記述言語：日本語   出版者・発行元：日本作物学会  

野外に生育する植物の葉のCO₂同化速度を評価する方法は，専用のガス交換測定装置を持ち運び，測定対象葉を同化箱に挟んで数分間の待機を繰り返すことが一般的である．これには時間，労力，コストを要するため，1度の実験で測定できるサンプル数には限りがあった．そこで筆者らは，新型の赤外線ガス分析機構を搭載した新たなCO₂同化速度測定装置MIC-100を開発した．閉鎖系測定装置であるMIC-100は，一般的に使用される開放系測定装置に比べて葉1枚あたりの測定時間を約1/7に短縮し，かつ強光条件下では開放系測定装置と同様の測定値を示した．さらに筆者らは，野外圃場で栽培したイネの光合成測定をより簡便化・迅速化するため，アシストスーツによる測定者の身体的負担の軽減策ならびに市販のドキュメントスキャナを利用した効率的な葉面積計測手法を考案した．これら一連の測定システムによって過去に例を見ない大規模な光合成測定実験が可能となり，イネ遺伝資源の多様性解析や多数のイネ系統の時系列解析などを実施できるようになった．MIC-100とその関連技術は，様々な植物の光合成研究や，作物の生育管理等へ活用されることが期待される．

DOI： 10.1626/jcs.92.289

CiNii Books

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その他リンク： https://ndlsearch.ndl.go.jp/books/R000000004-I033254766

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.34133/plantphenomics.0073

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記述言語：日本語   出版者・発行元：日本作物学会  

DOI： 10.14829/jcsproc.255.0_132

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）  

Above-ground biomass (AGB) is an important indicator of crop productivity. Destructive measurements of AGB incur huge costs, and most non-destructive estimations cannot be applied to diverse cultivars having different canopy architectures. This insufficient access to AGB data has potentially limited improvements in crop productivity. Recently, a deep learning technique called convolutional neural network (CNN) has been applied to estimate crop AGB due to its high capacity for digital image recognition. However, the versatility of the CNN-based AGB estimation for diverse cultivars is still unclear. We established and evaluated a CNN-based estimation method for rice AGB using digital images with 59 diverse cultivars which were mostly in World Rice Core Collection. Across two years at two locations, we took 12,183 images of 59 cultivars with commercial digital cameras and manually obtained their corresponding AGB. The CNN model was established by using 28 cultivars and showed high accuracy (R2 = 0.95) to the test dataset. We further evaluated the performance of the CNN model by using 31 cultivars, which were not in the model establishment. The CNN model successfully estimated AGB when the observed AGB was lesser than 924 g m−2 (R2 = 0.87), whereas it underestimated AGB when the observed AGB was greater than 924 g m−2 (R2 = 0.02). This underestimation might be improved by adding training data with a greater AGB in further study. The present study indicates that this CNN-based estimation method is highly versatile and could be a practical tool for monitoring crop AGB in diverse cultivars.

DOI： 10.1080/1343943X.2023.2210767

Scopus

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記述言語：日本語   出版者・発行元：日本作物学会関東談話会  

DOI： 10.20768/jcskantod.38.0_56

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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）  

Photosynthetic induction, which is the response of the CO2 assimilation rate to a stepwise increase in light intensity, potentially affects plant carbon gain and crop productivity in field environments. Although natural variations in photosynthetic induction are determined by CO2 supply and its fixation, detailed factors, especially CO2 supply, are unclear. This study investigated photosynthesis at steady and non-steady states in three rice (Oryza sativa L.) genotypes: ARC 11094, Takanari and Koshihikari. Stomatal traits and water relations in the plants were evaluated to characterise CO2 supply. Photosynthetic induction in ARC 11094 and Takanari was superior to that in Koshihikari owing to an efficient CO2 supply. The CO2 supply in Takanari is attributed to its high stomatal density, small guard cell length and extensive root mass, whereas that in ARC 11094 is attributed to its high stomatal conductance per stoma and stomatal opening in leaves with insufficient water (i.e., anisohydric stomatal behaviour). Our results suggest that there are various mechanisms for realising an efficient CO2 supply during the induction response. These characteristics can be useful for improving photosynthetic induction and, thus, crop productivity in field environments in future breeding programmes.

DOI： 10.1111/ppl.13825

PubMed

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Informa UK Limited  

DOI： 10.1080/1343943x.2022.2103003

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media SA  

The culmination of conventional yield improving parameters has widened the margin between food demand and crop yield, leaving the potential yield productivity to be bridged by the manipulation of photosynthetic processes in plants. Efficient strategies to assess photosynthetic capacity in crops need to be developed to identify suitable targets that have the potential to improve photosynthetic efficiencies. Here, we assessed the photosynthetic capacity of the Japanese soybean mini core collection (GmJMC) using a newly developed high-throughput photosynthesis measurement system “MIC-100” to analyze physiological mechanisms and genetic architecture underpinning photosynthesis. K-means clustering of light-saturated photosynthesis (A_sat) classified GmJMC accessions into four distinct clusters with Cluster2 comprised of highly photosynthesizing accessions. Genome-wide association analysis based on the variation of A_sat revealed a significant association with a single nucleotide polymorphism (SNP) on chromosome 17. Among the candidate genes related to photosynthesis in the genomic region, variation in expression of a gene encoding G protein alpha subunit 1 (GPA1) showed a strong correlation (r = 0.72, p < 0.01) with that of A_sat. Among GmJMC accessions, GmJMC47 was characterized by the highest A_sat, stomatal conductance (g_s), stomatal density (S_Density), electron transfer rate (ETR), and light use efficiency of photosystem II (Fv’/Fm′) and the lowest non-photochemical quenching [NPQ(t)], indicating that GmJMC47 has greater CO₂ supply and efficient light-harvesting systems. These results provide strong evidence that exploration of plant germplasm is a useful strategy to unlock the potential of resource use efficiencies for photosynthesis.

DOI： 10.3389/fpls.2022.910527

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担当区分：最終著者,　責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

Abstract

Under field environments, fluctuating light conditions induce dynamic photosynthesis, which affects carbon gain by crop plants. Elucidating the natural genetic variations among untapped germplasm resources and their underlying mechanisms can provide an effective strategy to improve dynamic photosynthesis and, ultimately, improve crop yields through molecular breeding approaches. In this review, we first overview two processes affecting dynamic photosynthesis, namely (i) biochemical processes associated with CO2 fixation and photoprotection and (ii) gas diffusion processes from the atmosphere to the chloroplast stroma. Next, we review the intra- and interspecific variations in dynamic photosynthesis in relation to each of these two processes. It is suggested that plant adaptations to different hydrological environments underlie natural genetic variation explained by gas diffusion through stomata. This emphasizes the importance of the coordination of photosynthetic and stomatal dynamics to optimize the balance between carbon gain and water use efficiency under field environments. Finally, we discuss future challenges in improving dynamic photosynthesis by utilizing natural genetic variation. The forward genetic approach supported by high-throughput phenotyping should be introduced to evaluate the effects of genetic and environmental factors and their interactions on the natural variation in dynamic photosynthesis.

DOI： 10.1093/jxb/erac100

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その他リンク： https://academic.oup.com/jxb/article-pdf/73/10/3109/43802194/erac100.pdf

担当区分：最終著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

DOI： 10.1111/ppl.13603

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その他リンク： https://onlinelibrary.wiley.com/doi/full-xml/10.1111/ppl.13603

担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

Photosynthesis occurs mainly in plant leaves and is a fundamental process in the global carbon cycle and in crop production. The exploitation of natural genetic variation in leaf photosynthetic capacity is a promising strategy to meet the increasing demand for crops. The present study reports the newly developed photosynthesis measurement system 'MIC-100,' with a higher throughput for measuring instantaneous photosynthetic rate in the field. MIC-100 is established based on the closed system and directly detects the CO2 absorption in the leaf chamber. The reproducibility, accuracy, and measurement throughput of MIC-100 were tested using soybean (Glycine max L. (Merr.)) and rice (Oryza sativa L.) grown under field conditions. In most cases, the coefficient of variance (CV) for repeated-measurements of the same leaf was less than 0.1. The photosynthetic rates measured with the MIC-100 model showed a significant correlation (R2 = 0.93-0.95) with rates measured by a widely used gas-exchange system. The measurement throughput of the MIC-100 is significantly greater than that of conventional open gas-exchange systems under field conditions. Although MIC-100 solely detects the instantaneous photosynthetic rate under a given environment, this study demonstrated that the MIC-100 enables the rough evaluation of leaf photosynthesis within the large-scale plant populations grown in the field.

DOI： 10.1071/FP21029

PubMed

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

DOI： 10.1016/j.biosystemseng.2021.01.016

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担当区分：最終著者   出版者・発行元：Authorea, Inc.  

<p id="p1">Drought stress is a major limiting factor for crop growth and yield.
Water availability in the field can cyclically change between drought
and rewatering conditions, depending on precipitation patterns.
Concurrently, light intensity under field conditions can fluctuate,
inducing dynamic photosynthesis and transpiration during crop growth
period. The present study aimed to characterize carbon gain and water
use in fluctuating light under drought and rewatering conditions by
conducting gas exchange measurements in two major crops, namely rice and
soybean. In both crops, drought stress reduced steady-state
photosynthesis and/or photosynthetic capacity, and delayed
photosynthetic induction even when it had relatively small impact on
photosynthetic capacity, suggesting that the drought effects on
photosynthesis should be evaluated based on induction, maximum, and
steady states. This delayed photosynthetic induction resulted in a
substantial loss of carbon gain under fluctuating light conditions,
which can be a limiting factor for crop growth and yield in the field.
Meanwhile, rewatering after drought conditions completely recovered
photosynthetic capacity and induction in both crops, whereas drought
experience would be memorized to slow down the stomatal opening.
Therefore, the stability of photosynthetic induction can be a promising
target to improve drought tolerance during crop breeding in the future.

DOI： 10.22541/au.161281464.49728392/v1

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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：Informa UK Limited  

The enhancement of leaf photosynthesis is an enticing aspect for increasing crop seed yield. Using wild-related species in soybean breeding can be a potential source to enhance leaf photosynthesis. Two backcross-derived progenies of soybean (Glycine max) withGlycine tomentellaHayata were evaluated in terms of gas exchange, biomass, and seed yield. The gas exchange parameters along with Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) content, and leaf nitrogen content (LNC) were measured from flowering stage up to seed initiation stage. Results revealed significant increases ofnet photosynthetic rate (P-n), mesophyll activity(P-n/C-i), seed yield, and total aboveground dry weight (TDW) in progenies relative to Dwight. We observed significantly higher specific leaf weight (SLW) in progenies and was strongly correlated withP(n)(r = 0.86***). There was no significant difference between Dwight and the progenies instomatal conductance(g(s)), but Dwight, in fact, had higherintercellular CO(2)concentrations(C-i). It indicates that increases inP(n)were associated with improvedP(n)/C-i. These findings suggest the potential use of soybean wild relatives in breeding to enhance soybean leaf photosynthesis.

DOI： 10.1080/1343943x.2020.1807369

Web of Science

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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）   出版者・発行元：Frontiers Media SA  

Stomatal density (SD) is closely associated with photosynthetic and growth characteristics in plants. In the field, light intensity can fluctuate drastically within a day. The objective of the present study is to examine how higher SD affects stomatal conductance (g
s
) and CO2 assimilation rate (A) dynamics, biomass production and water use under fluctuating light. Here, we compared the photosynthetic and growth characteristics under constant and fluctuating light among three lines of Arabidopsis thaliana (L.): the wild type (WT), STOMAGEN/EPFL9-overexpressing line (ST-OX), and EPIDERMAL PATTERNING FACTOR 1 knockout line (epf1). ST-OX and epf1 showed 268.1 and 46.5% higher SD than WT (p < 0.05). Guard cell length of ST-OX was 10.0% lower than that of WT (p < 0.01). There were no significant variations in gas exchange parameters at steady state between WT and ST-OX or epf1, although these parameters tended to be higher in ST-OX and epf1 than WT. On the other hand, ST-OX and epf1 showed faster A induction than WT after step increase in light owing to the higher g
s
under initial dark condition. In addition, ST-OX and epf1 showed initially faster g
s
induction and, at the later phase, slower g
s
induction. Cumulative CO2 assimilation in ST-OX and epf1 was 57.6 and 78.8% higher than WT attributable to faster A induction with reduction of water use efficiency (WUE). epf1 yielded 25.6% higher biomass than WT under fluctuating light (p < 0.01). In the present study, higher SD resulted in faster photosynthetic induction owing to the higher initial g
s
. epf1, with a moderate increase in SD, achieved greater biomass production than WT under fluctuating light. These results suggest that higher SD can be beneficial to improve biomass production in plants under fluctuating light conditions.

DOI： 10.3389/fpls.2020.589603

PubMed

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Informa UK Limited  

DOI： 10.1080/1343943x.2020.1777878

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers Media SA  

Plants in the field experience dynamic changes of sunlight rather than steady-state irradiation. Therefore, increasing the photosynthetic rate of an individual leaf under fluctuating light is essential for improving crop productivity. The high-yieldingindicarice (Oryza sativaL.) cultivar Takanari is considered a potential donor of photosynthesis genes because of its higher steady-state photosynthesis at both atmospheric and elevated CO(2)concentrations than those of several Japanese commercial cultivars, including Koshihikari. Photosynthetic induction after a sudden increase in light intensity is faster in Takanari than in Koshihikari, but whether the daily carbon gain of Takanari outperforms that of Koshihikari under fluctuating light in the field is unclear. Here we report that Takanari has higher non-steady-state photosynthesis, especially under low nitrogen (N) supply, than Koshihikari. In a pot experiment, Takanari had greater leaf carbon gain during the initial 10 min after a sudden increase in irradiation and higher daily CO(2)assimilation under simulated natural fluctuating light, at both atmospheric (400 ppm) and elevated (800 ppm) CO(2)concentrations. The electron transport rate during a day under field conditions with low N supply was also higher in Takanari than in Koshihikari. Although the advantages of Takanari were diminished under high N supply, photosynthetic N use efficiency was consistently higher in Takanari than in Koshihikari, under both low and high N supply. This study demonstrates that Takanari is a promising donor parent to use in breeding programs aimed at increasing CO(2)assimilation in a wide range of environments, including future higher CO(2)concentrations.

DOI： 10.3389/fpls.2020.01308

Web of Science

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担当区分：責任著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Crop Science Society of Japan  

DOI： 10.1626/jcs.89.218

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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）  

There is a large variation in CO2 assimilation rate per unit of leaf area (A) within or among crop species, which can be exploited to improve A by elucidating the mechanisms underlying such variation. The objective of the present study is to elucidate the genetic factors affecting the variation in leaf photosynthetic capacity among soybeans. Here, we conducted field experiments over three years, using Enrei, a leading variety in Japan, Peking, a landrace from China and the chromosome segment substitution lines derived from their progenies. The gas exchange measurements were conducted to evaluate A among soybean. Peking showed higher A than Enrei after the flowering in all the years. The genetic analysis identified two novel quantitative trait loci (QTLs) related to variation in A, which were located on chromosome 13 (qLPC13) and 20 (qLPC20). The Peking allele at qLPC13 increased A by 8.3 % in the Enrei genetic background, while the Peking allele at qLPC20 decreased A by 15.3 %. The present study is the first report on QTLs affecting a genotypic variation in leaf photosynthetic capacity among field-grown soybeans. The identification of the causal genes in these QTLs can provide a novel strategy to enhance leaf photosynthetic capacity with soybean breeding.

DOI： 10.1016/j.plantsci.2019.110300

PubMed

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1093/jxb/erz304

Web of Science

PubMed

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その他リンク： http://academic.oup.com/jxb/article-pdf/70/19/5287/30152701/erz304.pdf

担当区分：筆頭著者,　責任著者  

DOI： 10.1016/j.pbi.2019.04.010

PubMed

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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）  

DOI： 10.1038/s41598-019-44127-0

PubMed

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担当区分：最終著者  

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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）  

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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：SPRINGER  

Irradiance continuously fluctuates during the day in the field. The speed of the induction response of photosynthesis in high light affects the cumulative carbon gain of the plant and could impact growth and yield. The photosynthetic induction response and its relationship with the photosynthetic capacity under steady-state conditions (P (max)) were evaluated in 37 diverse soybean [Glycine max (L.) Merr.] genotypes. The induction response of leaf photosynthesis showed large variation among the soybean genotypes. After 5 min illumination with strong light, genotype NAM23 had the highest leaf photosynthetic rate of 33.8 A mu mol CO2 m(-2) s(-1), while genotype NAM12 showed the lowest rate at 4.7 A mu mol CO2 m(-2) s(-1). Cumulative CO2 fixation (CCF) during the first 5 min of high light exposure ranged from 5.5 mmol CO2 m(-2) for NAM23 to 0.81 mmol CO2 m(-2) for NAM12. The difference in the induction response among genotypes was consistent throughout the growth season. However, there was no significant correlation between CCF and P (max) among genotypes suggesting that different mechanisms regulate P (max) and the induction response. The observed variation in the induction response was mainly attributed to ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activation, but soybean lines differing in the induction response did not differ in the leaf content of Rubisco activase alpha- and beta-proteins. Future studies will be focused on identifying molecular determinants of the photosynthetic induction response and determining whether this trait could be an important breeding target to achieve improved growth of soybeans in the field.

DOI： 10.1007/s11120-016-0323-1

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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：CROP SCIENCE SOC AMER  

Enhancement of leaf photosynthetic capacity can lead to greater biomass productivity in crop plants. Targets for improving leaf photosynthetic capacity in soybean [Glycine max (L.) Merr.], however, remain to be elucidated. The objective of this study was to identify the physiological and morphological factors underlying the diverse photosynthetic capacities of different soybean genotypes. Light-saturated CO2 assimilation rates ranged from 18.1 to 27.6. mol m(-2) s(-1) under controlled conditions among 34 genotypes. PI 594409 A (Line no. 13) and PI 603911 C (Line no. 14) showed extremely high photosynthetic rates. Line no. 14 consistently showed greater photosynthetic rates than other lines under field conditions and reached 34.8. mol m(-2) s(-1), which was 11% greater than that of a reference genotype, Tachinagaha. The analysis of the CO2 response curve of Line no. 14 showed greater CO2 fixation activity, represented by the maximum rates of carboxylation (Vc(max)) and electron transport (J(max)). The leaf ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) content of Line no. 14 tended to be higher than that of other lines, which is suggested to contribute to high CO2 fixation activity. We attribute the high photosynthetic capacity that was observed among soybean genotypes to high CO2 fixation activity.

DOI： 10.2135/cropsci2016.02.0122

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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：WILEY-BLACKWELL  

Crop leaves are subject to continually changing light levels in the field. Photosynthetic efficiency of a crop canopy and productivity will depend significantly on how quickly a leaf can acclimate to a change. One measure of speed of response is the rate of photosynthesis increase toward its steady state on transition from low to high light. This rate was measured for seven genotypes of soybean [ Glycine max ( L.) Merr.]. After 10 min of illumination, cultivar `UA4805' ( UA) had achieved a leaf photosynthetic rate ( Pn) of 23.2 mu mol center dot m-2 center dot s-1, close to its steady- state rate, while the slowest cultivar `Tachinagaha' ( Tc) had only reached 13.0 mu mol center dot m - 2 center dot s - 1 and was still many minutes from obtaining steady state. This difference was further investigated by examining induction at a range of carbon dioxide concentrations. Applying a biochemical model of limitations to photosynthesis to the responses of Pn to intercellular CO2 concentration ( Ci), it was found that the speed of apparent in vivo activation of ribulose- 1: 5- bisphosphate carbo xylase/ oxygenase ( Rubisco) was responsible for this difference. Sequence analysis of the Rubisco activase gene revealed single nucleotide polymorphisms that could relate to this difference. The results show a potential route for selection of cultivars with increased photosynthetic efficiency in fluctuating light.

DOI： 10.1111/pce.12674

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Taylor and Francis Ltd.  

The difference in yields of cultivars may be causing difference in soybean yield between Japan and the USA. The objective of this study was to identify the effect of the cultivar on dry matter production and to reveal the key factors causing the differences in yield by focusing utilization of solar radiation in recent Japanese and US soybean cultivars. Field experiments were conducted during two seasons in Takatsuki, Japan (34°50′), and in a single season in Fayetteville (36°04′), AR, USA. Five Japanese and 10 US cultivars were observed under near-optimal conditions in order to achieve yields as close to their physiological potential as possible. The seed yield and total aboveground dry matter (TDM) were measured at maturity as long as radiation was intercepted by the canopy. The seed yield ranged from 3.10t ha−1 to 5.91t ha−1. Throughout the three environments, the seed yield of US cultivars was significantly higher than that of Japanese cultivars. The seed yield correlated with the TDM rather than the HI with correlation coefficients from.519 to.928 for the TDM vs..175 to.800 for the HI, for each of the three environments. The higher TDM of US cultivars was caused by a higher radiation use efficiency rather than higher total intercepted radiation throughout the three environments. The seasonal change in the TDM observed in four cultivars indicated that dry matter productivity was different between cultivars, specifically during the seed-filling period.

DOI： 10.1080/1343943X.2015.1133235

CiNii Article

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担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）  

DOI： 10.1626/jcs.85.339

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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：TAYLOR & FRANCIS LTD  

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.

DOI： 10.1080/1343943X.2016.1149037

Web of Science

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1626/pps.18.166

Web of Science

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.fcr.2015.06.010

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

We detected a QTL for single seed weight in soybean that was stable across multiple environments and genetic backgrounds with the use of two recombinant inbred line populations.
Single seed weight (SSW) in soybean is a key determinant of both seed yield and the quality of soy food products, and it exhibits wide variation. SSW is under genetic control, but the molecular mechanisms of such control remain unclear. We have now investigated quantitative trait loci (QTLs) for SSW in soybean and have identified such a QTL that is stable across multiple environments and genetic backgrounds. Two populations of 225 and 250 recombinant inbred lines were developed from crosses between Japanese and US cultivars of soybean that differ in SSW by a factor of similar to 2, and these populations were grown in at least three different environments. A whole-genome panel comprising 304 simple sequence repeat (SSR) loci was applied to mapping in each population. We identified 15 significant QTLs for SSW dispersed among 11 chromosomes in the two populations. One QTL located between Sat_284 and Sat_292 on chromosome 17 was detected (3.6 &lt; LOD &lt; 14.1) in both populations grown in all environments. This QTL, tentatively designated qSw17-1, accounted for 9.4-20.9 % of phenotypic variation in SSW, with a dominant allele being associated with increased SSW. Given its substantial effect on SSW, qSw17-1 is an attractive target for positional cloning, and SSR markers closely associated with this locus may prove useful for marker-assisted selection for SSW control in soybean.

DOI： 10.1007/s00122-014-2304-0

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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：TAYLOR & FRANCIS LTD  

Single-leaf photosynthesis is a fundamental process in plant biomass production, and is a major research topic in crop physiology This paper reviews the recent achievements of research on the physiological determinants of the photosynthetic capacity from the perspective of energy flow and CO2 diffusion. Measurement of chlorophyll fluorescence is a popular method to diagnose the function of photosystem II, and is useful to assess the susceptibility to photoinhibition and allocation of energy, which are keys to improving both stress resistance and photosynthetic productivity Mesophyll conductance (g(m)) is the conductance to CO2 diffusion from intercellular airspaces to the chloroplast, and was long thought to be determined by leaf anatomical properties. However, recent studies showed that environmental conditions affect g(m). It is possible that g(m) is affected by the gating of the CO2-permeable aquaporins (cooporins). Stomatal morphology is revealed to be an important factor affecting gas exchange both in crop plants and in Arabidapsis thaliana. The knowledge of the stomatal differentiation in Arabidopsis will be applicable to various crops. g(m), stomatal conductance (g(s)) and leaf nitrogen content are the main factors to cause difference in leaf photosynthesis among rice lines, and recent activities are conducted to find genes to manipulate these factors. Although the association of leaf photosynthesis with crop productivity still has a large 'missing link', these achievements strongly suggest that the leaf photosynthetic capacity can be genetically improved in crop species.

DOI： 10.1626/pps.17.111

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

Photosynthetic rate is determined by CO2 fixation and CO2 entry into the plant through pores in the leaf epidermis called stomata. However, the effect of increased stomatal density on photosynthetic rate remains unclear. This work investigated the effect of alteration of stomatal density on leaf photosynthetic capacity in Arabidopsis thaliana. Stomatal density was modulated by overexpressing or silencing STOMAGEN, a positive regulator of stomatal development. Leaf photosynthetic capacity and plant growth were examined in transgenic plants. Increased stomatal density in STOMAGEN-overexpressing plants enhanced the photosynthetic rate by 30% compared to wild-type plants. Transgenic plants showed increased stomatal conductance under ambient CO2 conditions and did not show alterations in the maximum rate of carboxylation, indicating that the enhancement of photosynthetic rate was caused by gas diffusion changes. A leaf photosynthesis-intercellular CO2 concentration response curve showed that photosynthetic rate was increased under high CO2 conditions in association with increased stomatal density. STOMAGEN overexpression did not alter whole plant biomass, whereas its silencing caused biomass reduction. Our results indicate that increased stomatal density enhanced leaf photosynthetic capacity by modulating gas diffusion. Stomatal density may be a target trait for plant engineering to improve photosynthetic capacity.

DOI： 10.1111/nph.12186

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CROP SCIENCE SOC AMER  

Leaf epidermal structure is an important determinant of leaf gas exchange in soybeans [Glycine max (L) Merr.] and can be used as an indirect criterion for the selection of gas exchange traits. The objective of this study was to assess the genetic variation of leaf morphology among soybean cultivars and to examine how U.S. and Japanese cultivars differ with respect to gas exchange. Over 70 cultivars, including U.S. and Japanese soybean, were grown in the field over 2 yr to determine stomatal density, guard cell length, and potential stomatal conductance, along with other morphological leaf traits. Among cultivars, stomatal density ranged from 148 to 334 mm(-2). Large variation was found in potential stomatal conductance (g(p)), which was closely associated with stomatal conductance in the field for representative genotypes (r = 0.89, P &lt; 0.01). United States cultivars had larger g(p) values than Japanese and other Asian cultivars. This potential may give a physiological and morphological basis for the greater productivity observed in U.S. cultivars. On the other hand, PI 416937 showed lower stomatal conductance, which is consistent with the ability to conserve water. This study indicates the importance of leaf structure in determining gas exchange and suggests that these characteristics may be optimized to enhance dry matter productivity and water use.

DOI： 10.2135/cropsci2010.02.0058

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：OXFORD UNIV PRESS  

The stem growth habit, determinate or indeterminate, of soybean, Glycine max, varieties affects various plant morphological and developmental traits. The objective of this study is to identify the effect of stem growth habit in soybean on the stomatal conductance of single leaves in relation to their leaf morphology in order to better understand the ecological and agronomic significance of this plant trait.
The stomatal conductance of leaves on the main stem was measured periodically under favourable field conditions to evaluate g(max), defined as the maximum stomatal conductance at full leaf expansion, for four varieties of soybean and their respective determinate or indeterminate near isogenic lines (NILs). Leaf morphological traits including stomatal density, guard cell length and vein density were also measured.
The value of g(max) ranged from 0 center dot 383 to 0 center dot 754 mol H(2)O m(-2) s(-1) across all the genotypes for both years. For the four pairs of varieties, the indeterminate lines exhibited significantly greater g(max), stomatal density, numbers of epidermal cells per unit area and total vein length per unit area than their respective determinate NILs in both years. The guard cell length, leaf mass per area and single leaf size all tended to be greater in the determinate types. The variation of g(max) across genotypes and years was well explained by the product of stomatal density and guard cell length (r = 0 center dot 86, P &lt; 0 center dot 01).
The indeterminate stem growth habit resulted in a greater maximum stomatal conductance for soybean than the determinate habit, and this was attributed to the differences in leaf structure. This raises the further hypothesis that the difference in stem growth habit results in different water use characteristics of soybean plants in the field. Stomatal conductance under favourable conditions can be modified by leaf morphological traits.

DOI： 10.1093/aob/mcp240

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担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CROP SCIENCE SOC AMER  

Understanding the relationships between leaf photosynthetic activity and physiological and morphological traits of soybeans [Glycine max. (L.) Merr.] with different stem growth habits could be exploited for yield improvement. Leaf photosynthetic rate (P-n), stomatal conductance (g(s)), leaf mass per unit area (LMA), and leaf nitrogen content per unit area (LNC) were measured for field-grown progeny of a cross between an indeterminate type, 'Stressland', and a determinate type, 'Tachinagaha', soybean. The P-n of the uppermost fully expanded leaves of Stressland was 19% greater than Tachinagaha during the first 20 d after seed filling (growth stage R5) in 2005. Among 18 F3 lines, P-n at 14 d after R5 in 2005 varied from 22.1 to 34.2 mu mol CO2 m(-2) s(-1) and was more strongly and significantly correlated with g(s) (P &lt; 0.01) than with LMA (P &lt; 0.05) and LNC (P = 0.11). In 2006, P-n of eight selected F-4 genotypes and the parents varied from 27.9 to 35.0 mu mol CO2 m(-2) s(-1). Leaf gas exchange activity of the selected lines was represented by two attributes; the maximum of g(s) (g(max)), and functional leaf lifespan (LL). Values of g(max) were positively correlated with stomatal density (r = 0.91, P &lt; 0.01), and LL was positively correlated with LMA (r = 0.89, P &lt; 0.01). Some indeterminate types had very high g(max) but exhibited shorter LL. Genetic improvement of maximum leaf photosynthesis appears possible by increasing stomatal density, and the DO locus for stem habit has a positive effect on soybean leaf photosynthesis, both in its maximum and duration.

DOI： 10.2135/cropsci2007.12.0707

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記述言語：日本語   出版者・発行元：日本作物学会  

DOI： 10.14829/jcsproc.253.0_75

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掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）  

DOI： 10.14829/jcsproc.253.0_56

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記述言語：日本語   出版者・発行元：日本作物学会関東支部  

DOI： 10.20768/jcskanto.35.0_30

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掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）  

DOI： 10.14829/jcsproc.248.0_159

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記述言語：日本語   出版者・発行元：日本作物学会  

DOI： 10.14829/jcsproc.247.0_65

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DOI： 10.14829/jcsproc.245.0_104

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DOI： 10.14829/jcsproc.243.0_116

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記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

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記述言語：英語   掲載種別：記事・総説・解説・論説等（国際会議プロシーディングズ）  

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記述言語：日本語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）   出版者・発行元：日本作物学会  

DOI： 10.14829/jcsproc.237.0_368

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記述言語：日本語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）   出版者・発行元：日本作物学会  

DOI： 10.14829/jcsproc.235.0_176

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記述言語：日本語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）   出版者・発行元：日本作物学会  

DOI： 10.14829/jcsproc.235.0_382

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記述言語：日本語   掲載種別：研究発表ペーパー・要旨（全国大会，その他学術会議）   出版者・発行元：日本作物学会  

DOI： 10.14829/jcsproc.235.0_380

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DOI： 10.14829/jcsproc.231.0.218.0

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DOI： 10.14829/jcsproc.230.0.102.0

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DOI： 10.14829/jcsproc.227.0.320.0

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記述言語：日本語   出版者・発行元：日本作物学会  

DOI： 10.14829/jcsproc.226.0.114.0

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記述言語：日本語   出版者・発行元：日本作物学会  

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