研究者詳細 - 槇原　大悟

PubMed

Utilization of Genotyping-by-Sequencing (GBS) for Rice Pre-Breeding and Improvement: A Review 国際共著国際誌

Vincent Pamugas Reyes,Justine Kipruto Kitony, Shunsaku Nishiuchi, Daigo Makihara andKazuyuki Doi

Life 12 巻 ( 11 ) 2022年11月

The effect of environmental parameters and fertilization practices on yield and soil microbial diversity in a Kenyan paddy rice field 査読有り国際共著国際誌

Gorfer M., Borruso L., Deltedesco E., Gichuhi E.W., Menge D.M., Makihara D., Praeg N., Cesco S., Mimmo T., Merbold L., Leitner S.

Applied Soil Ecology 176 巻 2022年8月

記述言語：英語掲載種別：研究論文（学術雑誌）

Rice is gaining importance for nutrition in sub-Saharan Africa, but domestic production can only cover a fraction of the actual needs. Suboptimal fertilization limits production and affordable solutions are needed. It is, however, of utmost importance to minimize negative impacts on the environment and on soil health, which is largely determined by microbial processes. An agronomic field trial was conducted at the KALRO Mwea research site (Central Kenya) to compare mineral and organic fertilization effects on rice plant parameters and on soil microbial abundance and diversity. Abundance of fungi and bacteria was quantified by ddPCR and the community composition was determined by amplicon sequencing of the ITS2- and 16S-regions, respectively. Mineral fertilizer had a strong positive effect on panicle number, spikelet number, grain yield and straw dry weight, but fertilizer type did not significantly influence soil microbial community abundance or composition. The rice development stage shaped fungal communities with differences between the vegetative and the reproductive stages, whereas the bacterial communities were mainly influenced by soil depth in a range from 0 to 30 cm. Additionally, spatial effects between rows of the experimental field were observed, resulting in row-specific differences in soil organic carbon, total nitrogen and certain fungal taxa, notwithstanding that the field was manually ploughed to a depth of 30 cm before the experiment. This study is the first census of soil fungal and bacterial communities in an African paddy rice field and provides insights into similarities and differences to paddy rice fields in other regions. To increase local African rice production, manure application alone might not be sufficient due to the poor nutrient status of traditional farm-yard manure, yet it can be part of a sustainable and more efficient fertilization strategy.

DOI： 10.1016/j.apsoil.2022.104495

Alternate Wetting and Drying (AWD) Mitigates the Decline in Grain Filling of Basmati 370 Due to Low Temperature in Tropical Highlands 査読有り国際共著国際誌

Kakehashi T., Kikuta M., Menge D.M., Gichuhi E.W., Samejima H., Makihara D.

Agronomy 11 巻 ( 11 ) 2021年11月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

In the rice growing area of Kenya’s highlands, the development of a water-saving rice cultivation system is a key strategy because the shortage of irrigation water is a frequently occurring problem. The purpose of this study was to investigate the effect of alternate wetting and drying (AWD) on the growth and yield of rice under the unique cultivation environment of tropical highlands. Field experiments were performed over a period of four years (2014–2017) in a paddy field. Dry matter production of a lowland variety, Basmati 370, was greater under continuous flooding (CF) than under AWD. In years with low minimum temperature (less than 15◦C) during the reproductive and ripening stages, filled grain ratios were significantly higher under AWD than under CF. Accordingly, higher dry matter production under CF did not contribute to grain yield. In the years when rice was not exposed to low minimum temperature during the reproductive and ripening stages, filled grain ratio did not decrease even under CF. Therefore, there was no difference between filled grain ratio under AWD and CF. Our results indicated that AWD could mitigate the decline in grain filling, induced by low minimum temperature during the reproductive and ripening stages in Basmati 370, under the cultivation conditions in tropical highlands. Although AWD may reduce the above-ground biomass, its mitigation effect on grain filling could outweigh this drawback and can still be beneficial to rice farmers in the tropical highlands.

DOI： 10.3390/agronomy11112345

Factors Explaining Differences in Yield Response to High Nitrogen Fertilization among Rice Varieties under Tropical Highland Conditions in Central Kenya 査読有り国際共著国際誌

Samejima H., Katsura K., Kikuta M., Njinju S.M., Kimani J.M., Yamauchi A., Makihara D.

Japan Agricultural Research Quarterly 55 巻 ( 3 ) 頁： 209 - 216 2021年7月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：国立研究開発法人　国際農林水産業研究センター

A decrease in the filled grain ratio (FGR) under high nitrogen (N) conditions inhibits the increase in rice yield in the tropical highlands of equatorial East Africa. We hypothesized that, under high N fertilization, the decrease in FGR is due to low temperatures during the reproductive growth stages, and that high grain yield can be achieved using cold tolerant varieties. Two cold-susceptible varieties (BW196 and Komboka) and a cold-tolerant variety (NERICA 1) were grown under 57, 114, and 171 kg N ha−1of N fertilization. Grain yield increased with a higher N fertilization rate only in NERICA 1. Shoot dry weight and total spikelet number increased in all varieties under high N conditions. Although FGR decreased with increases in N fertilization rate in all varieties, the adverse effects of high N fertilization on FGR were least observed in NERICA 1. However, temperature did not affect FGR in all N treatments, growth stages, and varieties, except for Komboka during the ripening stage under high N conditions. The findings did not support the hypothesis that high-N-induced decreases in FGR are due to low temperatures. High-N-induced decreases in FGR in Komboka were mainly attributable to the poor filling of spikelets during the ripening stage due to excess total spikelets. Factors other than filling high-N-promoted increases in total spikelet number may affect FGR in BW196 and NERICA 1 under high N conditions in Mwea.

DOI： 10.6090/jarq.55.209

The outstanding rooting1 mutation gene maintains shoot growth and grain yield through promoting root development in rice under water deficit field environments 査読有り国際共著国際誌

Hasegawa T., Wainaina C.M., Shibata A., Lucob-Agustin N., Makihara D., Kikuta M., Menge D.M., Gichuhi E.W., Samejima H., Kano-Nakata M., Kimani J.M., Musila R.N., Yamauchi A., Inukai Y.

Journal of Agronomy and Crop Science 2021年6月

記述言語：英語掲載種別：研究論文（学術雑誌）

Drought is one of the most serious constraints to rice cultivation, even under alternate wetting and drying (AWD), which is a water-saving management practice. In rice, enhanced root development is essential for stable shoot growth, adaptability and productivity under water deficit environments. We identified and characterized outstanding rooting1 (our1) rice mutant using hydroponics. The present study sought to examine morphological root traits of the our1 mutant and the role of the mutation gene in shoot growth and yield under AWD. Thus, we evaluated the growth performance of the our1 rice mutant in pot experiments and under field AWD conditions in Kenya. The experiments were conducted with our1 mutant, its wild type and their progenies under both AWD and continuously waterlogged (CWL) conditions. The our1 mutant possessed a well-developed root system and exhibited particularly enhanced thin root development, which was maintained from the early vegetative stage through the reproductive stage under both pot and field AWD management. This enhanced root development promoted shoot growth through increased water uptake during rewatered conditions between drought periods in AWD. In addition, the our1 mutant showed enhanced shoot growth during the reproductive stage, resulting in the maintenance of yield under AWD fields. Genotypes harbouring our1 mutation gene showed higher yields compared to wild-type genotypes which was attributed to their higher photosynthetic ability as a result of enhanced root activity. These results suggest the important role of a well-developed root system architecture and enhanced root function in stabilizing rice yields under water-limited environments. Our findings indicate that the our1 mutation gene can serve as a novel breeding material to mitigate the impact of transient drought stress on yield under AWD.

DOI： 10.1111/jac.12524

Marker-assisted introgression and stacking of major QTLs controlling grain number (Grain number 1a (Gn1a)) and number of primary branching (Wealthy Farmer’s Panicle (WFP)) to NERICA cultivars 査読有り国際共著国際誌

Vincent Pamugas Reyes, Rosalyn B. Angeles-Shim, Merlyn S. Mendioro, Ma.Carmina C. Manuel, Ruby S. Lapis, Jung Hyun Shim, Hidehiko Sunohara, Shunsaku Nishiuchi, Mayumi Kikuta, Daigo Makihara, Kshirod K Jena, Motoyuki Ashikari, Kazuyuki Doi

Plants 10 巻 ( 5 ) 2021年4月

Sago palm (Metroxylon sagu Rottb.) response to drought condition in terms of leaf gas exchange and chlorophyll a fluorescence 査読有り国際共著国際誌

Azhar Aidil, Makihara Daigo, Naito Hitoshi, Asano Koki, Takagi Mai, Unoki Saeka, Tomita Rena, Abbas Barahima, Ehara Hiroshi

PLANT PRODUCTION SCIENCE 24 巻 ( 1 ) 頁： 65 - 72 2021年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

Sago palm (Metroxylon sagu Rottb.) photosynthetic performance was evaluated under drought conditions through leaf gas exchange and chlorophyll a fluorescence measurement. Drought has an impact on sago palm’s leaf gas exchange parameters and its chlorophyll fluorescence of PSII. Stomatal limitations were found to be the main factor limiting photosynthetic activities of sago palm under drought conditions. Photosynthetic rate decreased following the inhibition in the PSII reaction center. Early detection of interference upon the efficiency of the PSII reaction center due to drought stress was recorded by chlorophyll a fluorescence measurement.

DOI： 10.1080/1343943X.2020.1794914

Effect of nitrogen application on the expression of drought-induced root plasticity of upland NERICA rice (vol 22, pg 180, 2019) 査読有り国際共著国際誌

Menge Daniel Makori, Onyango John Collins, Yamauchi Akira, Kano-Nakata Mana, Asanuma Shuichi, Thi Tran Thiem, Inukai Yoshiaki, Kikuta Mayumi, Makihara Daigo

PLANT PRODUCTION SCIENCE 24 巻 ( 1 ) 頁： 135 - 135 2021年1月

The impact of different soil water levels on nitrogen, phosphorus, and potassium uptake, photosynthetic performance, and sugar distribution of sago palm seedlings 査読有り国際共著国際誌

Aidil Azhar, Fitri Audia, Koki Asano, Daigo Makihara, Hitoshi Naito, Daisuke Sugiura, Hiroshi Ehara

Agrosystems, Geosciences & Environment 4 巻 ( 3 ) 2021年1月

A method for evaluating cold tolerance in rice during reproductive growth stages under natural low-temperature conditions in tropical highlands in Kenya 査読有り国際共著国際誌

Samejima Hiroaki, Kikuta Mayumi, Katura Keisuke, Menge Daniel, Gichuhi Emily, Wainaina Cornelius, Kimani John, Inukai Yoshiaki, Yamauchi Akira, Makihara Daigo

PLANT PRODUCTION SCIENCE 23 巻 ( 4 ) 頁： 466 - 476 2020年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Cold tolerance of New Rice for Africa (NERICA) and their parent varieties was evaluated under natural air temperature conditions of Kenyan tropical highlands using the multiple-sown field evaluation method. Rice varieties were cultivated 10 times to expose them to a shift in temperature during 20-day periods before heading (critical period), measuring the average daily mean temperature during the critical period (Tmean) for each variety and filled grain ratio, which was used as an indicator of cold tolerance. Tmean of each variety was low in 6 out of 10 experiments. In the remaining four high-temperature experiments, there were no significant varietal differences in filled grain ratio. In the six low-temperature experiments, all varieties experienced 20.1−21.5°C Tmean. After comparison under virtually the same cold stress, NERICA 1, 3, 4, 7−10, 12, 17, 18, and WAB 56–104 were judged as cold-tolerant; NERICA 2, 5, 11, 13, and 14, and WAB 56–50 and 181–18 were moderately tolerant, and NERICA 6, 15, and 16 were cold-susceptible varieties. These evaluations generally corresponded with previous experimental results under temperature-controlled environments, showing the practicality of multiple-sown field cold tolerance evaluation in Kenya. It also indicated that NERICA varieties, which recorded different levels of cold tolerance and whose average number of days to heading in all experiments were 66−78, are suitable as a set of standard check varieties in this region to evaluate cold tolerance of rice varieties with this range of days to heading.

DOI： 10.1080/1343943X.2020.1777877

Analysis of rice yield response to various cropping seasons to develop optimal cropping calendars in Mwea, Kenya 査読有り国際共著国際誌

Samejima Hiroaki, Katsura Keisuke, Kikuta Mayumi, Njinju Symon Mugo, Kimani John Munji, Yamauchi Akira, Makihara Daigo

PLANT PRODUCTION SCIENCE 23 巻 ( 3 ) 頁： 297 - 305 2020年7月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Cropping calendar optimization contributes to an increase in rice yield. Information on the seasonal variation in grain yield and climate conditions is necessary to determine an appropriate cropping calendar. We sought to find the optimal cropping calendar in Mwea, Kenya, in a tropical highland in equatorial East Africa. We conducted a series of 58 experiments using a local popular rice variety, Basmati 370, between 2013 and 2016, using a secured water supply and adequate blast control, sowing every 15 days. The grain yield was 0–2 t ha−1 when the variety was sown between March and June. This poor grain yield was attributable to the low temperature and low solar radiation from May to September. In contrast, the grain yield was always more than 3 t ha−1 when the variety was sown between July and February. Sowing Basmati 370 between March and June is not recommended, because it may lead to a suboptimal yield due to cold stress. The current cropping calendar (July–December or August–January) is acceptable even under abundant year-round water supply, but sowing between October and February is a good alternative sowing period for single rice cropping. Rice production per year is expected to increase to >100% with the introduction of double cropping by adding cultivation from between January and February before the current cropping calendar. These findings serve as useful references for considering and determining the appropriate calendar options for single and double cropping of rice in tropical highlands in equatorial East Africa.

DOI： 10.1080/1343943X.2020.1727752

Root and shoot responses of upland New Rice for Africa varieties to fluctuating soil moisture conditions as affected by different levels of nitrogen fertilization 査読有り国際共著国際誌

Menge Daniel Makori, Kano-Nakata Mana, Yamauchi Akira, Suralta Roel Rodriguez, Makihara Daigo

JOURNAL OF AGRONOMY AND CROP SCIENCE 206 巻 ( 3 ) 頁： 322 - 337 2020年6月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Drought cycling and soil re-watering trends due to intermittent rainfall patterns are key stress factors that influence rice growth and yield under upland cultivation conditions. However, upland rice adaptation responses to fluctuating soil moisture conditions remain poorly understood. This study investigated root and shoot responses of upland New Rice for Africa (NERICA) varieties to episodic drought and re-watering during growth. We examined root and shoot growth of NERICA 1 and NERICA 4 compared with those of IR72, an improved lowland variety, and Dular, a traditional drought-tolerant variety, in terms of soil moisture fluctuations with different levels of nitrogen fertilization under field conditions that impeded deep root development. During soil moisture fluctuation, all varieties reduced shoot dry weight compared with well-watered plants, regardless of nitrogen fertilization levels. However, total root length for the three upland varieties was enhanced by soil moisture fluctuations at moderate and high nitrogen fertilization, while that of the lowland variety was reduced. Comparing root development during water fluctuations revealed that NERICA 1 had a greater root system than NERICA 4, which was attributed to lateral root development. Furthermore, we found that NERICA varieties increase lateral root mass during soil desiccation under adequate nitrogen fertilization, while Dular and IR72 reduced their root growth rate during drought and increased it after re-watering. Both root growth patterns developed, from around maximum tillering to heading. The analysis of regression between root elongation and shoot growth with fluctuating soil moisture indicated that an enhanced root system during drought, on adequate nitrogen fertilization, can contribute to shoot growth when sufficient water becomes available, specifically around the maximum tillering to the heading growth stage of rice.

DOI： 10.1111/jac.12390

Agronomic traits and grain quality of upland rice cultivated in Southeast Sulawesi, Indonesia 査読有り国際共著国際誌

Mayumi KIKUTA, Daigo MAKIHARA, Yulius Barra PASOLON, Fransiscus Suramas REMBON, Akira MIYAZAKI, and Yoshinori YAMAMOTO

Journal of International Cooperation for Agricultural Development 18 巻頁： 41 - 47 2020年3月

Pathogenicities of Rice Blast (Pyricularia oryzae Cavara) Isolates From Kenya 査読有り国際共著国際誌

Fukuta Yoshimichi, Jeanie Telebanco-Yanoria Mary, Hayashi Nagao, Yanagihara Seiji, Machungo Catherine Wanjiku, Makihara Daigo

PLANT DISEASE 103 巻 ( 12 ) 頁： 3181 - 3188 2019年12月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

A total of 99 isolates of rice blast (Pyricularia oryzae Cavara) were collected from 2010 to 2015 from four regions in Kenya: Kirinyaga County and Embu County, Kisumu County, Tana River County, and Mombasa County. The pathogenicities of these isolates were clarified based on the reaction patterns of Lijiangxintuanheigu and differential varieties (DVs) targeting 23 resistance genes. The frequency of virulent isolates was high for DVs for Pib, Pia, Pii, Pi3, Pi5(t), Pik-s, Pik-m, Pi1, Pik-h, Pik, Pik-p, Pi7(t), Pi19(t), and Pi20(t); low for DVs for Pish, Pi9(t), Piz-5, and Piz-t; and intermediate for the remaining DVs for Pit, Piz, Pita-2, Pita, and Pi12(t). These blast isolates were classified into three cluster groups: Ia, Ib, and II. The frequencies of virulent isolates to DVs for Pit, Pii, Pik-m, Pi1, Pik-h, Pik, Pik-p, Pi7(t), Piz, and Pi12(t) differed markedly between clusters I and II, and those of DVs for Pib, Pit, Pia, Pi3, Pita-2, Pita, and Pi20(t) differed between Ia and Ib. The frequencies of cluster groups in the four geographical regions were different. A total of 62 races were found, with 19 blast isolates categorized into one race (U63-i7-k177-z00-ta003), whereas the other races included only some isolates in each.

DOI： 10.1094/PDIS-04-19-0870-RE

Effect of nitrogen application on the expression of drought-induced root plasticity of upland NERICA rice 査読有り国際共著国際誌

Menge Daniel Makori, Onyango John Collins, Yamauchi Akira, Kano-Nakata Mana, Asanuma Shuichi, Tran Thiem Thi, Inukai Yoshiaki, Kikuta Mayumi, Makihara Daigo

PLANT PRODUCTION SCIENCE 22 巻 ( 2 ) 頁： 180 - 191 2019年4月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

This study evaluated the effect of three N fertilization levels 60 (low), 120 (medium), and 180 (high) kg N ha−1 and soil moisture content gradients created by a line-source sprinkler on the expression of plasticity in lateral root branching and dry matter production (DMP) of upland new rice for Africa (NERICA) 1 and 4. There were no significant differences in DMP between NERICA 1 and 4 under well-watered, mild drought, and severe drought conditions regardless of N level. In contrast, under moderate drought (12–21% v/v of soil moisture content [SMC] in 2011 and 16–24% v/v of SMC in 2012), NERICA 1 had significantly higher shoot dry weight, total root length (TRL), lateral root length, and branching index than NERICA 4 at medium and high N; however, there was no significant difference between the two NERICAs in DMP at low N. TRL of NERICA 1 was significantly higher under moderate drought than well-watered conditions, but only with medium and high N. Regardless of N level, moderate drought did not enhance NERICA 4’s root system. Thus, NERICA 1’s root system exhibited plastic development, promoting lateral root branching at medium and high N. These morphological changes were associated with the greater DMP in NERICA 1 than NERICA 4 under moderate drought, whereas the lack of such plasticity at low N meant genotypic differences in DMP were obscured. Our findings implied that N application can improve upland NERICA productivity under moderate drought conditions, but differences in variety and field conditions may influence efficacy.

DOI： 10.1080/1343943X.2018.1561194

Effects of different water management practices on the dry matter production process and characteristics in NERICAs 査読有り国際誌

Kikuta Mayumi, Makihara Daigo, Arita Naoya, Miyazaki Akira, Yamamoto Yoshinori

PLANT PRODUCTION SCIENCE 22 巻 ( 2 ) 頁： 168 - 179 2019年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

In this study, we aimed to clarify the effects of different water management strategies on dry matter production and yield performance of New Rice for Africa (NERICA) varieties. Dry matter production of NERICA 1 and NERICA 5 was compared with that of Yumenohatamochi, a Japanese upland variety, and Hinohikari, a Japanese lowland variety under three water regimes, i.e. continuously flooded, supplemental irrigation, and non-irrigation (rainfed). Total carbohydrate content in the panicles under different watering regimes was more closely related to post-heading photosynthates than pre-heading reserve assimilates. Dry matter production during ripening tended to decrease under low soil water conditions, whereas the dry matter translocated from the leaf and stem to the panicle tended to increase. Consequently, the distribution ratio of post-heading photosynthates in the total carbohydrate content declined in response to the reduction in available soil moisture. These results indicate that the total carbohydrate content vary depending on the soil water conditions. In NERICAs, dry matter production during ripening was lower than that in Japanese varieties, indicating that their dependence on pre-heading reserve assimilates was greater. In particular, post-heading photosynthate content of NERICA 1 was strongly affected by the variation in water management in comparison with that of other varieties. The decrease in crop growth rate during ripening in NERICA 1 can be mainly attributed to the lower post-heading photosynthate content. Thus, the ability of NERICA 1 to assimilate carbon after heading was considered to be potentially low, which has to be improved to achieve higher yield.

DOI： 10.1080/1343943X.2018.1561195

Genetic variation of blast (Pyricularia oryzae Cavara) resistance in rice (Oryza sativa L.) accessions widely used in Kenya 査読有り国際共著国際誌

Fukuta Yoshimichi, Suzuki Tomohisa, Yanagihara Seiji, Obara Mitsuhiro, Tomita Asami, Ohsawa Ryo, Machungo Catherine Wanjiku, Hayashi Nagao, Makihara Daigo

Breeding Science 69 巻 ( 4 ) 頁： 672 - 679 2019年

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：日本育種学会

A total of 47 rice accessions collected from Kenya were investigated the genetic variations and classified into two cluster groups, A and B, by polymorphism data of 65 simple sequence repeat (SSR) markers. Clusters A and B corresponded to Japonica and Indica Groups, respectively. The number of Japonica Group accessions was limited in comparison with those of the Indica Group. Based on their patterns of reaction to standard differential blast isolates (SDBIs), these accessions and 57 control cultivars including differential varieties and several accessions harboring partial resistance genes were classified again into three cluster groups: Ia (high resistance), Ib (intermediate resistance) and II (susceptible). The rice accessions from Kenya were classified only into groups Ia and Ib. The accessions from Kenya were finally classified into three categories, A-Ia, B-Ia and B-Ib, based on the two classifications of polymorphism of SSR markers and resistance. The Indica Group accessions had wider genetic variation for blast resistance than did the Japonica Group accessions. The three leading cultivars (Basmati 217, Basmati 370 and ITA 310) categorized into Cluster group Ia were susceptible to some SDBIs from Kenya. The genetic variation for blast resistance in Kenya was demonstrated as the first report using SDBIs.

DOI： 10.1270/jsbbs.19065

QTL analysis for carbon assimilate translocation-related traits during maturity in rice (Oryza sativa L.) 査読有り国際共著国際誌

Phung H.D., Sugiura D., Sunohara H., Makihara D., Kondo M., Nishiuchi S., Doi K.

Breeding Science 69 巻 ( 2 ) 頁： 289 - 296 2019年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：日本育種学会

Problems with carbon assimilate translocation from source organs to sink (grains) during ripening cause yield losses in rice (Oryza sativa L.), especially in high-sink-capacity varieties. We conducted a genetic analysis of traits related to such translocation by using recombinant inbred lines. Shoot weight (SW) of T65, a japonica parent, was retained from heading to late maturity, whereas that of DV85, an aus parent, was greater than that of T65 at 5 days after heading (DAH) and then decreased until 20 DAH. This difference was observed clearly under standard-fertilizer but not low-fertilizer conditions. Non-structural carbohydrate (NSC) contents in the parents showed a tendency similar to that for SW. QTL analysis revealed pleiotropic QTLs on chromosomes 5 and 10, probably by associations with heading date QTLs. A QTL associated with harvest index and NSC at 5 DAH was detected on chromosome 1. By considering the temporal changes of the traits, we found a QTL for decrease in SW on chromosome 11; the DV85 allele of this QTL facilitated assimilate translocation and suppressed biomass growth. A suggestive QTL for NSC decrease was located on chromosome 2. These QTLs could represent potential targets for controlling carbon assimilate translocation in breeding programs.

DOI： 10.1270/jsbbs.18203

Growth of Rice Varieties in Different Kenyan Soil Types Under Water-Deficit Conditions 査読有り国際共著国際誌

Magoti Rahab, Mayumi Kikuta, George Chemining’wa, Josiah Kinama, John Kimani, Hiroaki Samejima, Patrick Gicheru, Daigo Makihara

Journal of Agricultural Science 11 巻 ( 6 ) 頁： 1 - 11 2019年

Evaluation of a Newly Identified Mutation Gene that Promotes Root Elongation for Improvement of Drought Avoidance in Rice 査読有り国際共著国際誌

Hasegawa Tomomi, Shibata Akihide, Mbathi Wainaina Cornelius, Lucob-Agustin Nonawin, Makihara Daigo, Samejima Hiroaki, Kikuta Mayumi, Makori Menge Daniel, Munji Kimani John, Yamauchi Akira, Inukai Yoshiaki

Journal of International Cooperation for Agricultural Development 17 巻頁： 34 - 40 2019年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：International Center for Research and Education in Agriculture, Nagoya University

Drought is one of the most serious abiotic stresses for rice cultivation, even under a water saving production system such as the Alternate Wetting and Drying (AWD) system and upland irrigated fields. In this study, we evaluated the performance of larger root systems in a KM07 mutant under such water management conditions. This mutant line was utilized for breeding and development of new rice germplasm adaptable to drought stress conditions in Mwea, Kenya, by crossing it with the recurrent parent of New Rice for Africa (NERICA), WAB56-104. Three mutant-type F6 lines grown under AWD and upland irrigated conditions showed different responses to drought stress. The mutant type’s greater root growth was observed in lines 2 and 3 under AWD and upland irrigation conditions, respectively. These results suggest that the highly developed root system derived from the KM07 mutant can avoid drought stress under field conditions in Kenya, and it should be utilized as breeding material for drought stress avoidance, along with water management technology.

DOI： 10.50907/jicad.17.0_34

Evaluating sago palm (Metroxylon sagu Rottb.) photosynthetic performance in waterlogged conditions: utilizing pulse-amplitudemodulated (PAM) fluorometry as a waterlogging stress indicator 査読有り国際共著国際誌

Azhar, A, Makihara, D, Naito, H, Ehara, H

Journal of the Saudi Society of Agricultural Sciences 19 巻 ( 1 ) 頁： 37 - 42 2018年5月

記述言語：英語掲載種別：研究論文（学術雑誌）

Photosynthetic performance of sago palm (Metroxylon sagu Rottb.) was evaluated in normal and waterlogged conditions. Net assimilation rate (AN), light response curve of net assimilation rate (AN/I) and pulse-amplitude modulation fluorescence vs. irradiance (PAM/I), leaf water potential, leaf chlorophyll content and leaflet area were measured. AN was higher in a particular period of waterlogging than in the normal condition. However, prolonged waterlogging (more than two months) negatively affected sago palm photosynthetic capacity. This was indicated by reduction in several photosynthetic parameters such as AN, maximum value of AN obtained at maximum irradiance (AN (Imax)), quantum yield at zero to 200 µmol m−2 s−1 irradiance (ϕ(Io_I200)), asymptotic photosynthetic efficiency (αo), and maximum electron transport rate (ETRmax). The plants experiencing waterlogging produced high qNmax and NPQmax values. Prolonged waterlogging period also caused significant reduction in leaf water potential (ψleaf) and photosynthetic pigments content. Normal soil conditions with a sufficient amount of water are preferable in order for the plant to generate higher photosynthetic capacity and facilitate stable sago production.

DOI： 10.1016/j.jssas.2018.05.004

Photosynthesis of Sago Palm (Metroxylon sagu Rottb.) Seedling at Different Air Temperatures 査読有り国際共著国際誌

Azhar Aidil, Makihara Daigo, Naito Hitoshi, Ehara Hiroshi

AGRICULTURE-BASEL 8 巻 ( 1 ) 2018年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

Photosynthetic activities of the sago palm (Metroxylon sagu Rottb.) were studied to find out its sensitivity to changes in ambient air temperature. The minimum ambient air temperature designed for the experiment was 25–29 °C, while the higher end was 29–33 °C. Several photosynthetic parameters were studied to support our analysis in sago photosynthetic activity, including diurnal leaf gas exchange, assimilation rate vs. CO2 concentration, leaf greenness, leaf chlorophyll content, and photosynthetic rate vs. irradiance. We found that sago palm photosynthetic activity tends to be more sensitive to minimum than to maximum ambient air temperature. The plants exposed to higher air temperatures had dark green leaf color associated with higher rates of diurnal photosynthesis, chlorophyll content, and rubisco limited photosynthetic activity. They also exhibited higher trend in optimum irradiance absorption level. Consequently, maximum light energy dissipation occurred at higher temperatures.

DOI： 10.3390/agriculture8010004

Root plasticity under fluctuating soil moisture stress exhibited by backcross inbred line of a rice variety, Nipponbare carrying introgressed segments from KDML105 and detection of the associated QTLs 査読有り国際共著国際誌

Owusu-Nketia Stella, Inukai Yoshiaki, Ohashi Satomi, Rodriguez Suralta Roel, Doi Kazuyuki, Mitsuya Shiro, Kano-Nakata Mana, Manito Niones Jonathan, Dinh Thi Ngoc Nguyen, Takuya Kabuki, Makihara Daigo, Yamauchi Akira

PLANT PRODUCTION SCIENCE 21 巻 ( 2 ) 頁： 106 - 122 2018年

記述言語：英語掲載種別：研究論文（学術雑誌）

In rainfed lowland rice ecosystem, rice plants are often exposed to alternating recurrences of waterlogging and drought due to erratic rainfall. Such soil moisture fluctuation (SMF) which is completely different from simple or progressive drought could be stressful for plant growth, thereby causing reduction in yield. Root plasticity is one of the key traits that play important roles for plant adaptation under such conditions. This study aimed to evaluate root plasticity expression and its functional roles in dry matter production and yield under SMF using Nipponbare, KDML 105 and three backcross inbred lines (BILs) and to identify QTL(s) associated with root traits in response to SMF at two growth stages using Nipponbare/KDML105 F2 plants. A BIL, G3-3 showed higher shoot dry matter production and yield than Nipponbare due to its greater ability to maintain stomatal conductance concomitant with greater root system development caused by promoted production of nodal and lateral roots under SMF. QTLs were identified for total nodal root length, total lateral root length, total root length, number of nodal roots, and branching index under SMF at vegetative and reproductive stages. The QTLs detected at vegetative and reproductive stages were different. We discuss here that relationship between root system of G3-3 and the detected QTLs. Therefore, G3-3 and the identified QTLs could be useful genetic materials in breeding program for improving the adaptation of rice plants in target rainfed lowland areas.

DOI： 10.1080/1343943X.2018.1446759

Grain yield responses of lowland rice varieties to increased amount of nitrogen fertilizer under tropical highland conditions in central Kenya 査読有り国際共著国際誌

Njinju Symon M., Samejima Hiroaki, Katsura Keisuke, Kikuta Mayumi, Gweyi-Onyango Joseph P., Kimani John M., Yamauchi Akira, Makihara Daigo

PLANT PRODUCTION SCIENCE 21 巻 ( 2 ) 頁： 59 - 70 2018年

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Tropical highland conditions in Mwea Kenya, ensure the high radiation and the large day–night temperature differences. Such conditions are generally believed to promote rice growth and yield, but the current grain yield is lower than the expectation. In the current standard N fertilizer practice in Mwea, 75 kg nitrogen (N) ha−1 is applied in three splits at fixed timing. The effects of increases in N fertilizer amount (125, 175, and 225 kg N ha−1) on rice growth and yield were evaluated to test the hypothesis that unachieved high rice grain yield in Mwea is due to insufficient amount of N fertilizer. Two popular lowland varieties in Mwea (Basmati 370 and BW196) and two varieties reported as high yielding in other countries (Takanari and IR72) were used. Shoot dry weight (DW) increased with increases in the amount of N fertilizer applied in three splits at fixed timing, irrespective of variety. It reached approximately 20 t ha−1 under increased N conditions (>75 kg N ha−1) in several cases, indicating that high biomass production could be achieved by increasing N application rate. However, the increased biomass did not increase grain yield, due to decreased grain filling under high N conditions in all varieties. Thus, N amounts above 75 kg ha−1 were ineffective for increasing grain yields in Mwea, where N fertilizer was applied in three splits at fixed timing. Increasing influence of low temperature under high N conditions may be one of the reasons for the decreased grain filling in Mwea.

DOI： 10.1080/1343943X.2018.1436000

Effects of Slope-related Soil Properties on Upland Rice Growth and Yield under Slash-and-burn System in South Konawe Regency, Southeast Sulawesi Province, Indonesia 査読有り国際共著国際誌

KIKUTA Mayumi, YAMAMOTO Yoshinori, PASOLON Yulius Barra, REMBON Fransiscus Suramas, MIYAZAKI Akira, MAKIHARA Daigo

Tropical Agriculture and Development 62 巻 ( 2 ) 頁： 60 - 67 2018年

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：日本熱帯農業学会

This study examined how slope-related soil physicochemical properties affect the growth and yield of upland rice subjected to slash-and-burn. The yield survey and soil analysis were performed at a hillside farm in Southeast Sulawesi Province, Indonesia. Organic-C, total-N, available-P and exchangeable-Ca, Mg, and K tended to increase further down the slope, leading to greater rice growth and yield. The resultant yield increase was mainly attributable to higher spikelet number per square meter. Total-N explained variation in spikelet number per panicle, but not variation in grain yield. Among the tested soil physicochemical parameters, only organic-C was significantly and positively correlated with rice growth and yield. In addition, most other parameters increased with soil organic-C. These findings indicate that organic-C in the soil is important to the growth and yield of upland rice cultivated with slash-and-burn systems, although other complex relationships may exist between rice productivity, the environment, and agricultural management factors. Moreover, our results imply that position on a slope affect rice growth and yield.

DOI： 10.11248/jsta.62.60

Identification and validation of QTLs for cold tolerance at the booting stage and other agronomic traits in a rice cross of a Japanese tolerant variety, Hananomai, and a NERICA parent, WAB56-104 査読有り国際共著国際誌

Wainaina Cornelius Mbathi, Makihara Daigo, Nakamura Mitsuru, Ikeda Akihiro, Suzuki Taro, Mizukami Yuko, Nonoyama Toshihiro, Doi Kazuyuki, Kikuta Mayumi, Samejima Hiroaki, Menge Daniel Makori, Yamauchi Akira, Kitano Hidemi, Kimani John Munji, Inukai Yoshiaki

PLANT PRODUCTION SCIENCE 21 巻 ( 2 ) 頁： 132 - 143 2018年

記述言語：英語掲載種別：研究論文（学術雑誌）

In Africa, cold temperatures occur in the highlands of East and Southern Africa and in some areas of the Sahel region of West Africa leading to substantial rice yield losses. Cold tolerance (CT) at booting stage on basis of spikelet fertility after cold water irrigation was evaluated using F2 population derived from a cross between temperate japonica, Hananomai, and tropical japonica, WAB56-104. Two Quantitative trait loci (QTLs) for CT were detected on chromosome 8 and 10 with enhanced effects on the trait coming from Hananomai and WAB56-104 allele, respectively. The QTLs explained 30% and 33% of phenotypic variation in spikelet fertility, respectively. CT was negatively correlated with panicle number (r = −0.35, p < 0.01) and positively correlated with panicle weight (r = 0.61, p < 0.001). Selected BC1F4 and BC1F5 genotypes having homozygous alleles for both CT QTLs exhibited higher spikelet fertility under cold stress. The identified QTLs will be useful in the development of cold-tolerant varieties for production in high altitude areas through marker-assisted selection.

DOI： 10.1080/1343943X.2018.1440970

An Assessment of Paddy Production System in Central Kenya with Special Reference to Micronutrients 査読有り国際共著国際誌

Caroline A. Kundu, Masaya Ishii, Kuniaki Sato, Raphael K. Wanjogu, Daigo Makihara, Akira Yamauchi, Tsugiyuki Masunaga

Journal of Agricultural Science 9 巻頁： 49 - 63 2017年5月

Growth and yield responses of upland NERICAs to variable water management under field conditions 査読有り国際誌

Kikuta Mayumi, Makihara Daigo, Arita Naoya, Miyazaki Akira, Yamamoto Yoshinori

PLANT PRODUCTION SCIENCE 20 巻 ( 1 ) 頁： 36 - 46 2017年

記述言語：英語掲載種別：研究論文（学術雑誌）

This study aimed to investigate the possible causes for inconsistent performances of upland New Rice for Africa (NERICA) varieties in uplands and lowlands, while identifying important determinants in grain yield under deficient soil moisture. We compared the growth and yield of NERICA 1 and NERICA 5 to those of Yumenohatamochi, a Japanese upland variety, and Hinohikari, a Japanese lowland variety, subjected to different water management regimes (continually flooded, supplementary irrigation, and non-irrigation). Under conditions of deficient soil moisture, panicle number per square meter, spikelet number per panicle, and 1000-grain weight of NERICAs decreased, whereas the panicle number of the Japanese varieties experienced little change. In contrast, the grain filling ratio was unaffected by water management, irrespective of variety. The primary source of yield reduction under low soil water conditions was a decrease in spikelet number per panicle, and water stress intensity was the primary factor for the degree of this reduction. Variation in the abortion of secondary rachis-branches caused differences between NERICAs in their spikelet number response to soil moisture deficiency. The inconsistency in NERICA performance across uplands vs. lowlands can be partially attributed to variation in yield response to low soil water conditions. Moreover, water stress intensity and the presence of a water gradient along the vertical soil profile may combine to affect the fluctuation in NERICA performance under upland conditions.

DOI： 10.1080/1343943X.2016.1245102

東アフリカ高地を対象とした水管理による開花期の制御を通して低温ストレスを回避させうるイネ新栽培技術の開発査読有り国際共著国際誌

コーネリアスムバティワイナイナ，槇原大悟，鮫島啓彰，菊田真由実，ダニエルマコリメンゲ，ジョンムンジキマニ，犬飼義明

農学国際協力 15 巻頁： 32 - 41 2017年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：名古屋大学農学国際教育研究センター

低温ストレスは、種子稔性の低下を通してイネの収量を大きく低下させる。低温の程度や継続期間は年や季節によって異なるため、最も気温が低下する時期を回避して開花させうる新技術の開発が求められる。一般に、乾燥ストレスは出穂を遅延させる傾向があり、また根が浅く張る浅根性品種は軽微な乾燥ストレスに敏感に反応することが知られている。そこで本研究では、軽微な乾燥ストレス下で出穂期の遅延を示す突然変異体（T6-16）を選抜し、アフリカで有望視されているネリカ品種の反復親の1つであるWAB56-104と交配することで、本変異遺伝子の有用性を評価した。F2個体群のうち、変異体型個体の出穂日は軽微な乾燥ストレス下で平均11日間遅延する傾向を示した。特に3つのF2個体では、11〜17日間出穂日が遅延したが収量の低下は見られなかった。これらの結果は、浅根性に関わる遺伝子座の利用と軽微な灌水量の制限により、収量の減少を伴うことなく、最も厳しい低温期を回避して開花させうる新技術確立の可能性を示している。

DOI： 10.50907/jicad.15.0_32