Tropical Areas Research Articles

Tissue Culture in Banana Cultivation: A Review of its Impact on Disease Management, Yield Improvement, and Sustainable Production

In several tropical and subtropical areas, bananas (Musa spp.) are an important food source and commercial crop. Disease transmission and production uncertainty are common problems with traditional propagation techniques such as suckers. By supplying consistent, high-quality, and disease-free planting material, tissue culture, known as micro propagation, represents a potential alternative. The application of tissue culture has greatly enhanced disease management in banana cultivation. Reducing the incidence of ailments like Fusarium wilt, bacterial wilt, and Banana Bunchy Top Virus (BBTV), pathogen-free plantlets are grown in controlled conditions. This strategy lessens the demand for artificial fertilizers while also promoting healthier crops and lessening the impact on the environment. Micropropagated banana plants demonstrated consistent growth, early fruiting, and increased yield in contrast to conventionally propagated plants. Tissue-cultured plants exhibit strong development and genetic uniformity, which contribute to these advantages and more consistent and dependable harvests. By promoting efficient land use and reducing the need for chemical inputs, tissue culture enhances sustainability in the production of bananas. The growing demand for bananas may be met without requiring the increase of agricultural land thanks to tissue culture techniques, which enable the large-scale production of enhanced banana cultivars at a quick rate. Furthermore, using planting material free of disease lowers input costs and crop losses, supporting more environmentally friendly farming methods.

Fungal Bioluminescence: Past, Present, and Future

The complex and diverse phenomenon of fungal bioluminescence has captured human curiosity. Nevertheless, in the field of studies, there are not many attempts made particularly to reveal the new species of these interesting fungi. This study comprehensively reviews the diversity, distribution, evolution, bioluminescence mechanisms, ecological roles, and potential applications of these fungi. Most importantly, we also present an updated list of the reported bioluminescent fungi (122) so far identified from five distinct evolutionary lineages worldwide—Armillaria, Eoscyphella, Lucentipes, Mycenoid, and Omphalotus—mainly in tropical and subtropical areas. Bioluminescent fungi are descended from the last common ancestor of the Mycenoid and the Marasmioid clades of Agaricales, which have been maintained for at least 160 million years of evolution. We underscore the potential for future research to understand the ecological role of bioluminescent fungi, inspiring hope and optimism for the future of this field.

Spatial and temporal patterns of floating litter in shallow habitats: Insights from high-tourism tropical areas in Northeastern Brazil

We investigated the composition, quantity, distribution and potential sources of floating litter in the subtidal zones of tropical beaches. Marine sampling sites were selected based on the presence (protected/sheltered) or absence (non-protected) of reefs. Plastic was the most abundant material, and the presence of floating litter from land-based sources was confirmed, which was likely associated with domestic and tourism-related activities, owing to irregular waste disposal. Marine debris was more abundant during the rainy season, and marine beaches had more floating litter than estuarine beaches. Coastal reefs served as a barrier, impeding the transport of marine litter by coastal currents, explaining the greater abundance of floating litter on protected/sheltered marine beaches. Thus, three mechanisms seemed to drive the amount of floating litter in the subtidal zone of the tropical beaches: 1) the availability of floating litter in the water, 2) coastal hydrodynamics favoring the accumulation of floating litter, and 3) a beach’s capacity to retain floating litter. Our study demonstrates that marine litter is an important pollution source in sensitive areas that play a key role as nurseries for marine life, especially in beaches close to reef formations.

Carbon stocks in mangrove ecosystems of Sri Lanka: Average contributions and determinants of sequestration potential

Mangroves are crucial in carbon sequestration despite covering only a small percentage of the Earth's surface. Latitudinal gradient primarily determines the distribution of climatic zones of distinct sunlight, temperature, and precipitation patterns, which influence the community structure of the mangrove ecosystem. The tropical climate of Sri Lanka contributes to the island's lush mangrove forests. The present study estimated that the average island's carbon sequestration capacity of Sri Lankan mangrove ecosystems is 524.25 t/ha representing a substantial volume of carbon storage that contributes to offset greenhouse effect due to increasing atmospheric CO2. Our results substantiated that rainfall positively influences total carbon sequestration capacity of mangrove ecosystems.It was also revealed that a positive relationship exists between vegetation structural complexity and sediment organic carbon, highlighting the influence of vegetation structure, that is primarily dependent on climatic conditions, on production of organic matter and sediment carbon sequestration. Globally, the carbon sink function of mangrove ecosystems is reported to be highest in the tropical areas and it declines towards sub-tropical higher latitudes while those in the southern hemisphere perform better carbon sinks than those in the northern hemisphere.The vertical distribution of total organic matter content in mangrove sediments was revealed to be in a descending order, manifesting the weak tidal removal of surface organic matter under the microtidal conditions in Sri Lankan marine waters, thus qualifying mangrove ecosystems in microtidal coasts as effective carbon sinks.

Wild animal attacks and other occupational risks perceived by Indigenous hunters and fishers in the Yangambi landscape

ABSTRACT Hunting and fishing support diverse food systems in tropical forest areas, but carry serious occupational risks. Health and safety at work is important to human wellbeing and constitutes an element of Indigenous rights. This issue has received attention in the regulated sector, but needs additional focus in subsistence and informal economies. We draw on semi-structured interviews with Turumbo hunters and fishers in the Yangambi Biosphere Reserve region (DRC) to assess perceptions of occupational risk, especially attacks from wild animals. Fishers were concerned about drowning and cuts, while hunters cited bad weather and injuries from faulty equipment. There was gender-specific perception of risk from wild animals that reflected different roles: women noted snake bites and wasps, while men feared larger animals. Retaliatory behaviors among respondents included killing various species. The risks associated with fishing and hunting in tropical forests should be addressed in policies that consider the wellbeing of the poor.

Selection of tropical plants for an extensive green roof with abilities of thermal performance, energy conservation, and greenhouse gas mitigation

The development of green roofs to mitigate urban heat island effect is critical for conserving energy and reducing carbon footprint. This study evaluated the thermal performance of an extensive green roof design compared with a conventional roof and assessed the suitability of thirty-two plants for low-maintenance green roofs in a tropical area. Experiments were carried out in four phases, covering the tropical climatic conditions from June 2016 to December 2017. The results indicate that a green roof temperature was significantly lower than that of a conventional roof by 12 °C. This led to an 84 % reduction in heat transfer through the building, potentially leading to a decrease in electricity consumption by 0.20 kWh/m2/8 h and saving electricity costs by 0.019 USD/m2/8 h, achieved through a reduction in the cooling load on air conditioners. The highest carbon dioxide removal achieved in this study was 3.01 kgCO2/m2, with an effective mitigation of greenhouse gases by 28.46 kgCO2eq/m2/year. The top three plant species recommended for a low-maintenance green roof are Dracaena cochinchinensis, Santisukia kerrii, and Dracaena kaweesakii. The plant characteristics for low-maintenance green roofs in tropical climates include drought and extreme weather tolerance, disease and insect resistance, short and spreading roots, succulent leaves with ability to store water, low water requirements, slow growth rate, easy availability locally and affordability, thriving in low-nutrient conditions, and a high evapotranspiration rate. In applicable contexts, green roofs designed with suitable tropical plants could potentially enhance urban environments and contribute to achieving low-carbon and environmental sustainability.

A Multi-Baseline Forest Height Estimation Method Combining Analytic and Geometric Expression of the RVoG Model

As an important parameter of forest biomass, forest height is of great significance for the calculation of forest carbon stock and the study of the carbon cycle in large-scale regions. The main idea of the current forest height inversion methods using multi-baseline P-band polarimetric interferometric synthetic aperture radar (PolInSAR) data is to select the best baseline for forest height inversion. However, the approach of selecting the optimal baseline for forest height inversion results in the process of forest height inversion being unable to fully utilize the abundant observation data. In this paper, to solve the problem, we propose a multi-baseline forest height inversion method combining analytic and geometric expression of the random volume over ground (RVoG) model, which takes into account the advantages of the selection of the optimal observation baseline and the utilization of multi-baseline information. In this approach, for any related pixel, an optimal baseline is selected according to the geometric structure of the coherence region shape and the functional model for forest height inversion is established by the RVoG model’s analytic expression. In this way, the other baseline observations are transformed into a constraint condition according to the RVoG model’s geometric expression and are also involved in the forest height inversion. PolInSAR data were used to validate the proposed multi-baseline forest height inversion method. The results show that the accuracy of the forest height inversion with the algorithm proposed in this paper in a coniferous forest area and tropical rainforest area was improved by 17% and 39%, respectively. The method proposed in this paper provides a multi-baseline PolInSAR forest height inversion scheme for exploring regional high-precision forest height distribution. The scheme is an applicable method for large-scale, high-precision forest height inversion tasks.

Response of benthic assemblages to heavy metal contamination from shipbreaking operations in a tropical coastal area

The response of macrobenthic communities to both environmental and anthropogenic pressures serves as a valuable indicator of ecosystem integrity. This study aimed to unravel the benthic community structure, examine the heavy metal contamination status, and explore the response of the microbenthic community to heavy metals in a tropical shipbreaking region. For this, sediment and benthos samples were taken from different sampling stations of the shipbreaking area and the non-shipbreaking sites. The results showed the benthic community consisted of 23 taxa, including Polychaeta, Oligochaeta, Amphipoda, Decapoda, Gastropoda, Bivalvia, and Priapulida, with polychaetes being the predominant group. The benthic community and diversity values were significantly varied between the two sampling sites (p <0.05). Taxa richness was lower in the shipbreaking area, primarily characterized by the dominance of opportunistic benthic groups, particularly Capitella sp. The concentrations of heavy metals (µg. g−1) in the sediment varied within the following ranges: 35.54–258.021 for Zn, 4.84–132.08 for Pb, 22.82–75.25 for Cu, 198.74–764.16 for Mn, 14.57–42.13 for Cr, 4.03–42.23 for Ni, and 3.82–14.85 for Co. Based on concentration levels, Zn, Pb, and Cu were identified as major contaminants with moderate to high potential for adverse effects, particularly evident in the shipbreaking area compared to non-shipbreaking areas. Pollution indices, including enrichment factors and contamination factors, also highlighted contamination by Zn, Pb, and Cu. Among the benthic taxa, Polychaeta demonstrated a high degree of tolerance to elevated concentrations of these heavy metals. Amphipoda density was significantly negatively correlated with Zn, Pb, and Cu concentrations, with significant coefficients of determination (r2= 0.38, p <0.10; r2= 0.64, p <0.01 and r2 = 0.63, p <0.01, respectively). Multivariate analyses (cluster analyses, MDS and CCA) demonstrated both positive and negative relationships among heavy metals and benthic groups. Canonical Correspondence Analysis (CCA) showed the benthic community was negatively correlated with Zn, Pb, and Cu. This finding provided critical insights into the ecological health of aquatic ecosystems, aiding in the development of informed conservation and management strategies.

Complete Chloroplast Genome, Distribution, and Pharmacological Activities Pogostemon: A Mini Review

Pogostemon Desf. is the largest genus in the Pogostemoneae (Lamiaceae). The plastid genomes of Pogostemon species ranged from 151,824 to 152,707 bp in length and comprise 114 genes including 80 protein coding genes, 30 tRNA genes, and four rRNA genes. Pogostemon is found mostly in tropical and subtropical areas of Asia. P. cablin as one of the commercial species of the genus Pogostemon has various abundant pharmacological activities, such as anti-hypertension, anti-diabetic, anti-cancer, anti-inflammatory, anti-aging, etc. This review studied the complete chloroplast genome of Pogostemon, distribution of Pogostemon, and pharmacological activity of P. cablin. Online literature searches were carried out to compile the article. The following search terms were used to find online publications: Pogostemon, distribution of Pogostemon, complete chloroplast genome of Pogostemon, and pharmacological activity of P. cablin plants in PubMed (Medline) and Web of Science. Additionally, several assessments of prior and present data from the Pogostemon and P. cablin research publication were included into one review.

Pemanfaatan Serai sebagai Spray Anti Nyamuk oleh Mahasiswa KKNT Bela Negara di Desa Gedangan

Mosquito-borne diseases such as dengue fever, Zika, and malaria pose significant health threats in Indonesia, particularly in tropical areas like Gedangan Village, Jombang Regency. To reduce the risk of disease transmission, students of the Thematic Community Service Program (KKN) from Universitas Pembangunan Nasional "Veteran" Jawa Timur utilized lemongrass (Cymbopogon citratus) as the main ingredient in the production of mosquito repellent spray. This program aims to provide a safer and more environmentally friendly alternative compared to chemical-based products. The training and socialization conducted in Gedangan Village increased the community's understanding of the benefits of lemongrass and how to produce natural mosquito repellent spray. The results of this program show that lemongrass-based spray is effective as a mosquito repellent and can be a long-term solution in reducing dependence on chemical insecticides. The sustainability of this program is expected to be expanded to other villages, with support from the government and related institutions to strengthen its positive impact on public health and the environment.

Growth and Yield Response of Several Zucchini (Cucurbita Pepo L) Varieties to Auxin Application in The Midland in Tropical Area

Growth and Yield Response of Several Zucchini (Cucurbita Pepo L) Varieties to Auxin Application in The Midland in Tropical Area

Effects of Temperature and Nitrogen Limitation on Growth and Lipid Production of Oleaginous Microalgae from Hot Springs

Oleaginous microalgae have gained increasing attention as an alternative feedstock for biodiesel production due to the increasing demand of fuel, climate change, and global warming. This study aimed to isolate and screen robust microalgal strains from hot springs for cultivation in subtropical and tropical areas. The newly isolated oleaginous microalgae were cultivated at 30, 35 and 40 °C. Among mesophilic and thermophilic strains tested, Chlamydomonas sp. HP59 is considered the most robust strain as it showed high cell growth in a broad range of temperatures (30 - 40 °C), with the maximum dried cell weight at 40 °C. Un-optimal temperatures for cell growth did improve lipid content by 2 - 4 folds. To increase lipid production, the 2-stage cultivation, in which nitrogen-rich was applied to promote cell growth in the 1st stage and nitrogen-limitation was applied to stimulate lipid accumulation in the 2nd stage, was performed. The high temperature combined with nitrogen-limitation did improve lipid production by all microalgae. With this strategy, Chlamydomonas sp. HP59 showed the highest dried cell weight of 4.33 g/L and lipid production of 1.72 g/L. This study has shown the potential use of the newly isolated oleaginous microalgae from hot springs to be cultivated at high temperatures and under nitrogen-limited conditions for the production of biodiesel feedstocks. HIGHLIGHTS Mesophilic and thermophilic oleaginous microalgae were isolated from hot springs. Un-optimal temperatures for cell growth did improve lipid content by 2 - 4 folds. Combined effect of high temperature and nitrogen limitation effectively increased lipid content. Two-stage cultivation gave high dried cell weight and hence overall high lipid production. GRAPHICAL ABSTRACT

Structural Elucidation of Some Flavonoids Isolated from Litsea costalis and Their Biological Evaluation

Litsea costalis is a well-known medicinal plant in tropical and subtropical areas. Four significant flavonoids were extracted and characterized from the plant leaf extract. One component was discovered for the first time in flavonoid chemistry, flavan-4-ol, (3′, 4′-methylenedioxy-5,7-dimethoxy chroman-4-ol). Three flavonoids were discovered for the first time in this plant. The detected products are (+)-pinostrobin, (+)-onysilin, and (+)-pinocembrin. The fourth component was characterized for the first time in this plant and introduced in flavonoid chemistry. The extracted component antioxidant activity against DPPH indicated an IC50 value of around 30 µg/mL.

Hemoparasitism in grazing cattle and risk factors associated with husbandry management in an endemic area of Eastern Colombia

Vector-borne pathogens induce hemoparasitism in cattle causing substantial economic losses in tropical and subtropical areas. Infectious cattle actively contribute to maintaining the transmission cycle, and the presence of these animals must be associated with husbandry management and environmental changes. In the present study, we conducted a cross-sectional study sampling 1,000 bovines to identify infectious cattle diagnosed by a direct technique and employed a dichotomic questionnaire for association analyses, hierarchical clustering, and Principal Component Analysis (PCA). Overall prevalence with infectious cattle was 34.99%, where 97% of the farms had at least one infectious animal per genera, and the prevalence in properties ranged between 16.39 and 53.85%. Of these animals, 26.20% tested positive for Anaplasma sp., 8.40% for Babesia spp., and 1.30% for Trypanosome spp. The main co-infection showed 5% Anaplasma sp. – Trypanosome spp., followed by 4% Babesia spp. – Trypanosome spp. These bovines showed association with the use of the Jersey breed (OR = 2.016 C.I:1.188–3.419), selling animals for replacement (OR = 1.417 CI:1.022–1.965), participation in livestock exhibitions (OR = 2.009 CI:1.262–3.199), premises with burials (OR = 2,064 CR: 1.414–3.011), use of palm kernel (OR = 1.935 C.I:1.198–3.124), and the use of ivermectin (OR = 1.548 CI: 1.085–2.210) as a susceptibility. The hierarchical clustering revealed clusters among properties with different hemoparasite prevalence, with notable co-infections observed. The subsequent PCA identified that significant risk factors contributed to hemoparasitism positivity. We conclude that infectious cattle in the endemic area showed an association with husbandry management that permits the success of vector and maintenance of the enzootic or epizootic cycle in the herds.

Dengue Fever Manifesting as Haemorrhagic Bullae: A Rare Presentation

Abstract Dengue fever, a viral disease transmitted by Aedes mosquitoes, is a global health problem affecting millions of people each year. It is prevalent in tropical and subtropical areas, with epidemic potential due to climate change and increased travel. The disease commonly presents with cutaneous symptoms such as erythema, maculopapular rash and minor haemorrhagic lesions. This case is notable for the unusual presentation of haemorrhagic bullae, resembling drug eruption or autoimmune bullous disease. In the field of dermatology, tropical diseases like dengue have rarely been discussed. However, the recent increase in cases in Southeast Asia highlights the need for dermatologists to become familiar with dengue, as it often presents with diverse skin rashes. Herein, we report an unusual case of dengue fever presenting with haemorrhagic bullae.

Metal Geochemistry and Contamination Assessment of Tropical Mangrove Sediments

ABSTRACT The objective of this study was to evaluate the metal geochemistry and contamination assessment of the metals such as Fe, Co, Cd, Pb, Ni, Zn, Mg, Ca, and Sr from the surface sediment samples collected from seven stations from a tropical mangrove area in the Southwest coast of India. Metals like Ni and Fe were found in higher concentrations but never exceeded the contamination level in all the seasons whereas Cd was highly contaminated in all the seasons as well as stations. Pollution levels were measured using the indices including contamination Factor (CF), potential ecological risk coefficient (Eir), Enrichment Factor (EF), geoaccumulation index (Igeo), Pollution load index (PLI), Contamination degree (Cdegree), modified contamination degree (mCd) and Hazard Quotient (HQ). However, the level of contamination highlighted Cd has the maximum risk factors from the selected study area. All stations are contaminated by anthropogenic inputs. The pollution load index (PLI) revealed Pazhayangady, Valapattanam, Dharmadom (stations 1,2 and 3), Kumbalam (station5) and Munroe Thuruth (station 7) showed the presence of polluted sediments (PLI> 1).

A quick and effective trait-based protocol for selecting appropriate native plant species for the reforestation of degraded tropical mines.

A critical issue in tropical forests is that anthropogenic deforestation (i.e., mining) degrades the integrity of its ecosystem. Reforestation with appropriate native plant species helps to alleviate these detrimental impacts. A protocol to select appropriate plant species for this purpose currently lacks efficacy and timeliness. We provided a trait-based protocol to quickly and effectively select native plant species for mining reforestation. A 0.2-km2 area of Baopoling (BPL) at Hainan Island, China, was used as a study site, which has been severely degraded by 20 years of limestone mining for cement production. First, we identified the tree species in nearby undisturbed tropical forests, followed by evaluating the similarities in functional traits of the most dominant one (target species) and 60 local candidate native plant species (candidate species) whose saplings can be purchased from a local market. This dataset was used in our trait-based protocol, and only within 1 month, we successfully selected eight plant species which are very similar to target species from the 60 candidate species. We also quantified whether the eight selected plant species were indeed suitable for sustained reforestation by testing their effects on landscape and also their survival rate and recruitment ability after using them to perform reforestation in BPL from 2016 to 2023. Finally, these eight plant species are indeed suitable for reforestation due to their huge influences on a significant shift from originally degraded landscape (comprising only barren rocks) to a forest landscape totally and also their high survival rate (90%-97%) and ability for natural recruitment after 7 years' reforestation in BPL. Thus, we anticipate that this protocol would be integral to species selection during reforestation of tropical mining areas.

Edukasi Pemanfaatan Biji Nangka Berkhasiat sebagai Antibakteri

Jackfruit seeds contain several secondary metabolite compounds, including flavonoids, alkaloids, saponins, terpenoids and steroids. Jackfruit plants are one type of plant that can grow in tropical areas, so it is easy to find in Indonesia. The purpose of this community service is to improve and provide information and education to the community that the use of jackfruit seeds can be efficacious as an antibacterial. The results of the implementation of community service programs in the form of counseling to the community that there are benefits of jackfruit seeds used as antibacterial. So far, the public does not know that jackfruit seeds, which are often thrown away, can be efficacious as an antibacterial. The conclusion that the counseling was carried out according to the implementation and plan, received a good response from the surrounding community, the community also got information and knowledge and could apply the information for the family.

Exploration of Antibacterial and Antioxidant Potential of Eclipta prostrata Leaf Extract

Background: Eclipta prostrate also recognized as Bhringaraja is an annual herbaceous plant, commonly known as king of hairs. It is an erect or prostrate, much branched, roughly hairy, annual, rooting at the nodes; the leaves are opposite, sessile and lanceolate belonging to family Asteraceae. This plant is a significant medicinal plant in the tropical and subtropical areas. It is broadly used in treating different diseases of skin, liver and stomach in India, Nepal, Bangladesh and other countries. Methods: The main aim of this work was to collect and analyze the available information on traditional uses, phytoconstituents and biological activities of E. prostrata. Eclipta prostrata L. methanol extract was evaluated for its phytochemical compounds, ferric reducing antioxidant power (FRAP) and antibacterial activity. Result: Phytochemical analysis showed the presence of alkaloids, tannins, glycosides, steroids, glycoproteins and volatile oil the total saponin content was found to be 84.175 ± 0.575 in mg/g equivalent of diosgenin. The results of antioxidant activity measured by the FRAP method revealed stronger reducing power of the extract. Further antibacterial activity was observed against K. pneumoniae and S. aureus in potential of inhibiting the tested microorganisms. Crude methanolic extract of E. prostrate recorded a minimum inhibitory concentration of 2 mg/ml. The results of current study suggested that antioxidant activity and antibacterial activity could be due to polyphenols, however chiefly by various active compounds or substances present in the extract. Further isolation, characterization and identification of the potential phytochemical compound from crude extract needs to be addressed.

Multi-dimensional analysis of B cells reveals the expansion of memory and regulatory B cell clusters in humans living in rural tropical areas.

B-cells play a critical role in the formation of immune responses against pathogens by acting as antigen-presenting cells, by modulating immune responses and by generating immune memory and antibody responses. Here, we studied B-cell subset distributions between regions with higher and lower microbial exposure, i.e. by comparing peripheral blood B-cells from people living in Indonesia or Ghana to those from healthy Dutch residents using a 36-marker mass cytometry panel. By applying an unbiased multidimensional approach, we observed differences in the balance between the naïve and memory compartments, with higher CD11c+ and double negative (DN-IgDnegCD27neg) memory (M)B-cells in individuals from rural tropical areas, and conversely lower naïve B-cells compared to residents from an area with less pathogen exposure. Furthermore, characterization of total B-cell populations, CD11c+, DN and Breg cells showed the emergence of specific memory clusters in individuals living in rural tropical areas. Some of these differences were more pronounced in children compared to adults and suggest that a higher microbial exposure accelerates memory B cell formation, which 'normalizes' with age.