HIROOKA Yoshihiro

Department of Agricultural ScienceAssociate Professor

Last Updated :2024/06/18

■Researcher comments

List of press-related appearances


■Researcher basic information

Researcher number




Research Keyword

  • crop science   成長解析   非破壊計測   作物栽培   

Research Field

  • Environmental science/Agricultural science / Crop production science



  • 2023/04 - Today  Kindai UniversityFaculty of Agriculture准教授
  • 2019/04 - 2023/03  Kindai UniversityFaculty of AgricultureLecturer
  • 2016/04 - 2019/03  Kindai UniversityFaculty of AgricultureAssistant professor
  • 2013/04 - 2016/03  日本学術振興会特別研究員(DC1)

Educational Background

  • 2011/04 - 2016/03  京都大学大学院  農学研究科  農学専攻
  • 2007/04 - 2011/03  Kyoto University  Faculty of Agriculture  Faculty of Agriculture

■Research activity information


  • 2024 日本作物学会論文賞
     Temperature tolerance threshold and mechanism of oxidative damage in the leaf of Coffea arabica ‘Typica’ under heat stress 
    受賞者: Koji Yamane;Moena Nishikawa;Yoshihiro Hirooka;Kazuya Iwai;Morio Iijima
  • 2021 第25回 日本作物学会研究奨励賞


  • Yoshihiro Hirooka; Maho Motomura; Morio Iijima
    Plant Production Science Informa UK Limited 27 (2) 47 - 55 1343-943X 2024/04 [Refereed]
  • Koji Yamane; Miki Mariyama; Yoshihiro Hirooka; Morio Iijima
    Journal of Integrative Agriculture Elsevier BV 22 (4) 1035 - 1044 2095-3119 2023 [Refereed]
  • Yoshikatsu Ueda; Yasuhiro Izumi; Yoshihiro Hirooka; Yoshinori Watanabe; Morio Iijima
    Water Supply IWA Publishing 22 (11) 7972 - 7981 1606-9749 2022/11 [Refereed]
    Abstract The flotation method of ultra-fine bubbles (UFB) aims to address pollution and has been used for combating the undesirable water conditions of contaminated soils. Hence, water containing UFB is gaining increasing attention for potential agricultural applications. Although certain hypotheses have been proposed, such as the collection of ions in water through the electrical characteristic of UFB, no clear experimental data have been provided. We found that improvement in turbidity may cause the adsorption of fine soil particles in the water by the UFB, thereby improving the quality of the water. The data from the paddy field showed that a decrease in turbidity (below 2 nephelometric turbidity units) occurred over a short period of time (3 days). UFB concentration is directly related to turbidity with a coefficient of determination of 0.93. This phenomenon was also observed through the distribution of bubbles and soil particles, where the average particle size increased because of the aggregation of soil particles and the decrease in turbidity in the paddy field, indicating that UFB collect soil particles and thereby improve water quality. Therefore, UFB are highly effective in cleaning rice field water and will be a preferred method for purifying the environment in the future.
  • Yoshihiro Hirooka; Shintaro Kurashige; Koji Yamane; Misako Kakiuchi; Daisuke Ishikawa; Taku Miyagawa; Kazuya Iwai; Morio Iijima
    Weed Technology Cambridge University Press (CUP) 36 (5) 692 - 699 0890-037X 2022/10 [Refereed]
    Abstract The extensive and intensive use of herbicides has resulted in the spread of herbicide-resistant weeds in many crop production systems; therefore, it is imperative to devise new organic weed control methods. Recently, the application of spent coffee grounds (SCG) in agricultural fields has been found to inhibit plant growth and germination and is thus considered a potentially effective weed control measure. This study aimed to evaluate the effects of different amounts and methods of SCG application on weed growth through field experiments. The field experiments were conducted in an upland field converted from a paddy in western Japan. The results show that the plow-in application of over 10 kg m−2 of SCG and mulching application of 20 kg m−2 decreased the weed dry weight compared with the control. In addition, the growth of weed species of families other than Gramineae, such as wingleaf primrose-willow and horseweed, was not significantly affected by SCG application. Weed species of families other than Gramineae are dominant in some upland fields. Hence, the inhibitory effect of SCG on weeds may be lower in original upland fields than in the upland field converted from paddy field that was investigated in the present study. Overall, this study demonstrated that the plow-in application of 10 kg m−2 of SCG every 4 mo was effective for weed control in an upland field converted from a paddy field. Because SCG worked against grass weeds under the specific conditions in this study, it would be valuable to explore other potential applications of this novel means of weed control.
  • Rongling Ye; Taisuke Kodo; Yoshihiro Hirooka; Hor Sanara; Kim Soben; Satoru Kobayashi; Koki Homma
    Sustainability MDPI AG 14 (16) 10007  2022/08 [Refereed]
    Improving agricultural research and education is highly recommended to control agricultural development and environmental sustainability in Cambodia. Agricultural research mostly focuses on interviews with farmers as a first measure in developing countries, but a lack of quantitative accuracy remains one of the major constraints. In this situation, we conducted educational activities for master’s degree students of the Royal University of Agriculture (RUA) to append agronomic information with popular equipment in interdisciplinary fieldwork in Pursat Province, Cambodia. For the popular equipment, an RGB camera, a reflectometer as well as pH and EC meters were selected. The agronomic information collected by the students supported the results obtained during the interviews. For example, the difference in fertilizer application between the irrigated and nonirrigated areas was confirmed by the soil ammonium concentration evaluated with a reflectometer; the difference in rice growth among water conditions was confirmed by the leaf area percentage evaluated with an RGB camera. Since the majority of the students lacked agricultural and statistical knowledge, the agronomic information quantified by popular equipment provided proper educational materials. The interdisciplinary fieldwork also indicated serious problems in the study area, such as low beneficial crop production and environmental sustainability. To overcome these problems, improving agricultural education is required to foster skillful agricultural professionals, and the quantification of agronomic information is an essential issue.
  • Yoshihiro Hirooka; Shintaro Kurashige; Koji Yamane; Yoshinori Watanabe; Misako Kakiuchi; Daisuke Ishikawa; Taku Miyagawa; Kazuya Iwai; Morio Iijima
    Plant Production Science Informa UK Limited 25 (2) 148 - 156 1343-943X 2022/04 [Refereed]
  • Morio Iijima; Kaito Yamashita; Yoshihiro Hirooka; Yoshikatsu Ueda; Koji Yamane; Chikashi Kamimura
    Plant Production Science Informa UK Limited 25 (1) 78 - 83 1343-943X 2022/03 [Refereed]
  • Yuki Makino; Yoshihiro Hirooka; Koki Homma; Rintaro Kondo; Tian-Sheng Liu; Liang Tang; Tetsuya Nakazaki; Zheng-Jin Xu; Tatsuhiko Shiraiwa
    Plant Production Science Informa UK Limited 25 (1) 1 - 10 1343-943X 2022/03 [Refereed]
    Increasing the yield potential of rice (Oryza sativa) is the main objective of breeders and cultivators engaged in rice improvement programs. Erect panicle (EP) rice is generally high-yielding with panicles that remain non-curved until maturation. The aim of our study was to evaluate the association of agronomic traits with rice productivity in EP rice. Here, we used the recombinant inbred lines (RILs), crosses between Liaojing5 (erect panicle japonica type) and Wanlun422 (high-yielding indica type). The yield varied among the RILs, and the flag leaf length of EP RILs was negatively correlated with the yield; however, the correlation was not significant in the non-EP RILs. The flag leaf length of the EP RILs was also negatively correlated with biomass increase during the late ripening stage. This may reflect the canopy structure of the EP RILs with short flag leaves which had a larger leaf area index in the lower strata. Additionally, the chlorophyll content in the lower leaf significantly differed among the EP RILs with flag leaves of different lengths, resulting in a higher photosynthetic ability of the lower leaf of EP RILs with short flag leaves. In the present study, an EP line, which has the shortest flag leaf, showed a higher yield than Wanlun422 in both years. EP RILs with short flag leaves might show a higher canopy photosynthetic rate in the later ripening stage; therefore, this trait could be a potential phenotypic marker for achieving high yield of EP rice.
  • Temperature tolerance threshold and mechanism of oxidative damage in the leaf of coffea arabica ‘Typica’ under heat stress
    Koji Yamane; Moena Nishikawa; Yoshihiro Hirooka; Yusakui Narita; Tsukasa Kobayashi; Misako Kakiuchi; Kazuya Iwai; Morio Iijima
    Plant Production Science 25 (3) 337 - 349 2022 [Refereed]
  • Morio Iijima; Kaito Yamashita; Yoshihiro Hirooka; Yoshikatsu Ueda; Koji Yamane; Chikashi Kamimura
    Plant Production Science Informa UK Limited 25 (2) 218 - 223 1343-943X 2022 [Refereed]
  • Morio Iijima; Yoshihiro Hirooka; Yoshimasa Kawato; Hitoshi Shimamoto; Koji Yamane; Yoshinori Watanabe
    Plant Production Science Informa UK Limited 25 (2) 211 - 217 1343-943X 2022 [Refereed]
  • Yoshihiro Hirooka; Simon K. Awala; Kudakwashe Hove; Pamwenafye I. Nanhapo; Morio Iijima
    Agronomy MDPI AG 11 (9) 1767 - 1767 2021/08 [Refereed]
    The production of pearl millet (Pennisetum glaucum (L.) R.Br.) is important in Namibia, in sub-Saharan Africa, owing to the prevailing low precipitation conditions. Most fields supporting crop production in northern Namibia are located in a network of seasonal wetlands. The aim of the present study was to evaluate the effects of ridging and fertilizer application on the yield and the growth of pearl millet in the seasonal wetlands under different rainfall conditions. The study was conducted for two years (2017–2018) in the experimental fields in northern Namibia, and yield, yield components, and growth parameters were evaluated in relation to the application of different fertilizers (manure and mineral) with and without ridge-furrows. Manure fertilizer application presented the highest yield in 2018, whereas mineral fertilizer application showed the highest yield in 2017. The proportion of rainfall was the highest during the mid-growth period in 2017, and the reproductive stage in 2018. Thus, pearl millet plants under manure fertilization overcame damage resulting from waterlogging stress during the seed setting stage by improving the soil and plant nutrient conditions. In contrast, the plants under mineral fertilization were more tolerant to large amounts of rain during the mid-growth period. In this study, yield was mainly determined by total dry weight, and it was closely related to panicle density in both years. Therefore, we concluded that fertilizer application, including additional fertilizer based on the growth diagnostic, could be important for improving crop production in seasonal wetlands.
  • Yoshihiro Hirooka; Koki Homma; Tatsuhiko Shiraiwa
    Agronomy Journal Wiley 113 (5) 3922 - 3934 0002-1962 2021/07 [Refereed]
  • Yoshihiro Hirooka; Tadayoshi Masuda; Yoshinori Watanabe; Yasuhiro Izumi; Hiroyuki Inai; Simon Awala; Morio Iijima
    Agrekon Informa UK Limited 60 (2) 145 - 156 0303-1853 2021/05 [Refereed]
  • Growth and Productivity Assessment of Short-Duration Rice (Oryza sativa L. and Upland NERICA) Genotypes in Semiarid North-Central Namibia
    Simon Awala; Hove, K; Shivute, V; Valombola, J.S; Pamwe Nanhapo; Yoshihiro Hirooka; Osmund Mwandemele; Morio Iijima
    Advances in Agriculture 2021 (6676081) 2021/03 [Refereed]
  • Morio Iijima; Koji Yamane; Yoshihiro Hirooka; Kaede Wada; Yasuhisa Okada; Miki Mariyama; Yoshinori Watanabe
    Plant Production Science Informa UK Limited 23 (2) 220 - 225 1343-943X 2020 [Refereed]
  • Morio Iijima; Kaito Yamashita; Yoshihiro Hirooka; Yoshikatsu Ueda; Koji Yamane; Chikashi Kamimura
    Plant Production Science Informa UK Limited 23 (3) 366 - 373 1343-943X 2020 [Refereed]
  • Yoshihiro Hirooka; Koji Shoji; Yoshinori Watanabe; Yasuhiro Izumi; Simon Awala; Morio Iijima
    Soil & Tillage Research Elsevier {BV} 195 104429 - 104429 0167-1987 2019/12 [Refereed]
  • Tsujimoto K; Ohta T; Hirooka Y; Homma K
    Paddy and Water Environment Springer Science and Business Media {LLC} 17 (2) 83 - 90 1611-2490 2019 [Refereed]
  • Yoshihiro Hirooka; Koki Homma; Tatsuhiko Shiraiwa
    Scientific Reports Nature Publishing Group 8 (1) 6387  2045-2322 2018/12 [Refereed]
    Monitoring the vertical distribution of leaf area index (LAI) is an effective method for evaluating canopy photosynthesis and biomass productivity. In this study, we proposed a novel method to characterize LAI vertical distribution non-destructively by utilizing LAI-2200 plant canopy analyzer, followed by the application of statistical moment equations. Field experiments were conducted with 5 rice cultivars under 2 fertilizer treatments in 2013 and with 3 rice cultivars under 3 plant density treatments in 2014. LAI readings obtained by a plant canopy analyzer for non-destructive stratified measurements were relatively consistent with LAI estimations using the stratified clipping method for every cultivar and treatment. The parameters calculated using the statistical moment equations numerically showed the changes in LAI vertical distribution with plant growth up to the heading stage. The differences in the parameters also quantified the effect of cultivar, fertilizer, and plant density treatments. These results suggest that the non-destructive stratified measurements and the statistical moments evaluated in this study provide quantitative, reliable information on the dynamics of LAI vertical distribution. The method is expected to be utilized by researchers in various research fields sharing common interests.
  • Yoshihiro Hirooka; Koki Homma; Tatsuhiko Shiraiwa; Yuki Makino; Tian-sheng Liu; Zhengjin Xu; Liang Tang
    Plant Production Science Taylor and Francis Ltd. 21 (1) 1 - 7 1349-1008 2018/01 [Refereed]
    Erect panicle rice cultivars utilize solar energy effectively and have improved ecological growing conditions. Among such cultivars, Shennong265 has been grown successfully throughout Northern China. Nevertheless, no studies have yet examined the relationships between crop dry matter productivity, weather conditions, and nitrogen uptake of the erect panicle type rice cultivar in Japan. The objective of our study was to evaluate the productivity of erect panicle rice Shennong265 in Western Japan under varied conditions. Three rice cultivars, Shennong265, Nipponbare, and Takanari were grown in the field under different fertilizer and plant density conditions in Western Japan using this information, we compared yield and growth characteristics of Shennong265 with those of Nipponbare and Takanari. Although Shennong265 had radiation use efficiency similar to that of the high yielding cultivar (Takanari) and much higher leaf nitrogen content than Takanari and Nipponbare, the average grain yield of Shennong265 grown under normal fertilizer and plant density conditions was approximately 6.9 t ha−1 as against 6.2 t ha−1 for Nipponbare and 9.6 t ha−1 for Takanari. These results suggest that, while Shennong265 has a high yield potential, the environmental conditions including climate, fertilizer, and planting period provided in this study were not suitable for achieving its maximum yield. The reduced performance of Shennong265 may be caused by insufficient fertilizer after heading and by shorter growth periods, as well as by the climate of Western Japan. Additional fertilizer application during the heading stage and earlier transplanting may be needed to obtain higher Shennong265 yields in Western Japan.
  • Morio Iijima; Yoshihiro Hirooka; Yoshimasa Kawato; Yoshinori Watanabe; Kaede C. Wada; Nodoka Shinohara; Pamwenafye I. Nanhapo; Maliata A. Wanga; Koji Yamane
    Plant Production Science TAYLOR & FRANCIS LTD 20 (4) 434 - 440 1343-943X 2017 [Refereed]
    Mixed cropping is a cultivation method widely practiced in tropical regions. The newly developed close mixed planting technique mitigates the flood stress of drought-adapted upland cereal species by co-growing rice (Oryza sativa) plants under field flood conditions. We tested the hypothesis that O-2 was transferred from rice to upland crops using the model system of hydroponic culture. To confirm the hypothesis, the phenomena of O-2 absorption and release by plants were evaluated in a water culture condition without soil. Experiments were conducted in a climate chamber to estimate the amount of O-2 released from the roots of rice and pearl millet (Pennisetum glaucum) under both O-2 rich (20.0 +/- .0% conc. in phase I) and O-2-free dark (.8 +/- .0% conc. in phase II) conditions. The total O-2 change (between the two phases) in a single planting of rice and pearl millet was significantly higher than that of the mixed planting of rice and pearl millet, which indicated that O-2 was transferred from rice to pearl millet under a water culture condition. The result indicated that approximately 7 +/-mu M O-2 g fresh root weight(-1) h(-1) was transferred between the two plant species. O 2 transfer was confirmed between the two plant species in a mix cultured in water, implying its contribution to the phenomenon that improved the physiological status of drought-adapted upland crops under field flood conditions.
  • Tang Liang; Gao Hong; Hirooka Yoshihiro; Homma Koki; Nakazaki Tetsuya; Liu Tian-sheng; Shiraiwa Tatsuhiko; Xu Zheng-jin
    Journal of Integrative Agriculture ELSEVIER SCI LTD 16 (7) 1467 - 1473 2095-3119 2017 [Refereed]
    The erect panicle (Ep) type is an important characteristic for japonica super rice in Northeast China and plays a significant role in enhancing yield. The Ep type is considered to be a genetic ideotype resource to the japonica super rice group by virtue of its agronomic advantages such as grain number per panicle and biomass. This study addresses the effects of nitrogen and planting density conditions on yielding performance regarding panicle type (PT) using the recombinant inbred line (RIL) population derived from the cross between an Ep variety Liaogeng 5 and non-Ep variety Wanlun 422. The genetics underlying the Ep type proved to be robust not only for panicle-type optimization but also plant height, panicle length, flag leaf length and seed density. We also found that regardless of nitrogen and density, correlation between harvest index (HI) and plant height was not significant in Ep type whatever the nitrogen and density. The application of Ep type provides a potential strategy for yield improvement by increasing biomass through HI maintainable in rice.
  • Masayasu Maki; Kosuke Sekiguchi; Koki Homma; Yoshihiro Hirooka; Kazuo Oki
    Journal of Agricultural Meteorology SOC AGRICULTURAL METEOROLOGY JAPAN 73 (1) 2 - 8 0021-8588 2017/01 [Refereed]
    Food security has become a serious concern recently in Southeast Asia. The reduction of agricultural land because of economic development is decreasing the food supply. Simultaneously, due to rapid population growth, the food demand is increasing. Therefore, to ensure a stable food supply, it is important to estimate the supply capability of rice, which is the staple food in most Asian countries. In this study, a crop model (SIMRIW-RS) that can combine remote sensing data with a crop model (SIMRIW) was used to estimate rice yield at a regional scale. This model was applied to the estimation of rice yield in paddy fields located in the suburbs of Vientiane, Laos. Satellite (COSMO-SkyMed) -derived data for leaf area index (LAI) were integrated into SIMRIW-RS, and the transplanting date detected by COSMO-SkyMed was used to set the starting date of the simulation. Results were verified by surveying farmers. Transplanting dates were detected with high accuracy in all but a few fields. On the basis of the results of regression analysis between actual LAIs and the corresponding backscatter coefficients of COSMO-SkyMed, we suggest that COSMO-SkyMed can estimate LAIs at early growth stages when LAI is small. The results of yield estimation after integrating the LAIs derived from COSMO-SkyMed data into SIMRIW-RS indicated that the estimation accuracy of the rice yield was improved compared with the estimation result without adjusting parameters in the model, and this held so long as LAI was retrieved with high accuracy by satellite data. However, when LAI could not be estimated accurately, integration has the potential to worsen the model's accuracy compared with the estimation result without any such readjustment. This study therefore indicates that SIMRIW-RS has the potential to estimate rice yield accurately when the LAI of rice is estimated with high accuracy from satellite data.
  • Koki Homma; Masayasu Maki; Yoshihiro Hirooka
    Journal of Agricultural Meteorology SOC AGRICULTURAL METEOROLOGY JAPAN 73 (1) 9 - 15 0021-8588 2017/01 [Refereed]
    To evaluate rice production and management on a regional scale, a simulation model combined with remote-sensing is recommended. This study aimed to develop a simulation model for use with remote-sensing (SIMRIW-RS) to evaluate the field-to-field variation in rice production on a regional scale. This model was developed based on a simulation model for rice weather relations called SIMRIW and its derived models. The model consists of 6 components (water budget, nitrogen uptake, phenological development, leaf area index (LAI) growth, dry matter production and yield formation) and has 2 representative field parameters and 5 representative cultivar parameters. The parameters that were determined with the data from previous field studies seemed to be reflected with field and cultivar characteristics, and differences in the rice growth and production among the fields and cultivars were well explained by the model. The application of the model on a regional scale using remote sensing is discussed.
  • Yoshihiro Hirooka; Koki Homma; Masayasu Maki; Kosuke Sekiguchi; Tatsuhiko Shiraiwa; Koshi Yoshida
    Journal of Agricultural Meteorology SOC AGRICULTURAL METEOROLOGY JAPAN 73 (1) 16 - 21 0021-8588 2017/01 [Refereed]
    Rice is the most important crop in Lao People's Democratic Republic (Lao PDR). The improvement of its productivity is strongly recommended, but information about its growth characteristics in farmers' fields is limited. This study evaluated the dynamics of the leaf area index (LAI) and analyzed the relationship between the rice productivity and soil in farmers' fields in Vientiane province, Lao PDR. Because the LAI in the farmers' fields increased almost linearly, a straight-line regression was used for the analysis. The rice yield in the farmers' fields ranged from 63.8 g m(-2) to 411.8 g m(-2) and correlated with the LAI during the later growth stage. The variability in the LAI was explained by the LAI growth rate but rarely by the effective accumulated temperatures from the estimated transplanting date. The LAI growth rate was associated with the nitrogen and carbon content in the soil. These results suggest that the rice productivity in farmers' fields is governed by the soil fertility through LAI growth, and that LAI monitoring is an effective tool to evaluate the production.
  • Yoshihiro Hirooka; Koki Homma; Taisuke Kodo; Tatsuhiko Shiraiwa; Kim Soben; Mithona Chann; Kumiko Tsujimoto; Katsunori Tamagawa; Toshio Koike
    FIELD CROPS RESEARCH ELSEVIER SCIENCE BV 199 150 - 155 0378-4290 2016/12 [Refereed]
    Rice is by far the most important crop in Cambodia. The improvement of its productivity is strongly recommended, but information about cultivation environment, management and their effects on rice production in farmers' paddy fields is quite limited. This study periodically measured the leaf area index (LAI) by using a plant canopy analyzer and conducted yield, water, soil and management investigations in 77 farmers' paddy fields in the Bakan district, Pursat province, Cambodia in 2014. Because the LAI showed linear growth in almost all farmers' fields, the LAI growth rate was determined by linear regression. The grain yield ranged from 70.8 gm(-2) to 499.0 gm(-2) and was positively correlated with the maximum LAI. The variability in the maximum LAI was mainly explained by the LAI growth rate, while the growth period had a significant correlation with the maximum LAI only in the broadcast fields, where earlier planting led to larger LAI. The result of the ANCOVA shows that the LAI growth rate was affected by seeding date, water status and soil condition (C content and C/N ratio) while the effect of planting method (transplanting/broadcasting) and N fertilizer was non-significant. The non-significance of effect of N fertilizer may imply the timing or method of application is improper. The results suggest that the key means to improve rice productivity are effective application of fertilizer and selection of planting methods dependent on the soil fertility, together with water-saving irrigation method. (C) 2016 Elsevier B.V. All rights reserved.
  • Yoshihiro Hirooka; Koki Homma; Tatsuhiko Shiraiwa; Mitsuo Kuwada
    Field Crops Research ELSEVIER SCIENCE BV 186 117 - 123 0378-4290 2016/02 [Refereed]
    Monitoring leaf growth is a useful method for evaluating crop growth. In this study, frequent measurements of the rice canopy were conducted with a plant canopy analyzer, and parameters were estimated by applying several equations to evaluate leaf growth. The applicability of this evaluation method is discussed based on the statistical analysis of parameters. Experiments were conducted for 6 rice cultivars under 5 treatments in 2 years. Parameters describing the dynamics of leaf growth were obtained by applying 4 mathematical growth models in which the independent variable was the effective accumulated temperature. The parameters numerically represented the dynamics of leaf growth in each cultivar and treatment. In particular, maximum LAI and interception growth rates (MLGR and MIGR) which were obtained by applying logistic function to leaf area index (LAI) and diffuse non -light intercepted (DIFN), respectively, showed no interaction between the cultivar and environment. The lack of interaction may indicate that these parameters typically characterize cultivar and growth environments. The differences in the parameters could also be used to quantify the effect of basal fertilizer application on leaf growth enhancement and that of additional fertilizer on the extension of this enhancement. These results suggest that the applied method for parameterizing leaf growth based on frequent measurements with a canopy analyzer is suitable for evaluating the effects of genotype, management and the environment because it facilitates measurements in many plots. (C) 2015 Elsevier B.V. All rights reserved.
  • Chihiro Urairi; Yu Tanaka; Yoshihiro Hirooka; Koki Homma; Zhengjin Xu; Tatsuhiko Shiraiwa
    Plant Production Science TAYLOR & FRANCIS LTD 19 (3) 420 - 426 1343-943X 2016 [Refereed]
    Increasing the yield of rice per unit area is important because of the demand from the growing human population in Asia. A group of varieties called erect panicle-type rice (EP) achieves very high yields under conditions of high nitrogen availability. Little is known, however, regarding the leaf photosynthetic capacity of EP, which may be one of the physiological causes of high yield. We analyzed the factors contributing to leaf photosynthetic rate (P-n) and leaf mesophyll anatomy of Nipponbare, Takanari, and Shennong265 (a EP type rice cultivar) varieties subjected to different nitrogen treatments. In the field experiment, P-n of Shennong265 was 33.8 mu mol m(-2) s(-1) in the high-N treatment, and was higher than that of the other two cultivars because of its high leaf nitrogen content (LNC) and a large number of mesophyll cells between the small vascular bundles per unit length. In Takanari, the relatively high value of P-n (31.5 mu mol m(-2) s(-1)) was caused by the high stomatal conductance (g s;.72 mol m(-2) s(-1)) in the high-N treatment. In the pot experiment, the ratio of P-n/C-i to LNC, which may reflect mesophyll conductance (g(m)), was 20-30% higher in Nipponbare than in Takanari or Shennong265 in the high N availability treatment. The photosynthetic performance of Shennong265 might be improved by introducing the greater ratio of P-n/C-i to LNC found in Nipponbare and greater stomatal conductance found in Takanari.
  • Yoshihiro Hirooka; Koki Homma; Masayasu Maki; Kosuke Sekiguchi
    Field Crops Research ELSEVIER SCIENCE BV 176 119 - 122 0378-4290 2015/05 [Refereed]
    Rice is the most important crop in Lao People's Democratic Republic (Lao PDR). Synthetic aperture radar (SAR) is proposed as a more suitable method to evaluate rice growth in this area because it is independent from cloud and solar illumination. This study analyzed the relationship between the back scattering coefficient (BSC) in SAR images and leaf area index (LAI) of rice. Here, we discuss the applicability of SAR to estimate LAI and its growth rate in farmers' fields in Lao PDR. 30 farmers' paddy fields were selected for surveying throughout the growth period in the wet season of 2013, and both LAI and normalized difference vegetation index (NDVI) were measured at 4 time periods before the heading period for each field. X-band SAR images from the COSMO-SkyMed system (SAR) were used in this study. BSC was significantly correlated with LAI and NDVI. BSC at 28 of 30 fields was positively correlated with days after transplanting (DAT), and 10 of these results were significant. The increased rate in BSC obtained at the fields where BSC and DAT had a significant correlation, were significantly correlated with that in LAI. This finding suggests that if SAR images demonstrate significant increases of BSC against DAT, the increased rate may also represent LAI growth rate, although uncontrollable water levels and weeds occasionally interrupt observation. This study demonstrates the capacity of SAR to evaluate rice production in developing countries. (C) 2015 Elsevier B.V. All rights reserved.
  • Hirooka, Y; Irie, T; Homma, K; Shiraiwa, T; Toriumi, A
    Journal of Crop Research The Society of Crop Science and Breeding in Kinki, Japan 58 51 - 56 1882-885X 2013 [Refereed]
    Leaf dynamics is one of the important characteristics in rice (Oryza sativa L.) because it determines dry matter productivity. Nevertheless, few studies have evaluated the genotypic variation in leaf dynamics. This study conducted one-week-interval nondestructive measurements by using plant canopy analyzer, and parameterized leaf dynamics for a rice diversity research set of germplasm (RDRS) and high yielding varieties. Three year experiment in Kyoto University showed large genotypic variations in 5 indexes of leaf dynamics, which consisted of 4 parameters from the nondestructive measurements (relative growth rate of LAI, the maximum growth rate of light interception, days to 80% coverage and extinction coefficient) and LAI at heading from destructive measurement. The significant differences among genotypic groups were observed in relative growth rate of LAI, the maximum growth rate of light interception, days to 80% coverage. High-yielding varieties released by IRRI had higher values of the maximum growth rate of light interception, suggesting that the varieties have been improved in terms of canopy development. In contrast, since Takanari and Milyang23 didn't have extreme characteristics in leaf dynamics, further improvement may be possible.


  • Development of a method for evaluate crop growth characteristics based on non-destructive measurements
    Yoshihiro Hirooka  JAPR Journal  55-  (8)  17  -20  2021/10  [Invited]
  • Estimation of planting date in paddy fields by time-series MODIS data for basin-scale rice productin modeling
    Tsujimoto, K; Ohta, T; Hirooka, Y; Homma, K  PAWEES & INWEPF International Conference 2018  102  -111  2018/11  [Refereed]
  • Evaluation of rice productivity with plant canopy analyzer in farmers’ fields in Lao PDR
    Hirooka, Y; Homma, K; Maki, M; Sekiguchi, K  Proceedings of the 8th Asian Crop Science Association Conference. Sustainable Crop Production in response to Global Climate Change and Food Security  37  -42  2015
  • A report of educational program in Royal University of Agriculture in Cambodia: Water environment on rice cropping in Pursat Province
    Kodo, T; Homma, K; Hirooka, Y; Yagura, K; Soben, K; Kobayashi, S; Hori, M; Hoshikawa, K; Hyakumura, K; Kono, Y; Koike, T  Proc. The 11th International Symposium on Southeast Asian Water Environment (SEAWE 11)  436  -439  2014
  • Evaluation of the nutritional environment for rice in Cianjur, Indonesia, for development of an advanced basin model for Asia
    Homma, K; Sigit, G; Handarto; Maki, M; Hongo, C; Yoshida, K; Oki, K; Shirakawa, H; Shiraiwa, T; Hara, R; Kambayashi, M; Hirooka, Y; Iwamoto, H  Proc. the 7th Asian Crop Science Conference. Improving Food, Energy and Environment with Better Crops. Bogor, Indonesia.  96  -100  2013
  • The nutritional environment in nonfertilized rice production and its effect on the nutritional quality of brown rice
    Hara, R; Homma, K; Hirooka, Y; Kuwada, M; Shiraiwa, T  Proc. the 7th Asian Crop Science Conference. Improving Food, Energy and Environment with Better Crops. Bogor, Indonesia.  101  -106  2013
  • Mitsuo Kambayashi; Koki Homma; Masayasu Maki; Yoshihiro Hirooka; Tatsuhiko Shiraiwa  33rd Asian Conference on Remote Sensing 2012, ACRS 2012  3-  2030  -2037  2012

Lectures, oral presentations, etc.

  • Canopy structure affects the estimation accuracy of the leaf area index when using vegetation index derived from spectral reflectance in rice  [Not invited]
    Yu Iwahashi; Yoshihiro Hirooka; Hiromo Inoue; Zhenjing Xu; Tatsuhiko Shiraiwa; Tetsuya Nakazaki
    6th International Rice Congress  2023/10
  • ウルトラファインバブル水灌漑がダイズとトウモロコシの生育に及ぼす影響
    社内 幸音; 山本 一輝; 飯嶋 盛雄; 廣岡 義博
    第256回日本作物学会講演会  2023/09
  • 接触混植と亀裂処理の組み合わせによるダイズの湿害緩和効果の検討
    大塚 珠映; 廣岡 義博; 泉 泰弘; 庄司 浩一; 飯嶋 盛雄
    第255回日本作物学会講演会  2023/03
  • ダイズの栽培途上における亀裂処理の効果
    長坂明佑子; 廣岡義博; 泉泰弘; 飯嶋盛雄; 庄司浩一
    関西農業食料工学会第149回例会  2023/03
  • ウルトラファインバブル水の水田への灌漑が水稲生育と水田土壌に及ぼす影響  [Not invited]
    飯嶋 盛雄; 廣岡 義博; 泉 泰弘; 渡邊 芳倫; 上田 義勝; 坂田 衛星
    日本作物学会第 254回講演会  2022/09
  • Relationship between competition and complementary effect of close-mixed planting of rice and soybean
    大塚 珠映; 赤司 匠; 廣岡 義博; 飯嶋 盛雄
    日本作物学会第 253 回講演会  2022/03
  • Mitigation of soil drought stress in pot grown coffee (Coffea arabica) by ultra-fine bubble irrigation
    元村 真歩; 廣岡 義博; 山根 浩二; 坂田 衛星; 飯嶋 盛雄
    日本作物学会第 253 回講演会  2022/03
  • The effects of ultra-fine bubble irrigation on yield of pot grown rice under soil nutrient stress condition
    大南正悟; 立石祐貴; 廣岡義博; 坂田衛星; 飯嶋盛雄
    日本作物学会第 253 回講演会  2022/03
  • The effect of ultra-fine bubble on soybean growth under osmotic stress condition  [Not invited]
    Kaito Yamashita; Yoshihiro Hirooka; Yoshikatsu Ueda; Koji Yamane; Chikashi Kamimura; Morio Iijima
    10th Asian Crop Science Association Conference (ACSAC10)  2021/09
  • Rice introduction to Botswana through the collaboration with Namibia and Japan; Natural and Social environment for rice cropping in Okavango Delta  [Not invited]
    Keotshephile Kashe; Simon K. Awala; Pamwenafye; I. Nanhapo; Yoshihiro Hirooka; Morio Iijima
    10th Asian Crop Science Association Conference (ACSAC10)  2021/09
  • Enhancement of drought-tolerance of sorghum by the close mixed-planting of pearl millet  [Not invited]
    Morio Iijima; Simon K. Awala; Pamwenafye I. Nanhapo; Yoshihiro Hirooka; Keotshephile Kashec
    10th Asian Crop Science Association Conference (ACSAC10)  2021/09
  • Effects of ridging and fertilizer application on crop yield and growth under unstable water environments  [Not invited]
    Yoshihiro Hirooka, Simon K. Awala, ⁠Pamwenafye I. Nanhapo, Koichi Shoji⁠⁠, Yoshinori Watanabe, Yasuhiro Izumi, Morio Iijima
    10th Asian Crop Science Association Conference (ACSAC10)  2021/09
  • 非破壊計測を利用した作物の成長動態および栽培環境の評価  [Invited]
    廣岡 義博
    第251回日本作物学会講演会  2021/03
  • ウルトラファインバブルが乾燥ストレス環境下におけるコーヒー生育に及ぼす影響
    元村 真歩; 廣岡 義博; 山根 浩二; 上田 義勝; 上村 親士; 飯嶋 盛雄
    第250回日本作物学会講演会  2020/09
  • 接触混植された作物の生育に及ぼすウルトラファインバブルの影響
    飯嶋 盛雄; 山下 海斗; 山本 一輝; 廣岡 義博; 山根 浩二; 上田 義勝; 上村 親士
    第250回日本作物学会講演会  2020/09
  • Overcoming the crop growth inhibitory effect of coffee grounds: Relations with germination inhibition by caffeic acid
    西野大暉; 廣岡義博; 山根浩二; 福永泰司; 岩井和也; 成田優作; 小林司; 垣内美紗子; 髙畑理; 飯嶋盛雄
    第249回日本作物学会講演会  2020/03
  • Elucidation of the mechanism of high temperature damage expression in coffee (Coffea arabica) intact plant
    西川萌菜; 山根浩二; 廣岡義博; 福永泰司; 岩井和也; 成田優作; 小林司; 垣内美沙子; 高畑理; 飯嶋盛雄
    第249回日本作物学会講演会  2020/03
  • Evaluation of factors for alleviating waterlogging damage in soybean by crack fertilization
    須浪章裕; 廣岡義博; 山根浩二; 飯嶋盛雄
    第249回日本作物学会講演会  2020/03
  • The effect of ultra-fine bubble on crop growth: Alleviative effects on Osmotic Stress
    山下海斗; 廣岡義博; 上田義勝; 山根浩二; 上村親士; 飯嶋盛雄
    第249回日本作物学会講演会  2020/03
  • Mitigation effect of close mixed-planting of rice and iceplant on multiple environmental stress caused by salt and flood
    春名啓介; 山根浩二; 廣岡義博; Nanhapo Pamwenafye I.; 飯嶋盛雄
    第249回日本作物学会講演会  2020/03
  • ダイズ/イネ接触混植におけるイネの適正個体数  [Not invited]
    米谷拓朗; 廣岡義博; 山根浩二; 飯嶋盛雄
    第248回日本作物学会講演会  2019/09
  • コーヒー抽出残渣のマルチ施用が作物・雑草生育に与える影響  [Not invited]
    倉重真太郎; 廣岡義博; 山根浩二; 成田 優作; 小林司; 垣内美紗子; 福永泰司; 飯嶋盛雄
    第248回日本作物学会講演会  2019/09
  • ウルトラファインバブルが作物生育に及ぼす影響: 水耕栽培条件での作物種間比較  [Not invited]
    山下海斗; 廣岡義博; 上田義勝; 山根浩二; 上村親士; 飯嶋盛雄
    第248回日本作物学会講演会  2019/09
  • The effect of ultra-fine bubble on crop growth: soybean seedling growth under different nutrient, dissolved oxygen and stirred conditions in water culture  [Not invited]
    飯嶋盛雄; 山下海斗; 廣岡義博; 上田義勝; 山根浩二; 上村親士
    第284回日本作物学会講演会  2019/09
  • The effects of soil tillage methods and fertilizer application on the yield and growth of pearl millet in northern Namibia  [Not invited]
    Yoshihiro Hirooka; Simon K. Awala; Kudakwashe Hove; Pamwenafye; I. Nanhapo; Morio Iijima
    第247回日本作物学会  2019/03
  • Overcoming the crop growth inhibitory effect of coffee residue: Resisitant species and residue treatment  [Not invited]
    Nishino D; Hirooka Y; Yamane K; Narita Y; Kobayashi T; Kakiuchi M; Fukunaga T; Iijima M
    第247回日本作物学会  2019/03
  • The evaluation of the tolerance for high or low temperature stresses in the coffee  [Not invited]
    Nishikawa M; Yamane K; Hirooka Y; Narita Y; Kobayashi T; Kakiuchi M; Fukunaga T; Iijima M
    第247回日本作物学会  2019/03
  • Close mixed-planting enhances both flood- and drought- tolerance of upland crops and rice  [Not invited]
    Iijima M; Yamane K; Hirooka Y
    3rd International conference on Agricultural and Food Science  2018/11
  • Estimation of planting date in paddy felds by time‑series MODIS data for basin‑scale rice production modeling  [Not invited]
    Tsujimoto K; Ohta T; Hirooka Y; Homma K
    PAWEES & INWEPF International Conference 2018 Nara, Japan  2018/11
  • Growth and yield performance of short-duration rice (Oryza sativa L.) genotypes in North-Central Namibia  [Not invited]
    Amwenyo MLD; Awala SK; Lwiinga T; Hirata N; Nanhapo PI; Hove K; Mwandemele OD; Wanga MA; Yamane K; Hirooka Y; Iijima M
    2nd International Conference on Agriculture and Natural Resources Research and Innovation  2018/10
  • Yield and yield components of early-maturing rice (Oryza sativa L.) genotypes  [Not invited]
    Shivute V; Awala SK; Lwiinga T; Hirata N; Hove K; Nanhapo PI; Mwandemele OD; Wanga MA; Yamane K; Hirooka Y; Iijima M
    2nd International Conference on Agriculture and Natural Resources Research and Innovation  2018/10
  • A study on the effect of fertilizer application on growth and yield components of pearl millet (Pennisetum glaucum L.) subjected to field flooding  [Not invited]
    Hailemo RWN; Awala SK; Hirooka Y; Nanhapo PI; Iijima M
    2nd International Conference on Agriculture and Natural Resources Research and Innovation  2018/10
  • 接触混植はイネの塩ストレスとアイスプラントの湛水ストレスの両者とも緩和した  [Not invited]
    春名 啓介; 山根 浩二; 廣岡 義博; 飯嶋 盛雄
    第246回日本作物学会  2018/09
  • 亀裂施肥によるダイズの耐湿性強化  [Not invited]
    飯嶋 盛雄; 泉 泰弘; 山根 浩二; 廣岡 義博
    第246回日本作物学会  2018/09
  • イネとの接触混植によるダイズの耐湿性強化:圃場と水耕栽培による生理指標の検討  [Not invited]
    島本雅之; 廣岡義博; 渡邉芳倫; 山根浩二; 飯嶋盛雄
    第245回日本作物学会  2018/03
  • ダイズの幼植物体における根接ぎ技術の開発  [Not invited]
    篠原和; 廣岡義博; 和田楓; 山根浩二; 飯嶋盛雄
    第244回日本作物学会  2017/09
  • ナミビア季節性湿地帯における畝立て方法がトウジンビエの生育・収量に与える影響  [Not invited]
    廣岡義博; 渡邊芳倫; 庄司浩一; 土屋賢太; 泉泰弘; 宇都宮鑑彦; Simon K. Awala; 飯嶋 盛雄
    第244回日本作物学会  2017/09
  • イネとの接触混植によるダイズの耐湿性強化  [Not invited]
    飯嶋盛雄; 川戸良将; 島本雅之; 山根浩二; 廣岡義博; 渡邉芳倫
    第244回日本作物学会  2017/09
  • Enhancement of flood stress tolerance for upland-adapted cereal crops by the close mixed-planting with rice  [Not invited]
    Iijima, M; Awala, S.K; Hirooka, Y; Yamane, K
    9th Asian Crop Science Association Conference  2017/06
  • Exploration of suitable rice cultivars for close mixed planting with upland-adapted cereal crop  [Not invited]
    Shinohara, N; Shimamoto, H; Kawato, Y; Wanga, A. M; Hirooka, Y; Yamane, K; Iijima, M
    9th Asian Crop Science Association Conference  2017/06
  • イネ根圏における酸素放出能の品種間比較  [Not invited]
    篠原和; 島本雅之; 川戸良将; Maliata A. Wanga; 廣岡義博; 山根浩二; 飯嶋 盛雄
    第243回日本作物学会  2017/03
  • Drought stress mitigation on sorghum by the close mixed-planting with pearl millet  [Not invited]
    Wanga, M.A; Kawato, Y; Shimamoto, H; Hirooka, Y; Yamane, K; Iijima, M
    第243回日本作物学会  2017/03
  • ナミビア季節湿地帯における 畝立ての方法がササゲの生育・収量に与 える影響  [Not invited]
    土屋賢太; 庄司浩一; 渡邊芳倫; 廣岡義博; 泉 泰弘; 宇都宮鑑彦; Simon K. Awala; 飯嶋盛雄
    日本農作業学会 2017年度 春季大会  2017/03
  • イネ直立穂品種「瀋農265」における群落構造の定量化  [Not invited]
    廣岡義博; 本間 香貴; 白岩 立彦; Xu Zhengjin・Tang Liang
    第242回日本作物学会  2016/03
  • Development of a method for evaluating vertical leaf area distribution in rice  [Not invited]
    Hirooka, Y; Homma, K; Shiraiwa, T
    ASA, CSSA, SSSA International Annual Meeting, Minneapolis, MN, USA  2015/11
  • 合成開口レーダー(SAR)を利用したラオス農家圃場における葉面積指数(LAI )の評価  [Not invited]
    廣岡義博; 本間香貴; 牧雅康; 関口晃介
    システム農学会 2015年度秋季大会  2015/10
  • カンボジアのイネ農家圃場におけるLAIの経時的測定に基づく栽培管理の評価  [Not invited]
    廣岡義博; 本間香貴; 高堂泰輔; 白岩立彦; Kim Soben; Mithona Chann
    第240回日本作物学会講演会  2015/09
  • Development of evaluation method of rice productiviry in farmers’ fields in Vientiane Province, Lao  [Not invited]
    Hirooka, Y
    Joint workshop on sustainability development in rural areas considering nexus among water, food and energy in Laos  2015/07
  • 栽植密度がイネ直立穂品種の収量・生育特性に与える効果  [Not invited]
    廣岡義博; 本間 香貴; 白岩 立彦; 徐正進; 唐亮
    第239回日本作物学会講演会  2015/03
  • Analysis of characteristic of canopy structure in erect panicle type of rice  [Not invited]
    Hirooka, Y; Homma, K; Shiraiwa, T; Xu, Z; Tang L
    4th International Rice Congress  2014/11
  • イネ直立穂品種の京都における収量及び施肥反応性  [Not invited]
    廣岡義博; 本間香貴; 白岩 立彦; 徐正進; 唐亮
    第238回日本作物学会講演会  2014/09
  • Evaluation of rice growth environment in farmers' field in Lao PDR by remote sensing  [Not invited]
    Hirooka,Y; Homma,K; Maki,M; Sekiguchi,K
    8th Asian Crop Science Association Conference (ACSAC)  2014/09
  • Evaluation on dynamics of leaf area index (LAI) of rice in farmer's fields in Vientiane Province, Lao PDR  [Not invited]
    Hirooka, Y; Homma, K; Maki,M; Sekiguchi, K
    International Symposium on Agricultural Meteorology, Sapporo, Japan  2014/03
  • イネにおける葉群の垂直分布の経時的モニタリング  [Not invited]
    廣岡 義博; 本間 香貴; 白岩 立彦
    第237回日本作物学会講演会  2014/03
  • イネ直立穂品種における個葉光合成速度の窒素応答およびその支配要因の解析  [Not invited]
    浦入千宗; 田中佑; 川崎洋平; 廣岡義博; 徐正進; 白岩立彦
    第237回日本作物学会講演会  2014/03
  • プラントキャノピーアナライザー(LI-COR LAI-2000)を用いた葉面積動態評価法  [Not invited]
    廣岡義博; 本間香貴; 神林満男; 桒田光雄; 白岩立彦
    2012年度 無施肥無農薬栽培研究報告会  2013/03
  • 分光反射計測による葉群構造発達指標TIPS(Time-series change Index of Plant Structure)を用いたイネの葉面積および群落吸光係数の計測  [Not invited]
    神林満男; 本間香貴; 白岩立彦; 廣岡 義博; 牧雅康
    第235回日本作物学会講演会  2013/03
  • プラントキャノピーアナライザーを利用したイネの窒素吸収速度の推定  [Not invited]
    廣岡義博; 本間 香貴; 白岩立彦; 桒田光雄
    第235回日本作物学会講演会  2013/03
  • 世界のイネ・コアコレクションを用いた収量関連形質の遺伝的多様性の解析 第8報 プラントキャノピーアナライザーを用いた葉面積動態の解析  [Not invited]
    廣岡義博; 入江拓也; 本間香貴; 鳥海明子; 白岩立彦
    第234回日本作物学会講演会  2012/09
  • Evaluation of the effects of cultivars and nutritional environments on dynamics of leaf area index of rice by using plant canopy analyzer  [Not invited]
    Hirooka,Y; Homma,K; Shiraiwa,T; Kuwada, M
    6th International Crop Science Congress  2012/08
  • プラントキャノピーアナライザー(LAI2000)の推定精度の検証  [Not invited]
    廣岡義博; 本間香貴; 白岩立彦; 桒田光雄; 佐藤博一; 神林満男; 原律子; 岩本啓己
    近畿作物・育種研究会 第174回例会  2012/07
  • プラントキャノピーアナライザーによる葉面積指数(LAI)動態の評価  [Not invited]
    廣岡義博; 本間香貴; 白岩立彦; 桒田光雄
    第233回日本作物学会講演会  2012/03

Affiliated academic society


Research Themes

  • 日本学術振興会:科学研究費助成事業
    Date (from‐to) : 2024/04 -2027/03 
    Author : 廣岡 義博、岩橋優
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research
    Date (from‐to) : 2023/04 -2027/03 
    Author : 飯嶋 盛雄; 庄司 浩一; 大門 弘幸; 牛尾 昭浩; 泉 泰弘; 廣岡 義博
  • 農作物に対するMKグリーンの効果について
    Date (from‐to) : 2022/09 -2025/03 
    Author : 廣岡義博
  • 日本学術振興会:科学研究費助成事業
    Date (from‐to) : 2021/04 -2024/03 
    Author : 廣岡 義博
    研究代表者は現在までに作物の生育動態に関する定量的評価手法の開発を行ってきたが,この手法では群落閉鎖後の生育状態に関する評価は難しく,また,広域評価も困難であった.そこで本研究では,生育期間を通して作物の生育情報を収集するための手法を開発し,さらに手法の広域展開可能性を検討することを目的として,以下の解析・実験を行った. ①生育期間を通した生育情報収集技術の開発:広範な栄養環境下で多様なイネ6品種を用いて行った3か年の栽培試験結果から,現在までに開発してきた生育動態を評価するパラメータのうち被覆率増加に関するパラメータがバイオマス生産をよく反映していることがわかった.さらに,これらのパラメータに加えて,群落閉鎖後の葉身窒素含量のような品種固有の生理パラメータを利用することで,収量の推定精度が改善されることを示唆した. ②ドローン計測による被覆率計測手法の検討:収量変動の大きい圃場でダイズの栽培試験を行い,異なる距離からのドローン撮影による被覆率計測を試みた.近距離(約7m)からのドローン計測と比較して,遠距離(約20m)からの計測による収量推定精度が高かった.遠距離からの撮影は雑草等の誤差要因を小さくすることが明らかとなり,より簡易的に広域のデータ収集が可能であることを示した. ③機械学習を利用したササゲ収量推定精度の検証:西アフリカでササゲ20品種を用いた栽培試験を行った。通常マメ科は水平葉であるため,被覆率を生産性評価に利用することは難しいが,本研究対象地域のような低生産性地域では被覆率が重要なパラメータであることがわかった.簡易的な3時期の非破壊的な被覆率計測によって,対象地域のササゲ収量を高精度で推定できることが示された.ここでは,4手法の機械学習を試し,手法による推定精度の違いを検出することができた.
  • 日本学術振興会:科学研究費助成事業
    Date (from‐to) : 2019/10 -2023/03 
    Author : 飯嶋 盛雄; 庄司 浩一; 山根 浩二; 廣岡 義博
    新型コロナウイルス(Covid-19)禍により渡航が制限されたため、オンラインによりナミビア、ボツワナ、日本の3ヵ国での試験や研究成果を詳細に打ち合わせ、以下の研究と、研究成果の共同執筆・国際会議での報告などを実施した。① 接触混植試験:ナミビア北部では、ソルガムとトウジンビエの接触混植が農家の自助努力などにより徐々に広がりを見せている。そこで、ナミビア大学オゴンゴ校内の附属農場施設内で、トウジンビエとソルガムの接触混植試験を実施した。農家圃場においても栽培を希望する農家に種子を提供し、農家圃場における栽培試験を実施した。② 亀裂施肥試験:本試験のためにナミビア国で作成した新型の亀裂施肥機をベースにして日本ではコストを考慮し、亀裂処理に特化した新型アタッチメントを作成した。その走行試験を神戸大学等で実施し、今後の普及を検討中である。 ③ ボツワナ大学では、ナミビアから導入したイネ品種群の栽培試験を2019/2020作付け期に開始し、2021/2022まで3か年に渡る栽培トライアルを継続中である。2021/2022からは小規模フィ―ルドでの作付けを開始し、種子の更新と栽培試験を拡大した。 ④ ナミビアとボツワナの研究サイト周辺の農家圃場では季節湿地が形成されるためメタン発生の増大が懸念される。そこで地球温暖化の進行を阻止するためウルトラファインバブル水灌漑によるメタン削減の可能性を議論し、現地への導入を目指したフィールド試験を日本で開始した。 ⑤ 研究成果5報の原著論文がアクセプトされた。 ⑥ 国際学会(アジア作物学会議)で4報の口頭発表と、国内学会(日本作物学会)で2報の口頭発表を実施した。
  • ナミビア北中部における非破壊計測を利用した現地主要作物の栽培管理技術の検討
    Date (from‐to) : 2018/04 -2021/03 
    Author : 廣岡 義博
  • ダイズ群落の湿害ストレス応答に関する定量的評価手法開発
    Date (from‐to) : 2018/04 -2019/03 
    Author : 廣岡義博
  • 多様な水環境下における混作作物のストレス応答の定量的評価
    科学研究費補助金 研究活動スタート支援
    Date (from‐to) : 2016/08 -2018/03 
    Author : 廣岡 義博
  • 生育・収量予測モデルと非破壊計測を利用したイネの生育環境及び管理方法の評価
    科学研究費補助金 特別研究員奨励費
    Date (from‐to) : 2013/04 -2016/03 
    Author : 廣岡 義博