Hemarthria Compressa Research Articles

Morphological and molecular response mechanisms of the root system of different Hemarthria compressa species to submergence stress.

The severity of flood disasters is increasing due to climate change, resulting in a significant reduction in the yield and quality of forage crops worldwide. This poses a serious threat to the development of agriculture and livestock. Hemarthria compressa is an important high-quality forage grass in southern China. In recent years, frequent flooding has caused varying degrees of impacts on H. compressa and their ecological environment. In this study, we evaluated differences in flooding tolerance between the root systems of the experimental materials GY (Guang Yi, flood-tolerant) and N1291 (N201801291, flood-sensitive). We measured their morphological indexes after 7 d, 14 d, and 21 d of submergence stress and sequenced their transcriptomes at 8 h and 24 h, with 0 h as the control. During submergence stress, the number of adventitious roots and root length of both GY and N1291 tended to increase, but the overall growth of GY was significantly higher than that of N1291. RNA-seq analysis revealed that 6046 and 7493 DEGs were identified in GY-8h and GY-24h, respectively, and 9198 and 4236 DEGs in N1291-8h and N1291-24h, respectively, compared with the control. The GO and KEGG enrichment analysis results indicated the GO terms mainly enriched among the DEGs were oxidation-reduction process, obsolete peroxidase reaction, and other antioxidant-related terms. The KEGG pathways that were most significantly enriched were phenylpropanoid biosynthesis, plant hormone signal transduction etc. The genes of transcription factor families, such as C2H2, bHLH and bZIP, were highly expressed in the H. compressa after submergence, which might be closely related to the submergence adaptive response mechanisms of H. compressa. This study provides basic data for analyzing the molecular and morphological mechanisms of H. compressa in response to submergence stress, and also provides theoretical support for the subsequent improvement of submergence tolerance traits of H. compressa.

Utilization of Forage Crops as an Effective and Eco-friendly Method for Weed Growth Control and Distribution in an Immature Rubber Plantation

Rubber plantation, especially in the immature phase, is usually infested by various local weed species in the inter-row spaces of the rubber trees. This study aimed to evaluate the distribution of weed species and the growth and yield of forage crops for weed control and management in an immature rubber plantation. The field study was conducted with four treatments of forage crops. The first treatment was a control plot in which local weeds were growing naturally without forage crops. The plot was compared with the other three immature plots wherein native tropical carpet grass (Axonopus compressus), native whip grass (Hemarthria compressa) and high productive yield ruzi grass (Brachiaria ruziziensis) were planted, respectively, in the inter-row of the rubber trees. The study period was split into four seasons: S0 – January to June 2016; S1 – July to September 2016; S2 – October to December 2016; and S3 – January to March 2017. Results showed that three families of narrow-leaf and nine families of broad-leaf weeds were found in the study area. A large number of common weed families were observed more in the S3 than those in other seasons. Moreover, all forage crops were effective in suppressing weeds, with ruzi grass demonstrating the highest level of competitiveness and yield among the native forage crops reaching 1.50 Mg ha-1 in the S3. Therefore, implementing an indirect weed control approach using forage crops in rubber plantations could serve as a sustainable and environmentally friendly alternative to chemical herbicides.

Seasonal pattern of food habits of large herbivores in riverine alluvial grasslands of Brahmaputra floodplains, Assam

Jarman–Bell (1974) hypothesized that in the dry savanna of Africa, small-bodied herbivores tend to browse more on forage with high protein and low fibre content. This implies browsing on high nutritive forage by meso-herbivores, and grazing and mixed feeding on coarse forage by mega-herbivores. We tested this hypothesis in the riverine alluvial grasslands of the Kaziranga National Park (KNP), where seasonal flood and fire play an important role in shaping the vegetation structure. We analyzed the feeding habits and quality of major forage species consumed by three mega-herbivores, viz. greater one-horned rhino, Asian elephant, and Asiatic wild buffalo, and three meso-herbivores, viz. swamp deer, hog deer, and sambar. We found that both mega and meso-herbivores were grazers and mixed feeders. Overall, 25 forage plants constituted more than 70% of their diet. Among monocots, family Poaceae with Saccharum spp. (contributing > 9% of the diet), and, among dicots, family Rhamnaceae with Ziziphus jujuba (contributing > 4% of the diet) fulfilled the dietary needs. In the dry season, the concentration of crude protein, neutral detergent fibre, calcium, sodium, and phosphorous varied significantly between monocots and dicots, whereas only calcium and sodium concentrations varied significantly in the wet season. Dicots were found to be more nutritious throughout the year. Compared to the dry season, the monocots, viz. Alpinia nigra, Carex vesicaria, Cynodon dactylon, Echinochloa crus-galli, Hemarthria compressa, Imperata cylindrica, and Saccharum spp., with their significantly high crude protein, were more nutritious during the wet season. Possibly due to the availability of higher quality monocots in the wet season, both mega and meso-herbivores consume it in high proportion. We concluded that the Jarman–Bell principle does not apply to riverine alluvial grasslands as body size did not explain the interspecific dietary patterns of the mega and meso-herbivores. This can be attributed to seasonal floods, habitat and forage availability, predation risk, and management practices such as controlled burning of the grasslands. The ongoing succession and invasion processes, anthropogenic pressures, and lack of grassland conservation policy are expected to affect the availability of the principal forage and suitable habitat of large herbivores in the Brahmaputra floodplains, which necessitates wet grassland-based management interventions for the continued co-existence of large herbivores in such habitats.

Industrial water treatment within a wetland planted with Hemarthria compressa and subsequent effluent reuse to grow Abelmoschus esculentus

This study assesses the potential of constructed wetland systems to treat tannery effluent (TE) and mixed industry effluent (MIE). After each of the three influent cells acting as settling cells, three treatment cells in horizontal series along with a Control were applied. Each of the cells was subjected to horizontal surface flow and planted with Hemarthria compressa (L.f.) R.Br. (perennial whip grass). The percent decline in heavy metal concentrations between settling and Cell 3 over a period of 60 days varied as follows: zinc (Zn; 35.83–95.59), chromium (Cr; 30.63–95.49), copper (Cu; 24.3–97.05) and nickel (Ni; 20.3–93.2). The drop in chemical oxygen demand (COD mg L−1) ranged between 3.95 and 72.14%, whilst the total dissolved solids (TDS g L−1) decline was between 3.23 and 98.75%. The pH and electrical conductivity (EC) drop ranges were between 1.4 and 11.72% along with up to 92.92%, respectively. The determined decline rates of pollutants and the cumulative biomass yield of H. compressa at p = 0.05 were between 0.76 and 0.96 (20 d−1). The heavy metal tolerance index for H. compressa in TE and MIE were 0.25–3.25 and 0.25–2.2, respectively. Although treated TE and MIE discharged from Cell 3 of each of the effluent treatment series on the 60th day had Zn, Ni, Cr and Cu concentrations greater than the local permissible limits (Punjab Environmental Quality Standards) of Liquid Industrial Effluents. The treated water through the constructed wetland system proved safe for cultivation of okra (Abelmoscus esculentus (L.) Moench) vegetables.

Hemarthria compressa—Aspergillus niger—Trichoderma pseudokoningii Mediated Trilateral Perspective for Bioremediation and Detoxification of Industrial Paper Sludge

The present study was carried out to evaluate the effects of different fungal species on the metal uptake from paper sludge by Hemarthria compressa L. Paper sludge (PS) in various concentrations (0, 30% and 60%) were used with four treatments of two fungal species (F0 = Control, F1 = Aspergillus niger, F2 = Trichoderma pseudokoningii, F3 = A. niger + T. pseudokoningii). Paper sludge as rooting medium steadily influenced growth and physio-biochemical attributes of H. compressa in F0. Results revealed discrete variations in growth attributes with different PS concentrations and each fungal treatment. The maximum damages in ionic homeostasis (Na+, K+, Ca2+, Mg2+) due to PS toxicity were evident in parallel with declined chlorophyll concentration. The highest growth, total chlorophyll and biomass of the plants were observed when PS was treated with combined fungal strains (F3). Translocation factor decreased with F3 that is indicative of changes in Cd, Pb, and Cu movement to shoot from root. The plants with combined fungal treatment also showed greater catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) activity. Ions, such as Ca, Mg, and Na, also increased gradually with combined fungal treatment. The correlation matrix displayed a close association among diverse fungal and PS levels with multiple plant attributes. PCA-Biplot confirmed the outcome of correlational analyses among different characters of H. compressa. The combined fungal mediate the extraction of heavy metals from the paper sludge by H. compressa recommends the high accumulation of heavy metal (HM) and possible reutilization of metal free sludge as a fertilizer, for application in cultivated fields. Furthermore, the effects of fungal species on HM attenuation in PS are linear and can be used in different habitats. Advancement in such research work will also be helpful in understanding the mechanisms and enhancing the ability of other native microbes to remediate metals.

Soil anti-scourability enhanced by herbaceous species roots in a reservoir water level fluctuation zone

Revegetation is one of the successful approaches to soil consolidation and streambank protection in reservoir water level fluctuation zones (WLFZs). However, little research has been conducted to explore the impact of herbaceous species roots on soil anti-scourability during different growth stages and under different degrees of inundation in this zone. This study sampled two typical grasslands (Hemarthria compressa grassland and Xanthium sibiricum grassland) at two elevations (172 and 165 m a.s.l.) in the water level fluctuation zone (WLFZ) in the Three Gorges Reservoir (TGR) of China to quantify the changes in soil and root properties and their effects on soil anti-scourability. A simulated scouring experiment was conducted to test the soil anti-scourability in April and August of 2018. The results showed that the discrepancy in inundation duration and predominant herbaceous species was associated with a difference in root biomass between the two grasslands. The root weight density (RWD) values in the topsoil (0-10 cm) ranged from 7.31 to 13 mg cm−3 for the Hemarthria compressa grassland, while smaller values ranging from 0.48 to 8.61 mg cm−3 were observed for the Xanthium sibiricum grassland. In addition, the root biomass of the two herbs was significantly greater at 172 m a.s.l. than that at 165 m a.s.l. in the early recovery growth period (April). Both herbs can effectively improve the soil properties; the organic matter contents of the grasslands were 128.06% to 191.99% higher than that in the bare land (CK), while the increase in the water-stable aggregate ranged from 8.21% to 18.56%. Similarly, the topsoil anti-scourability indices in both the herbaceous grasslands were larger than those in the CK. The correlation coefficients between the root length density (RLD), root surface area density (RSAD) and root volume density (RVD) of fine roots and the soil anti-scourability index were 0.501, 0.776 and 0.936, respectively. Moreover, the change in the soil anti-scourability index was more sensitive to alternations in the RLD with diameters less than 0.5 mm. Overall, the present study showed that the perennial herbaceous (H. compressa) has great potential as a countermeasure to reduce or mitigate the impact of erosion in the WLFZ of the Three Gorges Reservoir.

Reference gene selection for real-time quantitative PCR normalization in Hemarthria compressa and Hemarthria altissima leaf tissue.

Hemarthria compressa and Hemarthria altissima are widely used as livestock forage and play important roles in tropical and subtropical grassland agricultural systems promoting healthy ecological environment and the development of animal husbandry. Leaf tissue of "Yaan" limpograss (H. compressa) and "H255" whip grass (H. altissima) were used to test the mRNA expression levels of 12 reference genes using RT-qPCR. The Delta-Ct method, BestKeeper (ver. 1.0), Genorm (ver. 3.5), Normfinder (ver. 0.953) and RefFinder were used to analyze the expression stability of the 12 reference genes under drought, salt, acid-aluminum and cold stresses to provide significant technical support for the study of gene expression under various abiotic stresses in Hemarthria. The results showed that the candidate reference genes showed divergent expression levels under various abiotic stresses. Among the genes that were selected, CL18892 showed the highest expression stability under salt stress in the leaf tissue. eEF-1α was the most stable gene under cold and acid-aluminum stresses and CL16384 was comparatively the most suitable genes under drought stress. As a whole, according to RefFinder analysis, CYP5, BMK.74327 and CL21527 were the most suitable reference genes for studying the effects of abiotic stress in Hemarthria. In general, CL16812 and CL18038 were not suitable reference genes under abiotic stress conditions that were examined in this study.

Soil nutrients in relation to vertical roots distribution in the riparian zone of Three Gorges Reservoir, China

Since the impoundment of the Three Gorges Reservoir (TGR), the riparian zone has been subjected to numerous environmental changes. This study was conducted to recognize the distribution of grass roots and its impacts on soil nutrients in the water level fluctuation zone of TGR. Roots of four predominant herbaceous plants in the study area, specifically, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, and their corresponding relation with soil nutrient contents were investigated. Root surface area density was determined with WinRHIZO, and the relationships of root distribution with soil depths and soil nutrient contents were studied. The results indicates that most roots are distributed in the top soil layer of 0-10 cm. Estimated root surface area density for the selected grass species ranges from 0.16 to 13.44 cm2/cm3, and decreases exponentially with an increase in soil depth. Soil organic matter and total nitrogen contents are significantly lower on bare control area than the corresponding values on the grasslands. Total nutrient contents on grasslands of C. dactylon and H. compressa are higher than those of other grass areas. Root length density and root surface area density are significantly correlated with soil organic matter and total nitrogen content for the four grasslands. The present results suggests that plant roots have significant effects on the distribution of soil nutrients in soil profiles in the riparian zone along the TGR. Nevertheless, additional investigations are needed to reveal the specific interactions between plant roots distribution, soil nutrients and water level fluctuations.

不同水分处理和密度配置对牛鞭草与狗牙根生长与种间竞争的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 不同水分处理和密度配置对牛鞭草与狗牙根生长与种间竞争的影响 DOI: 10.5846/stxb201703140427 作者: 作者单位: 三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院,三峡库区生态环境教育部重点实验室，重庆市三峡库区植物生态与资源重点实验室，西南大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 重庆市林业重点科技攻关项目（渝林科研2016-8）；国家国际科技合作专项（2015DFA90900）；中央财政林业科技推广示范项目（渝林科推[2017-12]） Effects of different water conditions and plant density on the growth and interspecific competition of Hemarthria compressa and Cynodon dactylon Author: Affiliation: Key Laboratory of Eco-environment in the Three Gorges Reservoir Region of the Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in the Three Gorges Reservoir Region , School of Life Sciences, Southwest University,Key Laboratory of Eco-environment in the Three Gorges Reservoir Region of the Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in the Three Gorges Reservoir Region , School of Life Sciences, Southwest University,Key Laboratory of Eco-environment in the Three Gorges Reservoir Region of the Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in the Three Gorges Reservoir Region , School of Life Sciences, Southwest University,Key Laboratory of Eco-environment in the Three Gorges Reservoir Region of the Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in the Three Gorges Reservoir Region , School of Life Sciences, Southwest University,Key Laboratory of Eco-environment in the Three Gorges Reservoir Region of the Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in the Three Gorges Reservoir Region , School of Life Sciences, Southwest University,Key Laboratory of Eco-environment in the Three Gorges Reservoir Region of the Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in the Three Gorges Reservoir Region , School of Life Sciences, Southwest University,Key Laboratory of Eco-environment in the Three Gorges Reservoir Region of the Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources Research in the Three Gorges Reservoir Region , School of Life Sciences, Southwest University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为合理利用三峡库区消落带优良草本植物进行退化植被恢复，并探索恢复过程中草本植物的最佳混植比例，选取三峡库区消落带适生先锋草本植物牛鞭草（Hemarthria compressa）（H）和狗牙根（Cynodon dactylon）（C）为研究材料，于2016年4月29日在盆栽控制条件下设置3种不同水分条件（对照组——CK组、浅淹组——SF组、全淹组——TF组）、7种配置比例，每盆牛鞭草与狗牙根株数分别按2株进行递增与递减，具体的配比分别为H0C12，H2C10，H4C8，H6C6，H8C4，H10C2、H12C0，比较研究混植条件下牛鞭草与狗牙根在水淹环境中的生长及二者的竞争作用。研究发现：（1）无论在单植还是二者混植条件下，水分胁迫均显著降低狗牙根与牛鞭草生物量，且牛鞭草对水淹胁迫的响应更敏感；（2）狗牙根和牛鞭草的生长均具有明显的密度制约效应，但狗牙根的反应更为强烈；（3）不同水分与密度条件下，混植体系总相对生物量均大于1。在CK组，狗牙根与牛鞭草表现出竞争关系；在SF组和TF组，二者之间的竞争作用减小，表现出一定的促进作用。综合分析本试验不同水分与密度条件下牛鞭草与狗牙根的总生物量、根冠比、竞争系数（相对总生物量），发现常规供水处理下牛鞭草和狗牙根的最佳配置比例为H2C10，而浅水淹和深水淹处理下最佳配置比例为H8C4。研究结果可以为三峡库区消落带不同海拔位草本植被的恢复及管理提供依据，也为生态类型相同或相似地区人工恢复草本植被提供理论参考。 Abstract:To restore the degraded grass vegetation and reveal the best ratio of grass species for artificial restoration of the riparian zone of the Three Gorges Reservoir area, the local dominant species, Hemarthria compressa (H) and Cynodon dactylon (C) were used to investigate the growth and intraspecific and interspecific competition under different water conditions. On April 29, 2016, a pot experiment was conducted using a replacement series design in which H. compressa and C. dactylon were planted at seven ratios (H0C12, H2C10, H4C8, H6C6, H8C4, H10C2, and H12C0) under three water treatments, including normal growth water condition (CK), flooding at 10 cm above the soil surface (SF) and flooding at 2 m above the soil surface (TF). Results showed that:(1) Regardless of the planting being a monoculture or a combination of the two species, biomass production of both species decreased under water stress. H. compressa was more sensitive to water stress than C. dactylon; (2) There was a density-dependent effect on the growth of both species and this effect was stronger on C. dactylon; (3) Under all three water treatments, the relative yield total (RYT) was greater than 1 when both species were planted. Under CK, the two species showed a competitive relationship, whereas under SF and TF, they were facilitated by each other. Taking maximizing biomass production, the root:shoot ratio, and the competitive ability of the species into consideration, we suggest that under CK, the best ratio for planting of H. compressa and C. dactylon is 2:10, whereas under SF and TF, the best ratio is 8:4. These results provide a baseline reference for vegetation restoration and reconstruction in the riparian zone of the Three Gorges Reservoir area, and provide a theoretical reference for the establishment of artificial grass vegetation in similar areas. 参考文献 相似文献 引证文献

Studies on genetic diversity and phylogenetic relationships of limpograss (Hemarthria altissima) and related species based on combined chloroplast DNA intergenic spacer data

Hemarthria R. Br. is a genus which includes important forage grasses. However, there is currently a lack of data analysis on the chloroplast DNA (cpDNA) of Hemarthria species. This study is to use three cpDNA intergenic spacers (trnL-F, trnC-ycf6 and psbC-trnS) to obtain phylogenetic information in 36 Hemarthria samples including four Hemarthria species: Hemarthria altissima (Poir.) Stapf et C. E. Hubb., Hemarthria compressa (L. f.) R. Br., Hemarthria uncinata R. Br., and Hemarthria japonica (Hack.) Roshev. Data analysis revealed that non-significant genetic diversity existed in our samples, which was implied by nucleotide sequences information and the results of haplotypic and nucleotide diversity. The results of phylogenetic trees based on maximum likelihood (ML) and Bayesian inference (BI) revealed that H. altissima and H. compressa samples were not entirely distinct, suggesting that the two species share an intimate genetic relationship. A haplotype median-joining (MJ) network revealed broadly similar results to those derived from the ML and BI trees and implied that haplotype H3 may represent an ancient haplotype. Analysis of the population statistic FST revealed little genetic differentiation among the seven populations of H. altissima in Africa.

Cloning and characterization of an ABA-independent DREB transcription factor gene, HcDREB2, in Hemarthria compressa.

Background Hemarthria compressa is a stoloniferous perennial tropical forage grass with a wide geographic distribution; however, environmental stress has a great influence on its growth. The DREB transcription factor family genes contains candidate genes for improving plant stress tolerance.ResultsFrom cold-treated H. compressa plants, a putative DREB2 gene (HcDREB2) was cloned using the RACE-PCR method. HcDREB2 was 1296 bp in length and encoded a putative protein 264 amino acid residues long. HcDREB2 shared the highest sequence identity with DREB2 in sorghum. The expression of HcDREB2 was independent of ABA treatment, but inducible by low temperatures as well as drought and high salinity treatments. Yeast one-hybrid assays showed that HcDREB2 directly bound the DRE cis-acting element to transactivate the expression of the downstream reporter genes.ConclusionsHcDREB2, a stress-inducible but ABA-independent transcription factor gene, can transactivate downstream genes by binding to the DRE cis-element. The current results are a foundation for making use of this stress tolerance gene in future H. compressa studies.Electronic supplementary materialThe online version of this article (doi:10.1186/s41065-016-0008-y) contains supplementary material, which is available to authorized users.

Estimation of soil reinforcement by the roots of four post-dam prevailing grass species in the riparian zone of Three Gorges Reservoir, China

Soil erosion and bank degradation is a major post-dam concern regarding the riparian zone of the Three Gorges Reservoir. The development and succession of vegetation is a main countermeasure, especially to enhance bank stability and mitigate soil erosion by the root system. In this study, the roots of four prevailing grass species, namely, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, in the riparian zone were investigated in relation to additional soil cohesion. Roots were sampled using a single root auger. Root length density (RLD) and root area ratio (RAR) were measured by using the WinRHIZO image analysis system. Root tensile strength (T-R) was performed using a manual dynamometer, and the soil reinforcement caused by the roots was estimated using the simple Wu's perpendicular model. Results showed that RLD values of the studied species ranged from 0.24 cm/cm(3) to 20.89 cm/cm(3) at different soil layers, and RLD were significantly greater at 0-10 cm depth in comparison to the deeper soil layers (> 10 cm). RAR measurements revealed that on average 0.21% of the reference soil area was occupied by grass roots for all the investigated species. The measured root tensile strength was the highest for P. paspaloides (62.26 MPa) followed by C. dactylon (51.49 MPa), H. compressa (50.66 MPa), and H. altissima (48.81 MPa). Nevertheless, the estimated maximum root reinforcement in this investigation was 22.5 kPa for H. altissima followed by H. compressa (21.1 kPa), P. paspaloides (19.5 kPa), and C. dactylon (15.4 kPa) at 0-5 cm depth soil layer. The root cohesion values estimated for all species were generally distributed at the 0-10 cm depth and decreased with the increment of soil depth. The higher root cohesion associated with H. altissima and H. compressa implies their suitability for revegetation purposes to strengthen the shallow soil in the riparian zone of the Three Gorges Reservoir. Although the soil reinforcement induced by roots is only assessed from indirect indicators, the present results still useful for species selection in the framework of implementing and future vegetation recovery actions in the riparian zone of the Three Gorges Reservoir and similar areas in the Yangtze River Basin.

Molecular Insights into the Genetic Diversity of Hemarthria compressa Germplasm Collections Native to Southwest China

Start codon targeted polymorphism (SCoT) analysis was employed to distinguish 37 whipgrass (Hemarthria compressa L.) clones and assess the genetic diversity and population structure among these genotypes. The informativeness of markers was also estimated using various parameters. Using 25 highly reproducible primer sets, 368 discernible fragments were generated. Of these, 282 (77.21%) were polymorphic. The number of alleles per locus ranged from five to 21, and the genetic variation indices varied. The polymorphism information content (PIC) was 0.358, the Shannon diversity index (H) was 0.534, the marker index (MI) was 4.040, the resolving power (RP) was 6.108, and the genotype index (GI) was 0.782. Genetic similarity coefficients (GS) between the accessions ranged from 0.563 to 0.872, with a mean of 0.685. Their patterns observed in a dendrogram constructed using the unweighted pair group method with arithmetic mean analysis (UPGMA) based on GS largely confirmed the results of principal coordinate analysis (PCoA). PCoA was further confirmed by Bayesian model-based STRUCTURE analysis, which revealed no direct association between genetic relationship and geographical origins as validated by Mantel’s test (r = 0.2268, p = 0.9999). In addition, high-level genetic variation within geographical groups was significantly greater than that between groups, as determined by Shannon diversity analysis, analysis of molecular variance (AMOVA) and Bayesian analysis. Overall, SCoT analysis is a simple, effective and reliable technique for characterizing and maintaining germplasm collections of whipgrass and related species.

Genetic diversity of Hemarthria altissima and its related species by EST-SSR and SCoT markers

There is a need for an appropriate evaluation of Hemarthria germplasm resources using genetic analysis. Understanding their genetic background will promote effective development and utilization of its germplasm resources in plant breeding. We examined the genetic diversity and relationships among 46 Hemarthria germplasm resources from four continents. Expressed Sequence Tags-Simple Sequence Repeat (EST-SSR) and Start Codon Targeted (SCoT) markers were used to investigate species Hemarthria altissima (36), Hemarthria compressa (8) and Hemarthria uncinata (2). We selected 19 EST-SSR primers and generated 550 polymorphic (94.7%). Twenty one SCoT primers were selected and amplified to produce 597 bands with 89.4% of polymorphic bands. The Mantel test between EST-SSR and SCoT matrices revealed significant correlations (r = 0.854) and the data from both markers were combined for cluster analysis. The 46 materials were clustered into two main groups by UPGMA clustering with a similarity coefficient ranging from 0.573 to 0.940 and the dendrogram was basically concordant with geographical origins and species. Among the three Hemarthria species, H. altissima was genetically closest to H. compressa while it was not close to H. uncinata. When the utility of the two markers were compared, we found EST-SSR to be more efficient than SCoT in determining the genetic diversity study of Hemarthria species.

Effects of Water Stresses on the Photosynthetic Characteristics of Hemarthria Compressa

The photosynthetic characteristic of plants may reflect the situation of growth and drought resistance. This study showed that drought affected significantly the Pn and Tr of Hemarthria compressa, the daily variation of Pn and Tr showed the “single peak” curve under different water condition, however, the change trend was totally opposite; the Gs and the Ci decreased with the increase of water stresses; the peak value of WUE of different water condition appeared before 10:00AM; the WUE decreased with the increase of Tr after 10:00AM. The WUE of different water stresses were higher than control before 12:00AM, however, less than control during 12:00 to 18:00. Hemarthria compressa generally tends to reduce the stomatal opening and transpiration in order to achieve high WUE under the water deficit, which belongs to strong drought resistance forage species.

Spatial arrangements affect suppression of invasive Alternanthera philoxeroides by native Hemarthria compressa

It has been hypothesized that differences in spatial arrangements change the relative frequency of intra- and interspecific encounters between plant species. Manipulating spatial arrangement may play a role in invasive plant suppression when native species are used as competitors against introduced species. In this study, a replacement series experiment was performed to investigate the effects of intraspecifically random and aggregated spatial arrangements on interactions between the native plant Hemarthria compressa and the invasive plant Alternanthera philoxeroides, to test the possibility and effectiveness of H. compressa in suppressing A. philoxeroides. When both species were planted in intraspecifically random spatial patterns, H. compressa had a competitive advantage over A. philoxeroides at relative densities of 2:2 and 3:1. However, aggregation increased the strength, and therefore the cost, of intraspecific competition in H. compressa, resulting in lower biomass production, which reduced its effectiveness as an interspecific competitor. As the relative density of H. compressa in mixtures decreased, plants allocated more biomass to belowground parts, but fewer interspecific encounters lowered its inhibitory effects on A. philoxeroides. The results not only confirm that the frequency of conspecific and heterospecific encounters can influence competitive outcomes, but also suggest that a reduction in the degree of spatial aggregation in H. compressa and an increase in its relative densities may be essential to increase the suppression of A. philoxeroides.

Genetic stability and DNA fingerprinting of the Hemarthria compressa cultivar “Guangyi”

Genetic stability and DNA fingerprinting of the Hemarthria compressa cultivar “Guangyi”

The Response of SOC Content and Seasonal Dynamics of Three <i>Alnus formosana</i> Forests under Different Herb Layer to the Fertilization

Alnus formosana + Hemarthria compressa (A+H), Alnus formosana + Lolium multiflorum Lam (A+L), and Alnus formosana + natural grass (A+N), the comparative analysis of SOC(SOC) content, vertical distribution and seasonal dynamics of the three kinds of forest modes and the response of which to the fertilization suggests that the content of the SOC of the three kinds of forest lands under different herb layer in the soil which has been fertilized and unfertilized respectively are: A+L >A+H >A+N. The results mainly caused by the differences among herb layers. The vertical distribution law of organic carbon is no difference among three kinds of modes that the content of organic carbon would be decreased with the depth of soil layers. However, the reduction rate of organic carbon content in soil layers in the depth 0~20cm is more obvious than in 20~40cm. Fertilization can increase the SOC content, and especially in the shallow surface. The seasonal dynamics of the three kinds of SOC modes are basically same: the SOC content will reach the minimum in autumn, and then it will be gradually increased until the maximum is reached in the next summer. The main characteristic is that the relatively higher content of SOC is presented in spring and summer, which on the contrary in autumn and winter. The seasonal dynamics of SOC is insignificantly influenced by fertilization. For the soil organic content, the A+L is better than the A+H.

Water Stress Effects on Growth, Yield and Water Use Efficiency of Hemarthria Compressa

Water stress is an important approach to use water resources efficiently and remit the agricultural water shortage. Hemarthria compressa is one of perennial grasses, a pasture of high quality, which has abundant species resources in China. To explore the response of the growth, yield and water use efficiency(WUE) of Hemarthria compressa under water stress, this study, adapting pot experiment, imposed three water stress degree (LD, MD and SD) treatments and a control treatment on Hemarthria compressa. The data of growth indicators during control period, yield and total water consumption were obtained. The results show a noticeable inhibitory action of water stress on the growth of Hemarthria compressa. Along with the intensifying of water stress, plant height increment, leaf area, total biomass, dry matter of each organ and yield decreased, and the root-shoot ratio increased firstly and inclined to slump finally. Plants under the middle water stress treatment achieved the greatest WUE of 38.25 kg/m3. The first 10d in the water control period was the most sensitive period of the pasture responding to water stress.

Molecular diversity and population structure of the forage grass Hemarthria compressa (Poaceae) in south China based on SRAP markers

Hemarthria compressa is one of the most important and widely utilized forage crops in south China, owing to its high forage yield and capability of adaptation to hot and humid conditions. We examined the population structure and genetic variation within and among 12 populations of H. compressa in south China using sequence-related amplified polymorphism (SRAP) markers. High genetic diversity was found in these samples [percentage polymorphic bands (PPB) = 82.21%, Shannon's diversity index (I) = 0.352]. However, there was relatively low level of genetic diversity at the population level (PPB = 29.17%, I = 0.155). A high degree of genetic differentiation among populations was detected based on other measures and molecular markers (Nei's genetic diversity analysis: G(ST) = 54.19%; AMOVA analysis: F(ST) = 53.35%). The SRAP markers were found to be more efficient than ISSR markers for evaluating population diversity. Based on these findings, we propose changes in sampling strategies for appraising and utilizing the genetic resources of this species.