Papers - OKAZAWA Hiromu
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Effects of Biochar on Growth, Response to Water Stress, and Post-Stress Recovery in Underutilized Vegetable Hibiscus sabdariffa from Malawi Reviewed International coauthorship International journal
Mazibuko, Dickson Mgangathweni, Sarvesh Maskey, Kiseki Kurashina, Hiromu Okazawa, Hiroyuki Oshima, Taku Kato, and Hidehiko Kikuno
Crops 5 ( 2 ) 2025.03
Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI
Globally, Hibiscus sabdariffa L. (Malvaceae), commonly known as roselle or hibiscus, is a multipurpose vegetable crop. In Malawi, where it is referred to as ‘Chidede’ (Chichewa), it is recognized as an underutilized traditional plant with significant potential. Traditional vegetable production in Malawi is being promoted to enhance nutritional food security and climate change mitigation. Recently, biochar has become increasingly used to improve agricultural productivity through climate-smart technologies. To date, the influence of rice husk biochar (RHB) on H. sabdariffa remains underexplored. This study aims to evaluate the effects of RHB on the vegetative growth, response to water stress, and post-stress recovery of H. sabdariffa using a greenhouse pot experiment. Our findings indicate that biochar-amended soil enhanced plant height, stem thickness, and total leaf area by 16.5%, 12.0%, and 12.9%, respectively. Water stress significantly reduced all assessed growth parameters (p < 0.05) except total leaf area and average leaf area per plant. Under water stress conditions, biochar-treated plants were significantly taller (p < 0.05) and had a higher specific leaf area (p < 0.05), demonstrating a positive effect. A post-stress recovery analysis revealed that H. sabdariffa fully recovered in height and biomass, while partial recovery was observed for root collar diameter and compensatory recovery for total leaf area and average leaf area. Biochar-treated plants exhibited superior post-stress recovery compared to those grown in unamended soil. Overall, plants grown with biochar were taller and had a larger root collar diameter, higher stem and leaf fresh biomass, and greater total leaf area. These findings underscore biochar’s potential as a sustainable soil amendment for enhancing growth and resilience in underutilized crops. Further studies should explore field experiments to access environmental heterogeneity and examine the diverse factors influencing biochar efficiency.
DOI： https://doi.org/10.3390/crops5020013
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Unravelling the diversity and utilisation of emerging spices and herbs in Malawi: a pathway to diversified nutrition and community health Reviewed International coauthorship International journal
Dickson Mgangathweni Mazibuko, Ruth Nyambura Maru, Hiroko Gono, Hiromu Okazawa
Transactions of the Royal Society of South Africa 1 - 18 2025.02
Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Taylor&Francis
To date, spices remain comparatively the least produced and utilised of all crops in Malawi irrespective of their nutraceutical importance. Onions (Allium sp.) and peppers (Capsicum sp.) are Malawi's main spices, and to a lesser extent ginger (Zingiber officinale) and garlic (Allium sativum); they are commonly used in cooking and as medicine. Recently, “new” spices, with high nutraceutical values documented in other countries, are emerging on Malawi's local markets. This points to an increasing pool of spice crops whose diversity and comparative utilisation dynamics remain poorly understood. This study aimed firstly to determine spice species diversity, secondly to determine the context of utilisation (culinary and medicinal) and finally to trace scientific validation of the bioactivity for spices ‘reported’ to be used in treating various ailments. The main intention was to expose the potential of spice crops in improving household and community diets and health. Data was collected from interviews with spice traders and customers/consumers. In this study 33 spice species belonging to 29 genera and 14 families were found in markets. Twenty species had a reported medicinal purpose, of which 80% had scientific validation from experiments on humans (55%) and animals (25%). Common ailments managed by spice usage in Malawi include diabetes, hypertension, obesity, and immunity boosting, all identified as emerging health concerns in the country. In Malawi, 80% of the population is reliant on plant-based medicines. Deliberate promotion of spice consumption and production is a pivotal pathway to diversifying plant-based medicine resources along with increasing agrobiodiversity and the associated dietary diversity. Coordination among health, nutrition, and agriculture experts and policymakers will be key in unlocking the potential that spice crops hold for Malawi.
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Precise LULC classification of rural area combining elevational and reflectance characteristics using UAV International coauthorship
Ke Zhang, Lameck Fiwa, Madoka Kurata, Hiromu Okazawa, Kenford A.B. Luweya, Mohammad Shamim Hasan Mandal, Toru Sakai
Scientific African 26 ( e02431 ) 2024.10
Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER
With the development of unmanned aerial vehicle (UAV) in the recent decade, very high-
resolution aerial imagery has been used for precise land use/land cover classification (LULC).
However, special structures in rural areas of developing countries such as traditional thatched
houses have posed challenges for precise LULC classification due to their undistinctive appearance
and confusable characteristics in both reflectance and structure. LULC mapping is essential
particularly in rural areas which have high data scarcity and vulnerability to natural disasters.
With high-resolution observation has been achieved by UAVs, it is important to propose high-
precision LULC classification methods which can fully use the advantages of UAVs. To emphasize
the differences among the common LULC types in rural areas, this study proposed an original
index, the rural residence classification index (RCI). RCI was calculated as the product of the
above ground height and the square of the difference between the NDVI value and one. Then, a
comprehensive classification method was established by combining the RCI, the traditional
threshold method and a machine learning method. As a result of the comparison with the
traditional threshold method, object-based image analysis, and random forest methods, the
method by this study achieved the highest overall accuracy (overall accuracy =0.903, kappa =
0.875) and classification accuracy for detecting thatched houses (user’s accuracy =0.802, producer’s
accuracy =0.920). These findings showed the possibility on identifying the confusable
structures in rural areas using remote sensing data, which was found difficult by the previous
studies so far. The method by this study can promote the further utility of UAVs in LULC classification
in rural areas in developing countries, thereby providing precise and reliable material
for hydrological, hydraulic or ecosystem modelling, which eventually contributes to more accurate
natural hazard risk assessment, rural development, and natural resource management.DOI： https://doi.org/10.1016/j.sciaf.2024.e02431
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Evaluation of Growth, Yield and Bioactive Compounds of Ethiopian Kale (Brassica carinata A. Braun) Microgreens under Different LED Light Spectra and Substrates Reviewed International coauthorship
Maru, Ruth Nyambura, John Wesonga, Hiromu Okazawa, Agnes Kavoo, Johnstone O. Neondo, Dickson Mgangathweni Mazibuko, Sarvesh Maskey, and Francesco Orsini
Horticulturae 10 ( 5 ) 2024.04
Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI
Microgreens are innovative vegetable products whose production and consumption are gaining popularity globally thanks to their recognized nutraceutical properties. To date, the effects of lighting conditions and growing substrate on the performances of Brassica carinata microgreens (indigenous to Africa) remain underexplored. The present study aimed at providing insights into the influence of different lighting treatments provided by LEDs, namely monochromatic blue (B), red (R), cool white (W) and a combination of three color diodes (B + R + W), and substrates (cocopeat, sand and cocopeat–sand mix (v/v) (1:1)) on the growth, yield and bioactive compounds of B. carinata microgreens. Seeds were germinated in dark chambers and cultivated in growth chambers equipped with LED lighting systems for 14 days under a fixed light intensity of 160 ± 2.5 µmol m−2 s−1 and photoperiod of 12 h d−1. The best performances were associated with the spectrum that combined B + R + W LEDs and with substrate resulting from the cocopeat–sand mix, including the highest yield (19.19 g plant−1), plant height (9.94 cm), leaf area (68.11 mm2) and canopy cover (55.9%). Enhanced carotenoid and flavonoid contents were obtained with B + R + W LEDs, while the B LED increased the total amount of chlorophyll (11,880 mg kg−1). For plants grown under B + R + W LEDs in cocopeat, high nitrate levels were observed. Our results demonstrate that substrate and light environment interact to influence the growth, yield and concentration of bioactive compounds of B. carinata microgreens.
DOI： https://doi.org/10.3390/horticulturae10050436
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Insights into the journey towards development of dietary guidelines: An exploration of synergy between fruit and vegetable research with food composition tables in Malawi "jointly worked" Reviewed International coauthorship
Dickson Mgangathweni Mazibuko, Victoria Ndolo, Satoko Akiyama, Hiromu Okazawa
African Journal of Food Science 17 ( 2 ) 256 - 267 2023.12
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Academic Journals
Publication of the Malawi Food Composition Database (MFCDB) is a milestone towards improving the nutritional status and overall health of citizens. Following the establishment of this database, the next step involves formulating food-based dietary guidelines tailored for Malawi. However, both the database and the planned dietary guidelines are dependent on robust research on food composition. This analytical review utilizes fruit and vegetable research done in Malawi, to analyze synergies with the published food composition tables and limitations. Results point to inadequate fruit and vegetable nutrition research in Malawi. Less than 1% of published vegetable research has dealt with nutrient composition. Of this, only 15% has contributed to the food composition database, forcing 52 and 39% of entries (values) for fruits and vegetables, respectively to be borrowed. However, more research on fruit and vegetable species has been done than is captured in the database. There exists dissonance in analytical methods between research and database needs. This lack of methodology impacts overall data comparability and reliability. It is suggested that the Malawian Food Data System, provide standardized methods of analysis for various food composition parameters, priority list of species, and nutrient profiles of immediate national relevance. The planned dietary guidelines will require a multisectoral approach, and policy modifications to facilitate fit-for-purpose research in fruits and vegetables.
DOI： 10.5897/AJFS
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Quantification of Amu River Riverbank Erosion in Balkh Province of Afghanistan during 2004–2020 "jointly worked" Reviewed International coauthorship International journal
Mahmoodzada, Abdul Basir, Divyesh Varade, Sawahiko Shimada, Hiromu Okazawa, Shafiqullah Aryan, Gulbuddin Gulab, Abd El-Zaher M. A. Mustafa, Humaira Rizwana, Yogesh K. Ahlawat, and Hosam O. Elansary
Land 12 ( 10 ) 1890 2023.10
Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI
In this study, we propose quantifying the Amu River riverbank erosion with the modelled river discharge in Kaldar District, Balkh Province of Afghanistan from 2004 to 2020. We propose a framework synergizing multi-source information for modelling the erosion area based on three components: (1) river discharge, (2) river width, and (3) erosion area. The total river discharge for the watershed shared by Afghanistan and Tajikistan was modelled using hydrological parameters from the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) data through multivariate linear regression with ground station data. The river width was determined manually using the Normalized Difference Water Index (NDWI) derived from Landsat data. The riverbank erosion area was derived from the digital shoreline analysis using the NDWI. The digital shoreline analysis showed that, between 2008 and 2020, the average riverbank erosion area in Kaldar District is about 5.4 km2 per year, and, overall, 86.3 km2 during 2004–2020 due to flood events. The significantly higher land loss events occurred at 10 km2 bank erosion during the years 2008–2009 and 2015–2016, and 19 km2 peak erosion occurred during 2011–2012. A linear relation between the erosion area with respect to the discharge intensity and the specific stream power was observed with an R2 of 0.84 and RMSE of 1.761 for both.
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The Sustainable Niche for Vegetable Production within the Contentious Sustainable Agriculture Discourse: Barriers, Opportunities and Future Approaches "jointly worked" Reviewed International coauthorship International journal
Mazibuko Dickson Mgangathweni, Hiroko Gono, Sarvesh Maskey, Hiromu Okazawa, Lameck Fiwa, Hidehiko Kikuno, and Tetsu Sato
Sustainability 15 ( 6 ) 4747 - 4747 2023.03
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI
Agricultural productivity impacts the environment and natural resources in various ways. The severity of these impacts has triggered the emergence of natural resource management and the related, highly criticized science of agroecology. Vegetable production has known environmental impacts. However, the extent of its participation in sustainable production has not been adequately explored. This review sought to explore the spaciotemporal position of vegetables in a suite of existing sustainable agricultural practices, explore regional variations and discover lessons that can guide the future of vegetable production. There are regional differences regarding sustainable production practices and the associated barriers to their adoption. Generally, sustainable agricultural practices with a societal history in a region tend to be successful, unlike when they are “new” innovations. The major barriers to sustainable agricultural practices in vegetable production are economy-related (total investment cost) and crop-related and are also related to the technology transmission approaches. Unfulfilled expectations and a lack of community participation in technology development are noted challenges, which have led to dis-adoption. A farmer-centered approach to technology promotion could help. Comparatively, southern Africa has the most challenges in the adoption of sustainable agricultural practices. From the lessons learned from other regions, agroecology in vegetable cultivation is not unachievable in Africa. The projected challenges mean that sustainable vegetable production is inevitable.
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The Status of Vegetables Research in Malawi, Capacity, Progress, Gaps, and Way Forward—A Scoping Review "jointly worked" Reviewed International coauthorship International journal
Dickson Mazibuko, Hiromu Okazawa, Hiroko Gono, Sarvesh Maskey
Agricultural Sciences 14 269 - 297 2023.02
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Scientific Research Publishing Inc.
Vegetables are key to nutrition and economic security, especially for developing societies. Research in vegetables has been historically key. From early domestication efforts to modern-day breeding and value addition, research has enabled vegetable productivity to support the nutritional and economic needs of societies. Impactful research, however, requires competent research capacity and a guiding framework, in a continuously changing socio-climatic world. Vegetable research appraisal in Malawi, especially regarding capacity, focus, and a guiding framework, is lacking. By using 5 search engines and 506 analyzed publications, this review sought to first examine the existing research capacity in Malawi and assess the vegetable research focus in terms of both value chain analysis themes and specific vegetable tax. This approach allowed for the isolation and flagging out of key emerging issues from existing research that positively contextualize future vegetable research direction in Malawi. It has been found that Malawi has adequate institutional and expertise capacity to further vegetable research. The identified challenges include local funding and infrastructural capacity to leverage donor funding. Three key emerging issues of climate change, modeling, and biofortification in vegetable crops have been identified. It is suggested that, with Malawi facing the climate change challenge, research focus in these areas, will enhance not only nutritional and economic security, but also overall climate change readiness. Key to climate change readiness is the involvement of indigenous vegetable production. As a package, vegetable cultivation can play a critical role in contributing to the achievement of pillar 1 of the Malawi vision 2063, which seeks to leverage agricultural productivity and commercialization with a focus on climate change resilience.
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Identification of potential locations for small hydropower plant based on resources time footprint: A case study in Dan River Basin, China "jointly worked" Reviewed International coauthorship International journal
Xiaoxun Huang, Kiichiro Hayashi, Minoru Fujii, Ferdinando Villa, Yuri Yamazaki, Hiromu Okazawa
Renewable Energy 205 293 - 304 2023.01
Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier
Small hydropower has attracted extensive interest as a clean technology. This study first identified possible sites of small hydropower plants with estimated capacity, and then utilized resources time footprint as a novel way to evaluate the impact of small hydropower plants on the aspects of materials, CO2, labor, and land. Resources time footprint is a sustainability indicator that uses a uniform time unit (years). It assesses whether the usage of resources exceeds the amount allocated to different people and generations. The smaller the value of resources time footprint, the more environmentally friendly is the process. Preferential locations for small hydropower in Dan River were specified, with a potential capacity ranging from 273 to 1175 kW. Resources time footprint of copper is 8.9–47.3 times as large as that of steel. Resources time footprint of CO2 emissions is much smaller than that of other aspects, revealing that small hydropower has a great potential to mitigate the greenhouse effect. The overall resources time footprint decreases with an increase in the installed capacity. The methodology proposed in this study can be used to identify the ideal locations for setting up small hydropower plants in other regions as well.
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Assessment of Three Automated Identification Methods for Ground Object Based on UAV Imagery "jointly worked" Reviewed International coauthorship International journal
Ke Zhang, Sarvesh Maskey, Hiromu Okazawa, Kiichiro Hayashi, Tamano Hayashi, Ayako Sekiyama, Sawahiko Shimada and Lameck Fiwa
Sustainability 14 ( 21 ) 2022.11
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI
This study compared three classification methods: A. NDVI threshold, B. RGB image-based machine learning, and C. object-based image analysis (OBIA). Method A was the least time-consuming and could identify vegetation and soil with high accuracy (user’s accuracy > 0.80), but had poor performance at classifying dead vegetation, plastic, and metal (user’s accuracy < 0.50). Both Methods B and C were time- and labor-consuming, but had very high accuracy in separating vegetation, soil, plastic, and metal (user’s accuracy ≥ 0.70 for all classes). Method B showed a good performance in identifying objects with bright colors, whereas Method C showed a high ability in separating objects with similar visual appearances. Scientifically, this study has verified the possibility of using the existing classification methods on identifying small ground objects with a size of less than 1 m, and has discussed the reasons for the different accuracy of the three methods. Practically, these results help users from different fields to choose an appropriate method that suits their target, so that different wastes or multiple resources can be monitored at the same time by combining different methods, which contributes to an improved integrated resource management system.
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Optimization of Ground Control Point Distribution for Unmanned Aerial Vehicle Photogrammetry for Inaccessible Fields "jointly worked" Reviewed International coauthorship International journal
Ke Zhang, Hiromu Okazawa, Kiichiro Hayashi, Tamano Hayashi, Lameck Fiwa and Sarvesh Maskey
Sustainability 14 ( 15 ) 1 - 21 2022.08
Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)
In this research, 88 GCP patterns have been validated and compared at an
18 ha farm. Results show that the patterns with GCPs distributed evenly around the field provided the best calibration (RMSE = 0.15 m). If this kind of pattern is not achievable because of obstructions, patterns with GCPs distributed evenly around half of the field or forming an evenly distributed triangle can provide moderate accuracy (RMSE = 0.18 m and 0.43 m, respectively). Patterns with GCPs forming a straight line yielded the worst accuracy (RMSE = 2.10 m). This shows that GCP distributions of a two-dimensional shape, even if the surrounding area is small, are better calibrated than a long, straight line. These results strongly suggest that appropriate GCP distribution patterns in the study areas will provide satisfactory accuracy for constructing integrated monitoring systems of diverse resources. -
A Comparative Evaluation of Lumped and Semi-Distributed Conceptual Hydrological Models: Does Model Complexity Enhance Hydrograph Prediction? "jointly worked" Reviewed International journal
Emmanuel Okiria, Hiromu Okazawa, Keigo Noda, Yukimitsu Kobayashi, Shinji Suzuki and Yuri Yamazaki
Hydrology 9 ( 5 ) 2022.05
Language：English Publishing type：Research paper (scientific journal) Publisher：MDPI
The prediction of hydrological phenomena using simpler hydrological models requires less computing power and input data compared to the more complex models. Ordinarily, a more complex, white-box model would be expected to have better predictive capabilities than a simple grey box or black-box model. But complexity may not necessarily translate to better prediction accuracy or might be unfeasible in data scarce areas or when computer power is limited. Therefore, the shift of hydrological science towards the more process-based models needs to be justified. To answer this, the paper compares 2 hydrological models: (a) the simpler tank model; and (b) the more complex TOPMODEL. More precisely, the difference in performance between tank model as a lumped model and the TOPMODEL concept as a semi-distributed model in Atari River catchment, in Eastern Uganda was conducted. The objectives were: (1) To calibrate tank model and TOPMODEL; (2) To validate tank model and TOPMODEL; and (3) To compare the performance of tank model and TOPMODEL. During calibration, both models exhibited equifinality, with many parameter sets equally likely to make acceptable hydrological simulations. In calibration, the tank model and TOPMODEL performances were close in terms of ‘Nash-Sutcliffe efficiency’ and ‘RMSE-observations standard deviation ratio’ indices. However, during the validation period, TOPMODEL performed much better than tank model. Owing to TOPMODEL’s better performance during model validation, it was judged to be better suited for making runoff forecasts in Atari River catchment.
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Plant Growth and Fruit Quality of Tomato (Solanum lycopersicum) Using Advanced Treated Water in Hydroponics "jointly worked" Reviewed International coauthorship International journal
Antonio Perez Fuentes, Kazuha Wakasugi, Sarvesh Maskey, Dickson M. Mazibuko, Takahiko Nakamura, Hiroyuki Oshima, Taku Kato, Ayako Sekiyama and Hiromu Okazawa
International Journal of Environmental and Rural Development 15 ( 2 ) 123 - 128 2024.12
Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Environmental Rehabilitation and Conservation (ERECON)
International Journal of Environmental and Rural Development
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A Multispecies Growth and Yield Performance Comparison of Vegetables Cultivated Under Hydroponics Using Sewage Wastewater "jointly worked" Reviewed International coauthorship International journal
Dickson Mgangathweni Mazibuko, Antonio Perez Fuentes, Kazuha Wakasugi, Sarvesh Maskey, Takahiko Nakamura and Hiromu Okazawa
International Journal of Environmental and Rural Development 15 ( 2 ) 167 - 173 2024.12
Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Environmental Rehabilitation and Conservation (ERECON)
Reusing sewage wastewater for vegetable cultivation is becoming a solution to sustainable water utilization, particularly in water-scarce regions. Using two types of sewage wastewater, Biologically Treated Water (BTW) and Chlorine Disinfected Water (CDW), and tap water, this study aimed at making a comparison of and understanding the yield performance and chlorophyll content in three vegetables, Phaseolus vulgaris (common beans), Brassica rapa var. perviridis (komatsuna), and Solanum lycopersicum (tomato), grown under hydroponics. The experiment was carried out in the hydroponics greenhouse within the Yokohama Wastewater Reclamation Center, between May 2023 and August 2023. We used a Nutrient Film Technique (NFT) hydroponic system supplied with BTW, CDW, and tap water. The three water types served as our treatments. The plants were grown to maturity at a controlled water temperature. In comparing vegetable yield, an ANOVA test demonstrated significant differences among the treatments for common beans, komatsuna, and tomatoes. The Post hoc test showed significantly higher chlorophyll content for common beans and tomatoes grown in tap water, compared to BTW and CDW. Regarding yield, common beans performed best in the tap water hydroponic system, while tomato and komatsuna performed best in the BTW and CDW hydroponic systems. Results indicate a vegetable differential preference for the three water types used. These three vegetables can thus be cultivated concurrently. Research on the safety of vegetables grown in sewage wastewater and the economic feasibility of using treated sewage wastewater for vegetable production is urged before upscaling this technology.
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Effects of LED Lighting and Media on Vitamin C and Phenol Content in Ethiopian Kale (Brassica carinata) Microgreens "jointly worked" Reviewed International coauthorship
Ruth Maru, John Wesonga, Dickson Mazibuko, Satoko Akiyama, Ayako Sekiyama, Shotaro Kawakami, Sarvesh Maskey, Agnes Kavoo, Johnstone Neondo and Hiromu Okazawa
International Journal of Environmental and Rural Development 15 ( 2 ) 151 - 156 2024.12
Authorship：Last author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Environmental Rehabilitation and Conservation (ERECON)
Microgreens are innovative vegetable products related to their novelty and healthpromoting benefits. However, growth media and light conditions affect microgreens' nutritional content, which may limit their production in rural community settings. Brassica carinata is an essential local Kenyan vegetable, but its production and full utilization are limited by its early maturity. The potential of using B. carinata as a microgreen would be an excellent alternative production technique to minimize its early maturity limitation. This study investigated the influence of white and blue light on Vitamin C and phenol content in B. carinata microgreens grown using sand and cocopeat. B. carinata microgreens were grown for 14 days in a growth chamber using plastic punnet containers filled with cocopeat and sand under white and blue light. The capillary wick watering technique was used for irrigation. Temperature and relative humidity were monitored and maintained at 26°C± 2, and 60%, respectively. The photoperiod and intensity of light were also maintained at 12 hr Ⓒ ISERD 151 and 160 ± 2.5 µmol m−2s−1) respectively. After 14 days, microgreens were harvested and freeze-dried to analyze Vitamin C and phenol content. And. Data was subjected to ANOVA and was separated by Tukey’s multiple comparison test. Results indicated that light had no significant effect on B. carinata microgreens phenol content. However, microgreens grown in locally available sand showed statistically higher amounts of phenol content than those grown using cocopeat. For vitamin C content, media and light had no significant effect. Our results show that sand medium can be used equally to produce microgreens with higher phenol content for Brassica carinata.
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Development Challenges and Directions of Climate Change Measures in Paddy Agriculture in Southeast Asia Reviewed International journal
Hiromichi Kitada, Maskey Sarvesh, Taro Izumi, Hiromu Okazawa
International Journal of Environmental and Rural Development 15 ( 2 ) 143 - 150 2024.12
Authorship：Last author Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Environmental Rehabilitation and Conservation (ERECON)
Institute of Environmental Rehabilitation and Conservation (ERECON)
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Evaluation of Soil Micronutrients Across Selected Land Use Types in Chembe Enclave Village, Lake Malawi National Park "jointly worked" Reviewed International coauthorship International journal
Placid Mpeketula, Dickson M. Mazibuko, Hiroko Gono, Lameck Fiwa, Sarvesh Maskey and Hiromu Okazawa
International Journal of Environmental and Rural Development 15 ( 2 ) 136 - 142 2024.12
Authorship：Last author, Corresponding author Language：English Publishing type：Research paper (scientific journal)
Knowledge and management of soil micronutrients are vital for maximizing crop production, ecosystem health, functionality, and sustainability. This is especially relevant for the soils of Chembe enclave village, located within Lake Malawi National Park (LMNP), a world heritage site. This study obtained micronutrient baseline data for soils across various land use types and provides benchmark data for long-term monitoring and management. Local soil was measured for the concentration of a panel of micronutrients using Atomic Absorption Spectrometry (AAS) after acid block digestion with a mixture of concentrated nitric acid (70% HNO3) and Hydrogen peroxide (30% H2O2). Measured micronutrients included zinc (Zn), manganese (Mn), copper (Cu), iron (Fe), and selenium (Se). Soil samples were obtained from five different land use types, including community gardens, farmland, Dambo, bare land, and forest land at depths of 0-5 cm and 5 -20 cm. Results indicated that land use type and soil depth are essential factors impacting micronutrient concentrations. Mean soil Zn and Mn concentrations were significantly higher in the community garden (1.51 and 663 mg/kg, respectively) in the topsoil compared to the rest of the land use types (p<0.0001). On the other hand, topsoil from the forest had significantly higher levels of Cu and Fe (3.7 and 329 mg/kg respectively). The maize farmland had the highest concentrations of Se (0.28 mg/kg), while the Dambo and the community garden had the lowest levels (0.01 mg/ kg). These findings suggest that micronutrient levels are tightly linked to land use type and soil depth. Further research should investigate the impacts of micronutrient levels and changes on crop productivity and broader ecosystem-wide implications at multiple scales from the enclave village, across LMNP, and the region as a whole.
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A method to statistically and correctly determine environmental noise and target noise in EIA: Proposal to an adoption statistical probability assessment
UCHIDA Hideo, OKAZAWA Hiromu
Impact Assessment 22 ( 2 ) 32 - 38 2024.08
Language：Japanese Publisher：Japan Society for Impact Assessment
<p>The research examined the reliability of environmental noise (EN) data by varying the measurement period of EN from 1, 3, 5, to 7 days. EN data were collected at four sites in urban and rural areas at 10-minute intervals for more than one year. Using these data, the mean and standard deviation of the EN for different measurement periods were calculated at each site. The probability that the EN would be erroneously judged to have "not increased in noise level" was calculated from the EN determination if a steady noise or a 3 dB louder noise with a 1 dB variation was added to the EN. As a result, it clarifies that in locations where the standard deviation is large, not only should the number of days of measurement be increased, but also measures should be taken to avoid misjudgments depending on the measurement timing.</p>
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Crop Growth Model for Hydroponic Cultivation of <i>Solanum lycopersicum </i>(Tomato) in a Semi-automated System
PEREZ-FUENTES ANTONIO, MASKEY SARVESH, MAZIBUKO DICKSON M., OKAZAWA HIROMU, NAKAMURA TAKAHIKO, SEKIYAMA AYAKO
International Journal of Environmental and Rural Development 15 ( 1 ) 35 - 40 2024
Language：English Publisher：Institute of Environmental Rehabilitation and Conservation, Research Center
<p>Hydroponics can be integrated into Controlled Environment Agriculture (CEA), in combination with greenhouses. They can successfully optimize the use of fertilizers and water for arid zones. Elevated costs of this type of agriculture lead farmers to implement semiautomated systems and use recyclable materials to stabilize plant productivity. This paper discusses the different growth ratios of tomato plants estimated with logistic curves when tap water with fertilizer (T1), Oxidixed Water-OW [reclaimed water] (T2), and Disinfected Tertiary Recycled Water- DTRW [renewable water] (T3) are used; additionally, a new module is presented to avoid underestimation of plant height when fertilization is carried out at the flowering stage. This model was adapted only for treatment 1. Logistic curves were created with low RMSE values using the least-square method. Despite presenting better mass volume and fruit quantity in OW [reclaimed water] treatment at the final stage of the plant, a t-test revealed that there is not a significant difference among treatments of OW and DTRW [renewable and reclaimed water] for the height of plants. The adjustment of a logistic equation with the inclusion of a linear module allowed to decrease in the RMSE from 73 to 21 mm.</p>
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Evaluation of the Effect of Alternate Wetting and Drying Irrigation on the Growth of Paddy Rice Plant Height Using a Logistic Model "jointly worked" Reviewed International coauthorship International journal
Kiseki Kurashina, Sarvesh Maskey, Dickson M. Mazibuko and Hiromu Okazawa
International Journal of Environmental and Rural Development 14 ( 2 ) 20 - 26 2023.12
Authorship：Last author, Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Institute of Environmental Rehabilitation and Conservation (ERECON)
Climate change poses a challenge to irrigation water supply, especially in the case of the continuous flood irrigation method (CF). Alternate wetting and drying irrigation (AWD) is a method of rice cultivation widely used as a mitigation measure for water consumption, without reducing yields. To better promote AWD in areas where water scarcity occurs in the future, it is necessary to quantify the impact of AWD on growth. The objective of this study was to evaluate the impact of AWD on rice growth under AWD irrigation using logistic curves. Subsequent analysis demonstrated that by using AWD, irrigation capacity was reduced by approximately 19%. Additionally, multiple regression analysis indicated that temperature, sunshine hours, and relative humidity had significant effects on plant growth. A growth model (RMSE = 2.98 cm to 3.82 cm) was generated by applying a logistic curve where the daily mean integrated values of meteorological data as explanatory variables and plant growth as the objective variable. Using the model, it was found that AWD increased the growth rate of the rice plant; however, rice plant growth in the initial period was lower compared to CF.