Regulation of the growth of sprouting roots of black locust seedlings using root barrier panels

How can we regulate an invasive alien species of high commercial value?Black locust(Robinia pseudoacacia L.)has a unique capacity for seed dispersal and high germination.Field surveys indicate that black locust increases its growing area with sprouting roots and the elongation of horizontal roots at a soil depth of 10 cm.Therefore,a method to regulate the development of horizontal roots could be eff ective in slowing the invasiveness of black locust.In this study,root barrier panels were tested to inhibit the growth of horizontal roots.Since it is labor intensive to observe the growth of roots in the fi eld,it was investigated in a nursery setting.The decrease in secondary fl ush,an increase in yellowed leafl ets,and the height in the seedlings were measured.Installing root barrier panels to a depth of 30 cm eff ectively inhibit the growth of horizontal roots of young black locust.

Different mechanisms underlie similar species-area relationships in two tropical archipelagoes

Despite much research in the field of island biogeography,mechanisms regulating insular diversity remain elusive.Here,we aim to explore mechanisms underlying plant species-area relationships in two tropical archipelagoes in the South China Sea.We found positive plant species-area relationships for both coral and continental archipelagoes.However,our results showed that different mechanisms contributed to similar plant species-area relationships between the two archipelagoes.For coral islands,soil nutrients and spatial distance among communities played major roles in shaping plant community structure and species diversity.By contrast,the direct effect of island area,and to a lesser extent,soil nutrients determined plant species richness on continental islands.Intriguingly,increasing soil nutrients availability(N,P,K)had opposite effects on plant diversity between the two archipelagoes.In summary,the habitat quality effect and dispersal limitation are important for regulating plant diversity on coral islands,whereas the passive sampling effect,and to a lesser extent,the habitat quality effect are important for regulating plant diversity on continental islands.More generally,our findings indicate that island plant species-area relationships are outcomes of the interplay of both niche and neutral processes,but the driving mechanisms behind these relationships depends on the type of islands.

Tissue Culture and Rapid Propagation of Spathiphyllum kochii Engl. et Krause

[Objectives] This study was conducted on tissue-culture rapid propagation techniques of Spathiphyllum kochii Engl. et Krause. [Methods] With lateral buds of S. kochii as explants, the effects of such four basic media as MS, B5, Nitsch and Wpm and the ratio of two hormones(1, 2, 3 mg/L 6-BA and 0.1, 0.3, 0.5 mg/L NAA) on bud proliferation of S. kochii were studied by the complete test method, and the effect of the ratio of the two hormones(0.25, 0.50, 1.00 mg/L NAA and 1.0, 1.5 mg/L IBA) on rooting of S. kochii as well as the effect of substrate ratio(perlite and peat soil at 1∶9, 2∶8, 3∶7, 4∶6 and 5∶5) on its transplanting survival rate were also studied. [Results] The best basic medium for the rapid propagation of S. kochii was MS. The best hormone ratio suitable for bud proliferation was 2 mg/L6-BA+0.1 mg/L NAA, and the average number of buds proliferated at 45 d was 3.04. The average bud height was 2.05 cm; the most suitable medium for rooting was 1/2 MS+1 mg/L IBA+0.25 mg/L NAA, and its rooting rate was 100%; and the best transplanting substrate was 5∶5 perlite and peat. The soil ratio had a survival rate of 94%. [Conclusions] This study provides a theoretical basis for the improvement of the transplanting survival rate of test-tube S. kochii plantlets.

Genetic diversity analysis of Sinojackia microcarpa, a rare tree species endemic in China, based on simple sequence repeat markers

Although most Sinojackia species are endangered, they contribute greatly to the biodiversity of local ecosystems. Sinojackia microcarpa, an endangered species, is distributed only in three provinces of eastern China. Determining the genetic diversity of S. microcarpa provides key information for germplasm evaluation and species conservation. Here we used simple sequence repeat (SSR) markers to investigate the genetic diversity of eight natural populations of S. microcarpa. Leaf samples were collected from 144 individuals in 8 wild populations. The 156 bands were generated from 14 pairs of informative SSR primers, with an average percentage of polymorphic bands of 45.67%. The average values of Nei’s genetic diversity (He) and Shannon’s diversity index (I) were 0.1007 and 0.1658, respectively. The total genetic variation of S. microcarpa existed mainly within the eight populations, rather than among populations, and reached 86.41%. A cluster analysis showed that the eight wild populations of S. microcarpa could be classified into four groups, at a threshold of 4.0, based on an analysis of the SSR genotypes. Furthermore, there was a significant association between the phylogenetic relationships and the geographic locations of the S. microcarpa populations. In particular, populations from Fuyang, Jiande, and Lin’an in Zhejiang Province had close phylogenetic relationships and geographic distances. In addition, these three populations had the highest genetic diversity and the most individuals, suggesting that these three locations may be the S.microcarpa distribution center. This study serves as a model for studying the genetic diversity of endangered plant species.

Investigation of the mechanism of adult-stage resistance to barley yellow dwarf virus associated with awheat-Thinopyrum intermedium translocation

Barley yellow dwarf virus(BYDV)can infect wheat(Triticum aestivum L.),leading to yield loss.Among four BYDV strains(GAV,GPV,PAV,and RMV)identified in China,BYDV-GAV is the prevailing isolate.YW642,a wheat–Thinopyrum intermedium translocation line,is resistant to BYDV isolates at both seedling and adult stages.Zhong 8601 is the wheat recurrent parent of YW642 and is susceptible to BYDV.In this study,we investigated the adult-stage resistance mechanism of YW642,measured BYDV titer and hydrogen peroxide(H_2O_2) in adult-stage leaves of YW642 and Zhong 8601 inoculated with BYDV-GAV,and identified transcriptional differences between YW642 and Zhong 8601 using microarray-based comparative transcriptomics.Enzyme-linked immunosorbent assay and H_2O_2assay showed that both BYDV titer and H_2O_2 content were markedly lower in YW642 than in Zhong 8601 at 21,28,35,and 40 days post-inoculation(dpi).The transcriptomic comparison revealed that many types of genes were significantly up-regulated at 35 dpi in adult-stage leaves of YW642 compared to Zhong 8601.The important up-regulated genes associated with the adult-stage resistance encoded 15 resistance-like proteins,pathogenesis-related proteins(such as defensin and lipid transfer proteins),protein kinase homologs,transcription factors,reactive oxygen species scavenging-related proteins,and jasmonic acid and gibberellic acid biosynthesis enzymes.These results suggest that precise expression regulation of these proteins plays a crucial role in adult-stage resistance of YW642 against BYDV infection.

Optimization of Germinated Conditions for Somatic Embryos in Liriodendron Hybrids

The development of somatic embryos is a key technology in plant breeding. To gain the best cultural conditions,the factors influencing on germination and transplanting survival rate of the somatic embryos in Liriodendron hybrids were optimized,including the development period of somatic embryos,macro-element,Vitamin C,genotypes,plant hormones and transplant medium in this study. The results showed that the optimal development phase of germination was torpedo-shaped embryo,and the base cultural medium of 3/4 MS with vitamin C can keep normal form from somatic embryos. The germination rate of somatic embryo had obvious genotype difference,among which the hybrid 1 × 5002 was the most sensitive( 82. 46%),and the hybrid 1 × 4088 was the most insensitive( 13. 24%). The medium with 0. 1 mg/L of KT + 0. 1 mg/L of IBA can help promote the germination of somatic embryogenesis. In addition,the yellow soil was more suitable than mixed peat soil for transplanting Liriodendron hybrids seedlings. Therefore,the obtainment of the optimal conditions has important guidance for production practices of Liriodendron hybrids.

Study on Response Characteristics of Styrax tonkinensis to Heavy Metal Stress

[Objectives]To explore the response characteristics of chlorophyll and photosynthesis in Styrax tonkinensis under different concentrations of copper and cadmium stress and analyze the internal mechanism of the effects of copper and cadmium pollution stress on photosynthesis.[Methods]Taking seedlings of S.tonkinensis as the research object,the response characteristics of chlorophyll and photosynthesis of S.tonkinensis were compared under different concentrations of copper and cadmium.[Results]With the increase of copper and cadmium treatment concentrations,the chlorophyll content first rose and then fell.With the increase of cadmium concentration,the net photosynthetic rate of S.tonkinensis plants increased from decrease to increase,and the stomatal conductance,transpiration rate and intercellular CO_(2) concentration all increased.[Conclusions]Under the stress of different concentrations of cadmium,the photosynthetic characteristics of S.tonkinensis were not obviously inhibited.Copper stress has inhibitory effect on photosynthesis of S.tonkinensis.

Trends in Domestic Soundscape Research: Knowledge Graph Analysis Based on Cite Space

The development of soundscape has a history of over 20 years to this day. Based on the CNKI database, a contact graph of authors in the field of soundscape is drawn using Cite Space software, and the number of core authors in the field of soundscape is determined to be 30. Based on the number of papers and the evolution of keywords over the years, the development of soundscape research is divided into three stages: exploration stage(1995-2006), pre development stage(2007-2015), and post development stage(2016-present). The research direction is divided into three categories: soundscape perception, soundscape evaluation, and soundscape design. According to various graph analysis, with the continuous development of science and technology, soundscape research fields and methods are gradually diversified, and fields such as soundscape evaluation, soundscape, landscape architecture, soundscape perception and sound stroll have gradually become hot spots in soundscape research.

高效液相色谱法与光度法测定人造板中甲醛释放量的对比

分别对高效液相色谱法和分光光度法测定甲醛释放量的线性范围、精密度及检出限等进行对比分析,并利用高效液相色谱法和分光光度法对10种中密度纤维板甲醛释放量进行测定分析。结果表明:2种方法测定结果差异不显著,都可以用于测定人造板甲醛释放量,但分光光度法操作简便,费用少,建议使用分光光度法测定人造板甲醛释放量。

Uncertainties in above ground tree biomass estimation

Models of above-ground tree biomass have been widely used to estimate forest biomass using national forest inventory data.However,many sources of uncertainty affect above-ground biomass estimation and are challenging to assess.In this study,the uncertainties associated with the measurement error in independent variables(diameter at breast height,tree height),residual variability,variances of the parameter estimates,and the sampling variability of national inventory data are estimated for five above-ground biomass models.The results show sampling variability is the most significant source of uncertainty.The measurement error and residual variability have negligible effects on forests above-ground biomass estimations.Thus,a reduction in the uncertainty of the sampling variability has the greatest potential to decrease the overall uncertainty.The power model containing only the diameter at breast height has the smallest uncertainty.The findings of this study provide suggestions to achieve a trade-off between accuracy and cost for above-ground biomass estimation using field work.

Toxicity mechanisms and bioavailability of copper to fish based on an adverse outcome pathway analysis

Copper(Cu)exists in a variety of forms in different aquatic environments,and affects their bioavailability.In this study we provide a systematic review on toxicity of Cu which focuses on identifying evidence in the mechanisms of Cu toxicity,and apply an adverse outcome pathway(AOP)analysis to identify multiple potential mechanisms and their interactions of Cu toxicity to fish.This analysis process included the mechanisms of behavior toxicant,oxidative toxicant,ion regulation disruption toxicity,as well as endocrine disruption toxicity.It was found that at low levels of Cu exposure,swimming,avoid predators,locating prey and other sensory functions will be impaired,and the organism will suffer from metabolic alkalosis and respiratory acidosis following the inhibition of the carbonic anhydrase active.The main pathway of acute toxicity of Cu to fish is the inhibition of the Na^(+)/K^(+)-ATPase enzyme,and lead to reduced intracellular sodium absorption,as well as Cu-induced increased cell permeability,in turn resulting in increased sodium ion loss,leading to cardiovascular collapse and respiratory insufficiency.The endocrine disruption toxicity of Cu to fish caused growth inhibition and reproductive reduction.In addition,there are several key pathways of Cu toxicity that are affected by hardness(e.g.,Ca^(2+))and intracellular DOC concentrations,including inhibiting Cu-induction,improving branchial gas exchange,altering membrane transport functions,decreasing Na+loss,and increasing Na+uptake.The results of the AOP analysis will provide a robust framework for future directed research on the mechanisms of Cu toxicity.

Isolation,Identification,and Characterization of an Aluminum-Tolerant Bacterium Burkholderia sp.SB1 from an Acidic Red Soil

Aluminum(Al) toxicity usually occurs in acidic soils worldwide, which is detrimental to the growth of organisms. An Al-tolerant bacterium, SB1, was isolated from an acidic red soil of Chingkang Mountain, located in Jiangxi Province of China. Polyphasic analysis,including a 16 S rDNA phylogenetic tree as well as morphological and physicochemical properties, revealed that the isolate was a gramnegative, rod-shaped bacterium, which was recognized as Burkholderia sp. SB1 and had extreme acidity tolerance(pH 2.2) and excellent Al resistance(270 mg L^(-1) Al^(3+)). It could remove Al by up to 97.7% at a concentration of 54 mg L^(-1) Al^(3+). SB1 behavior under different temperatures and antibiotics was also examined. SB1 preferred moderate temperature conditions, ranging from 25 to37?C, and exhibited notable resistance to multiple antibiotics(including ampicillin, streptomycin, and tetracycline), except for being sensitive to chloramphenicol. Therefore, as the first reported bacterium to possess favorable Al resistance and excellent Al removal,Burkholderia sp. SB1 can potentially be used as an agent for bioremediation of Al-contaminated acidic red soils.

Regioselective Synthesis of SCF3-Substituted 2,4-Diarylquinazoline Using AgSCF3 as Trifluoromethylthiolation Reagent

A facile and efficient route to 4-aryl-2-[2-（trifluoromethylthio） aryl]quinazoline derivatives through a tandem directed Rh-catalyzed C-H iodination and trifluoromethylthiolation is described. The reaction proceeded under mild reaction conditions, exhibited good functional group tolerance with a broad scope of substrate and excellent regi- oselectivity in good to excellent yields.

Efects of sulfuric,nitric,and mixed acid rain on the decomposition of fne root litter in Southern China

Background:China has been increasingly subject to signifcant acid rain,which has negative impacts on forest ecosystems.Recently,the concentrations of NO_(3)^(−)in acid rain have increased in conjunction with the rapid rise of nitrogen deposition,which makes it difcult to precisely quantify the impacts of acid rain on forest ecosystems.Methods:For this study,mesocosm experiments employed a random block design,comprised of ten treatments involving 120 discrete plots(0.6 m×2.0 m).The decomposition of fne roots and dynamics of nutrient loss were evaluated under the stress of three acid rain analogues(e.g.,sulfuric(SO_(4)^(2−)/NO_(3)^(−)5:1),nitric(1:5),and mixed(1:1)).Furthermore,the infuences of soil properties(e.g.,soil pH,soil total carbon,nitrogen,C/N ratio,available phosphorus,available potassium,and enzyme activity)on the decomposition of fne roots were analyzed.Results:The soil pH and decomposition rate of fne root litter decreased when exposed to simulated acid rain with lower pH levels and higher NO_(3)^(−)concentrations.The activities of soil enzymes were signifcantly reduced when subjected to acid rain with higher acidity.The activities of soil urease were more sensitive to the efects of the SO_(4)^(2−)/NO_(3)^(−)(S/N)ratio of acid rain than other soil enzyme activities over four decomposition time periods.Furthermore,the acid rain pH signifcantly infuenced the total carbon(TC)of fne roots during decomposition.However,the S/N ratio of acid rain had signifcant impacts on the total nitrogen(TN).In addition,the pH and S/N ratio of the acid rain had greater impacts on the metal elements(K,Ca,and Al)of fne roots than did TC,TN,and total phosphorus.Structural equation modeling results revealed that the acid rain pH had a stronger indirect impact(0.757)on the decomposition rate of fne roots(via altered soil pH and enzyme activities)than direct efects.However,the indirect efects of the acid rain S/N ratio(0.265)on the fne root decomposition rate through changes in soil urease activities and the content of litter elements were lower than the pH of acid rain.Conclusions:Our results suggested that the acid rain S/N ratio exacerbates the inhibitory efects of acid rain pH on the decomposition of fne root litter.

Study on Litter Water Interception Capacity of Phyllostachys edulis Plantations with Different Densities

The litter amount and the water holding characteristic parameters,such as the maximum water holding capacity and rate,the water absorption rate and the modified interception amount of Phyllostachys edulis plantations with four densities were studied in Huangshan district.The results are as follows:The total amount,thickness and natural water content of litters under all the four stands tested were different.The total litter amount in different stands ranged between 3.98 t·ha-1 to 6.00 t·ha-1, which in the stand with the density of 3 000 stems·ha-1 was the most.The ratio of maximum water-holding capacity of litter in various stands ranged from 317.09%to 347.58%.The maximum water holding capacity of litter in the stand with the density of 3 000 stems·ha-1 was 20.70 t·ha-1. By analyzing,the relationship between the water holding capacity of litter and the immersion time followed the equation of:S = alnt + b（a is the coefficient;b is the constant term）.The relationship between the water absorption speed of the litter and the immerse time followed the equation of: V = ctd（c is the coefficient;d is the exponential term）.The litter water capacity increased rapidly within the first four hours,and then increased slowly.The results also showed that the hydrological character of litter was positively related to density in Ph.Edulis forest.Therefore, it is important to choose appropriate density for enhancing the eco-hydrological benefits of litter layer in Ph.edulis forest.

Mating patterns and pollen dispersal in a Japanese larch(Larix kaempferi) clonal seed orchard： a case study

Pollination dynamics highly determines the genetic quality of seed orchard crops. However, there is less research about the effect of mating patterns on seed productivity of orchard crops. So far, clonal seed orchards have been producing genetically improved seedlings used for most Japanese larch(Larix kaempferi(Lamb.) Carr.) plantations in China. In the present study, a total of 17 highly variable simple sequence repeat(SSR) markers were used for genotyping a progeny trial population consisting of 647 open-pollinated progenies germinated from seeds which were collected from 63 maternal clones with 140 potential paternal clones in a Japanese larch clonal seed orchard in China. Paternity analysis was used in the present case study in order to evaluate the level of paternal gametic contribution, estimate pollen contamination and selfing rates, and investigate pollination patterns,pollen dispersal patterns and the impact of mating patterns on seed productivity of orchard crops. We observed 93.7% of the success rate of the parental assignment, unequal paternal gametic contribution(0–12.4%) with 6.3% of the progenies derived from pollen contamination or unsampled pollen donors, and absence of evidence for selfing. We also found that pollination rate highly depended on the distance between pollen donors and maternal parents, the majority of the identified crossing(65.7%)occurred between clones within a 150-m radius, and large variations in growth performance existed among the paternal halfsiblings. Progeny growth performance(diameter at breast(DBH) and height(HGT)) was measured at Age-20 in order to investigate the impact of mating patterns on timber production of orchard crops. As either the paternal or maternal, two clones(i.e., clones Z38 and Z62) were identified to have produced progenies with higher average stem volume breeding values than that of all of the progenies. Specifically, the genetic gains for volume were 3.53% for the two clones as paternal parents, and 8.26% as the maternal parents at Age-20. Thus, both elite clones were ideal candidates for the construction of next-generation clonal seed orchards due to their synchronous reproductive phenology with greater crossing rate and higher genetic gain. These results improved the pedigree information to provide solid evidence of mating patterns for future design and effective management of seed orchards and for the development of viable long-term breeding strategies for other coniferous species.

Bird Species Diversity and Spatio-temporal Variation in the Sihong Hongze Lake Wetland National Nature Reserve in Eastern China

As an important hub on the East Asian-Australian Flyway(EAAF),Hongze Lake is an important migratory stopover and wintering site for hundreds of thousands of birds.However,research on bird community diversity in this area is still lacking.We conducted a bird survey from July 2020 to June 2021 using the line transect method on the terrestrial habitat,as well as the fixed-point method in the lake wetland at the Sihong Hongze Lake Wetland National Nature Reserve located in northwestern Hongze Lake,and analyzed the temporal-spatial variation in the bird community.The results showed that a total of 170432 detections of 215 bird species belonging to 18 orders and 55 families were recorded.In terms of species composition,the proportion of terrestrial birds was relatively high,followed by waterfowl richness,with high numbers of Anatidae species and shorebirds.For bird species abundance,waterfowl had the highest abundance of common coot(Fulica atra),belonging to the Rallidae family,followed by Anatidae and Ardeidae species.The abundance of shorebirds was extremely low,and that of non-waterfowl was also low.In terms of temporal patterns,the number of bird species and richness index were higher in spring and autumn but lower in winter and summer.The bird abundance was the highest in winter,and the remaining three seasons were similar in terms of bird abundance.The diversity index and evenness index were higher in spring,summer and autumn,and lowest in winter.For the spatial pattern,the open water in the western part of the reserve included the most densely distributed areas for birds,and the number of bird species and their abundance were both the highest in that part.There were significant differences in the bird community structures among the four habitats.The species number and richness index of birds in the reed habitat were the highest,and the bird abundance was also high,but the diversity index and evenness index were low.Although the bird abundance in the lake habitat was much higher than in the other habitats,the diversity index,evenness index and richness index were the lowest.The numbers of bird species and individuals in tourist attraction land and farmland were low,but the diversity index,evenness index and richness index were high.Our results reveal the spatial and temporal patterns of bird species diversity and abundance in Sihong Hongze Lake Wetland National Nature Reserve,and reflect the effects of different habitat types on bird diversity.