Plant biodiversity has been studied to explore allelopathic species for the sustainable managemen... more Plant biodiversity has been studied to explore allelopathic species for the sustainable management of weeds to reduce the reliance on synthetic herbicides. Rosemary (Rosmarinus officinalis L., syn Salvia rosmarinus Spenn.), was found to have plant growth-inhibitory effects, and carnosic acid was reported as an allelochemical in the plant. In this study, the effects of seasonal variation (2011–2012) on the carnosic acid concentration and phytotoxicity of rosemary leaves from two locations in Tunisia (Fahs and Matmata) were investigated. The carnosic acid concentration in rosemary leaves was determined by HPLC, and lettuce (Lactuca sativa L.) was used as the receptor plant in the phytotoxicity bioassay. The highest carnosic acid concentration was found in rosemary samples collected in June 2011, which also had the highest inhibitory activity. Furthermore, a significant inverse correlation (r = −0.529; p < 0.01) was found between the inhibitory activity on lettuce hypocotyl and the ...
Application of bio-fertilizer with the ability to promote root development in legume plants could... more Application of bio-fertilizer with the ability to promote root development in legume plants could be beneficial, and it is vital to find an inoculation method that does not inhibit symbiosis between rhizobium and plants. However, co-inoculation of rhizobia with different microorganisms on legumes generally inhibits interdependency with rhizobia. The present study was conducted to determine the ideal inoculation method of the bio-fertilizer 'Yume-bio' containing <i>Bacillus pumilus</i> TUAT1, which has plant growth-promoting activity, without inhibiting rhizobial infection of soybean. Soybean plants were inoculated with <i>Bradyrhizobium diazoefficiens</i> USDA110 during the time of sowing seeds. Then, two types of 'Yume-bio' applications were conducted: simultaneous inoculation with the rhizobia (SI) and 1 week after inoculation the rhizobia (I). No inoculation (NI) was used as the control. Four weeks after sowing, biomass dry weight (shoot an...
Flowering time is closely associated with grain yield in rice (Oryza sativa L.). In temperate reg... more Flowering time is closely associated with grain yield in rice (Oryza sativa L.). In temperate regions, seasonal changes in day length (known as the photoperiod) are an important environmental cue for floral initiation. The timing of flowering is important not only for successful reproduction, but also for determining the ideal balance between vegetative growth and reproductive growth duration. Recent molecular genetics studies have revealed key flower-ing time genes responsible for photoperiod sensitivity. In this study, we investigated the effect of three recessive photoperiod-insensitive alleles, se13, hd1 and ghd7, on yield components in rice under Ehd1-deficient genetic background conditions to ensure vegetative growth of each line. We found that se13-bearing plants had fewer panicles, hd1-bearing plants showed decreased grain-filling percentage, and ghd7-bearing plants appeared to have fewer grains per panicle and fewer secondary branches. Our results indicate that the pleiotro...
Sotaro Honda Graduate School of Agriculture, Tokyo University of Agriculture and Technology Satos... more Sotaro Honda Graduate School of Agriculture, Tokyo University of Agriculture and Technology Satoshi Ohkubo Graduate School of Agriculture, Tokyo University of Agriculture and Technology Nan San Graduate School of Agriculture, Tokyo University of Agriculture and Technology Anothai Nakkasame Graduate School of Agriculture, Tokyo University of Agriculture and Technology Kazuki Tomisawa Graduate School of Agriculture, Tokyo University of Agriculture and Technology Keisuke Katsura Graduate School of Agriculture, Tokyo University of Agriculture and Technology Taiichiro Ookawa Graduate School of Agriculture, Tokyo University of Agriculture and Technology Atsushi Nagano Faculty of Agriculture, Ryukoku University Shunsuke Adachi ( shunsuke.adachi.0210@vc.ibaraki.ac.jp ) College of Agriculture, Ibaraki University
In many sub-Saharan African countries, it is fundamental to boost rice production because the inc... more In many sub-Saharan African countries, it is fundamental to boost rice production because the increased rice consumption exceeds the growth in domestic rice production. Kenya has currently implemented a policy to double its rice production which, however, has been suffering from serious constraints. Nagoya University and Kenya Agricultural and Livestock Research Organization, in collaboration with other Japanese and Kenyan research institutions, have identified several biotic and abiotic stresses such as drought, cold temperatures at high elevations, high salinity, low soil fertility, and rice blast disease as such constraints and then initiated an international joint research project titled “The project on rice research for tailor-made breeding and cultivation technology development in Kenya” from May 22, 2013, to May 21, 2018. Using technologies such as molecular breeding and DNA marker-assisted selection, the project has advanced the development of rice varieties carrying useful genes/QTL to overcome stress conditions in Kenya. For phenotyping and examination of incorporated gene/QTL expression, we have developed unique evaluation systems for plant adaptability against drought, low temperatures, high salinity, low fertility, and rice blast disease in Kenya. After assessing current cultivation practices and environments, the project aimed to develop cultivation technologies that maximize the potential of rice varieties carrying useful genes/QTL. Eventually, superior varieties and customized cultivation technology will be disseminated to the farmers. The project has also assisted the development of human resources for rice research both in Kenya and Japan. Based upon our research, we will persist in our efforts to establish an international network as a framework for variety improvement and cultivation technology development customized to the sub-Saharan African environment.
Recently, food security has become a major world-wide concern. The development of a stable food s... more Recently, food security has become a major world-wide concern. The development of a stable food supply system is necessary. Therefore, the practice of precision agriculture has received a great deal of attention. The management of crop growth is one of the most important aspects of precision agriculture, and it requires the accurate monitoring of the spatial distribution of the leaf area index (LAI) of target crops at the field scale. In recent years, unmanned aerial vehicles (UAVs) have been used to monitor the spatial distribution of the LAI of target crops at the field scale. The use of UAVs for LAI monitoring is expected to contribute to the efficiency of farming. However, no method for accurately estimating the spatial distribution of LAI using UAV has been established yet. In this study, several empirical regression models for estimating the LAI of paddy rice from several vegetation indices derived from UAV images were compared to help establish a precise estimation method of ...
Leaf photosynthetic rate changes across the growing season as crop plants age. Most studies of le... more Leaf photosynthetic rate changes across the growing season as crop plants age. Most studies of leaf photosynthesis focus on a specific growth stage, leaving the question of which pattern of photosynthetic dynamics maximizes crop productivity unanswered. Here we obtained high-frequency data of canopy leaf CO2 assimilation rate (A) of two elite rice (Oryza sativa) cultivars and 76 inbred lines across the whole growing season. The integrated A value after heading was positively associated with crop growth rate (CGR) from heading to harvest, but that before heading was not. A curve-smoothing analysis of A after heading showed that accumulated A at > 80% of its maximum (A80) was positively correlated with CGR in analyses of all lines mixed and of lines grouped by genetic background, while the maximum A and accumulated A at ≤ 80% were less strongly correlated with CGR. We also found a genomic region (~ 12.2 Mb) that may enhance both A80 and aboveground biomass at harvest. We propose th...
The average soybean yield in Japan is stagnated around 1.7 t ha -1 , which is quite low level com... more The average soybean yield in Japan is stagnated around 1.7 t ha -1 , which is quite low level compared to that in USA (around 2.7 t ha -1 ). The objective of this study was to reveal the factors causing this yield gap between Japan and USA. To examine the variety effect on the yield gap, we conducted yield test at Osaka (central Japan, 34 o 51‘N), Hokkaido (northern Japan, 43 o 03‘N), Feyetteville, AR (south-central USA, 36 o 03‘N), and Champaign, IL (mid-western USA, 40 o 06‘N), in 2009 using 4–6 Japanese and 5–10 USA varieties. Averaged yield of USA varieties was 8–59 % higher than that of Japanese varieties in each experimental site, which means the yield potential of USA varieties was higher than that of Japanese varieties. To examine the environmental effect on the yield gap, we estimated the potential yield (Yp) at Hokkaido, Shiga (central Japan, 35 o 16‘N), Arkansas, AR (south-central USA, 34 o 30‘N), and Champaign, IL, by simple simulation model, where we assumed that Yp was...
Crop productivity is poorly assessed globally. Here, we provide a deep learning-based approach fo... more Crop productivity is poorly assessed globally. Here, we provide a deep learning-based approach for estimating rice yield using RGB images. During ripening stage and at harvest, over 22,000 digital images were captured vertically downwards over the rice canopy from a distance of 0.8 to 0.9 m, and rice yields were obtained in the corresponding area ranging from 0.1 and 16.1 t ha−1. A convolutional neural network (CNN) applied to these data at harvest predicted 70% variation in rice yield with a relative root mean square error (rRMSE) of 0.22. Images obtained during the ripening stage can also be used to forecast the final rice yield. Our work suggests that this low-cost, hands-on, and rapid approach can provide a breakthrough solution to assess the impact of productivity-enhancing interventions and identify fields where these are needed to sustainably increase crop production.
Leaf area index (LAI) is a vital parameter for predicting rice yield. Unmanned aerial vehicle (UA... more Leaf area index (LAI) is a vital parameter for predicting rice yield. Unmanned aerial vehicle (UAV) surveillance with an RGB camera has been shown to have potential as a low-cost and efficient tool for monitoring crop growth. Simultaneously, deep learning (DL) algorithms have attracted attention as a promising tool for the task of image recognition. The principal aim of this research was to evaluate the feasibility of combining DL and RGB images obtained by a UAV for rice LAI estimation. In the present study, an LAI estimation model developed by DL with RGB images was compared to three other practical methods: a plant canopy analyzer (PCA); regression models based on color indices (CIs) obtained from an RGB camera; and vegetation indices (VIs) obtained from a multispectral camera. The results showed that the estimation accuracy of the model developed by DL with RGB images (R2 = 0.963 and RMSE = 0.334) was higher than those of the PCA (R2 = 0.934 and RMSE = 0.555) and the regression ...
Plant biodiversity has been studied to explore allelopathic species for the sustainable managemen... more Plant biodiversity has been studied to explore allelopathic species for the sustainable management of weeds to reduce the reliance on synthetic herbicides. Rosemary (Rosmarinus officinalis L., syn Salvia rosmarinus Spenn.), was found to have plant growth-inhibitory effects, and carnosic acid was reported as an allelochemical in the plant. In this study, the effects of seasonal variation (2011–2012) on the carnosic acid concentration and phytotoxicity of rosemary leaves from two locations in Tunisia (Fahs and Matmata) were investigated. The carnosic acid concentration in rosemary leaves was determined by HPLC, and lettuce (Lactuca sativa L.) was used as the receptor plant in the phytotoxicity bioassay. The highest carnosic acid concentration was found in rosemary samples collected in June 2011, which also had the highest inhibitory activity. Furthermore, a significant inverse correlation (r = −0.529; p < 0.01) was found between the inhibitory activity on lettuce hypocotyl and the ...
Application of bio-fertilizer with the ability to promote root development in legume plants could... more Application of bio-fertilizer with the ability to promote root development in legume plants could be beneficial, and it is vital to find an inoculation method that does not inhibit symbiosis between rhizobium and plants. However, co-inoculation of rhizobia with different microorganisms on legumes generally inhibits interdependency with rhizobia. The present study was conducted to determine the ideal inoculation method of the bio-fertilizer 'Yume-bio' containing <i>Bacillus pumilus</i> TUAT1, which has plant growth-promoting activity, without inhibiting rhizobial infection of soybean. Soybean plants were inoculated with <i>Bradyrhizobium diazoefficiens</i> USDA110 during the time of sowing seeds. Then, two types of 'Yume-bio' applications were conducted: simultaneous inoculation with the rhizobia (SI) and 1 week after inoculation the rhizobia (I). No inoculation (NI) was used as the control. Four weeks after sowing, biomass dry weight (shoot an...
Flowering time is closely associated with grain yield in rice (Oryza sativa L.). In temperate reg... more Flowering time is closely associated with grain yield in rice (Oryza sativa L.). In temperate regions, seasonal changes in day length (known as the photoperiod) are an important environmental cue for floral initiation. The timing of flowering is important not only for successful reproduction, but also for determining the ideal balance between vegetative growth and reproductive growth duration. Recent molecular genetics studies have revealed key flower-ing time genes responsible for photoperiod sensitivity. In this study, we investigated the effect of three recessive photoperiod-insensitive alleles, se13, hd1 and ghd7, on yield components in rice under Ehd1-deficient genetic background conditions to ensure vegetative growth of each line. We found that se13-bearing plants had fewer panicles, hd1-bearing plants showed decreased grain-filling percentage, and ghd7-bearing plants appeared to have fewer grains per panicle and fewer secondary branches. Our results indicate that the pleiotro...
Sotaro Honda Graduate School of Agriculture, Tokyo University of Agriculture and Technology Satos... more Sotaro Honda Graduate School of Agriculture, Tokyo University of Agriculture and Technology Satoshi Ohkubo Graduate School of Agriculture, Tokyo University of Agriculture and Technology Nan San Graduate School of Agriculture, Tokyo University of Agriculture and Technology Anothai Nakkasame Graduate School of Agriculture, Tokyo University of Agriculture and Technology Kazuki Tomisawa Graduate School of Agriculture, Tokyo University of Agriculture and Technology Keisuke Katsura Graduate School of Agriculture, Tokyo University of Agriculture and Technology Taiichiro Ookawa Graduate School of Agriculture, Tokyo University of Agriculture and Technology Atsushi Nagano Faculty of Agriculture, Ryukoku University Shunsuke Adachi ( shunsuke.adachi.0210@vc.ibaraki.ac.jp ) College of Agriculture, Ibaraki University
In many sub-Saharan African countries, it is fundamental to boost rice production because the inc... more In many sub-Saharan African countries, it is fundamental to boost rice production because the increased rice consumption exceeds the growth in domestic rice production. Kenya has currently implemented a policy to double its rice production which, however, has been suffering from serious constraints. Nagoya University and Kenya Agricultural and Livestock Research Organization, in collaboration with other Japanese and Kenyan research institutions, have identified several biotic and abiotic stresses such as drought, cold temperatures at high elevations, high salinity, low soil fertility, and rice blast disease as such constraints and then initiated an international joint research project titled “The project on rice research for tailor-made breeding and cultivation technology development in Kenya” from May 22, 2013, to May 21, 2018. Using technologies such as molecular breeding and DNA marker-assisted selection, the project has advanced the development of rice varieties carrying useful genes/QTL to overcome stress conditions in Kenya. For phenotyping and examination of incorporated gene/QTL expression, we have developed unique evaluation systems for plant adaptability against drought, low temperatures, high salinity, low fertility, and rice blast disease in Kenya. After assessing current cultivation practices and environments, the project aimed to develop cultivation technologies that maximize the potential of rice varieties carrying useful genes/QTL. Eventually, superior varieties and customized cultivation technology will be disseminated to the farmers. The project has also assisted the development of human resources for rice research both in Kenya and Japan. Based upon our research, we will persist in our efforts to establish an international network as a framework for variety improvement and cultivation technology development customized to the sub-Saharan African environment.
Recently, food security has become a major world-wide concern. The development of a stable food s... more Recently, food security has become a major world-wide concern. The development of a stable food supply system is necessary. Therefore, the practice of precision agriculture has received a great deal of attention. The management of crop growth is one of the most important aspects of precision agriculture, and it requires the accurate monitoring of the spatial distribution of the leaf area index (LAI) of target crops at the field scale. In recent years, unmanned aerial vehicles (UAVs) have been used to monitor the spatial distribution of the LAI of target crops at the field scale. The use of UAVs for LAI monitoring is expected to contribute to the efficiency of farming. However, no method for accurately estimating the spatial distribution of LAI using UAV has been established yet. In this study, several empirical regression models for estimating the LAI of paddy rice from several vegetation indices derived from UAV images were compared to help establish a precise estimation method of ...
Leaf photosynthetic rate changes across the growing season as crop plants age. Most studies of le... more Leaf photosynthetic rate changes across the growing season as crop plants age. Most studies of leaf photosynthesis focus on a specific growth stage, leaving the question of which pattern of photosynthetic dynamics maximizes crop productivity unanswered. Here we obtained high-frequency data of canopy leaf CO2 assimilation rate (A) of two elite rice (Oryza sativa) cultivars and 76 inbred lines across the whole growing season. The integrated A value after heading was positively associated with crop growth rate (CGR) from heading to harvest, but that before heading was not. A curve-smoothing analysis of A after heading showed that accumulated A at > 80% of its maximum (A80) was positively correlated with CGR in analyses of all lines mixed and of lines grouped by genetic background, while the maximum A and accumulated A at ≤ 80% were less strongly correlated with CGR. We also found a genomic region (~ 12.2 Mb) that may enhance both A80 and aboveground biomass at harvest. We propose th...
The average soybean yield in Japan is stagnated around 1.7 t ha -1 , which is quite low level com... more The average soybean yield in Japan is stagnated around 1.7 t ha -1 , which is quite low level compared to that in USA (around 2.7 t ha -1 ). The objective of this study was to reveal the factors causing this yield gap between Japan and USA. To examine the variety effect on the yield gap, we conducted yield test at Osaka (central Japan, 34 o 51‘N), Hokkaido (northern Japan, 43 o 03‘N), Feyetteville, AR (south-central USA, 36 o 03‘N), and Champaign, IL (mid-western USA, 40 o 06‘N), in 2009 using 4–6 Japanese and 5–10 USA varieties. Averaged yield of USA varieties was 8–59 % higher than that of Japanese varieties in each experimental site, which means the yield potential of USA varieties was higher than that of Japanese varieties. To examine the environmental effect on the yield gap, we estimated the potential yield (Yp) at Hokkaido, Shiga (central Japan, 35 o 16‘N), Arkansas, AR (south-central USA, 34 o 30‘N), and Champaign, IL, by simple simulation model, where we assumed that Yp was...
Crop productivity is poorly assessed globally. Here, we provide a deep learning-based approach fo... more Crop productivity is poorly assessed globally. Here, we provide a deep learning-based approach for estimating rice yield using RGB images. During ripening stage and at harvest, over 22,000 digital images were captured vertically downwards over the rice canopy from a distance of 0.8 to 0.9 m, and rice yields were obtained in the corresponding area ranging from 0.1 and 16.1 t ha−1. A convolutional neural network (CNN) applied to these data at harvest predicted 70% variation in rice yield with a relative root mean square error (rRMSE) of 0.22. Images obtained during the ripening stage can also be used to forecast the final rice yield. Our work suggests that this low-cost, hands-on, and rapid approach can provide a breakthrough solution to assess the impact of productivity-enhancing interventions and identify fields where these are needed to sustainably increase crop production.
Leaf area index (LAI) is a vital parameter for predicting rice yield. Unmanned aerial vehicle (UA... more Leaf area index (LAI) is a vital parameter for predicting rice yield. Unmanned aerial vehicle (UAV) surveillance with an RGB camera has been shown to have potential as a low-cost and efficient tool for monitoring crop growth. Simultaneously, deep learning (DL) algorithms have attracted attention as a promising tool for the task of image recognition. The principal aim of this research was to evaluate the feasibility of combining DL and RGB images obtained by a UAV for rice LAI estimation. In the present study, an LAI estimation model developed by DL with RGB images was compared to three other practical methods: a plant canopy analyzer (PCA); regression models based on color indices (CIs) obtained from an RGB camera; and vegetation indices (VIs) obtained from a multispectral camera. The results showed that the estimation accuracy of the model developed by DL with RGB images (R2 = 0.963 and RMSE = 0.334) was higher than those of the PCA (R2 = 0.934 and RMSE = 0.555) and the regression ...
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Papers by Keisuke Katsura