Kiyoshi Nagasuga

Mie University, Tu, Mie, Japan

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Publications (25)23.46 Total impact

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    ABSTRACT: Soybean plant growth during reproductive stage controls strongly seed yield. Two field experiments were conducted to analyze whether water condition improve soybean plant growth from flowering to the beginning of seed developing stage and which growth factors were related. One experiment was the comparison in plant growth between 2008, a wetter season, and 2009, a drier season. Crop growth rate (CGR) from flowering to beginning seed stage in 2008 was higher than that of 2009 and this was associated with higher mean leaf area index (LAI). Relative growth rate (RGR) in 2008 was as high as that of 2009 and this was associated with higher mean specific leaf area (SLA) in spite of lower net assimilation rate (NAR). The other was the irrigation experiment where we irrigated a half of experimental field during emergence to maturity. Although the differences between the treatments were smaller, CGR, LAI and mean SLA increased by irrigation. These results indicate that the improvement of soil water condition increased CGR with the increase in LAI and keep RGR by high SLA in spite of high total dry weight at flowering and lower NAR during reproductive stage.
    No preview · Article · Jan 2014 · Environmental Control in Biology
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    ABSTRACT: Light interception by leaves is crucial to crop production. In order to compare the light-intercepting characteristics of soybean 'Misato-zairai' (unstable yield) with those of 'Fukuyutaka' (stable yield), we cultivated these cultivars under the different soil water condition and measured the light extinction coefficient (K) with two different photometers. In 2010, 'Misato-zairai' had a higher proportion of upper-layer LAI and a significantly lower leaf inclination angle (closer to horizontal), but there was no difference in K between the cultivars. In 2011, irrigation increased LAI, but there was no difference in LAI between the cultivars. As before, 'Misato-zairai' had a significantly higher upper-layer LAI and a lower leaf inclination angle, but there was no difference in K. These suggested that unstable yield of 'Misato-zairai' should not be due to low light capture in spite of a higher proportion of upper-layer LAI and unerect leaflets.
    No preview · Article · Jan 2013 · Environmental Control in Biology
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    ABSTRACT: Leaflet inclination angle before paraheliotropism controls seed production of soybean plants. We examined the effect of water condition on the inclination angle of leaflets and petioles of two soybean cultivars. Angles measured in the morning were larger in 2008, a wetter season, than in 2009, a drier season. Angles were similarly larger in irrigated plants than in unirrigated plants. The imposition of drought stress on plants grown in pots reduced these angles with the decline in water content of these tissues. There were significant correlations between inclination angle and water content in leaflets and petioles of plants grown both in the field and in pots. These results indicate that water condition controls leaflet and petiole inclination.
    No preview · Article · Jan 2013 · Environmental Control in Biology
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    ABSTRACT: The effects of low air humidity and low root temperature (LRT) on water uptake, growth and aquaporin gene expression were investigated in rice plants. The daily transpiration of the plants grown at low humidity was 1.5- to 2-fold higher than that at high humidity. LRT at 13°C reduced transpiration, and the extent was larger at lower humidity. LRT also reduced total dry matter production and leaf area expansion, and the extent was again larger at lower humidity. These observations suggest that the suppression of plant growth by LRT is associated with water stress due to decreased water uptake ability of the root. On the other hand, the net assimilation rate was not affected by low humidity and LRT, and water use efficiency was larger for LRT. We found that low humidity induced coordinated up-regulation of many PIP and TIP aquaporin genes in both the leaves and the roots. Expression levels of two root-specific aquaporin genes, OsPIP2;4 and OsPIP2;5, were increased significantly after 6 and 13 d of LRT exposure. Taken together, we discuss the possibility that aquaporins are part of an integrated response of this crop to low air humidity and LRT.
    Full-text · Article · Jun 2012 · Plant and Cell Physiology
  • Kiyoshi NAGASUGA · Fumitake KUBOTA
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    ABSTRACT: The hydraulic acclimation of napiergrass (Pennisetum purpureum Schumach.) shoots to shading depends on that of stem. In this study, we measured the hydraulic and morphological properties of a stem segment (a node + an internode), node and internode of napiergrass and compared these properties among treatments to investigate the effect of shading on the hydraulic acclimation of stems. Plants were grown under shade conditions (30% of full sunlight) for 30 d (S plants), shade conditions for 24 d followed by full-sunlight conditions for 6 d (SF plants), or full sunlight for 30 d (control, C plants). The response of total hydraulic resistance (R) of stem segment was similar to that of internode, S plants showed the highest R and SF plants had an intermediate value between the other plants. Shading made internode long and narrow, resulting in the increase in R. In addition, normalizing internodal R by length and cross-sectional area (Rsp) was co-related with cross-sectional area. While, there was no significant difference in R of node among the treatments, Rsp was co-related with vascular bundle density. The response of R to light treatment in napiergrass stems depended on that of internode through the morphological changes.
    No preview · Article · Jan 2012 · Environmental Control in Biology
  • Kiyoshi Nagasuga · Mari Murai-Hatano · Tsuneo Kuwagata
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    ABSTRACT: Chilling is a major constraint in rice production in cool climates. In rice (Oryza saliva L.) plants, both the air temperature and the water (soil) temperature affect various growth processes independently, and low root zone temperature (thus, root temperature) can inhibit rice growth and yield. In this study, we investigated the effect of low root temperature on rice growth in relation to dry matter production and root water uptake. Plants were grown in hydroponic solutions at two temperatures, one equivalent to air temperature and the other 14 degrees C for 15 d starting 11 d after germination. Low temperature of the solution (low root temperature) inhibited dry matter production of rice plants by decreasing leaf area rather than photosynthetic rate. The response of leaf area was affected by changes in plant water status, that is relative water content (RWC) of stem was decreased by low root temperature resulting in reduced leaf area. The decrease in RWC caused by low root temperature was related to that in root hydraulic conductance (K-r). The responses of transpiration (E) and K-r to the low root temperature depended more on root surface area than on changes in hydraulic conductance per unit root surface area (Lp(r)). These results suggest that dry matter production under the low root temperature condition is controlled mainly by quantitative growth parameters such as leaf area and root surface area.
    No preview · Article · Jan 2011 · Plant Production Science
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    ABSTRACT: The hydraulic characteristics of plant organs and the absorption functions of roots of corn and tomato plants were analyzed by using a specialized high-pressure flowmeter (HPFM), which was equipped with a root chamber as well as a coupling to connect to the plant organs. The HPFM can detect changes in the hydraulic properties of the respective parts of the plant body. The hydraulic resistances of the leaf and root decreased with an increase in the water flow rate; this dependence was remarkable at low water flow rates. On the other hand, the hydraulic resistance of the stem was only slightly affected by the water flow. However, a positive linear relationship between hydraulic conductance (reciprocal of resistance) and water flow rate was found for the shoot, stem, and root, respectively. Further, the rate of nutrient (NO3-1) absorption by the root was evaluated from the water flow (root water absorption) and NO3- concentration in the xylem sap exuded from the root stump. The high-pressure flowmeter with the root chamber can be used for studying water and nutrient transport in plants and their responses to environmental elements.
    No preview · Article · Jan 2011 · Environmental Control in Biology
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    ABSTRACT: Seed yield, dry matter weight and light intercepting characteristics of the local soybean cultivar 'Misato-zairai' were compared with those of Fukuyutaka in 2008 and 2009. In Misato-zairai, seed yield was similar to, but seed/stem ratio was lower, and length and dry weight of stem were higher than in Fukuyutaka. Total dry weight just before maturity was heavier in Misatozairai in both years, and the difference was distinct after flowering in 2008. The crop growth rate of Misato-zairai during one month after flowering varied with the year, but that during the succeeding one month was higher in Misato-zairai in both years. The leaf area index was higher in Misato-zairai in both years. In Misato-zairai, leaf area was concentrated above 60cm from the ground and the leaves were drooped, but the light extinction coefficient was similar to that in Fukuyutaka. Seed yield of Misatozairai was high in the middle layer, 40-60cm above the ground, and decreased in lower layers. On the other hand, seed yield of Fukuyutaka increased in lower layers and was highest at 20 - 40 cm from the ground. These results suggested that high seed yield of Misato-zairai was resulted from large leaf area in the higher layer of canopy and high light extinction coefficient as in Fukuyutaka.
    No preview · Article · Jan 2011 · Japanese Journal of Crop Science

  • No preview · Article · Dec 2009 · Cryobiology
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    ABSTRACT: The role of root temperature T(R) in regulating the water-uptake capability of rice roots and the possible relationship with aquaporins were investigated. The root hydraulic conductivity Lp(r) decreased with decreasing T(R) in a measured temperature range between 10 degrees C and 35 degrees C. A single break point (T(RC) = 15 degrees C) was detected in the Arrhenius plot for steady-state Lp(r). The temperature dependency of Lp(r) represented by activation energy was low (28 kJ mol(-1)) above T(RC), but the value is slightly higher than that for the water viscosity. Addition of an aquaporin inhibitor, HgCl(2), into root medium reduced osmotic exudation by 97% at 25 degrees C, signifying that aquaporins play a major role in regulating water uptake. Below T(RC), Lp(r) declined precipitously with decreasing T(R) (E(a) = 204 kJ mol(-1)). When T(R) is higher than T(RC), the transient time for reaching the steady-state of Lp(r) after the immediate change in T(R) (from 25 degrees C) was estimated as 10 min, while it was prolonged up to 2-3 h when T(R) < T(RC). The Lp(r) was completely recovered to the initial levels when T(R) was returned back to 25 degrees C. Immunoblot analysis using specific antibodies for the major aquaporin members of PIPs and TIPs in rice roots revealed that there were no significant changes in the abundance of aquaporins during 5 h of low temperature treatment. Considering this result and the significant inhibition of water-uptake by the aquaporin inhibitor, we hypothesize that the decrease in Lp(r) when T(R) < T(RC) was regulated by the activity of aquaporins rather than their abundance.
    Full-text · Article · Aug 2008 · Plant and Cell Physiology
  • Kiyoshi Nagasuga · Fumitake Kubota

    No preview · Article · Jul 2008 · Plant Production Science
  • Kensaku Suzuki · Kiyoshi Nagasuga · Masumi Okada
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    ABSTRACT: Root temperature is found to be a very important factor for leaves to alter the response and susceptibility to chilling stress. Severe visible damage was observed in the most active leaves of seedlings of a japonica rice (Oryza sativa cv. Akitakomachi), e.g. the third leaf at the third-leaf stage, after the treatment where only leaves but not roots were chilled (L/H). On the other hand, no visible damage was observed after the treatment where both leaves and roots were chilled simultaneously (L/L). The chilling injury induced by L/H, a novel type of chilling injury, required the light either during or after the chilling in order to develop the visible symptoms such as leaf bleaching and tissue necrosis. Chlorophyll fluorescence parameters measured after various lengths of chilling treatments showed that significant changes were induced before the visible injury. The effective quantum yield and photochemical quenching of PSII dropped dramatically within 24 h in both the presence and absence of a 12 h light period. The maximal quantum yield and non-photochemical quenching of PSII decreased significantly only in the presence of light. On the other hand, L/H chilling did not affect the function of PSI, but caused a significant decrease in the electron availability for PSI. These results suggest that the leaf chilling with high root temperature destroys some component between PSII and PSI without the aid of light, which causes the over-reduction of PSII in the light, and thereby the visible injury is induced only in the light.
    No preview · Article · Apr 2008 · Plant and Cell Physiology
  • K. Suzuki · K. Nagasuga · M. Okada

    No preview · Article · Mar 2007 · Plant and Cell Physiology
  • Kiyoshi Nagasuga · Fumitake Kubota
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    ABSTRACT: Acclimation to light condition is associated with change in water transport system in napiergrass. In this study, the effects of shading on shoot hydraulic resistance and morphology of napiergrass (Pennisetum purpureum Schumach.) were investigated. In the plants under shading (to 30% of full sunlight) for 30 days (S plants), total hydraulic resistance of a shoot (R-shoot) increased from that of full sunlight (control). In the plants grown under shade condition for 24 d followed by full sunlight conditions for 6 d (SF), the R-shoot value was intermediate between that of control and S plants. A similar response to shading was found in total hydraulic resistance of a stem (R-stem), which accounted for more than 60% of R-shoot, but the total hydraulic resistance of the leaves was not significantly affected by shading. Leaf length, leaf area and stem length were larger, but the stem cross-sectional area (SA) was smaller in S and SF plants than in the control plants. SF plants showed similar leaf length, leaf area and stem length to those in S plants, but the SA in SF plants was slightly larger. Normalization of R-stem by SA and stem length decreased the difference among the treatments, indicating the increase of R-shoot and R-stem under shading resulted from the decrease of SA and the increase of stem length.
    No preview · Article · Oct 2006 · Plant Production Science
  • K. Nagasuga · F. Kubota
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    ABSTRACT: Recovery of dry-matter production after drought stress is an important factor of drought resistance in plants. Napiergrass, whose dry matter weight largely decreased by soil drought treatment, increased dry-matter weight vigorously under the well-watered soil condition. In this study, the changes in total dry-matter weight (TDW), leaf area (LA) and photosynthetic rate (Pn) in napiergrass during and after the soil drought treatment were compared with those in maize grown in the same pots to clarify whether TDW of napiergrass quickly recovered after the soil drought treatment. In maize plants, TDW and LA during six days soil drought were as high as those in the control plants. Plant growth rate (PGR), relative growth rate (RGR) and net assimilation rate (NAR) under soil drought treatment remained as high as those in the control plants, but decreased to approximately 50% of that in the control plants after re-watering. In napiergrass, on the other hand, TDW and LA decreased under six days soil drought treatment to 70% and 30%, respectively, of control. However, LA increased to 50% of that in the control plants at the 6th day after re-watering. NAR did not decrease under drought stress though PGR and RGR decreased. Pn decreased slowly under soil drought condition but recovered quickly after re-watering. The increase in TDW was slight, but LA and Pn quickly recovered within six days after drought treatment.
    No preview · Article · Jan 2006 · Japanese Journal of Crop Science
  • K. Nagasuga · F. Kubota
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    ABSTRACT: The hydraulic resistances of each organ in napiergrass and maize shoots were measured with a pressure flow meter. The results obtained were as follows: 1) Hydraulic resistances of the shoot, leaf and stem, R shoot, R leaf and R stem, respectively, in napiergrass were significantly higher than those in maize. Particularly, R stem in napiergrass was about four-fold larger than that in maize. 2) The cross sectional area of a stem (SA) was smaller in napiergrass than in maize, and the difference between napiergrass and maize in R stem normalized by SA (R Sstem) was smaller than that in R stem However, R Sstem in napiergrass was still about two-fold larger than that in maize, indicating that napiergrass has a higher hydraulic resistance in the stem due to the synergistic effect of these two factors. 3) The hydraulic resistance of a stem was divided into three components, the resistance toward the leaf sheath of the nodal stem (r r), the resistance toward the stem apex of the nodal stem (r a) and the resistance of the inter-nodal stem (r in). Both r r and r a were high in napiergrass and the difference between napiergrass and maize was particularly large in r r. These results suggested that a high R Sstem in napiergrass was related with the water transport through the nodal stem. It was considered that a small stem diameter and high hydraulic resistance of nodal stem would result in a high resistance to water flow in napiergrass stem.
    No preview · Article · Jun 2005 · Japanese Journal of Crop Science
  • K. Nagasuga
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    ABSTRACT: The characteristics of economical water transport in napiergrass were investigated with respect to water transport regulation by the nodal stem and a water storage capacity (WSC), partly compensation for transpiration with water in the plant. Changes in leaf photosynthesis after plant excisions suggested that water transport to the leaves was mainly regulated by the nodal stem in the morning and the stem base regulated instead in the afternoon. Contrary to Plant transpiration rate (PTr), water absorption rate by roots (SF) increased slowly and leaf water potential (ψleaf) decreased in the morning. However, because of SF increase, ψleaf gradually recovered in the afternoon. It was considered that water conditions would be related to the change in regulating position. Gap of diurnal changes in two parameters suggested WSC could contribute to maintenance of PTr, and it was estimated that WSC compensated 8% of total PTr. On the other hand, WSC of pot-cultivated plant was estimated to be 3% and WSC in stem was higher than that of leaf from the relationship between PTr and decrease in water content of plant parts. It was considered that these were involved in controlling water balance in napiergrass.
    No preview · Article · Oct 2004 · Journal- Faculty of Agriculture Kyushu University
  • K. Nagasuga · F. Kubota · C.-E. Nishiyama
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    ABSTRACT: The specific difference in water transport regulation in a plant was investigated by the plant excision diagnosis (PED) using two C4 plant species, napiergrass, Pennisetum purpureum Schumach. and maize, Zea Mays L. Under the full sunlight condition, the water transport to a leaf in napiergrass was regulated by the stem node connected to the leaf, whereas in maize the stem base functioned as a strong regulator of the water transport from roots to the stem and leaves. Unlike this evidence, the water transport in shade-grown napiergrass was regulated at the stem base, not at the individual stem nodes, and such a regulating position or organ was not identified in maize grown in shade. As compared with maize, napiergrass is likely capable of doing a fine regulation of water transport according to the different growth conditions. Napiergrass is possible to perform a large production through a more efficient water distribution and utilization in a plant.
    No preview · Article · Oct 2002 · Journal- Faculty of Agriculture Kyushu University
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    ABSTRACT: In order to elucidate stomatal response to wind, leaf gas exchange and stomatal conductance in an intact leaf of cucumber plants (Cucumis sativus L.) were measured under different conditions of air current and humidity. A leaf gas exchange cuvette was improved for individual measurements on the abaxial and adaxial leaf surfaces and for adjustment of the leaf boundary air current, where leaf boundary layer conductance can be adjusted at a desired value within a range from 0.3mol m^<-2>s^<-1> to 1.0mol m^<-2>s^<-1>. Rates of leaf gas exchange and stomatal conductance were higher on the abaxial surface than on the adaxial surface. Stomatal response to wind was appeared more sensitive on the abaxial surface, while leaf gas exchange and stomatal conductance on the adaxial surface was scarcely affected by wind. Under the humid air condition, increase in leaf boundary layer conductance significantly enhanced stomatal conductance as well as rates of transpiration and photosynthesis on the abaxial surface. On the other hand, under the dry air condition, stomatal conductance was depressed by increase in leaf boundary layer conductance with little effect on transpiration and photosynthesis. These opposite changes in stomatal conductance found under the humid and dry air conditions were proved visually as change in stomatal aperture by the microscopic observation of the abaxial leaf surface. This stomatal response to wind found on the abaxial surface was not related to feedback stomatal response to transpirational water loss and intercellular CO_2 concentration in the leaf. The mechanism of stomatal response to wind was explained on the basis of water balance within the stomatal complex and on the antagonism relationship between turgors in guard and epidermal cells.
    Full-text · Article · Jan 2001
  • D. Yasutake · M. Kitano · T. Araki · K. Nagasuga · T. Kawano · M. Hamakoga
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    ABSTRACT: In order to elucidate stomatal response to wind, leaf gas exchange and stomatal conductance in an intact leaf of cucumber plants (Cucumis sativus L.) were measured under different conditions of air current and humidity. A leaf gas exchange cuvette was improved for individual measurements on the abaxial and adaxial leaf surfaces and for adjustment of the leaf boundary air current, where leaf boundary layer conductance can be adjusted at a desired value within a range from 0.3 mol m-2s-1 to 1.0 mol m-2s-1. Rates of leaf gas exchange and stomatal conductance were higher on the abaxial surface than on the adaxial surface. Stomatal response to wind was appeared more sensitive on the abaxial surface, while leaf gas exchange and stomatal conductance on the adaxial surface was scarcely affected by wind. Under the humid air condition, increase in leaf boundary layer conductance significantly enhanced stomatal conductance as well as rates of transpiration and photosynthesis on the abaxial surface. On the other hand, under the dry air condition, stomatal conductance was depressed by increase in leaf boundary layer conductance with little effect on transpiration and photosynthesis. These opposite changes in stomatal conductance found under the humid and dry air conditions were proved visually as change in stomatal aperture by the microscopic observation of the abaxial leaf surface. This stomatal response to wind found on the abaxial surface was not related to feedback stomatal response to transpirational water loss and intercellular CO2 concentration in the leaf. The mechanism of stomatal response to wind was explained on the basis of water balance within the stomatal complex and on the antagonism relationship between turgors in guard and epidermal cells.
    No preview · Article · Jan 2001

Publication Stats

148 Citations
23.46 Total Impact Points

Institutions

  • 2009-2012
    • Mie University
      • • Faculty of Bioresources
      • • Graduate School of Bioresources
      Tu, Mie, Japan
  • 2000-2008
    • Kyushu University
      • • Graduate School of Bioresource and Bioenvironmental Sciences
      • • Faculty of Agriculture
      • • Department of Agro-environmental Sciences
      Hukuoka, Fukuoka, Japan