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Volume 71, Issue 2
Displaying 1-11 of 11 articles from this issue
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Costas J. SAITANIS, George PANAGOPOULOS, Vasiliki DASOPOULOU, Evgenios ...2015 Volume 71 Issue 2 Pages 55-64
Published: 2015
Released on J-STAGE: June 10, 2015
JOURNAL FREE ACCESSThis is the first report of air pollution monitored in Greece's Tripolis Plateau. We investigated ambient ozone concentrations and estimated its phytotoxicity potential based on three approaches: i) continuous instrumental monitoring at one station in the town, ii) phytodetection mapping with Bel-W3 tobacco plants in a network of 15 stations and iii) evaluation of ozone phytotoxicity by using the resistant (NC-R) and the sensitive (NC-S) white clover genotypes (the latter group was either sprayed or not sprayed with Ethylenediurea (EDU) or Azoxystrobin as ozone protectants).
The hourly ozone concentrations often exceeded 70 nmol mol-1. The average ozone concentration during the early afternoon hours (12:00-19:00) for June, July and August was 65.4 nmol mol-1. The monthly AOT40 (accumulated ozone mixing ratios over the threshold of 40 nmol mol-1) value was higher in July (9,123 nmol mol-1 h) and lower in October (2,022 nmol mol-1 h).
The Bel-W3 plants showed characteristic ozone-induced visible foliar injury symptoms at all the stations of the network, suggesting that ozone was at phytotoxic levels not only in the town, where it was measured, but also throughout the plateau.
The white clover revealed a reduction of the epigeous biomass of the NC-S by 36-57% in five harvests. The application of EDU prevented biomass reduction in the NC-S genotype, while Azoxystrobin did not offer significant protection.
These results indicate that, in rural areas of Greece, ambient ozone occurs at potentially phytotoxic levels, at least for sensitive plant species.View full abstractDownload PDF (2798K) -
Yoshinobu HARAZONO, Hiroki IWATA, Ayaka SAKABE, Masahito UEYAMA, Kensh ...2015 Volume 71 Issue 2 Pages 65-76
Published: 2015
Released on J-STAGE: June 10, 2015
JOURNAL FREE ACCESSThe effect of water vapor dilution on CH4 flux was examined here using dynamic chamber measurements at the forest floor of a black spruce forest in interior Alaska. CH4 and CO2 concentrations were differently diluted by increased water vapor in each chamber. After correction for water vapor dilution was applied, source (positive) CH4 flux was enhanced, whereas sink (negative) flux was reduced, and magnitude changed depending on the condition of water vapor.
Several methods were examined to practically correct water vapor dilution for fluxes previously measured. Numerical correction for all data sampled at high frequency intervals (DAE-method) is highly recommended. Water vapor dilution correction for ensemble-averaged data (SA-method) is also applicable, though not recommended in case of long-term average data for accurate flux determination, especially for data obtained at irregular source strength plots. When evapotranspiration is measured in parallel to CH4 flux, the removal of the water vapor increment due to evapotranspiration in the chamber is another option for correction (HCE-method). This method resulted in similar accuracy to the DAE-method, as long as continuously sampled data were applicable.
The application of the correction for water vapor dilution to previous tower-based flux data (measured over a wet sedge tundra in Barrow throughout the month of August, 2000) also resulted in an increase in source (positive) flux of 6.6% on average.
This study concludes that either accurate flux must be determined using mixing ratio, or a water vapor dilution correction must be applied using simultaneously measured water vapor and trace gases.View full abstractDownload PDF (4307K) -
Shin FUKUI, Yasushi ISHIGOOKA, Tsuneo KUWAGATA, Toshihiro HASEGAWA2015 Volume 71 Issue 2 Pages 77-89
Published: 2015
Released on J-STAGE: June 10, 2015
Advance online publication: April 01, 2015JOURNAL FREE ACCESSCrop phenology models play a pivotal role in predicting yields under climate change. Cultivar-specific model parameters are essential for accurate prediction, but their estimation generally requires elaborate and laborious experiments, and such parameter sets have therefore been available only for a small number of cultivars. We propose methodology for estimating phenological parameters, combining a stochastic parameter estimation method (genetic algorithm) with the use of a database comprising 30 years of records from variety trials conducted at experimental stations across Japan. Optimal parameter sets were selected based on the results of cross-validation tests. This methodology allowed us to estimate phenological parameters objectively. We estimated phenological parameters for the 10 leading cultivars currently planted in Japan, and showed that these parameters reflect the cultivars' sensitivity to temperature and/or photoperiod. The proposed methodology can be used to provide quantitative evaluations of the environmental responses of rice cultivars, without relying on elaborate and laborious experiments, and substantially improves the efficiency of phenological trait phenotyping.View full abstractDownload PDF (3244K) -
Sanz Grifrio LIMIN, Hiroki OUE, Keiji TAKASE2015 Volume 71 Issue 2 Pages 90-97
Published: 2015
Released on J-STAGE: June 10, 2015
JOURNAL FREE ACCESSThis paper evaluated the applicability of four AAR (areal average rainfall) estimation methods in the mountainous Kamo River watershed by using measured monthly rainfall at nine stations within and near this watershed between 1998 and 2010. The four methods were (i) the arithmetic mean, (ii) the Thiessen polygon, (iii) the elevation regression and (iv) the combination of (ii) and (iii). Method (iv) was newly developed in this study. For methods (iii) and (iv), linear monthly relationship between elevation and monthly rainfall was applied and it was evaluated as useful for predicting rainfall even at a high elevation.
Firstly, the applicability of the four AAR methods was evaluated by relationships between annual AAR (= P) and annual evapotranspiration ratio (Et/Ep). Annual evapotranspiration (Et) was obtained using the water balance equation by incorporating each AAR and measured discharge, and Ep was calculated using Penman equation. The low Et/Ep by methods (i) and (ii) was caused by the underestimation of AAR, which resulted in the underestimation of Et, mainly because these methods did not include the effect of larger rainfall in the higher elevation area. Methods (iii) and (iv) produced Et/Ep reasonably and demonstrated closer relationship to that in another mountainous watershed.
Secondly, the applicability was evaluated by examining relationships between annual Ep/P and annual Et/P with a rational method of Fu (1981), where the watershed parameter w was optimized for each method. Methods (i) and (ii) produced relatively low w as a value of a mountainous watershed, which would be caused by the underestimation of annual AAR. Method (iii) produced relatively high w as a value of a mountainous watershed and R2 was relatively low. As a result, the newly presented combination method (iv) was determined to be most applicable for AAR method in this mountainous watershed.View full abstractDownload PDF (4516K) -
Satoshi NAKANO, Custodio R. P. TACARINDUA, Keiichiro NAKASHIMA, Koki H ...2015 Volume 71 Issue 2 Pages 98-105
Published: 2015
Released on J-STAGE: June 10, 2015
JOURNAL FREE ACCESSThis study aimed to investigate the effects of increasing temperature on the transpiration rate and canopy conductance of soybean grown in temperature gradient chambers under drought and wet conditions. The heat balance method was used to measure the transpiration rate from sap flow; additionally, canopy conductance was continuously estimated from the transpiration rate and vapor pressure deficit (VPD). An increase of 3°C in temperature resulted in an increased transpiration rate but decreased canopy conductance. Further, the differences in canopy conductance observed at high and low temperature treatments were more remarkable during the morning than around noon. This suggested that there was concomitant increase in VPD with increasing temperature when solar radiation was low during the morning. Although the transpiration rate and canopy conductance decreased during drought conditions, the overall tendency of the response to the changes in temperature and VPD was similar to those in the well-watered condition. The partial correlation coefficients between canopy conductance and VPD were negative when the temperature effect was held constant. However, those between canopy conductance and temperature showed opposite trends in the two years of study—negative in 2011 but positive in 2012. These results suggest that the decrease of canopy conductance in a high temperature treatment is more likely caused by increasing VPD than by increasing temperature itself.View full abstractDownload PDF (747K) -
Daisuke SAKAMOTO, Hiromichi INOUE, Shinnosuke KUSABA, Takaya MORIGUCHI ...2015 Volume 71 Issue 2 Pages 106-110
Published: 2015
Released on J-STAGE: June 10, 2015
JOURNAL FREE ACCESSThe relationship between temperature and endodormancy progression was studied in the Japanese chestnut ‘Porotan’. We randomly selected 30～40 cm long current shoots from potted trees and placed them in continuously dark and chilled conditions (0, 3, 6, 9 and 12°C in 2012, and 0, 3, 6, 9, 12 and 15°C in 2013) beginning in mid-October. After low temperature treatment for varying lengths of time, cut shoots were placed in plastic containers with Rockwool cubes containing distilled water and incubated in a growth-chamber at 20°C under dark conditions for forcing. We defined endodormancy completion as the condition when greater than 70% of the buds sprouted. Bud sprouting was defined as when green tissue was visible under the bud scales. The results showed that 816, 1056 and 1284 chilling hours were required for endodormancy release of Japanese chestnut ‘Porotan’ buds at 0～6°C, 9°C and 12°C, respectively, while endodormancy could not be completed at 15°C. A model for estimating endodormancy progression, i.e. developmental index (DVI), was created based on the relationship between the measured developmental rate (DVR) and temperature. Experimental validation of DVR model was confirmed by comparison with observed endodormancy completion dates in the open field.View full abstractDownload PDF (1214K) -
Takenobu SHISHIDO, Hirakazu SEKI2015 Volume 71 Issue 2 Pages 111-123
Published: 2015
Released on J-STAGE: June 10, 2015
JOURNAL FREE ACCESSWe conducted a laboratory-scale composting experiment with forced aeration using two fermenters with the same shape and geometry under the same material and operating conditions to certify the reproducibility and construct a mathematical model for the proposed composting process as an ecosystem phenomenon. Overall, the reproducibility of the composting process was relatively good, although small differences in the temperature and heat generation rate between the two fermenters occurred after 100 h, and these differences gradually increased toward the end of the experiment. Based on these results, it seems feasible to simulate the composting process with a deterministic model to examine the behavior of the entire system for the purposes of basic system design. We propose a deterministic model for heat and mass transfer in the composting process, emphasizing that the transformation process of released biochemical energy to heat involves an “energy dissipation mechanism” as a successive substrate decomposition process. The simulated model results of the temperature, moisture content, weight, oxygen concentration, and heat generation rate were in fairly good agreement with the experimental results. However, the course of the heat generation rate over time, that is, the reaction rate at any height in the vertical direction, somewhat differed from those estimated by the measured temperature profile.View full abstractDownload PDF (8922K) -
Mari Murai-HATANO, Tsuneo KUWAGATA, Hidehiro HAYASHI, Junko Ishikawa-S ...2015 Volume 71 Issue 2 Pages 124-135
Published: 2015
Released on J-STAGE: June 10, 2015
Advance online publication: May 01, 2015JOURNAL FREE ACCESSTranspiration, the evaporation from aerial parts of plants, is major driving force for the roots to uptake water from the soil. Aquaporins, the water channel proteins, are thought to play crucial roles in regulation of root hydraulic conductivity. Here we demonstrate that the evaporative demand plays a dominant role in the induction of specific aquaporins in rice (Oryza sativa) roots in seedlings grown hydroponically and then transferred to an open field. We found that the abundance of the root-specific aquaporin transcripts, OsPIP2;4, OsPIP2;5 and OsTIP2;1 at 8 a.m. is highly correlated with the evaporative demand in the morning (evaluated from potential evaporation averaged over 4 h before root sampling). Aquaporin isoforms with higher correlation to potential evaporation showed higher diurnal amplitude of their expression. Our study suggests that rice plants sense daily weather and responded to it by adjusting the expression of specific root aquaporin genes.View full abstractDownload PDF (4949K)
Short Paper
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Fumiki HOSOI, Kenji OMASA2015 Volume 71 Issue 2 Pages 136-141
Published: 2015
Released on J-STAGE: June 10, 2015
JOURNAL FREE ACCESSWe estimated the distribution of leaf inclination angle (LIA) throughout the canopy of three broad-leaved trees by a portable high-resolution scanning lidar. Each canopy was scanned from three positions surrounding it and the data were co-registered. The 3-D images were divided into five horizontal layers, and the LIA distribution of each layer was estimated by a fitted plane to each leaf and taking the zenith angle of the plane. The LIA decreased significantly with increasing canopy height. The degree of the LIA decrease was different in each specimen. The mean LIA values of each layer were 36.7° to 43.8° in Camellia sasanqua, 34.6° to 45.9° in Osmanthus fragrans, and 48.9° to 65.4° in Camellia japonica. The differences in LIA distribution were explained mainly by the light conditions around the trees.View full abstractDownload PDF (1563K)
Review Paper
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Evgenios AGATHOKLEOUS, Costas J. SAITANIS, Takayoshi KOIKE2015 Volume 71 Issue 2 Pages 142-152
Published: 2015
Released on J-STAGE: June 10, 2015
JOURNAL FREE ACCESSAmbient ozone (O3) poses a growing threat to the global ecosystems due to its high phytotoxicity: it may possibly reduce the productivity of wild plants as well as the species' biodiversity. Asia hosts a remarkable number of wild plant species; thus, studies dealing with Asian species' responses to O3 are of great importance. We have retrieved, from scientific databases, 195 papers dealing with the response of 473 wild plants species to O3. Some species we characterize as “ozonophobic” have been reported to be negatively affected by O3, even at O3 levels lower than the AOT40 threshold. This review revealed the lack of research dealing with the effects of O3 on endangered or threatened plant species, as well as on important medical plants. Such research is needed not only from an ecological point of view or in terms of biodiversity value, but also from an anthropocentric point of view. Several wild species carry unique substances that are used in medicines for healing human diseases or in agro-industry for the production of agrochemicals, thus securing human welfare.View full abstractDownload PDF (723K)
Full Paper
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Shan LU, Satoshi INOUE, Hiroyuki SHIBAIKE, Shigeto KAWASHIMA, Seiichir ...2015 Volume 71 Issue 2 Pages 153-160
Published: 2015
Released on J-STAGE: June 10, 2015
JOURNAL FREE ACCESSMonitoring pollen release is important for investigating growth stages and pollen dynamics of agro-ecosystems. The objective of this study is to evaluate the possibility of using four vegetation indices (normalized difference vegetation index, NDVI; optimized soil-adjusted vegetation index, OSAVI; photochemical reflectance index, PRI; and, water band index, WBI) and the red edge to relate tassel condition and pollen release number during the maize flowering season by non-destructive optical observation of hyperspectral reflectance. Canopy reflectance of the maize crop was measured by a spectroradiometer within the spectral range of 300-1100 nm. A Durham sampler was used to collect the pollen. The results showed that the pollen number increased rapidly from the onset of the pollen release and then decreased slowly until the tassel withered. The OSAVI and PRI decreased most conspicuously after the maize began pollen dispersal. The temporal difference of the vegetation index, particularly that of OSAVI, also corresponded to the change in pollen release. The correlation between the vegetation index of the first derivative of the reflectance spectra at the red edge and the 2-day average pollen amount (August 5 to 14) was detected by correlation analysis (R2=0.26 for NDVI; 0.72 for OSAVI; 0.68 for PRI; 0.56 for WBI and 0.85 for the first derivative at the red edge position). Therefore, the first derivative of the reflectance spectra at the red edge position allowed prediction of the onset and peak of pollen release, which are promising for assessing the potential for pollen contamination.View full abstractDownload PDF (2785K)
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