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Blepharostoma is one of the most ancient extant liverwort genera, within which the genetic diversity is quite high, whereas the morphological diversity, owing to the supposed stasis, is quite low. Unusually large plants of this genus were collected in North Vietnam and are described here as new-to-science species via an integrative approach. The two studied specimens do not reveal variability in the sequenced ITS1-2 nrDNA and trnL-F cpDNA loci, are clearly separated from other species by the level of genetic distances, and maintain a stable position on the reconstructed phylogenetic trees. This species is characterized, in addition to the large overall size of the plants, by larger leaf segment cells and a mixed character of oil bodies (i.e., small homogeneous and larger finely papillose ones within one cell). A description of the new taxon; its diagnostic characteristics; photographs; and discussions regarding its ecology, morphological similarities, and potential distribution are provided. [ABSTRACT FROM AUTHOR]

Cinnamomum balansae Lecomte (Lauraceae), an economically important forest tree, is distributed in the tropical forests of central and northern Vietnam, which has been threatened in recent decades due to the destruction of its habitat and over-exploitation. The genetic diversity and population structure of the species have not been fully evaluated. We used a set of 15 microsatellites to analyze 161 adult trees from 9 different populations, representing the geographical distribution of C. balansae. Ninety-two different alleles were identified. Here our results showed a low genetic diversity level with an average H o = 0.246 and H e = 0.262, and a high level of genetic differentiation (F ST = 0.601). The bottleneck tests indicated evidence of a reduction in the population size of the two populations (TC and CP). Additionally, all three clustering methods (Bayesian analysis, principal coordinate analysis, and Neighbor-joining tree) were identified in the two genetic groups. The Mantel test showed a significant positive correlation between genetic distance and geographic distance (R 2 = 0.7331). This study will provide a platform for the conservation of C. balansae both in ex-situ and in-situ plans.

Given that rice husk biochar has been shown to modulate salinity in salt-affected acid soils, the objective of this study was to investigate the effects of organic amendment of salinized acid soils on P fractions, enzyme activities, and associated rice yield. Four treatments, viz. Rice–Rice–Rice, [RRR]; Fallow–Rice–Rice, [FRR]; Fallow–Rice–Rice + 3 Mg ha−1 of compost [FRR + Comp]; and Fallow–Rice–Rice + 10 Mg ha−1 of biochar [FRR + BC] were established at Ben Tre and Kien Giang sites, Viet Nam, over six consecutive crops. Soil properties at harvest of the sixth crop showed that there were diverse patterns of fractionation between P forms with respect to treatment. Overarchingly, biochar increased labile and moderately labile inorganic P and organic P by 30% to 70%, respectively, whilst compost had a relatively modest effect on these pools. Soil phosphatase activities at crop tillering increased following the FRR + Comp and FRR + BC treatments compared with those in RRR, except for acid phosphatase at Ben Tre. At harvest, there were no significant differences between the enzyme activities among the treatments. Rice yield was positively correlated with the more labile forms of P, soil C, and acid phosphatase activity. In the absence of organic amendments, there was no effect of triple versus double rice crops being grown in one-year cycle. Repeated application of biochar (10 Mg ha−1 × 5 times) showed potential to increase grain yields and total soil C in salt-affected acid soils, via modulation of P transformations to more plant-available forms.

Gottschelia, collected for the first time in Indochina, inspired an attempt to review the genus phylogeny to identify a more precise position of Indochinese plants. The genetic distance between African and Asian populations of G. schizopleura sensu lato was confirmed. The two groups should be treated as different species. A new combination, G. microphylla comb. nov., has been proposed for Asian plants. Aside from molecular genetics, distinguishing this species from the presumable strictly African G. schizopleura is also possible by morphological characteristics, as well as by its distribution. At the same time, at least three groups are distinguished among Asian haplotypes of G. microphylla, each of which can be interpreted as a species or, at least, subspecies. A morphological description, intravital photographs of the general habitat, and details of the morphological structures are provided. The position of Gottschelia in the phylogenetic schema of Jungermanniales does not allow us to attribute it to any of the known families and forces us to describe a new family, Gottscheliaceae, which is phylogenetically somewhat related to the Chaetophyllopsidaceae re-evaluated here and very different from Gottscheliaceae morphologically. [ABSTRACT FROM AUTHOR]

Mung bean residues stimulate the hatching of soybean cyst nematode (SCN). In our previous study, combined incorporation of mung bean residues and biochar into soil can be effective in suppression of the soybean cyst nematode (SCN), Heterodera glycines, in the upper layer soil. However, there are no data available as to whether such effects are transmissible, and could for example be manifest in subsoil zones where such incorporation is confined to topsoils, via water-based pathways. We evaluated the effects of leachate passage from a biochar-amended soil in an upper soil zone to a lower zone in a microcosm-based system, upon a range of physicochemical properties and density of SCN. Disturbed soil was filled in a total of 9 cylindrical cores with two layers. The upper layer (0–15 cm) was amended with biochar at rates equivalent to 0, 0.3% or 1.8%, with bulk density set at of 1.1 g cm−3. The lower layer (15–25 cm) without biochar amendment was compacted to 1.2 g cm−3. Mung beans were grown for two weeks and incorporated into the upper layer. Water was surface-applied to the cores 4, 6, and 8 weeks after mung bean incorporation. After 16 weeks, the upper and lower layer soils were separately collected and assayed. The presence of biochar in the upper layer reduced the abundance of free-living nematodes, mainly bacterivorous, but increased that of a predator genus Ecumenicus in this zone. In the lower layer of soil under a biochar-amended upper layer, available P and soluble cations were increased as were abundances of total nematodes including Ecumenicus, resulting in greater maturity index, basal and structure indices. Notably, SCN density was decreased in lower zones by more than 90% compared to zero-biochar controls. This demonstrates that the effects of biochar upon soil properties, including impacts on biota and plant pathogens, are transmissible.

Cinnamomum parthenoxylon (Jack) Meisn. is a tree in genus Cinnamomum that has been facing global threats due to forest degradation and habitat fragmentation. Many recent studies aim to describe habitats and assess population and species genetic diversity for species conservation by expanding afforestation models for this species. Understanding their current and future potential distribution plays a major role in guiding conservation efforts. Using five modern machine-learning algorithms available on Google Earth Engine helped us evaluate suitable habitats for the species. The results revealed that Random Forest (RF) had the highest accuracy for model comparison, outperforming Support Vector Machine (SVM), Classification and Regression Trees (CART), Gradient Boosting Decision Tree (GBDT) and Maximum Entropy (MaxEnt). The results also showed that the extremely suitable ecological areas for the species are mostly distributed in northern Vietnam, followed by the North Central Coast and the Central Highlands. Elevation, Temperature Annual Range and Mean Diurnal Range were the three most important parameters affecting the potential distribution of C. parthenoxylon. Evaluation of the impact of climate on its distribution under different climate scenarios in the past (Last Glacial Maximum and Mid-Holocene), in the present (Worldclim) and in the future (using four climate change scenarios: ACCESS, MIROC6, EC-Earth3-Veg and MRI-ESM2-0) revealed that of C. parthenoxylon would likely expand to the northeast, while a large area of central Vietnam will gradually lose its adaptive capacity by 2100. [ABSTRACT FROM AUTHOR]

Biochar has the potential for improving soil properties and supporting ecological functions, but it has negative impacts on soil organisms in some cases. This study aimed to assess the effect of biochar application at rates of 0 (B0), 5 Mg ha−1 (B5), 20 Mg−1 (B20), and 40 Mg ha−1 (B40) on soil nematode community under upland and flooded conditions in a short-term microcosm experiment. After biochar application, soil was incubated for 2 to 8 weeks and nematodes were identified for community composition, trophic structures, functional guilds, maturity index and metabolic footprints. The chemical properties of the soils were also analyzed. General linear model revealed that biochar increased soil pH, EC, NO3−-N, available phosphorus, total C, and C/N ratio, particularly in the highest application rate and shifted the composition of nematodes. The greatest abundances of omnivores (Mesodorylaimus, Thornenema), predator (Nygolaimus) and functional guilds of cp5 were observed in B5, resulting in greatest structure footprint and composite footprint, (omnivorous + predator) footprint and total biomass in B5. While abundances of nematodes tended to decrease with the biochar applicate rates, the abundance of Prismatolaimus was the highest in B40. During the 8-week incubation period, the abundances of Achromadora, Alaimus, Aporcelaimellus, Cryptonchus, Mononchus, and Tobrilus remained stable in upland conditions. Under flooded conditions, the abundances of almost all taxa were markedly lower than those under upland conditions irrespective of biochar application, except for Acrobeloides, Alaimus, Aphelenchoides, and Ditylenchus. We highlighted that 5 Mg ha−1 of rice husk biochar can be the optimum in shaping the nematode community.

The distribution of known Syzygiella taxa in Indochina was reviewed. Currently, four species are known in Indochina: S. autumnalis, S. elongella, S. nipponica, and S. securifolia. This genus is reported for the first time in the flora of Cambodia, and S. securifolia is newly recorded for Vietnam. Herein, a description of oil bodies for S. securifolia is provided for the first time. A morphological description of the species and intravital photographs, as well as line-art illustrations, are provided along with the identification key to the Syzygiella taxa known in Indochina. A comparison of the climatic parameters of the collection sites for four known species showed that three of them occupy a relatively marginal position in the flora of Indochina as a whole and are known from colder biomes on the very northern edge of the peninsula. The locations of Syzygiella securifolia are scattered not only on the geographical map of Indochina but also on the bioclimatic scatterplot; these locations are likely an underestimation of the distribution of this taxon in Indochina, although it is generally rare worldwide. A comparison of lists of liverworts across the countries of Indochina will help identify groups of taxa for further targeted searches with the purpose of obtaining more comprehensive knowledge of the biodiversity of still poorly studied Indochina countries. [ABSTRACT FROM AUTHOR]

Dichotomous keys are the most popular type of identification keys. Studies have been conducted to evaluate dichotomous keys in many aspects. In this paper we propose an index for quantitative evaluation of dichotomous keys (Edicho). The index is based on the evenness and allows comparing identification keys of different sizes.

Avoidance of intensive rice cultivation (IRC) and soil amendments are potential practices to enhance soil properties. There is only limited information on the effects of reduced IRC and its mixture with compost or silicate fertilizer (Si) on the soil nematode community in salt–affected soils. This study aimed to assess the shifts of soil nematode community by reducing a rice crop from triple rice system (RRR) to a double rice system and mixed with compost or Si in paddy fields in acid sulfate soil (ASS) and alluvial soil (AL) in the Mekong Delta, Vietnam. Field experiments were designed with four treatments in four replicates, including RRR and a proposed system of double–rice followed by a fallow (FRR) and with 3 Mg ha–1 crop−1 compost or 100 kg ha–1 crop−1 Si. Soils were collected at harvest after the 2 year experiment, reflecting the fifth and third consecutive rice crop in RRR and FRR system, respectively. Results showed that reduced IRC gave a significant reduction in abundance of plant–parasitic nematodes (PPN), dominated by Hirschmanniella and increased abundance bacterivorous nematodes when mixed to compost and silicate fertilizer in ASS. In addition, reduced IRC increased nematode biodiversity Hill’s indices and reduced herbivorous footprint in ASS. Proposed system having compost or Si had strongly increased in bacterivorous and omnivorous footprints. Particularly, reduced IRC mixture with Si increased abundance of Rhabdolaimus, Mesodorylaimus and Aquatides, metabolic footprints (structure footprint, bacterivorous, omnivorous and predator) and diversity Hill’s N1 index in ASS. Our results highlighted that reduced IRC was a beneficial practice for decreasing abundance of PPN in salt-affected soils and increasing abundance of FLN in ASS. IRC mixture with compost or Si had potential in structuring the nematode communities with increasing biodiversity, trophic structure, and metabolic footprints.

Meso-and microforming is a technology to shape parts from extremely small metal billets. Parts with geometric dimensions are a few millimetres to a few micrometres. With the rapid development of the electrical-electronics industry and biomedical engineering, the technology of forming microscopic parts has been researched and applied because of its efficiency, accuracy, and high productivity. Deep drawing is an operation that turns flat sheet metal blanks into hollow, open-mouth parts. It is an essential process in sheet metal stamping. Micro deep drawing is one of the micro-shaping technologies that has been widely studied and applied in recent years. However, the bases for calculating technological and geometrical parameters in the micro-deep drawing have not yet been analyzed and evaluated in detail. Therefore, this paper has proposed a theoretical basis combined with simulation applied to the design of technology to manufacture a connector head part drawing die with a diameter of 300µm and height of 1500µm using materials SUS304 material. Numerical simulation also allows evaluation of the stamping part's internal stress state, the ability to pull the workpiece into the die, and the thickness distribution on the product wall. Experimental research has also verified that, with the determined parameters, the stamping parts meet the quality requirements. This indicates the proposed calculation methods for the tiny deep drawing operation are entirely suitable. The results of this research can be wholly applied to the production of micro-sized cylindrical cup parts using the deep drawing method. [ABSTRACT FROM AUTHOR]

Soil salinity may damage crop production. Besides proper management of irrigation water, salinity reduction can be achieved through soil amendment. The objectives of this study were to evaluate the effects of rice husk biochar and compost amendments on alleviation of salinity and rice growth. Field experiments were conducted at two salt-affected paddy rice fields located in distinct sites for five continuous crops. Treatments, with four replicates, consisted of continuous three rice crops per year (RRR), two rice crops rotated with fallow in spring–summer crop (FRR), FRR plus compost at 3 Mg ha−1 crop−1 (FRR + Comp), and biochar at 10 Mg ha−1 crop−1 (FRR + BC). Salt contents and hydraulic properties of soils, plant biomass, and plant uptake of cations were investigated. Soil bulk density (BD), exchangeable sodium (Na+), and exchangeable sodium percentage (ESP) were reduced remarkably by biochar application. Biochar application significantly increased other soil properties including total porosity, saturated hydraulic conductivity (Ksat), soluble and exchangeable potassium (K+), K+/Na+ ratio, available P, and total C. Compost application also improved BD, total porosity, and available P, but not exchangeable Na+ and ESP. Total aboveground biomass of rice showed a trend of FRR + BC > FRR + Comp > FRR > RRR. Relatively higher K+ uptake and lower Na+ uptake in rice straw in FRR + BC resulted in a significant two times higher K+/Na+ ratio over other treatments. Our results highlight that biochar amendment is a beneficial option for reducing ESP and providing available K+ and P under salinity-affected P-deficient conditions, hence improving straw biomass.

Acid sulfate soil (ASS) has major problems related to phosphorus deficiency and high potential for N2O emissions, as well as strong acidity. The objective of this study was to evaluate the effects of rice husk biochar and compost on P availability and greenhouse gas (GHG) emissions in ASS in in vitro incubation studies. An ASS was amended with two types of rice husk biochar (at rates of 0 g kg−1, 20 g kg−1, and 50 g kg−1, equivalent to 0 Mg ha−1, 20 Mg ha−1, and 50 Mg ha−1, assuming that bulk density was 1 g cm−3 and evenly applied for 10 cm in depth) and compost (at rates of 0 g kg−1, 10 g kg−1, and 20 g kg−1, equivalent to 0 Mg ha−1, 10 Mg ha−1, and 20 Mg ha−1) and incubated. Application of compost increased labile P by 100% and 200% at rates of 10 g kg−1 and 20 g kg−1, respectively. Both biochars showed an increase in NaHCO3-soluble inorganic P by 16% to 30%, decreases in NaOH-soluble inorganic P and NaHCO3-soluble organic P. N2O emissions were significantly decreased by 80% by a biochar with a higher surface area and higher NH4+ adsorption capacity at a rate of 50 g kg−1 as compared with those in un-amended soil. In contrast, compost amendment at a rate of 10 g kg−1 significantly increased N2O emission by 150%. These results suggest that in ASS, whilst compost is more effective in improving P availability, biochar is more effective in mitigating GHG emissions, emphasizing that fundamental characteristics of organic amendments influenced the outcomes in terms of desirable effects.

The study of the flora located in the central part of the Hoàng Liên Sơn Range in the northern region of Indochina has revealed 279 species of liverwort and hornwort, 26 of which are newly reported for the flora of Vietnam. The uniqueness and peculiarity of the studied flora are explained by the significant altitudinal range in the area treated and its position in the contact zone of the Sikang-Yunnan floristic province of the East Asian Floristic Region with the Indochina Floristic Region. The checklist includes data on the distribution of each species in the studied region, habitats, and accompanying taxa. The high disunity of the regional floras of the southern tip of the East Asian region compared to the lesser disunity of the regional floras in the north of the East Asian region is shown. In general, the studied flora possess Sino-Himalayan mountain subtropical characteristics with the large participation of tropical elements. [ABSTRACT FROM AUTHOR]