Relative Density Of Species Research Articles

KERAGAMAN SPESIES HERBA DAN KEMIRIPAN KOMUNITAS TUMBUHAN PADA DUA PERIODE PEMANTAUAN BERURUTAN DI AREA REKLAMASI PT ADARO INDONESIA, PROVINSI KALIMANTAN SELATAN, INDONESIA

The development of herbaceous species according to the time of monitoring at certain sample locations in the PT Adaro Indonesia reclamation area has never been published. The purpose of the study was to compare the diversity of species and the similarity of plant communities growing in certain locations in two consecutive monitoring periods. Four locations that have been revegetated were sampled. At each location, 13 measuring plots (20 m x 20 m) were made and placed systematically. In each of these plots, 2 sub-plots (5 m x 5 m) were placed in 2 angles in opposite positions. From each sub-plot data in the form of herbaceous species names and number of individuals were collected. In one location, the number of plots changed because part of this location turned out to be active mining areas. The number of remaining plots (6 plots) was considered to not affect the results. Data is processed to obtain the density of each species at a certain location (Ki), the relative density of certain species (KRi), the frequency of each species at a certain location (Fi), the relative frequency of certain species (FRi), the importance value index (IVI), the index of species diversity Shannon-Wienner (H'), and the similarity index of the Dice community (IS). The number of species varies at each sample location and shows an increase from first monitoring to second monitoring. The species diversity index also increases. Community similarity index varies, both with calculations based on the presence or absence of species and based on the IVI. Both methods of calculation can be used but it is recommended to use calculations based on IVI.Keywords: Diversity, Monitoring period, Reclamation area, Similarity

A Comparative Study on Earthworm Biodiversity & Species Habitat-Relationship of Hilly and Plain Areas of Sirohi District of Rajasthan, India

Extensive surveys of earthworm diversity were done in different habitats of plain and hilly areas of Sirohi district of Rajasthan, India. Earthworms differed in their ecomorphological characteristics and relative abundances in different habitats. A total twelve species of earthworms Pontoscolex corethrurus, Amynthas morrisi, Lampito mauritii, Metaphire posthuma, Megascolex konkanensis, Metaphire houlleti, Perionyx sansibaricus, Polypheretima elongata, Ocnerodrilus occidentalis, Dichogaster bolaui, Octochaetona beatrix and Gordiodrilus sp. were recorded from hilly and plain areas. Among these, ten species were found from plain area and nine from hilly area. Five earthworm species (M. konkanensis, M. houlleti, P. elongata, O. beatrix, Gordiodrilus sp.) were recorded for the first-time from Rajasthan. The plain area species P. elongata, O. beatrix and Gordiodrilus sp. were replaced by M. konkanensis and M. houlleti in hilly region. This showed the habitat preferences of earthworm species. Few species were present in a particular habitat of plain area, but they were absent in the same type of habitat in hilly area. The relative density, frequency and species diversity index of earthworm species differed in different habitats and areas. Earthworm diversity exhibited differing species-habitat relationship in hilly and plain areas. These findings may be utilized for eco-restoration of degraded land in similar habitats.

KEANEKARAGAMAN DAN KEPADATAN ECHINOIDEA DAN ASTEROIDEA DI RATAAN TERUMBU KARANG PERAIRAN TONGKAINA DAN BAHOWO KOTA MANADO (

The waters of Tongkaina, which are part of northern Manado's waters, are known to have mangrove, seagrass, and seaweed ecosystems. Therefore efforts are needed to manage the population and diversity of echinoderms in these waters. Echinoderms' ecology has an essential role in maintaining the marine ecosystem's balance, which plays a role in recycling nutrients. This study aimed to determine diversity, species density, species relative density, species frequency, species relative frequency, dominance, and the index of importance of Echinoidea and Asteroidea's species in the waters of the Tongkaina Village and their density. The method used in this research is the quadratic line transect method. First of all, the survey was conducted to the sampling site's location in the coral reef flats of Tongkaina Village's waters, including Tongkaina beach and Bahowo beach, before operating the sampling. Then the observation stations were determined, namely Tongkaina waters (near Batu Meja) and Bahowo waters. The quadratic line transect method is used in this research. Species of class Echinoidea and Asteroidea in the quadrat were recorded among the total of individuals, and the species is documented. This study's results indicate that six species were found, including the survey, and five species were found based on the line transect method with 182 individuals. Including Asteroidea 85 Individuals and Echinoidea 99 Individuals. Value of Diversity at station 1 has a value of H '= 1.170 with a dominance of C = 0.364, while at Station 2 has a value of H' = 1.232 and dominance value of C = 0.316. the highest density in Station 1 is Diadema savigny 1.967 ind/m2 relative 50.86%, and Linckia laevigata with the highest frequency Fi = 0.533. The highest important value index is Diadema savigny, with a value of 81.09%, while at station 2, the Protoreaster nodosus has the highest value of important value index with a value of 87.51%. These species also have the highest density of 0.933 ind/m2 and a relative number of 41.79%.Keywords: Tongkaina, Echinoderm, Line Transect Quadrat Method, Asteroidea, Echinoidea, Coral Reef Flat

Optimal transportation theory for species interaction networks.

Observed biotic interactions between species, such as in pollination, predation, and competition, are determined by combinations of population densities, matching in functional traits and phenology among the organisms, and stochastic events (neutral effects).We propose optimal transportation theory as a unified view for modeling species interaction networks with different intensities of interactions. We pose the coupling of two distributions as a constrained optimization problem, maximizing both the system's average utility and its global entropy, that is, randomness. Our model follows naturally from applying the MaxEnt principle to this problem setting.This approach allows for simulating changes in species relative densities as well as to disentangle the impact of trait matching and neutral forces.We provide a framework for estimating the pairwise species utilities from data. Experimentally, we show how to use this framework to perform trait matching and predict the coupling in pollination and host–parasite networks.

STRUKTUR KOMUNITAS PADANG LAMUN DI PERAIRAN PANTAI PANDAWA, BALI

This research aimed to determine the types and structure of seagrass community based on species density, species relative density, diversity index, uniformity index, and dominance index of the seagrass. This research was conducted along Pandawa Beach, Kutuh Village, South Kuta District, Badung Regency, Bali from November to December 2019. Data of seagrass were collected from 3 line transects, 3 kuadran transects from each transect, repeated 3 times. Water quality data were collected 3 times within 4 weeks. Eight species of seagrass were identified, namely: Thalassia hemprichii, Cymodocea serrulata, Halodule pinifolia, Halodule uninervis, Halophila ovalis, Halophila decipiens, Syringodium isoetifolium, and Thalassodendron ciliatum. The highest species density found at station I that was Thalassodendron ciliatum, as well as for its relative density, and the lowest was Thalassia hemprichii. At station II and III, the highest species density was found on Cymodocea serrulata and the lowest was on Halophila ovalis. The study found that the species density of seagrasses at Pandawa Beach was categorized as high density, which dominated by Thalassodendron ciliatum at station I and by Cymodocea serrulata at station II and III. Diversity index of seagrass species at station I and II was categorized as medium species diversity and low species diversity for the station III. Dominance index of seagrass species at the three station was categorized as high dominance. Similarity index of seagrass species was categorized as medium or unstable community for the station I and II, and low similarity for the station III.

Vegetation Structure and Damage Level Mangrove Forest in Manomadehe Island, Subdistrict South Jailolo, North Maluku Province

Mangrove forest is a natural resource typical of tropical coasts, which has multiple benefits with a very broad impact when viewed from social, economic and ecological aspects. Management of natural resources must be very prudent because it takes a long time to be able to recover when damage / extinction has occurred. The purpose of this study was to determine the composition of mangrove species, the structure of mangrove forest vegetation (species density, relative density of species, frequency of species, relative frequency of species, species cover, relative cover of species and important values) and to determine the level of damage. Extraction of mangrove vegetation using the "spot check" method. The transects are drawn perpendicular to the coastline along the mangrove vegetation. The composition of mangrove species were 7 species, namely Rhizophora apiculata, R. stylosa, Bruguirea gymnorrhiza, Ceriops tagal, Sonneratia alba, Xylocarpus granatum and Aegiceras floridum. In the vegetation structure, the highest density and relative density were found in Rhizophora stylosa and the lowest was Xylocarpus granatum. The highest species and relative frequencies were Rhizophora stylosa, R. apiculata and the lowest were Bruguiera gymnorrhiza. The highest type and closure were Sonneratia alba and the lowest was Ceriops tagal. Meanwhile, the highest importance was in Sonneratia alba and the lowest was Xylocarpus granatum. Overall, the density value of mangrove species on Manomadehe Island is 2796 trees / ha so that the condition of the mangrove forests on Manomadehe Island is still in the good category (very dense).

Parkland Trees under Severe Drought: An Assessment of Species Diversity and Abundance across Three Agroecological Zones of Northern Nigeria

The appraisal of tree stand structure on parklands is crucial for sustainable agroforestry management decisions, particularly in the drylands of Nigeria. An assessment of tree species distribution in farm plots across the three driest Agroecological zones (AEZ) within Northern Nigeria was performed to determine diversity and abundance in a changing climate. The AEZ include Sudan savannah (SS), Northern Guinea savannah (NGS) and Southern Guinea savannah (SGS). In each AEZ, 3 transects were laid per village and a total of 4 sample plots were located along each transect. Tree bole diameter of all the sampled woody perennials with dbh ≥ 10 cm was measured and identified to species level. The measurement and computation include basal area, species relative density and dominance as well as the important value index (IVI). Results showed that across the AEZs, Parkia biglobosa trees had the highest IVI but reduces from the driest zone, SS (50.25%) through the transitional zone, NGS (38.45%) to the wettest AEZ, the SGS (35.43%). The lowest IVI recorded were in Gliricidia sepium (0.62%), Psidium guajava (2.89%) and Eucalyptus camaldulensis (1.83) in the SGS, NGS and SGS respectively. Parkia biglobosa and Mangifera indica dominated the landscapes and are classified as the landscapes’ habitat generalists. Despite the low organic matter content, Sudan savannah had more diverse species on its farm landscapes than the two other AEZ but with less tree popuplation density. The potential contribution of agroforestry parkland trees to agrobiodiversity in reducing drought and improving soil fertility is essential for sustainable agricultural productivity and landscape restoration.

Physical interpretation of a pulsed atmospheric pressure plasma jet following parametric study of the UV–to–NIR emission

In the present report, an atmospheric pressure plasma jet is sustained in a helium channel by high square wave unipolar voltage. The gas flow rate and the square wave features (amplitude, frequency, and duty cycle) are varied over a wide range, while the plasma ultraviolet to near infrared emission is recorded. The plasma emission pattern, the propagation dynamics of the involved ionization fronts, the relative density of critical excited species, and the rotational and vibrational temperatures of neutral and ionic species are measured. An optimum operational window is found corresponding to a helium flow rate of 2 slm, a pulse amplitude of 7.5 kV, a pulse repetition rate of 10 kHz, and a pulse duty cycle of 5%–7%. Under these conditions, a plasma jet length close to 45 mm and a gas temperature close to 325 K are obtained, while a high yield of OH, N2(SPS), N2+(FNS), N2(FPS), He*, O*, and NOγ is achieved. The results are found to be in good agreement with the bibliography and motivate a consideration on the involved physical mechanisms. The plasma jet propagation with respect to the reactive species production is discussed based on the local electric field variation over the high voltage pulse width.

Growing Site Characteristics of Agathis labillardieri Warb in the Natural Forests of Siwi Momiwaren, West Papua

Agathis labillardieri Warb is one of the copal-producing tree species that only distributed in Papua. In connection with regional development, the existence of this species has been a significant concern. Therefore, it is necessary to study the characteristics of A. labillardieri Warb in their natural growing areas in the natural protected forest of Siwi Momiwaren. The data were collected by using the line plot method systematic sampling method with nesting plot. The data were then analyzed to determine the species relative density, frequency, dominance, important value index (IVI), and growth characteristics. The results showed that A. labillardieri Warb had the highest IVI at all levels of growth, with the highest diversity index at the seedling level of 3,49. When viewed from the relationship of the presence of species with the characteristics of the growing site, the content of Mg and Na significantly affected the presence of this species in the natural forest area of South Manokwari Siwi Momiwaren.Keywords: Agathis labillardieri Warb, growing site characteristics, Siwi Momiwaren, West Papua

생태하천으로 조성된 반석천의 물새류 출현특성

This study was conducted as a basic research to create a sound and vital ecological environment in the city compared to the appearance characteristics of Gap stream(G-stream), which are the main stream of Banseok stream(B-stream), by analyzing the characteristics of waterbirds, including Wild Spot-billed Duck (S-Duck), that live in B-stream built as ecological stream. The waterbird survey was conducted by the line census for 3.2km, Jukdong-bridge to Jamiseon-bridge, from January to August 2018. The analysis of the survey was conducted with Relative species density(RD) of the emerging waterbird species, the Species diversity and Density Per Unit area for 100m²(DPU). The waterbird survey results of B-stream was conducted 65 times. The five types of water birds that appeared during the survey were Spot-billed Duck(Anas poecilorhyncha), Teal(Anas crecca), Little Egret(Egretta garzetta), Great Egret(Egretta alba), and Grey Heron(Ardea cinerea). As a result, for S-Duck at B-stream, RD was 89.9%, monthly species diversity was simple as 0.3801 in January, 0.5943 in February and 0.3501 in August. The DPU of the S-Duck was 0.165/100m² in the B-Stream survey section which was 4.9 times higher than the main stream section, G-stream. The non-freezing zone of the city’s small stream is expected to play an important role as a winter stop for wild birds such as S-Duck during the freezing period of the huge stream. For this reason, considering the ecological characteristics of wild waterbirds such as S-Duck when creating ecological stream, a: space and linear selection of waterways which can minimize the impact of natural enemy and increasing the number of walkers, b: management water-friendly plants in the low flow channel, c: arrangement walking-bicycle road will be necessary.

Spatial structure arising from chase-escape interactions with crowding

Movement of individuals, mediated by localised interactions, plays a key role in numerous processes including cell biology and ecology. In this work, we investigate an individual-based model accounting for various intraspecies and interspecies interactions in a community consisting of two distinct species. In this framework we consider one species to be chasers and the other species to be escapees, and we focus on chase-escape dynamics where the chasers are biased to move towards the escapees, and the escapees are biased to move away from the chasers. This framework allows us to explore how individual-level directional interactions scale up to influence spatial structure at the macroscale. To focus exclusively on the role of motility and directional bias in determining spatial structure, we consider conservative communities where the number of individuals in each species remains constant. To provide additional information about the individual-based model, we also present a mathematically tractable deterministic approximation based on describing the evolution of the spatial moments. We explore how different features of interactions including interaction strength, spatial extent of interaction, and relative density of species influence the formation of the macroscale spatial patterns.

MOLECULAR-GENETIC IDENTIFICATION OF CAUSAL AGENTS OF FUNGAL DISEASES ON POTATO AND TOMATO COLLECTED UNDER PRODUCTION STORAGE

The expansion of exports and imports of potato and tomato crops between countries contributes to the rapid spread of the most harmful species and strains of phytopathogenic fungi around the world. Due to it, the identification of phytopathogenic fungi is important for agriculture. Currently, molecular-genetic methods are considered as one of the modern and promising methods for the diagnosis and identification of plant diseases, which allow identifying microorganisms without any knowledge of its biological features. One of the recommended methods for identification and classification of taxa is the determination of the nucleotide sequence of nuclear ribosomal gene regions.
 276 infected potato tubers and tomato fruits were used to identify phytopathogenic fungi isolates, which were collected from production storages. Molecular-genetic identification of microorganisms based on the analysis of the nucleotide sequences of the ITS region made it possible to taxonomically identify 102 isolates of phytopathogenic fungi that belong to 7 genera. It was revealed that the proportion of fungi, which belohg to the genera Fusarium (60%), Penicillium (15%) and Clonostachys (12%), Alternaria (9%) were dominated in the generic structure.
 The isolation frequency (Fr) and relative density (RD) of 7 generaphytopathogenic fungi were calculated according to the results of molecular-genetic identification.Isolation frequency (Fr)of fungi genera ranged from 0.3% to 22.1%. Relative density of fungi species ranged varied 0.9% to 59.8%.
 Thereby, molecular-genetic identification based on the analysis of the nucleotide sequence of the ITS region made it possible to perform identification of pathogens on potato and tomato under production storage.Also, fungi Clonostachys and Acrostalagmus genera were isolated, which are not pathogens of potato and tomato diseases.

Green manure and phosphorus fertilization affect weed community composition and crop/weed competition in organic maize

AbstractGreen manure and compost-enriched in phosphorus can promote the sustainability of cropping systems by increasing soil fertility over the long term. They can also be used to manage crop/weed interactions, a key element in guaranteeing an appropriate level of satisfactory crop yields. We studied how green manuring with hairy vetch (Vicia villosaRoth.) and the application of different types of phosphorous-enriched compost affect weed/maize (Zea maysL.) interactions in an organic stockless Mediterranean agroecosystem for two consecutive dry years. Green manure stimulated the expression of maize traits related to a higher competitive ability against weeds, such as early growth, height and leaf area index, while the effect of compost was less clear. Regarding crop/weed competition, both green manuring and a phosphorus-enriched compost application gave a significant advantage to maize. Neither green manure nor compost increased total weed density and biomass compared to the control. Green manuring significantly affected the weed community composition. The relative density of ruderal and competitive-ruderal species (according to Grime's classification) was higher in plots where the green manure was applied. The use of green manure, together with novel composting techniques, significantly affected crop/weed competitive interactions, favoring maize, but also creating favorable conditions for unwanted weed species such as competitive-ruderals. Increasing nitrogen availability in the early growth stages of maize through green manuring can increase crop competitive ability. However, this may not suffice to preserve the system from future weed problems, should potentially detrimental species be selected. Dedicated strategies for the control of emerging weed species may thus be needed.

Susceptibility of non-cereal crops to Fusarium graminearum complex and their role within cereal crop rotation as a source of inoculum for Fusarium head blight

Fusarium graminearum, the cause of Fusarium head blight (FHB), is an important cereal pathogen. Moreover, some non-graminaceous crops are also known to be susceptible to F. graminearum infection. This study assessed the presence of F. graminearum species complex on non-cereal plants, grown in a cereal crop rotation and evaluated its pathogenicity to non-cereal plants in vitro and to spring wheat under field conditions. The relative density of Fusarium species isolated from oilseed rape, pea, potato and sugar beet plants was assessed in 2015 and 2016. A total of 403 isolates of Fusarium spp. were obtained from non-cereal plants and only 5% of the isolates were identified as F. graminearum. The pathogenicity test revealed that isolates of F. graminearum from spring wheat and non-cereal plants caused discolourations on leaves of faba bean, fodder beet, oilseed rape, pea, potato and sugar beet. The pea was the crop most susceptible to F. graminearum isolated from spring wheat. The pathogenicity of F. graminearum from sugar beet, oilseed rape, pea and potato to the same hosts differed depending on isolate and inoculated plant. Under field conditions, F. graminearum isolates from pea, potato, oilseed rape and wild viola were able to cause typical FHB symptoms in spring wheat. Based on the information generated in this study, we conclude that under congenial conditions, growing faba bean, pea, sugar beet, fodder beet, oilseed rape and potato plants in a cereal crop rotation may serve as alternative or reservoir hosts for F. graminearum pathogens.

Composition of Birds in Agricultural Landscapes of Peddagattu and Sherpally Area: A Proposed Uranium Mining Sites in Nalgonda, Telangana, India

The study was carried out from December 2010 to March 2014 to obtain the list of bird species, their density, diversity, species richness and evenness associated with five different crops viz., Paddy, Cotton, Castor, Red gram and Fruit garden in agricultural habitat of Nalgonda district. The current study highlights the status of avian diversity in relation to different crops, order wise versus crop wise species distribution and their clusters among the over- lapping species. A unique attempt of assembling birds, between crops and among the species shows significant variation in the relative density and diet selection of each bird species. Among which seven threatened bird species (IUCN Red list) were documented.

Prevalence of and risk factors for abnormal vaginal flora and its association with adverse pregnancy outcomes in a rural district in north-east Bangladesh.

The role of screening and treatment for abnormal vaginal flora (AVF) on adverse pregnancy outcomes remains unclear. Using data from women who participated in a population-based cluster randomized trial who were screened and treated for AVF, we report risk factors for AVF and association of persistent AVF with adverse perinatal outcomes. Pregnant women (n=4221) <19weeks of gestation provided self-administered mid-vaginal swabs; smears were Nugent-scored. AVF was treated with oral clindamycin; if AVF was present 3weeks after treatment, persistent AVF was re-treated. We examined risk factors for AVF and the association of persistent AVF with adverse pregnancy outcomes. The prevalence of AVF was 16.5%: 9.8% of women had bacterial vaginosis and 6.8% had intermediate flora. Lower economic and educational status of women were associated with increased risk of AVF. One-third of women with AVF had persistent abnormal flora; these women had a higher risk of a composite measure of adverse pregnancy outcomes from 20 to <37weeks (preterm live birth, preterm still birth, late miscarriage) (relative risk [RR] 1.33, 95% confidence interval [CI] 1.07-1.65) and of late miscarriage alone (RR 4.15, 95% CI 2.12-8.12) compared to women without AVF. In this study in Sylhet District, Bangladesh, rates of AVF and persistent AVF were high and persistent AVF was associated with adverse pregnancy outcomes, with an especially high associated risk for late miscarriage. Further characterization of the microbiome and relative bacterial species density associated with persistent AVF is needed.

Status of sea cucumber fishery and populations across sites with different levels of management in Palawan, Philippines

This study was conducted to investigate the sea cucumber fishery and compare populations between exploited and unexploited sites. Three islands were selected, the Arrecife Island as the unexploited site and the Johnson and Green Islands representing the exploited sites. In each site, sea cucumber species richness, diversity and densities were assessed by laying as much as 15 transects (50 m × 5 m) per habitat in each island. Differences in species richness, diversity and relative densities across sites and habitats were tested using a Two-way Analysis of Variance (ANOVA) and Tukey test for post hoc comparisons. An interview with gatherers, key informants and focus group discussions were also conducted to gather information on the sea cucumber fishery and its management. Results showed that the unexploited site had a higher species richness (14 vs. 7 and 7). Relative density of species was also higher in the unexploited site at 1245 ind ha−1 while it was only 78 and 39 ind ha−1 in exploited sites (p < 0.05). Interviews and a focus group discussion revealed that national regulations on permit system and size limits were not enforced at the local level and that gatherers had low levels of awareness regarding regulations on sea cucumber harvest. Current management measures appear to be ineffective and insufficient, leaving the sea cucumbers in areas open to exploitation at risk of depletion. Given that sea cucumbers provide substantial income to local communities, the depletion of this resource could compromise the livelihood of people in island communities that rely heavily on marine resources for living. Thus, this study highlights the need to review national policies on sea cucumber fishery and place the management at the local level.

Composition effect on thermophobicity of ternary mixtures: An enhanced molecular dynamics method.

Thermodiffusion or the Ludwig-Soret effect is known as the cross effect between the temperature gradient and induced separation of mixture species in multicomponent mixtures. The performance of the boundary driven non-equilibrium molecular dynamics enhanced heat exchange (eHEX) algorithm was validated by evaluating the sign and magnitude of the thermodiffusion process in methane/n-butane/n-dodecane (nC1-nC4-nC12) ternary mixtures. The eHEX algorithm consists of an extended version of the HEX algorithm with an improved energy conservation property. In addition to this, the transferable potentials for phase equilibria-united atom augmented force field was employed in all molecular dynamics (MD) simulations to accurately represent molecular interactions in the fluid. Our newly employed MD algorithm was capable to appropriately reflect the thermophobicity concept and the coupled effect of relative density and mole fraction of the mixture species on the thermodiffusion process. The separation ratio of the ternary mixture for five different compositions (at 333.15 K and 35 MPa) showed good agreement with experimental data and better accuracy in predicting the sign change of the intermediate component (nC4) as its concentration in the mixture increases, when compared to other MD models.

Non-intrusive measurement of electron, vibrational, rotational temperatures and active species concentration in N2-H2 cathodic cage plasma

The cathodic cage plasma nitriding (CCPN) is an innovative surface engineering method, which overcomes the shortcomings associated with conventional plasma nitriding (CPN). In current study, optical emission spectroscopy (OES) and optical actinometry are used to diagnose the electron, vibrational and rotational temperature, relative active species density (N, N2+) and nitrogen dissociation fraction in hydrogen admixed nitrogen plasma (with 4% argon as actinometer) in CCPN reactor. The electron temperature is estimated using modified Boltzmann plot method, vibrational temperature using N2(C,v′) state distribution, while rotational temperature is estimated using Boltzmann plot method. To estimate the nitrogen dissociation fraction, actinometery as well as intensity ratio method is employed. The electron and vibrational temperature depicts an increasing trend, while rotational temperature decreases with hydrogen admixture. The relative density of [N] is found to be increasing up to 40% hydrogen admixture, however, relative density of [N2+] is decreasing. This study presents clear picture of hydrogen admixing on the surface characteristics: it depicts that with hydrogen admixture, in addition to oxide layer removal and increased ionization, the generation of active species is also influenced. It suggests that with regard to both N and N2+ density, 40% hydrogen is beneficial.

EFFECT OF PLANTING DENSITIES OF “BRS PRINCESS” BANANA TREE IN THE SUPPRESSION OF WEEDS

ABSTRACT The objective is to evaluate the effects of plant density in banana crops against weed suppression. Six treatments were used: 1,200 (3.33 x 2.5 m), 1,600 (2.5 x 2.5 m), 2,000 (2.0 x 2.5 m), 2,400 (1.67 x 2.5 m), 2,800 (1.43 x 2.5 m) and 3,200 (1.25 x 2.5 m) banana plants per hectare, arranged in an experimental design of randomized blocks with four replications. The phytosociological study of weed communities was carried out one month after transplanting and then every 90 days, totaling six samples in 16 months of cultivation, always those being held 15 days after mowing. With the data of dry mass and number of individuals per species Relative density (De.R) Relative frequency (Fr.R) Relative dominance (Do.R), importance value value (IVI) of weed communities were calculated. Forty-three 43 species of weeds associated with the crop were identified, especially in the early stages of culture, of species such as Panicum maximum and nut grass. After 90 DAT it was found that the increase in the diversity of weed species, besides the reduction in IVI of P. maximum and C. rotundus, and increased IVI for species such as C. benghalensis and Vernonia cinerea, were more adapted to shade conditions. There was a reduction in the density dominance of weeds in higher plant density treatments, especially between 210 and 300 DAT. There was a change in the population of weeds, depending on the plant spacings in the banana crop.