Stages Of Vegetative Development Research Articles

Ornithogenic vegetation: How significant has the seabird influence been on the Aleutian Island vegetation during the Holocene?

In the Aleutian Islands during the Holocene, terrestrial predators were actually absent; as a result, large seabird colonies thrived along the coasts or across entire islands. Bird guano enriches the soil with nitrogen, which can lead to the formation of highly modified ornithogenic (bird‐formed) ecosystems. For a more detailed investigation of avian influence, we reconstructed more than 10,000‐year‐old vegetation dynamics of the coast of Shemya Island (Near Islands) by pollen analysis. At the initial stages of vegetation development (10,000–4,600 cal year BP), sedge–heather tundra grew in the studied area. A seabird colony existed on Shemya from 4,600 to 2,400 cal year BP according to stable isotope analysis. During a period of at least 2,200 years, nitrogen enrichment led to the development of ornithogenic herb meadows with a high presence of Apiaceae. A long‐term increase in δ15N above 9–10‰ led to radical shifts in vegetation. Noticeable reduction of seabird colonies due to human hunting led to grass‐meadows spreading. After a prolonged decrease δ15N below 9–10‰ (2,400 cal year BP to present), there was a shift toward less productive sedge‐tundra communities. However, the significant enrichment of guano affected only the coastal vegetation and did not alter the inland Shemya Island.

Transplanting as an option to cope with abiotic stress in high‐altitude lowland rice production systems in East Africa

AbstractThe current practice of direct seeding in East‐African high‐altitude rice farming systems is constrained by water availability early in the season and low temperatures later in the season at the crop's critical reproductive stage. Thus, productivity is restricted as only short‐duration varieties can be grown due to the risk of crop failure. To fully exploit the yield potential of such rainfed systems, the best combination of crop establishment methods and climatic ‘best fit’ genotypes is required. In this study, nine rice genotypes were evaluated under direct seeding and transplanting in the 2016 and 2017 cropping seasons with the aim of identifying genotype by environment by management combinations best fitting the high‐altitude, rainfed rice production systems. On average across all genotypes, transplanting had a positive yield effect of 18% in 2016 and 23% in 2017. Regarding the phenological development, individual phenophases were not significantly affected by transplanting relative to direct seeding; however, vegetative development stages in transplanted rice tended to be about 15% longer than when direct seeded. Even though transplanting led to extended vegetative growth, the time in the nursery allowed the plants to escape the cold spell late in the season. The results from the current study provide options to adapt cropping calendars by combining genetic resources with targeted crop management, thus improving and stabilizing yields of rainfed lowland rice farming systems at high altitude.

Evaluation of Salt Tolerance in Italian Ryegrass at Different Developmental Stages

Soil salinity is one of the major abiotic stresses that continues to threaten plant growth and agricultural productivity. Screening germplasm with salinity tolerance is therefore necessary. This study was designed to evaluate salt tolerance based on the integrated tolerance index. Fifteen Italian ryegrass cultivars were used to evaluate the degree of genotypic variation in salt tolerance at the germination and vegetative growth stages of plant development. Evident variations in salt tolerance were observed at the germination stage under 255 mM NaCl treatment. Root growth rate, chlorophyll content, and germination rates played a vital role in determining salt tolerance. Based on combined attributes at the germination and vegetative growth stages, Gongniu, Chuangnong, Splendor, and Abundant were identified as the most tolerant cultivars. Furthermore, the constant crude protein, lower neutral detergent fiber, and acid detergent fiber contents were measured under salinity. Compared to the control, the cultivars Tetragold, Abundant, Splendor, Muyao, Harukaze, Tegao, Dongmu 70, and Doraian were identified to have high forage quality under salt stress. Finally, we selected Splendor and Abundant as the cultivars that expressed the highest degree of salt tolerance based on combined attributes related to germination, salt tolerance, and overall forage quality. In addition, gene expression analysis between salinity tolerant and sensitive cultivars revealed that the gene response to photosystem and carbohydrate synthesis may have played a mediating role in providing tolerance to salt stress.

Influence of crude oil pollution on the content and electrophoretic spectrum of proteins in Carex hirta plants at the initial stages of vegetative development

The role of proteins in the general adaptive response of Carex hirta plants to soil pollution by crude oil has been studied. It was established that a possible element of the process of adaptation of C. hirta plants to combined stress – conditions of soil polluted by crude oil – may be the synthesis of stress proteins – high molecular weight of more than 60 kD and low molecular weight, not exceeding 22–45 kD. The synthesis of all 5 HSP families was detected in the leaves and rhizomes, and only sHSP (starting from Mr 32 kD), Hsp 60 and Hsp 100 proteins were synthesized in the roots under the influence of crude oil pollution. The development of C. hirta adaptation syndrome under the influence of crude oil pollution of the soil was promoted by enhanced synthesis of proteins with Mr 85, 77, 64, 60 and 27 kD in the leaves, 118 and 41 kD in the rhizomes and proteins with Mr 105, 53, 50 and 43 kD in the roots of the plants. The decrease in the amount of proteins with Mr 91, 45, 28 kD in the leaves, proteins with Mr 85, 76 and 23 kD in rhizomes and proteins with Mr 64 and 39 in the roots of C. hirta plants under conditions of crude oil polluted soil could be a consequence of inhibition of synthesis or degradation of protein molecules providing the required level of low molecular weight protective compounds in cells. The root system and rhizomes of C. hirta plants undergo a greater crude oil load, which leads to increased protein synthesis in these organs and decreased in the leaves, correspondingly. However, a decrease in protein content in the leaves may indicate their outflow in the roots and rhizomes. Сrude oil contaminated soil as a polycomponent stressor accelerated the aging of leaves of C. hirta plants, which could be caused by increased synthesis of ABA. ABA in its turn induced the synthesis of leaf-specific protein with Mr 27 kD. These proteins bind significant amounts of water with their hydrate shells maintaining the high water holding capacity of the cytoplasm under drought conditions. ABA inhibits the mRNA synthesis and their corresponding proteins, which are characteristic under normal conditions, and induces the expression of genes and, consequently, the synthesis of specific proteins including 27 kD protein. By stimulating the expression of individual genes and the synthesis of new polypeptides, ABA promotes the formation of protective reactions and increases the resistance of plants to crude oil pollution.

MAIN STAGES OF DEVELOPMENT OF THE LATE CARBONIFEROUS FLORA AND VEGETATION IN THE DONETS BASIN AS THE BASIS OF JUSTIFICATION OF REGIONAL STRATIGRAPHIC UNITS AT THE PALAEOECOSYSTEM LEVEL

Four stages of development of the late Carboniferous vegetation cover have been established that correspond to the time intervals of four regional subdivisions of the Donets Basin − the Toretsian and Kalynovian Regional Stages, the Luganskian and Vyskrivskian Horizons of the Myronivskian Regional Stage. The analysis of phytostratigraphic and paleophytocenological data showed that the stages of vegetation development are characterized by the dominant plant communities in rank of orders of widespread landscapes. Сhanges from one stage to another are considered as the paleophytocenotic events, which are expressed by the changes of dominant communities of certain landscape types. The levels of paleophytocenotic events coincid with the bases of regional subdivisions The bases of the Toretsian and Kalynovian correspond to the levels of paleophytocenotic events, which were manifested by the formation of new communities types as a result of the evolutionary renewal of composition of wetland calamitean-fern and fern-pteridosperm forests of coastal lowlands as well as lycopsid and calamitean-fern forests of deltaic plains. The base of the Myronivskian (Luganskian Horizon) corresponds to the level of the paleophytocenotic event that was expressed by, firstly, the appearance of new communities types of seasonally dry pteridosperm woodlands of river valleys as a result of the evolutionary renewal of their composition, secondly, the appearance of new communities types of wetland calamitean-fern woodlands of coastal lowlands and calamitean-fern and pteridosperm woodlands of deltaic plains, the formation of which were due to the reduction of species compositions and the changes of dominants. The lower boundary of the Vyskrivskian Horizon corresponds to the level of the paleophytocenotic event that was expressed by the appearance of new communities types of wetland calamitean-fern and fern-pteridosperm woodlands of coastal lowlands and seasonally dry fern-pteridosperm woodlands of lacustrine-lagoon plains, the formation of which were associated with plant migrations and the appearance of new dominants. The considered paleophytocenotic events are manifestations of phytocoenogenetic processes, which led to paleophytocenotic changes, and mark main palaeoecosystem transformations in view of vegetation development stages.

Field efficacy of Bt cotton containing events DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 against lepidopteran pests and impact on the non-target arthropod community in Brazil.

The efficacy and non-target arthropod effects of transgenic DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 Bt cotton, expressing proteins Cry1Ac, Cry1F and Vip3Aa19, was examined through field trials in Brazil. Fifteen field efficacy experiments were conducted from 2014 through the 2020 growing season across six different states in Brazil to evaluate performance against key lepidopteran pests through artificial infestations of Chrysodeixis includens (Walker), Spodoptera frugiperda (J.E. Smith,1797), Spodoptera cosmioides (Walker, 1858) and Chloridea virescens (F., 1781), and natural infestations of Alabama argillacea (Hübner) and S. frugiperda. The impact of this Bt cotton technology on the non-target arthropod community in Brazilian cotton production systems was also assessed in a multi-site experiment. DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 cotton significantly reduced the feeding damage caused by S. frugiperda, S. cosmioides, C. includens, C. virescens and A. argillacea, causing high levels of mortality (greater than 99%) to all target lepidopteran pests evaluated during vegetative and/or reproductive stages of crop development. Non-target arthropod community-level analyses confirmed no unintended effects on the arthropod groups monitored. These results demonstrate the value of transgenic Bt cotton containing event DAS-21023-5 × DAS-24236-5 × SYN-IR102-7 for consideration as part of an integrated approach for managing key lepidopteran pests in Brazilian cotton production systems.

Temperature Impact on Telenomus podisi Emergence in Field Releases of Unprotected and Encapsulated Parasitoid Pupae.

This work aimed to evaluate the influence of temperature on the emergence of Telenomus podisi throughout the soybean development cycle, using encapsulated and unprotected pupae releases, in four different possible locations where pupae can be deposited during release. The trial was carried out in a randomized block design in a 2 × 4 factorial scheme: two parasitoid pupae release strategies (encapsulated and unprotected) × four pupae locations (between soybean lines of planting, bottom third, middle third, or upper third of plant canopy) with 5 replicates. There were no significant interactions between the studied factors. In the vegetative stage (V2 and V9), a smaller percentage of emergence of parasitoid adults was observed between soybean lines of planting (37.1% and 23.4% for V2 and V9 , respectively). The highest maximum temperatures were recorded between the soybean lines, with the greatest variations in maximum and minimum temperatures (55.2°C and 21.3°C) in V2 and (52.8°C and 23.9°C) inV9. In the reproductive stages (R1, R4, and R7), the observed temperatures were lower when compared to those observed in the vegetative stages (V2 and V9), with no difference in the emergence of parasitoid adults, which was above 70% in stage R1 and above 80% in R4 and R7. Regarding the pupae (encapsulated or unprotected), both allowed similar adult emergence. Therefore, it can be concluded that both unprotected and encapsulated pupae can be released, but those releases during the soybean vegetative development stage should be avoided due to the high temperatures to which pupae can be exposed.

Species of the genus Epilobium (Onagraceae) in plant communities in Ukraine

To assess the coenotic peculiarities of species of the genus Epilobium (Onagraceae), in particular their coenotic amplitudes in the syntaxa of vegetation of Ukraine, 986 relevés from literature sources were analyzed. The names of syntaxa are provided in accordance with the Prodromus of the vegetation of Ukraine. Species of the genus Epilobium are widely represented in many plant communities and participate in the formation of natural, semi-natural and ruderal coenoses, where they are often diagnostic or characteristic species of associations, alliances, orders and classes of vegetation, or only present in their floristic composition. Epilobium species are present in 28 classes, which is evidence of their broad coenotic amplitudes and representation in different vegetation types: wetland, grassland, halophytic, forest, shrubs, chasmophytic, alpine, and anthropogenic (synanthropic). The widest coenotic amplitudes were revealed in such species as: E. hirsutum, E. palustre, E. angustifolium, E. parviflorum, E. tetragonum, E. montanum, E. alsinifolium, and E. collinum. According to the range of coenotic amplitude, all species can be subdivided into three groups: hemistenotopic, which occur within one class (E. adenocaulon, E. dodonaei, E. lamyi, E. nutans), hemi-eurytopic (within two or three classes) – E. alpestre, E. roseum, and eurytopic (within more than three classes) – E. alsinifolium, E. angustifolium, E. collinum, E. hirsutum, E. montanum, E. palustre, E. parviflorum, E. tetragonum. As for participation of species in the coenosis, the vast majority of them are assectators, and only a small portion can be temporary edificators (in some groups, at certain successive stages of vegetation development: E. angustifolium). Plants of Epilobium species can reproduce rapidly, both vegetatively and by seeds, which promotes their active colonization of new habitats. However, they usually do not tolerate increased shading and coenotic competition with other plant species, so their strategy is mainly ruderal.

СКРИНИНГ НА УСТОЙЧИВОСТЬ К ТВЕРДОЙ ГОЛОВНЕ (TILLETIA CARIES (DC.) ПШЕНИЦЫ

Common bunt (Tilletia caries (DC.) the disease occurs in areas where autumn wheat is grown. In our country, most of the zoned wheat varieties are infected with this disease. Therefore, foreign germoplasm should look for sources of strength. In our research in the field of artificial epizootic environment, the Hungarian 21 varieties of soft wheat Tilletia caries (DC.) of the pathogen was made the phytopathological and genetic-selection analysis. The study revealed that 15 wheat varieties are resistant to diseases, of which 8 wheat varieties were highly resistant to diseases (IT-0). They are; Ati, Békés, Berény, Csillag, Futár, Pilis, Szala and Rege. We say 7 varieties that are resistant to common bunt (IT-1), they are Kalász, Mentor, Göncöl, Fény, Garaboly, Szemes and Vitorlás. The indicator of the biomass index (NDVI) was determined at the stages of vegetative development of plants in ears, flowering phase and milky stage. The average value of the biomass index is higher than 0.70, with a high score of 9 varieties that have Ati, Mentor, Hajnal, Göncöl, Tisza, Csillag, Futár, Garaboly and Szala. As a result of the analysis of structural characteristics, the varieties Körös, Mentor, Tisza, Szala, Szemes and Rege showed a high index for all characteristics. As a result, disease-resistant and high-performance varieties can be presented as common bunt resistant specimens in immune selection.

Assessment of future climate change impact on rainfed wheat yield in the semi-arid Eastern High Plain of Algeria using a crop model

Maintaining sustainability in rainfed wheat production under changing climate is a grave concern for food security in Algeria. This study aims to assess the impact of future climate change on rainfed wheat yield in the semiarid Eastern High Plains (Setif and Bordj Bou Arreridj (BBA)) in Algeria using AquaCrop model. For this purpose, the EURO-CORDEX climate projections by 2035–2064 and 2065–2094 were downscaled using ICHEC_KNMI model under two representative concentration pathway (RCP) scenarios RCP 4.5 and RCP 8.5. The crop model predicted wheat yield increase by 82–95% and 77–118% at Setif and by 8–16% and 133–135% at BBA under the RCP 4.5 (2035–64 and 2065–94) and RCP 8.5 (2035–64 and 2065–94) scenarios, respectively, compared to the yield of the baseline period of 1981–2010. Future yield improvement is due to the fertilizing effect of the elevated carbon dioxide (CO2) concentration in the atmosphere, which offsets the negative impacts of rising temperature, decreasing precipitations and the net solar radiation. The expected increase in yield is much higher under RCP 8.5 compared to RCP 4.5 because CO2 concentration is higher under RCP 8.5. The model predicted an increase in wheat water productivity because of the expected decrease in evapotranspiration losses. To adapt rainfed wheat to future climate change in the study area, early sowing in mid-October provides better yields because it allows the wheat crop to take more benefits from increased precipitation during the vegetative development stage and to avoid the spring warming temperature.

Crop Coefficient for Potato Crop Evapotranspiration Estimation by Field Water Balance Method in Semi-Arid Region, Maharashtra, India

Crop evapotranspiration (ETc) estimation is essential for many studies such as irrigation system design and management, crop yield simulation, and water resource planning and management. Field studies were conducted at MPKV Rahuri, Maharashtra from 2015 - 2016 and 2016 - 2017 (2 years) in clay soils to determine crop evapotranspiration and crop coefficients (Kc) of the potato crop. The experimental area was cultivated with irrigation applied at 7-days interval. The irrigation scheduling was based on the field water balance approach. The crop evapotranspiration was determined by the field water balance; reference evapotranspiration (ETo) by the Penman-Monteith method and crop coefficients were computed using the standard FAO-56 methodology. The total reference evapotranspiration (ETo) and crop evapotranspiration (ETc) were 226 and 240 mm for the year 2015–2016 and 248 and 250 mm for the year 2016–2017, respectively. The 2-year average reference evapotranspiration was 237 mm and the crop evapotranspiration was 245 mm. The average estimated Kc values for the semi-arid region during the vegetative, tuber development, and maturity stages for potato are 0.55, 1.11, and 1.01, respectively. The calculated values are slightly lower than those suggested by FAO-56 for the vegetative and tuber development stages and higher for the maturity stage of potato. The estimated values of crop coefficients for potato are 11.25% higher than those suggested by FAO-56. However, observed variation between values from the FAO-Kc and Kc calculated by the field water balance is not significant. So, these values can be used for irrigation scheduling of potato in the semi-arid region.

Voxel carving-based 3D reconstruction of sorghum identifies genetic determinants of light interception efficiency.

Changes in canopy architecture traits have been shown to contribute to yield increases. Optimizing both light interception and light interception efficiency of agricultural crop canopies will be essential to meeting the growing food needs. Canopy architecture is inherently three‐dimensional (3D), but many approaches to measuring canopy architecture component traits treat the canopy as a two‐dimensional (2D) structure to make large scale measurement, selective breeding, and gene identification logistically feasible. We develop a high throughput voxel carving strategy to reconstruct 3D representations of sorghum from a small number of RGB photos. Our approach builds on the voxel carving algorithm to allow for fully automatic reconstruction of hundreds of plants. It was employed to generate 3D reconstructions of individual plants within a sorghum association population at the late vegetative stage of development. Light interception parameters estimated from these reconstructions enabled the identification of known and previously unreported loci controlling light interception efficiency in sorghum. The approach is generalizable and scalable, and it enables 3D reconstructions from existing plant high throughput phenotyping datasets. We also propose a set of best practices to increase 3D reconstructions’ accuracy.

The AtMYB2 inhibits the formation of axillary meristem in Arabidopsis by repressing RAX1 gene under environmental stresses.

AtMYB2 protein represses the formation of axillary meristems in response to environmental stresses so that plants can undergo a shorter vegetative development stage under environmental stresses. Shoot branching is an important event determined by endogenous factors during the development of plants. The formation of axillary meristem is also significantly repressed by environmental stresses and the underlying mechanism is largely unknown. The REGULATOR OF AXILLARY MERISTEMS (RAX) genes encode the R2R3 MYB transcription factors that have been shown to regulate the formation of axillary meristems in Arabidopsis. The AtMYB2 is also a member of R2R3 MYB gene family whose expression is usually induced by the environmental stresses. In this study, our results showed that AtMYB2 protein plays a pivotal negative regulatory role in the formation of axillary meristem. AtMYB2 is mainly expressed in the leaf axils as that of RAX1. The environmental stresses can increase the expression of AtMYB2 protein which further inhibits the expression of RAX1 gene by binding to its promoter. Therefore, AtMYB2 protein represses the formation of axillary meristems in response to environmental stresses so that plants can undergo a shorter vegetative development stage under environmental stresses.

Ellagitannins in roots, leaves, and fruits of strawberry (Fragaria × ananassa Duch.) vary with developmental stage and cultivar

The study set out to determine changes in both the quantitative and qualitative composition of ellagitannins (ETs) in the roots, leaves, and fruits of six strawberry cultivars at the main stages of vegetative and generative plant development. Variability in the content of fragariin A was established for the first time. PCA and multivariate ANOVA revealed substantial variation in ET concentrations in strawberry roots, leaves, and fruits depending on the cultivar tested and plant growth stage. The average total ET content in the leaves, roots, and ripe fruits was 82, 8, and 9 mg/g dry weight, respectively, which indicates that ET biosynthesis and accumulation are the most effective in the leaves. A scheme was proposed to illustrate the pattern of transformations of the identified ETs, starting from pedunculagin as a substrate for monomers as well as for the condensation reaction in the three morphological parts of the plant.

Reevaluating the Economic Injury Level for Brown Stink Bug (Hemiptera: Pentatomidae) at Various Growth Stages of Maize.

Economic yield loss and reduction in grain quality from brown stink bug, Euschistus servus (Say), feeding injury in early and late stages of maize, Zea mays (Poales: Poaceae, Linnaeus), development was assessed in Virginia and North Carolina in 2018 and 2019. Varying levels of stink bug infestations were introduced to seedling maize (V2-early stage), and a range of late-stages of maize, including 1) the last stage of vegetative development (V12/V14), 2) prior to tasseling, 3) at tasseling (VT), and 4) across all tested late growth stages. Euschistus servus infestation levels included 33, 67, and 100% of maize seedlings, and 25, 50, 100, and 200% of plants during later stages. Infestations were maintained on seedling maize for 7 d, and 8 or 16 d in reproductive stages. Infestation level in seedling maize had an impact on grain yield. Infestation level and growth stage both had an impact on grain yield in reproductive maize. The percentage of discolored kernels was also affected by infestation level, but not growth stage. Regression analysis between grain yield and infestation level indicated that the average economic injury level is 7% in seedling maize (7 bugs/100 plants) and 12% (12 bugs/100 plants) from the last vegetative stages (V12/V14) through pollination (VT). The economic injury level in the late vegetative stages is only applicable when infestations are present for an extended period of time (16 d), emphasizing the need for continued scouting of maize throughout the season to make informed management decisions.

HEAVY METALS BIOABSORPTION AND SOIL STABILIZATION BY Sarcocornia neei FROM EXPERIMENTAL SOILS CONTAINING MINE TAILINGS

In the Atacama region of northern Chile, there are a large number of abandoned mines and dams with tailings and little flora development. Sarcocornia neei, a halophytic plant growing in Chilean coastal areas, is highly tolerant to contaminated soils associated with mine tailings. The potential for bioabsorption of heavy metals and arsenic and the substrate stabilization by this species was evaluated in soil experimentally contaminated with mine tailings from the Copiapó Valley. Sarcocornia neei grew well, although more slowly, in experimental soils containing mainly Fe, Cu and Mn. In an advanced vegetative development stage, S. neei roots were able to stabilize the contaminated experimental soils, agglomerating them in more than 80 % and extracting chemical elements from them. These characteristics are potentially useful for phytoremediation and reduction of contamination by fine-size particles from mine tailings and contaminated soils.

Genome-wide identification of WD40 genes reveals a functional diversification of COP1-like genes in Rosaceae.

Genome-wide identification of WD40-like genes reveals a duplication of COP1-like genes, one of the key players involved in regulation of flowering time and photomorphogenesis, with strong functional diversification in Rosaceae. WD40 proteins play crucial roles in a broad spectrum of developmental and physiological processes. Here, we conducted a systematic characterization of this family of genes in Rosa chinensis 'Old Blush' (OB), a founder genotype for modern rose domestication. We identified 187 rose WD40 genes and classified them into 5 clusters and 15 subfamilies with 11 of RcWD40s presumably generated via tandem duplication. We found RcWD40 genes were expressed differentially following stages of vegetative and reproductive development. We detected a duplication of CONSTITUTIVE PHOTOMORPHOGENIC1-like genes in rose (RcCOP1 and RcCOP1L) and other Rosaceae plants. Featuring a distinct expression pattern and a different profile of cis-regulatory-elements in the transcriptional regulatory regions, RcCOP1 seemed being evolutionarily conserved while RcCOP1L did not dimerize with RcHY5 and RcSPA4. Our data thus reveals a functional diversification of COP1-like genes in Rosacaeae plants, and provides a valuable resource to explore the potential function and evolution of WD40-like genes in Rosaceae plants.

Efecto de medicamentos homeopáticos en plantas de tomate (Solanum lycopersicum L.)

Agrochemical use in horticultural cultivations generates negative effects, thus the need for searching to decrease or eliminate its use by means of other less toxic techniques. Agricultural homeopathy represents an alternative for ecological agriculture, impacting positively in cultivation development. The effect of four homeopathic medicines for human use were assessed in two centesimal dynamizations (7CH and 13CH) [(Silicea Terra (SiT), Natrum muriaticum (NaM), Zincum phosphoricum (ZiP) and Phosphoricum acidum (PhA)], and a control treatment (distilled water) on tomato plant germination, emergence, and initial development. The treatments were established under a randomized complete block design with three repiclates. Germination and emergence rate and percentage and morphometric variables (plant height, radicle length, dry and wet weight) were assessed, including the variables in stem diameter and wet and dry leaf weight, number of branches, leaves, and buds in the vegetative development stage. Signif icant differences were observed in all the morphometric variables assessed in function of the different development stages, homeopathic medicines, and their different dynamizations. During germination, greater growth in stem length was observed with ZiP-7CH (5.5 ± 0.98 cm) compared to the control group (4.3 ± 1.10 cm). During the emergence stage, the treatments SiT-7CH (6.6 ± 1.11 cm) and ZiP-7CH (5.9 ± 1.41 cm) increased stem length signif icantly whereas with PhA-7CH, the best effects were obtained in the variables assessed during the vegetative development stage, LT (94 ± 8.31 cm), leaf number (No hojas) (131 ± 27.71), fresh stem biomass (BFT) (17.20 ± 2.45 g), wet leaf biomass (BFH) (30 ± 7.72 g), dry leaf biomass (BSH) (2 ± 0.61 g), fresh root biomass (BFR) (10 ± 6.26 g), dry root biomass (BSR) (1 ± 0.43 g), and number of flower buds (No H) (6 ± 7.10). The homeopathic medicines applied impacted positively during the initial and vegetative development stages of tomato under controlled conditions. This research study represents and advance in the sustainable management of tomato cultivation.

Switching of dominant positions between two sand‐fixing shrub species during the dune revegetation process is underlain by their contrasting xylem hydraulics and water‐use strategies

AbstractDifferences in key physiological characteristics between plant species can result in their contrasting performances in vegetation restoration projects, but ecophysiological comparative studies in close relation to ecological restoration projects are scarce. Hedysarum fruticosum Pall. and Caragana microphylla Lam. are two leguminous shrub species widely used in combination for fixation of active sand dunes in semiarid regions of northern China, but they clearly differ in fitness at different stages of dune vegetation development; that is, H. fruticosum quickly gains a community dominance at the initial stage but yields to C. microphylla in a few years after the fixation of dunes. To reveal the underlying mechanism of such a pattern, key physiological characteristics related to xylem water transport, leaf water use, and drought tolerance were compared between these two species at a typical site of sand dune fixation project in Inner Mongolia. Compared with C. microphylla, H. fruticosum shows an acquisitive and risky water management strategy with substantially higher hydraulic efficiency and photosynthetic capability but reduced resistance to drought‐induced xylem embolism, which endows it an advantage under conditions of relatively high soil water availability at the early stage of dune fixation. In contrast, C. microphylla exhibits more conservative water use and characteristics of greater drought tolerance, which results in greater dominance under the more drought‐stressed conditions of the later stage of dune fixation. Our study for the first time provides a potential mechanistic explanation for the clear switching of dominant positions between the two important sand‐fixing shrub species during the sand dune revegetation process.

Primary plant succession on freshly degraded yedoma (ice complex) in Lena delta (Eastern Siberia)

Primary plant succession was studied on freshly eroded yedoma in the southern part of Lena River Delta. Four stages of vegetation development were clearly distinguished. The first stage starts on bare ground and lasts from two-three months to one year. Its vegetation is represented only by fragmented cover of young mosses and a few seedlings of vascular plants. The most abundant moss species at this moment is Ceratodon purpureus. The second stage lasts from one to three years depending on slope steepness. Plants cover 20 to 60% of the soil surface. Main dominants are Descurainia sophioides and Tephroseris palustris. The third stage of succession presented by closed species-poor grasslands with Arctagrostis arundinacea as main dominant. This stage lasts for up to 20 years. The fourth stage is represented by species-rich herbaceous communities, which also have Arctagrostis arundinacea as main dominant but enriched with many perennial herbs. There is not enough data to determine the duration of this stage but it is at least few tens of years. This successional system requires a long time for its development. It means that IC degradation is not a recent process but accompanied yedoma deposits through all of its history.