the stipules, which transferred and acclimated to 5 °C (cold-acclimated). However, of all the cultivars, Enduro had the strongest inhibition of photosynthesis in new stipules that developed after the transition to cold (cold-developed). We conclude that the parameters of ChlF spatial imaging calculated as averages from whole plants are suboptimal for the characterization of various cold acclimation strategies. The most marked changes were obtained when the new cold-developed leaves were analyzed separately from the rest of the plant.

Influence of the trellis/training system on the physiology and production of Vitis labrusca cv. Niagara Rosada in Brazil

The trellis system used in grapevine cultivation greatly influences yield due to leaf surface exposure to solar radiation, which implies that physiological responses are involved in fruit production and quality. The American table grape cv. Niagara Rosada (Vitis labrusca) was first planted in Brazil using the vertically shoot-positioned (VSP) system. However, in areas where cv. Niagara Rosada replaced European table grapes (Vitis vinifera), growers usually use the existing overhead trellis system. This study evaluated the physiology and production of cv. Niagara Rosada grapevines grown on the overhead trellis system and VSP system. The trellis system had no influence on the duration in total days from the pruning-to-harvest period or on the absolute growth rate of shoots. The leaf area index and leaf surface area were higher on overhead trellis systems than on the VSP system. Fruit growth was similar regardless of the system adopted. Grapevines in the VSP system produced fruits with higher concentrations of soluble solids and anthocyanins than those in the overhead trellis system. Grapevines on the overhead trellis system present a better ratio between leaf surface area and production, as well as higher yields. However, grapevines grown on the VSP system have fruit with better qualities.

Root Growth and Architecture Responses of Bread Wheat Cultivars to Salinity Stress

The screening of genotypes that perform better in saline soils is important for food security as the arable land affected by this problem is increasing. To mimic the conditions found in saline fields, a saline soil‐based screening method was developed to distinguish genetic diversity in root growth responses and shoot growth rates of bread wheat (Triticum aestivum L.) cultivars, namely Roshan, Bam, Tabbasi, Mahooti, Shiraz, Qods, Falat, and Atrak. Soil‐filled polyvinyl chloride (PVC) tubes perfused with 50 to 200 mM NaCl and a standard nutrient solution was employed. A constant salt concentration was maintained throughout the soil profile in the PVC tubes. Genetic variation in root growth and leaf Na+ concentrations was observed between cultivars in response to salinity. Salinity decreased the relative growth rate, seminal and total root length, and the distance between root tip and the first lateral root but increased total branch roots. For most traits, the growth reductions due to salinity were higher in salt‐sensitive compared with salt‐tolerant cultivars. The seminal root length was reduced more than branch root length in all cultivars. Roshan and Tabbasi were identified as the most tolerant to salinity due to their longer seminal axile roots, shorter distance from the tip, higher distal branch root numbers, and higher branch root length compared to the other cultivars. A positive relationship between genetic variations in root growth response and relative growth rate indicates that root growth might be the key factor driving shoot growth and can be used as a criterion for screening salinity tolerance.Core Ideas Genetic variation was found in root growth traits and shoot growth rate in response to soil salinity. Salinity reduced shoot growth rate, seminal and total root length, but increased branch root length. A positive relationship was found between root growth response and shoot growth rate.

The negative effects of short-term extreme thermal events on the seagrass Posidonia oceanica are exacerbated by ammonium additions.

Global warming is increasingly affecting our biosphere. However, in addition to global warming, a panoply of local stressors caused by human activities is having a profound impact on our environment. The risk that these local stressors could modify the response of organisms to global warming has attracted interest and fostered research on their combined effect, especially with a view to identifying potential synergies. In coastal areas, where human activities are heavily concentrated, this scenario is particularly worrying, especially for foundation species such as seagrasses. In this study we explore these potential interactions in the seagrass Posidonia oceanica. This species is endemic to the Mediterranean Sea. It is well known that the Mediterranean is already experiencing the effects of global warming, especially in the form of heat waves, whose frequency and intensity are expected to increase in the coming decades. Moreover, this species is especially sensitive to stress and plays a key role as a foundation species. The aim of this work is thus to evaluate plant responses (in terms of photosynthetic efficiency and growth) to the combined effects of short-term temperature increases and ammonium additions.To achieve this, we conducted a mesocosm experiment in which plants were exposed to three thermal treatments (20°C, 30°C and 35°C) and three ammonium concentrations (ambient, 30 μM and 120 μM) in a full factorial experiment. We assessed plant performance by measuring chlorophyll fluorescence variables (maximum quantum yield (Fv/Fm), effective quantum yield of photosystem II (ΔF/Fm’), maximum electron transport rate (ETRmax) and non-photochemical quenching (NPQ)), shoot growth rate and leaf necrosis incidence. At ambient ammonium concentrations, P. oceanica tolerates short-term temperature increases up to 30°C. However, at 35°C, the plant loses functionality as indicated by a decrease in photosynthetic performance, an inhibition of plant growth and an increase of the necrosis incidence in leaves. On the other hand, ammonium additions at control temperatures showed only a minor effect on seagrass performance. However, the combined effects of warming and ammonium were much worse than those of each stressor in isolation, given that photosynthetic parameters and, above all, leaf growth were affected. This serves as a warning that the impact of global warming could be even worse than expected (based on temperature-only approaches) in environments that are already subject to eutrophication, especially in persistent seagrass species living in oligotrophic environments.

Reduced Growth and Nitrogen Uptake During Waterlogging at Tillering Permanently Affect Yield Components in Late Sown Oats.

In Mediterranean Europe, winter cereals can experience soil waterlogging starting from crop establishment up to stem elongation and, in late sowings, this stress is combined with temperatures favorable to plant metabolism. Oats response to waterlogging has been rarely investigated, but these species seems to recover better than other cereals. In a 2-year experiment, Avena sativa and Avena byzantina were sown at the end of winter in pots placed outdoors. At the two-tiller stage, plants were exposed to waterlogging for periods ranging from 0 to 35 days. The dry weight and the N-concentration of shoots and roots were determined on waterlogged plants and drained controls at the start and the end of each waterlogging period, and at maturity. At maturity, the grain yield and its components were determined. To relate oat response to its specific morphological and developmental traits, results were compared to the published results in wheat and barley. Both oat species suffered severe damage during waterlogging: the uptake of nitrogen and the N-concentration of shoots were reduced after 7 days, tiller initiation and root growth after 14 days, and shoot growth after 21 days. All plants survived waterlogging, and the relative growth rates of roots and shoots and the net uptake rate of nitrogen were resumed during recovery. Nevertheless, at maturity, the straw and root biomass were markedly lower with all waterlogging durations, and grain yield decreased by 42% up to approximately 81% following an asymptotic equation. The most affected yield components were the number of panicles per plant and the number of kernels per panicle, but their relative sensitivity changed according to waterlogging duration. The slight increase in tiller fertility in response to short waterlogging and the small and irregular decrease in the number of kernels per spikelet suggest that the two oats could recover the initiation and size of inflorescences better than other winter cereals. Despite this, waterlogging in spring was highly detrimental to these oats because of severe damage under waterlogging and because of the inability to initiate new tillers and adequately resume root growth during recovery, once plants had achieved the phase of stem elongation.

Salicylic acid seed priming improves tolerance to salinity, iron deficiency and their combined effect in two ecotypes of Alfalfa

The aim of this work was to investigate the role of salicylic acid (SA) seed priming on plant growth, chlorophyll content, photosynthesis and ionic composition in two ecotypes of Medicago sativa (Gabes and Presmenti) when subjected to salinity (75 mM) and iron deficiency (1 μM) either separately or combined. Our results showed that under unprimed conditions, salinity and iron (Fe) deficiency reduced shoot and root growth, photosynthetic and transpiration rates, chlorophyll concentration, stomatal conductance and ionic uptake. The reduction in all of these parameters was additive in the combined treatment with salinity and low Fe supply. This reduction depended on the ecotype, the tissue and the stress applied. However, under saline conditions, the Gabes ecotype showed tolerance by maintaining tissue hydration, growth, photosynthetic assimilation, chlorophyll biosynthesis and nutrient uptake, compared to the control. While priming seeds with 100 μM SA had the best positive impact on all studied physiological parameters under different stresses, and especially under the combined treatment, a 500 μM concentration had no effect. We conclude that the effect of seed priming with SA is dose-dependent and may vary depending on ecotypes and stress.

Growth dynamics of deciduous species during their life period: A case study of urban green space in India

It is evident that grass density (GD) and shoot growth rate (SGR) governs the differential settlement of substructure, groundwater recharge, and stability of green infrastructure. GD and SGR are usually assumed to be constant during the entire life period of vegetation. However, spatial and temporal dynamics of GD and SGR in urban green space were rarely explored previously. The main objective of this study is to explore the spatial and temporal dynamics of GD and SGR in urban space vegetated with deciduous species (mix grass i.e., Poaceae and Bauhinia purpurea). Field monitoring was conducted in the urban green space for one year (i.e., life period of selected species). The monitoring period includes the growth period and gradual wilting period. Substantial spatial variation of GD was found during the first six months. GD away from the tree trunk was found to be 1.02–56.3 times higher than that near the tree trunk during the first six months. Thereafter, any spatial variation of GD was not found in the next six months. Unlike the GD, SGR was found to vary during the entire life period of mix grass. In addition, SGR away from the tree trunk was found to be 1.1–4.6 times higher than that near the tree trunk. Any relationship between GD and rainfall depth was not found. Whereas, SGR mainly depends on rainfall depth. The hypothesis of uniformity in GD and SGR during the life period of deciduous species was not found to be true.

Rate of shoot development (phyllochron) is dependent of carbon availability, shoot type, and rank in peach trees

KEY MESSAGE: Crop load or carbohydrate availability, affects the phyllochron, leaf length, and leaf area of proleptic and epicormic shoots on mature, field-grown Prunus persica trees. It is well known that shoot growth rates can be strongly influenced by availability of carbohydrates to support growth. Additionally, carbohydrate availability for vegetative growth is influenced by crop load, since fruits are strong sinks for photosynthates. Thus, while crop load is known to have significant effects on shoot growth rates it is not clear whether this effect is limited to extension growth rates of internodes or whether it also affects shoot development such as the rate at which nodes are added to shoots, i.e., the phyllochron. In this study, we investigated the effect of the presence and absence of the crop on the phyllochron of proleptic and epicormic shoots on mature, field-grown peach trees. Leaf growth measurements were recorded three times per week from the beginning to the end of the growing season and used to calculate the phyllochron on trees from two treatments; one with 100% of the crop left on it (unthinned or fully cropped) and a treatment of trees where the crop was completely removed (non-cropped). The phyllochron fluctuated but generally increased over the season due to a rank effect. The phyllochron was longer on trees with heavy crop loads. Although there were large differences in phyllochrons between treatments in both shoot types, only differences observed in epicormic shoots were statistically significant. Additionally, leaf length and leaf area were also significantly reduced by crop load in both shoot types. These findings indicate that the phyllochron of field-grown peach trees is apparently sensitive to carbohydrate availability in the tree and should be considered when trying to accurately predict the timing of the addition of new phytomers along a shoot.

Metabolomic changes associated with elevated CO2-regulation of salt tolerance in Kentucky bluegrass

Salt stress caused by excessive sodium accumulation in the soil can result in various physiological damages in plants. Elevated CO2 concentration may cause metabolomic adjustment or reprogramming, protecting plants from salt damages. The objectives of this study were to identify CO2-reponsive metabolites in leaves and roots of Kentucky bluegrass (Poa pretensis) differently accumulated under salt stress and non-stress conditions and determine major metabolic pathways involved in CO2 responses that may contribute to CO2-enhanced salt tolerance. Plants were grown in growth chambers controlled at ambient CO2 concentration (400 ± 10 μmol mol−1) or elevated CO2 concentration (800 ± 10 μmol mol−1), and irrigated daily with 250 mL water (non-stress control) or 200 mM NaCl solution (salt stress). Elevated CO2 effectively ameliorated plant growth and physiological damages due to salt stress, as shown by the increase in turf quality, leaf relative water content, leaf chlorophyll content, shoot growth rate, net photosynthetic rate, and K + content, as well as by the reduction in electrolyte leakage and Na + content in both leaves and roots. Elevated CO2 concertation altered metabolic profiles of leaves and roots exposed to salt stress, with enhanced accumulation of organic acids (quinic acid, mucic acid, pyruvic acid, citric acid, lactic acid, malic acid, fumaric acid, and shikimic acid in leaves; citric acid, fumaric acid, gluconic acid, galacturonic acid, isocitric acid, glyceric acid, succinic acid, and malonic acid in roots), sugars (glucose, fructose, hexopyranose, gulose, tagatose, mannose, sucrose, trehalose, cellobiose in leaves; glucose, galactose, hexopyranose, sucrose, trehalose, lactose, turanose in roots), sugar alcohols (galactinol, glycerol in leaves and galactinol, glycerol, mannitol in roots), sterols (β-sitosterol in leaves and stigmasterol, β-sitosterol, campesterol in roots), and fatty acids (linolenic acid and palmitic acid in both leaves and roots). The accumulation of CO2-reponsive metabolites involved in sugar metabolism, fatty acid metabolism and respiratory metabolism could facilitate the improved salt tolerance in perennial grass due to elevated CO2 concentration.

Изучение биологической активности анионных аддуктов 5,7-динитробенз[d]оксазола

In this paper, we studied the effect of anionic adducts of 5,7-dinitrobenz[d]oxazole on the sowing properties of wheat seeds (germination energy and germination), the growth rate of wheat shoots, amylase activity in the roots and shoots of wheat. The evaluation of the toxicity of the tested compounds was carried out using the GUSAR on-line computer program. A prediction was made of bioaccumulation factor (BCF), the average lethal concentration for daphnia and minnow (LD50), the concentration of half-maximal growth inhibition (IGC50) and the acute toxicity indicators (LD50) for rats with different routes of administration. For the study were selected: 2-methoxy-5,7-dinitro-2 (piperidin-1-yl)-2,3-dihydrobenzo[d]oxazole, 2-methoxy-5,7-dinitro-1,2-dihydrobenzo[d]sodium oxazolide, 2-methyl-2-methoxy-5,7-dinitro-1,2-dihydro-benzo[d]cesium oxazolide, 2-phenyl-2-methoxy-5,7-dinitro-1,2-dihydrobenzo[d]sodium oxazolide and 2-methyl-2-ethoxy-5,7-dinitro-1,2-dihydrobenzo[d]oxazolid cesium. Biological activity was analyzed on wheat seeds of the winter variety Moskovskaya 39. Aqueous solutions of the studied substances were used with concentrations: 1·10-4 mol/l, 1·10-6 mol / l, 1·10-8 mol/l, 1·10-10 mol/l, 1·10-12 mol/l and 1·10-14 mol/l. The germination energy of wheat seeds was determined on day 3, and germination on the 9th day after sowing by counting germinated seeds. Values are expressed as a percentage of the total number of seeds sown. Biometric indicators (height of shoots) were determined on the 9th day after sowing. Amylase activity was measured in the roots and shoots of wheat plants by the amount of undecomposed starch using spectrophotometry. The data obtained allow us to conclude that different substituents in the anionic adducts of 5,7-dinitrobenz[d]oxazole in varying degrees contribute to the manifestation of biological activity at different stages of wheat plant growth. During the first three days, 2-methyl-2-ethoxy-5,7-dinitro-1,2-dihydrobenzo [d]oxazolid cesium affects the growth processes in wheat seeds most actively. The growth of wheat shoots is stimulated to a greater extent by solutions of 2-methoxy-5,7-dinitro-1,2-dihydrobenzo[d]oxazolid sodium with concentrations of 1·10–4 and 1·10–6 mol/l and solution 2-phenyl-2-methoxy-5,7-dinitro-1,2-dihydroben-zo[d]oxazolid sodium with a concentration of 1·10-8 mol/l. Amylase activity in wheat roots is increased by solutions of 2-methyl-2-methoxy-5,7-dinitro-1,2-dihydrobenzo[d]cesium oxazolid in the whole range of concentrations used, and in the shoots – solutions of 2-methoxy-5,7-dinitro-1,2-dihydrobenzo[d]oxazolid sodium in the range of all tested concentrations. In general, anionic adducts of 5,7-dinitrobenz[d]oxazole exhibit high biological activity in relation to wheat plants in the early stages of development.

The role of slab water content during supplemental lighting on shoot growth and physiological response of cut rose ‘Charming Black’

The critical water content in slab, and effects of drought on shoot growth and gas exchange characteristics of the cut rose ‘Charming Black’ were investigated. Four different irrigation regimes were applied to rose plants during supplemental lighting (90 µmol m−2 s−1 PAR). Water content in slab was controlled as 80%, 60%, 40%, and 20% in T1, T2, T3, and T4, respectively. No significant difference between T1 and T2 was found when water content in slab was above 60%. However, reduction in water use efficiency has been observed with the decline of water content in slab. When the water content dropped below 60% in slab, the shoot growth rate decreased, and a significant reduction of 30% and 38% in shoot growth, 44% and 51% in shoot weight, and 34% and 56% in leaf area have been observed under T3 and T4 respectively. Also, petal length and diameter of floral buds were hampered due to the water deficit. Lowest net CO2 assimilation rate occurred at the lowest water content in slab (20%). Besides, T3 (40%) also caused a significant reduction (63%) in photosynthesis. Sigmoid function was simulated to find the fraction of total available water that crop can extract from root zone without suffering from drought stress: the fraction is 0.42. Meanwhile, critical water content was calculated as 46.6%. This study showed that when the water content in slab was below the critical water content, drought stress occurred.

Regulation of water transport in Arabidopsis by methyl jasmonate

Following a stress event, jasmonate-dependent signaling pathway triggers a shift from growth to defense responses that are accompanied by the cessation of growth in many plants. However, the processes leading to this growth inhibition remain obscure. In this study, we provide evidence for a rapid inhibition of cell hydraulic conductivity (Lp) by methyl jasmonate (MeJA) in the roots of wild-type Arabidopsis within 0.5 h of 20 and 50 μM MeJA treatments. We also demonstrate that MeJA did not affect Lp in fad3-2 and fad7-2 Arabidopsis mutants that are deficient in jasmonate precursor, linolenic acid. The reductions of Lp in wild-type plants were accompanied by the down-regulation of several plasma membrane intrinsic protein (PIP) isoforms, and dephosphorylation. Treatments with HgCl2 did not further reduce Lp in the wild-type plants, but significantly reduced Lp in the fad3-2 and fad7-2 that had been first treated with MeJA. Continuous prolonged exposure to exogenous 50 μM MeJA inhibited the relative growth rates (RGR) of shoots and net photosynthesis (Pn) in the Arabidopsis wild-type and fad7-2 plants, but had no effect on the RGR of roots. The results demonstrated that a reduction of aquaporin (AQP)-mediated water transport was the initial target of MeJA exposure, and may contribute to the processes of growth inhibition by MeJA.