Samanea Saman Research Articles

The Phenology of Coffea arabica var. Esperanza L4A5 Under Different Agroforestry Associations and Fertilization Conditions in the Caribbean Region of Costa Rica

This study focused on the phenology of Coffea arabica var. Esperanza L4A5, an F1 interspecific hybrid obtained by crossing commercial varieties with wild genotypes from Ethiopia and Sudan. Most phenological studies on C. arabica have been conducted in traditional high-altitude regions, leaving a gap in the understanding of its behavior in non-traditional areas such as the Caribbean region of Costa Rica. To establish a baseline on the phenological behavior of the Esperanza L4A5 hybrid in this region, we conducted a four-year study examining the effects of different agroforestry associations: (1) Albizia saman; (2) Hymenaea courbaril and Erythrina poeppigiana; (3) Anacardium excelsum and Erythrina poeppigiana; and coffee plots under full sun. Additionally, the phenology of the coffee plants was evaluated under differentiated fertilizations (physical, chemical, and without fertilization), considering meteorological factors such as temperature, humidity, and rainfall. The observed variables included the development of floral nodes, pre-anthesis, anthesis, and fruiting stages. To analyze the relationships between environmental factors, tree cover, fertilization, and the phenological stages, we employed multiple linear regression (MLR), which revealed that both tree cover and physical and chemical fertilizations had significant effects on the presence of developed floral nodes and, consequently, on fruit production. Furthermore, the random forest (RF) model was applied to capture complex interactions between variables and to rank the importance of meteorological factors, tree cover, and fertilization practices. These analyses demonstrated that the Esperanza L4A5 hybrid exhibited viable phenological development under the atypical conditions of the Caribbean region of Costa Rica, suggesting its potential to adapt and thrive in non-traditional coffee-growing areas.

Plant Growth Promotion in Solanum lycopersicum through Endophytic bacteria Isolated from Flower of Samanea saman

Plant Growth Promotion in Solanum lycopersicum through Endophytic bacteria Isolated from Flower of Samanea saman

Growth and physiology responses of Samanea saman inoculated with arbuscular mycorrhizal fungi in silica post-mining soil media using biodegradable pots

Arbuscular mycorrhizal fungi (AMF) and biodegradable pots are environmentally friendly and enhance plant growth in adverse soil conditions. These studies explored AMF interactions and biodegradable pots in physiology, growth, and the uptake of nutrients in Samanea saman seedlings. The present research interactive effects of biodegradable pots with different compositions and raw material sizes with and without AMF inoculation on S. saman grown in silica post-mining soil media. Results indicated AMF inoculations significantly improved leaf chlorophyll content, photosynthetic rate, heights, diameters, biomass, as well as nutrient absorption of S. saman as compared with non-inoculated plants in biodegradable pots. AMF and biodegradable pots composed of 15% used newspaper, 70% compost, 5% cocopeat, and 10% rock phosphate showed the best results and increased the leaf chlorophyll content, photosynthesis rate, height, diameter, and total biomass of the plants by 161.1%, 208.7%, 263.6%, 118.1%, and 269.9%, respectively, compared to biodegradable pots composed only of used newspaper. Additionally, uptake of the nutrients nitrogen, phosphate, potassium, and magnesium increased by 365%, 800%, 369%, and 250%, respectively. By the fourteenth week after transplanting, the C/N ratio of the organic pot decreased significantly. Thus, AMF and biodegradable pots containing compost and rock phosphate interact positively and enhance the growth of S. saman under adverse soil conditions. These findings suggest that biodegradable pots containing compost and rock phosphate show potential as more environmentally friendly replacements for plastic bags (polybags) as growth medium containers for seedling production.

Growth and Productivity of Coffea arabica var. Esperanza L4A5 in Different Agroforestry Systems in the Caribbean Region of Costa Rica

This study focused on evaluating the growth and productivity of Coffea arabica var. Esperanza L4A5 in different agroforestry systems in the Caribbean region of Costa Rica, a non-traditional area for coffee cultivation due to its low altitude and challenging climatic conditions. Three tree coverages were investigated, in combination with two types of differentiated fertilization (physical and chemical), comparing the results with full sun coffee plots as a control: (1) Albizia saman, (2) Hymenaea courbaril + Erythrina poeppigiana, and (3) Anacardium excelsum + Erythrina poeppigiana. The results showed that tree associations significantly reduced the mortality of coffee plants and increased both the height and mature cherry production compared to full sun treatments. In particular, the tree coverages associated with chemical and physical fertilization achieved the highest growth and production rates, with A. excelsum + E. poeppigiana and H. courbaril + E. poeppigiana standing out with maximum mature cherry productions of 3.35 t/ha and 3.28 t/ha, respectively. Growth analysis revealed that rapid initial growth, especially under chemical fertilization, is crucial for maximizing productivity, although a rapid slowdown in growth was also observed after reaching the peak. These findings underscore the importance of combining tree coverages with appropriate fertilization strategies to optimize coffee production in agroforestry systems, particularly in low-altitude areas like the Costa Rican Caribbean. This study concludes that agroforestry systems not only improve the resilience of coffee crops to adverse environmental conditions but can also be a viable strategy for increasing productivity in non-conventional regions. This suggests the need for further research to assess the long-term impacts on soil health, biodiversity, and the economic viability of these systems.

Quality Characteristics, in vitro Gas Production and Degradability of Megathyrsus maximus Ensiled with Different Parts of Albizia saman

Quality Characteristics, in vitro Gas Production and Degradability of Megathyrsus maximus Ensiled with Different Parts of Albizia saman

Enhancing outdoor comfort in urban hot climates: investigating the cooling impact of two tropical trees through shade provision and transpiration

ABSTRACT One key ecosystem service widely known and attributed to trees in the urban environment is their ability to provide shade through their canopies and undertake evapotranspiration cooling. These in turn contribute to reduced atmospheric temperatures. A lesser-known aspect with little quantitative data is the heterogeneous temperature environment beneath the canopies at pedestrian or street level where the cooling will benefit thermal comfort. This study was conducted throughout 2022. It collected data where air temperature was measured under the canopies of two urban tropical tree species, Samanea saman and Peltophotum pterocarpum, at three different heights, which were 1, 3 and 5 m, respectively, from the ground. This was to investigate whether crown architectures and the associated shade and cooling effects via transpiration can have a significant change in the surrounding temperature. The study observed surface and air temperatures coupled with meteorological data across cool, warm, and hot periods of the year. It was observed that soil temperature increased alongside increases in atmospheric temperatures with a more significant rise observed for P. pterocarpum despite the observation of greater wind speeds for both night and day at the site where this species was situated. The soil moisture potential data indicated the reverse where S. saman showed more negative values with the greatest increase under warm conditions. Interestingly, sap flow rates also indicated that P. pterocarpum had more efficient rates whether conditions were cool, warm, or hot, suggestive of more active transpirational cooling. This was despite a lower leaf area index, smaller crown volume and sap wood area for this species. Relationship analyses between sap flow and air temperatures at different heights under the canopies showed a positive correlation. This demonstrates that apart from shade provided by the canopies, transpiration is also an important parameter for cooling. The mean daytime air temperature indicated that the greatest cooling effect was experienced at the lowest level from the ground (at 1 m), and this was consistent for both species across cool, warm, and hot conditions with a significant cooling effect of between 2.3 and 4°C. Temperature data under the canopy (1 to 5 m from the ground) compared to the air temperature of the grass that was shaded indicated temperature differences of between 2.3 and 7.9°C at 5 m and between 1.9 and 5.6°C at 1 m (for both species) with a bigger reduction attributed to S. saman.

Skin Prick Tests and Enzyme-Linked Immunosorbent Assays among Allergic Patients Using Allergenic Local Pollen Extracts.

Allergic respiratory diseases are prevalent in the Philippines, with allergic rhinitis and asthma occurring at 20% and 8.7% of the population, respectively. The diagnosis of respiratory allergies is achieved by a combination of patient history and different screening tools, especially for the identification of the allergic triggers such as allergy skin prick test (SPT) and serum-specific IgE enzyme-linked immunosorbent assays (sIgE ELISA). The Philippines, being a tropical country, have a wide variety of plant species with potential to produce allergenic pollen grains. Knowledge of the sensitization profiles of Filipino allergic patients to our local pollen allergens is currently limited. The aim of this study is to determine the sensitization profile of patients with respiratory allergies (allergic rhinitis and/or asthma) through the allergy skin prick test (SPT) using allergenic local pollen extracts. It also aimed to determine if there is a positive agreement between the SPT and sIgE ELISA positivity rate and whether the results have relationship with the pollen purity and the protein content of the extracts. Pollen allergens were extracted from Amaranthus spinosus (pigweed), Mimosa pudica (makahiya), Tridax procumbens (wild daisy), Imperata cylindrica (cogon), Oryza sativa (rice), Pennisetum polystachion (foxtail grass), Sorghum halepense (Johnson grass), Albizia saman (acacia), Cocos nucifera (coconut), Leucaena leucocephala (ipil-ipil), and Mangifera indica (mango). SPT was performed at the Allergy Clinic of the University of the Philippines-Philippine General Hospital on patients with allergic rhinitis and/or bronchial asthma. Blood samples were collected from patients who developed wheal diameters of 3 mm or more than the negative control. Sera were tested against the same pollen extracts using ELISA. Of the one hundred sixty-five (165) patients who submitted for skin prick test, 129 showed positive SPT results to the pollen extracts. Weeds were the most sensitizing (51.9%-58.1%). Blood samples were collected from these patients and tested for sIgE ELISA and among them, 71 were positive in the sIgE ELISA. Highest sensitization rates in sIgE ELISA were found in coconut, pigweed, Johnson grass, and rice. The highest positive agreements or the proportion of patients with positive sIgE ELISA among those with positive SPT were in coconut, followed by Johnson grass, pigweed, and rice. Most of the pollen sensitized patients on SPT are polysensitized. SPT is a safe, simple, and rapid method for the diagnosis of IgE-mediated allergy. The lower number of positive patients in sIgE ELISA may be attributed to the low serum IgE levels and low quantities of effectual allergen components in extracts. Results of both SPT and ELISA must be correlated with a patient's clinical history, particularly the patient's exposures, and physical examination.

CuO nanoparticles: green combustion synthesis, applications to antioxidant, photocatalytic and sensor studies.

The use of metal oxide nanoparticles for heterogeneous photodegradation is a prominent method for the removal of organic dyes from water resources. Compared to conventional approaches to treat polluted water, it is a more preferable method because of its environmental friendliness, low cost, and no requirement of extreme temperature and pressure. Among all the nanoparticles, CuO is a prominent material. Therefore, this study reports on the biogenic preparation of CuO nanoparticles by adopting a combustion method and Samanea saman pod extract as fuel. The synthesized nanoparticles were characterized through X-ray diffraction spectroscopy to confirm the crystallinity of CuO; the surface morphology of the material was studied using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) and the purity of the material was confirmed by energy dispersive X-ray spectroscopy. The degradation efficiency of CuO nanoparticles towards methylene blue dye, a model pollutant present in water resources, was assessed and found to be 97% after 90 minutes of light exposure. The synthesized CuO nanoparticles were also examined for antioxidant and electrochemical sensing studies using cyclic voltammetry. Results showed that CuO nanoparticles function as a strong antioxidant and are a very effective electrochemical sensor.

Evaluating The Physical Quality of Trembesi Seedlings (Samanea saman) in The Permanent Nursery of BPDAS Indragiri Rokan, Pekanbaru City, Riau Province

The availability of high-quality seedlings is crucial for reforestation and forest rehabilitation initiatives aimed at mitigating deforestation. This study assesses the physical quality of rain tree (Samanea saman) seedlings produced by the Permanent Nursery of BPDAS Indragiri Rokan, located in Pekanbaru, Riau Province. A systematic sampling method with a random start was employed, involving 15,155 raintree seedlings that were six months old, from which a sample size of 200 seedlings was selected following SNI 8420 of 2018. The parameters observed included seedling height, stem diameter, leaf count (LCR), compactness of the planting medium, and root crown ratio. Data analysis was conducted based on the general and specific quality requirements outlined in SNI and Perdirjen RLPS No. P.05/V-Set/2009. The findings revealed that 66.5% of the seedlings satisfied the general requirements, while 72.38% met the specific requirements. The rain tree seedlings were classified within quality class D, with a percentage of normal seedlings falling below 95% and several samples exhibiting damage from pests and diseases. These results underscore the necessity for enhancements in nursery management, particularly concerning pest and disease control, to elevate the quality of raintree seedlings in future production.

Characteristics of rain tree seed (Samanea saman) biochar at different pyrolysis temperatures

Abstract A Rain trees (Samanea saman) yield abundant seeds, averaging 200-250 kg of pods per season from mature trees. This high seed production often results in waste or undesired seedlings. To mitigate this issue, researchers are studying methods to utilize these seeds effectively. One promising approach involves converting rain tree seeds into biochar through pyrolysis, a process that transforms organic resources into valuable products. However, the characteristics of the biochar depend on the pyrolysis temperature. This study aims to examine how different temperatures affect the properties of rain tree seed biochar. The seeds were subjected to pyrolysis at temperatures of 300°C, 400°C, 500°C, and 600°C for four hours. The results show that increasing the pyrolysis temperature will decrease the biochar yield, with the highest yield at 300°C being 50.52%. Conversely, the ash content and fixed carbon increase with rising temperatures. SEM analysis indicates that pores begin to form at 400°C; however, at 600°C, extensive pore cracking is observed. Based on FTIR analysis, functional groups including -OH, C=C, C=O, C-O, and C-H were identified. XRF analysis reveals that the four dominant elements in biochar are K2O (55-59%), CaO (24-28%), P2O5 (11-12%), and MgO (1.5-1.9%). Based on these dominant elements, rain tree seed biochar has potential for soil amendment, containing macronutrients necessary for plant growth.

Thermoplastic bio-composites from natural Samanea Saman fillers loaded HDPE: Mechanical, thermal, and structural analysis

This study explores the potential of biodegradable Samanea saman (SS) flower fillers as reinforcements in high-density polyethylene (HDPE) composites, fabricated using injection molding techniques at various filler concentrations. Surface morphology and elemental composition were analyzed using Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray Spectroscopy (EDX), revealing a composition predominantly of Carbon (88.04 %), along with Oxygen, Silicon, Chlorine, Potassium, Calcium, Sodium, and Bromine. The crystal structure of the fillers was identified as orthorhombic via X-ray diffraction (XRD), and the crystallite size was measured at 62.78 nm. Thermal stability assessments conducted through Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) indicated stability up to 210 °C before degradation occurred. Mechanical properties were optimized at a filler content of 40 wt% for Shore D hardness (63.5 ± 0.5 SHN) and compressive strength (25.5 ± 0.5 MPa), and at 30 wt% for tensile (23.5 ± 0.5 MPa) and flexural strength (19.5 ± 0.5 MPa). These results suggest that SS-HDPE composites offer a viable, environmentally friendly alternative for non-load-bearing applications, potentially reducing HDPE usage by up to one-third.

The Effectiveness of Public Green Open Space Capabilities in Reducing Flooding

The Palopo City watershed could not accommodate the high discharge of rainfall that had fallen previously. The Green Open Space (GOS) had an ecological function by absorbing rainwater. Urban green open spaces absorbed surface flow water in the past, reducing the risk of flooding. In the past, this research measured the effectiveness of three green open spaces (Islamic Center, Pancasila Field, and Salubulo Field) in reducing flooding in Palopo City. We collected data on vegetation types, infiltration capacity, and runoff discharge. Data analysis involved the analysis of infiltration capacity (F), runoff discharge (Q), and green open space effectiveness. In the three green space locations, the following vegetation types were found: Katapang (Terminalia catappa), Palm (Dypsis lutescens), Trambesi (Samanea Saman), and Grass (Cyperus rotundus). The highest total infiltration capacity in the Salubulo Field Green Space resulted in 155 m3/hour (fast category). In the past, the most significant runoff discharge's total value was GOS Pancasila Field: 713.4 mm3/minute. The study concluded that the Salubulo Field Green Space had the highest infiltration capacity (160 m3/hour) and runoff discharge (69 mm3/minute), making it the most effective in reducing flooding in Palopo City in the past. This was > 1 (effectiveness criteria achieved), and the space was dominated by vegetation (trees and grasses).

The Essential of Trembesi in Djawatan: Identifikasi Persebaran Pohon Trembesi sebagai Penentu Biodiversitas di Kawasan Hutan Djawatan

Trembesi (Samanea saman) plays an important role in the Djawatan forest area. The presence of Djawatan forest in the city adds vital value to trembesi, such as maintaining ecosystem stability, soil stability, water supply stability, O2 supply, and CO2 absorption. This study aims to determine the density of trembesi trees in the Djawatan forest area. The presence of trembesi in the Djawatan forest is crucial for the numerous flora and fauna sheltered beneath it. Therefore, understanding the distribution pattern of trembesi in the Djawatan forest area is essential to ascertain environmental influences on the growth of trembesi. The research method used in this study was descriptive qualitative through observation and interviews. Trembesi distribution in this study was observed in four different zones: waterfront, rice field edge, central Djawatan forest, and settlement edge. Based on the research results, it is known that trembesi distribution is influenced by the surrounding environmental conditions. This is evidenced by data showing that the highest average density of trembesi is found in the central Djawatan forest area, which is 0.50%.

Short Communication: Habitat preferences of epiphytic orchids and potential pollinators in Sumber Pawon Forest, Kediri District, East Java, Indonesia

Abstract. Putra SRT, Trisnawati I. 2024. Short Communication: Habitat preferences of epiphytic orchids and potential pollinators in Sumber Pawon Forest, Kediri District, East Java, Indonesia. Biodiversitas 25: 2780-2787. Sumber Pawon Forest, a unique and biodiverse ecosystem in Kediri, Indonesia, is home to approximately 30,000 orchids (family Orchidaceae), which can grow terrestrial or as epiphytes. A diversity of different taxa has been recorded as orchid pollinators. The distribution of epiphytic orchids in this forest is determined by habitat preferences including vertical distribution zone and host tree's characteristics. This research, conducted in the captivating Sumber Pawon Forest, aims to determine habitat preferences influencing the abundance of epiphytic orchids and provide a review of potential epiphytic orchid pollinators. The data were collected by systematic sampling method. Analysis of epiphytic orchids' habitat preferences was done using the ordination method. The study found 3 epiphytic orchids and 5 species of host trees, revealing new insights into their distribution. Epiphytic orchids include Cymbidium sp., Dendrobium crumenatum, and Rhynchostylis retusa. The host trees include Alstonia scholaris, Artocarpus elasticus, Bischofia javanica, Ficus elastica, and Samanea saman. Epiphytic orchids were mainly found in zone 4 rather than in zone 5. The characteristics of host trees, which are preferentially selected by epiphytic orchids, include tree height (ranging from 28.65 to 33.65 m), large DBH (ranging from 165.61 to 175.80 m), and closed canopy cover (ranging from 51 to 75%). One of the pollinator taxa (named Hymenoptera) was found to pollinate epiphytic orchid species, adding to our understanding of their ecological interactions.

Effect of Soybean Meal Substitution Using Raintree (Samanea saman) Seed Meal on the Physical Quality of Feed and Growth Performance of the Juvenile White Shrimp, Litopenaeus vannamei

Effect of Soybean Meal Substitution Using Raintree (Samanea saman) Seed Meal on the Physical Quality of Feed and Growth Performance of the Juvenile White Shrimp, Litopenaeus vannamei

Relative Analysis for Carbon Sequestration Potential of Prominent Private and Public Green Spaces in Bengaluru, India

With the advent of Climate Change and Global Warming, highly populated urban spaces are becoming more prone to various Environmental disasters. While forest are good sinks of CO2, it is highly impossible to introduce them into urban-level planning. In this context, nurturing Urban Green Spaces within cities, can serve well to perform the regulatory functions just like forests do. However, it is also imperative that their inception, must also ensure effective carbon sequestration. The objective of current research includes determination of carbon sequestration value for various ‘tree’ species, which eventually would serve to identify species with potential to serve better in Strategic Climate Sustainable Township Guidelines. To accomplish this objective, firstly three observatories (Richard’s Park, BMSIT&M Green Campus, and Lalbagh Botanical Garden) having distinct floral diversity were selected. Further, physical data collection was undertaken at these observatories and employed for biomass computation viz. ‘Biostatistics-based Allometric’ equation. Statistical Validation of data was accomplished viz. Multiple Linear Regression Modelling and One-way ANOVA. The average value of carbon sequestered (in tonnes per species) was found to be 20.13, 0.727 and 0.292, at Lalbagh Botanical Garden, Richard’s Park, and BMSIT&M, respectively. Upon comprehensive evaluation, it was found that best three species offering high carbon sequestration potential are Eucalyptus grandis, Eucalyptus globus and Samanea saman. These species would hence be keystone species that could play a potential role in naturally lowering CO2 levels in intra-urban spaces. These species would serve well in empowering Green Spaces to behave as Urban Cool Islands, to combat Urban/Global Warming.

Assessment of decay caused by Trametes flavida and Daldinia eschscholtzii on several hardwood species

AbstractWood‐decay fungi are major contributors to damage wood and logs, resulting in substantial economic losses. This study assessed the decay caused by Trametes flavida and Daldinia eschscholtzii on Gmelina arborea, Samanea saman, Albizia lebbeck, Acacia auriculiformis and Swietenia mahagoni. Both fungi demonstrated their ability to decay wood. However, the extent of damage varied significantly among the tested hardwood species. Findings showed that Trametes flavida caused greater wood mass and density loss than Daldinia eschscholtzii. Among the tested hardwood species, G. arborea was found to be more susceptible to the decay fungi, followed by S. saman, A. lebbeck, A. auriculiformis and S. mahagoni, respectively. The study will encourage the scientific management of timber and logs in sawmill depots to minimize the decay of wood and incurred economic loss.

Triterpenoids III: Lupeol from <i>Samanea saman</i> (JACQ.) Merr.

Lupeol has been isolated in 0.07% yield in the non-saponifiable fraction of the pericarp-mesocarp portion of the pods of Samanea saman (Jacq.) Merr.

Soil depth constraints in the revegetation of reclaimed coal mine land

Abstract. Hartati W, Syahrinudin, Sudarmadji T. 2024. Soil depth constraints in the revegetation of reclaimed coal mine land. Biodiversitas 25: 1838-1845. Plants require adequate root space, nutrients, water, and air for optimal growth. This study analyzed the relationship between plant growth (i.e., diameter) and soil properties (i.e., thickness, organic matter content, texture) on revegetated post-coal mining land in East Kalimantan, Indonesia. Field research was conducted at revegetated area primarily planted with four species (Hibiscus tiliaceus, Enterolobium cyclocarpum, Samanea saman and Acacia sp.) with age of 8 years. Data was collected from 30 plots of 0.05 ha. Plant diameter were recorded and soil samples were taken from 0-10, 10-30, and >30 cm depths using soil auger at three points per plot. Organic matter content was determined by the Walkley-Black method, and texture by the Pipette method. Multiple regression analysis was used to used to investigate the relationship between plant diameter and soil properties. The study found that different species showed varying correlations between soil properties and growth. Acacia sp. and S. saman exhibited strong correlations (r=0.78), while E. cyclocarpum had a low correlation (r=0.35), and H. tiliaceus a moderate one (r=0.49). Soil thickness had a stronger influence on H. tiliaceus (?=0.05) and S. saman (?=0.01) than other tested properties. For some species, diameter growth was primarily determined by soil thickness in the revegetated area. The study highlights the importance of considering species-specific soil requirements for successful revegetation and plant growth on post-coal mining sites.

Mechanism of the Pulvinus-Driven Leaf Movement: An Overview.

Leaf movement is a manifestation of plant response to the changing internal and external environment, aiming to optimize plant growth and development. Leaf movement is usually driven by a specialized motor organ, the pulvinus, and this movement is associated with different changes in volume and expansion on the two sides of the pulvinus. Blue light, auxin, GA, H+-ATPase, K+, Cl-, Ca2+, actin, and aquaporin collectively influence the changes in water flux in the tissue of the extensor and flexor of the pulvinus to establish a turgor pressure difference, thereby controlling leaf movement. However, how these factors regulate the multicellular motility of the pulvinus tissues in a species remains obscure. In addition, model plants such as Medicago truncatula, Mimosa pudica, and Samanea saman have been used to study pulvinus-driven leaf movement, showing a similarity in their pulvinus movement mechanisms. In this review, we summarize past research findings from the three model plants, and using Medicago truncatula as an example, suggest that genes regulating pulvinus movement are also involved in regulating plant growth and development. We also propose a model in which the variation of ion flux and water flux are critical steps to pulvinus movement and highlight questions for future research.