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Volume 66, Issue 4
Displaying 1-10 of 10 articles from this issue
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Full Papers
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Satoshi NAKANO, Yasuhiro KOMINAMI, Satoshi OHNO, Kotaro YOKOYAMA2010 Volume 66 Issue 4 Pages 207-216
Published: March 10, 2010
Released on J-STAGE: April 04, 2011
JOURNAL FREE ACCESSFoehn winds cause damage known as white head injury to paddy rice; and this damage is more severe at night than during the day. However, little has been reported about the nighttime effects of the foehn on other crops. We investigated the foehn's effects on soybean plants, and compared day- and nighttime responses. We measured sap flow, which is assumed to equal transpiration, by the heat balance method. The gauge conductance of sap flow sensors during the nighttime foehn was calibrated against values obtained in the pre- or post-foehn period. Stomatal conductance was calculated using sap flow data and meteorological data. At night, sap flow during foehns was greater than that in non-foehn conditions. During the foehns in 2007 and 2008, average nighttime sap flows were 4.3 g h-1 (2007) and 4.0 g h-1 (2008). The cumulative sap flow through the night during the foehns in 2007 and 2008 were 10.5% and 7.0% of their respective daytime values. In 2007, sap flow increased linearly with increasing vapor pressure deficit (Da) when Da exceeded 0.7 kPa. In 2008, however, sap flow increased rapidly when Da exceeded 0.8 kPa. These different responses of sap flow to Da in 2007 and 2008 were attributed to differences in regulation of stomatal conductance, which was low in 2007 but varied markedly in 2008. The reason for these differences may be the different soil moisture conditions in 2007 and 2008.View full abstractDownload PDF (956K) -
Ryo MATSUDA, Katsumi SUZUKI, Yuka NAKANO, Hidekazu SASAKI, Masuyuki TA ...2010 Volume 66 Issue 4 Pages 217-226
Published: March 10, 2010
Released on J-STAGE: April 04, 2011
Advance online publication: September 30, 2010JOURNAL FREE ACCESSThe efficacy of daily quantitative nutrient management (QNM) in tomato rockwool hydroponics under CO2-enriched conditions was tested. Three levels of nutrient supply based on daily water uptake were compared with conventional electrical conductivity (EC)-based management. A newly developed automatic QNM system with server and client controller prototypes was used to control nutrient supply. Plants in a greenhouse were supplied with 0.5 (S), 1.0 (M) or 1.5 (L) times the optimal daily amount of nutrients for normal CO2 conditions from October 2009 to February 2010. EC-based management produced highest cumulative total fruit yield during 16 weeks of fruit harvest followed by L, M and S treatments, in that order. There was no significant difference in cumulative marketable fruit yields in EC-based management, L and M treatments, but marketable yields from these three treatments were significantly higher than S treatment. Fruit dry matter content and fruit soluble solid content in QNM treatments were almost the same or higher than fruit grown in EC-based management. The amount of nutrient used during the experiment in S, M and L treatments was 10, 24 and 42%, respectively, of the amount used for EC-based management. Nutrient use efficiency (NUE), defined as marketable fruit yield per unit of the amount of nutrient used, in all three QNM treatments was higher than in EC-based management. Thus, daily QNM can reduce nutrient use without lowering fruit yields and quality under CO2-enriched conditions. The M or L treatment provided optimal balance between fruit yield and NUE. The L treatment gave slightly higher marketable yield but lower NUE than M treatment.View full abstractDownload PDF (793K) -
Tadaaki URANO, Mitsuru HIROTA, Byambakhuu ISHGALDAN, Sheng-Gong LI, Ju ...2010 Volume 66 Issue 4 Pages 227-236
Published: March 10, 2010
Released on J-STAGE: April 04, 2011
Advance online publication: November 02, 2010JOURNAL FREE ACCESSWe examined the effects of grazing on aboveground biomass (AGB), vegetation constitution, and gross primary productivity (GPP) at midday in midsummer on a Mongolian steppe with mixed vegetation consisting of C3 and C4 plants. A grazed area (GA) and a nongrazed area (NGA) created by an exclosure were established in 2002 on land with a history of conventional grazing management. AGB of the mixed C3-C4 vegetation was determined in the GA and NGA from 2003 to 2006. Nongrazing resulted in increased AGB and a decreased ratio of C4 AGB to total AGB. In 2003 and 2006 a dynamic closed-chamber method was used to measure midday GPP; there was no significant difference between the GA and NGA in either year. Partitioning analysis of midday GPP to C3 and C4 photosynthesis indicated that exclosure exerted little influence on the midday GPP in midsummer, because the enhancement of GPP by increased AGB was offset by the reduced AGB of C4 plants.View full abstractDownload PDF (767K)
Full Papers (in Japanese)
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Tomomi TAKEDA, Hiroyuki OGUMA, Fumiko ISHIHAMA, Akio TAKENAKA2010 Volume 66 Issue 4 Pages 237-244
Published: March 10, 2010
Released on J-STAGE: April 04, 2011
Advance online publication: November 02, 2010JOURNAL FREE ACCESSInformation on the ground surface can now be acquired easily and highly accurately using digital aerial photographs. A digital canopy model (DCM), which is calculated by subtracting a digital terrain model (DTM) from a digital surface model (DSM) of the vegetation, provides useful information for studies of wild animal habitats and plant species distributions. However, DCMs have been used mainly for forests, and their validity for herbaceous plants requires further verification. In this study, we used the ADS40 airborne digital sensor to clarify the relationship between a DCM and the height of herbaceous species. Our study area was the Watarase wetland in the northern Kanto Plain, central Japan. Suitable habitats for the many rare plants found in this wetland are maintained by controlled burning in early spring. We acquired three DSMs: just after the controlled burn in April 2006; in August 2006, when the vegetation height peaked; and in April 2007, also just after the controlled burn. We calculated the DCM based on the difference between the August DSM and a DTM developed by using the minimum height values from the two April DSMs. We also performed a field survey during the August DSM acquisition, during which we measured the height of the uppermost leaves with a measuring pole at 16 measurement points and estimated the vegetation structure from photosynthetic photon flux density (PPFD) profiles measured with quantum sensors at each point. The calculated DCM height correlated very well to the height of the uppermost leaves (r2 = 0.96), although it was about 100 cm lower. In contrast, the DCM and the height of maximum intercepted PPFD were highly correlated (r2 = 0.97) and showed a 1:1 relationship.View full abstractDownload PDF (1268K) -
Yoshitaka KUROSE2010 Volume 66 Issue 4 Pages 245-253
Published: March 10, 2010
Released on J-STAGE: April 04, 2011
JOURNAL FREE ACCESSUsing the air infiltration characteristics of a porous cup we developed a prototype measuring device that determines the degree of dryness of the soil (simple soil moisture measuring system). This simple soil moisture measuring system consists of a porous cup, a transparent polyvinyl-chloride pipe, and a silicon stopper. When the soil is drier than the air entry value of the porous cup, air enters into the polyvinyl-chloride pipe, which was made airtight by filling up water, via the porous cup. This air is pulled back through the negative pressure inside the polyvinyl-chloride pipe, and the water level inside the polyvinyl-chloride pipe drops. The drier the soil the more the water level inside the polyvinyl-chloride pipe drops. The simple soil moisture measuring system determines the degree of the dryness of the soil by using the drop of the water level inside the polyvinyl-chloride pipe as a marker.View full abstractDownload PDF (832K) -
Yasuyuki WAKIYAMA, Genji OHARA, Atsushi MARUYAMA2010 Volume 66 Issue 4 Pages 255-267
Published: March 10, 2010
Released on J-STAGE: April 04, 2011
JOURNAL FREE ACCESSData were analyzed to develop a model for predicting the incidence of immature rice kernels with white portions of the Hinohikari cultivar. The coefficient of determination (r2) between the incidence of white-based rice kernels and mean air temperature for 20 days after heading was high. Therefore, fitting a curve between these two parameters is a viable means of developing a prediction model for the incidence of white-based rice kernels. Milky white rice kernels are caused by high temperatures that accelerate the respiration rate of the rice plant, a lack of solar radiation, over-dense rice grains per m2 and low leaf blade nitrogen content, as well as heat that induces some ripening damage. Using these determinants, the following evaluation indicator was proposed:
DMG = SR × α × RUE/Gr
where SR is solar radiation, α the absorptance of solar radiation by the community of rice plants, RUE the radiation use efficiency and Gr the number of rice grains per m2. RUE could be influenced by air temperature and leaf blade nitrogen content. The relationship between air temperature and RUE was investigated considering the leaf color, which represents the leaf blade nitrogen content of the Koshihikari cultivar. RUE decreased with increasing air temperature and a high leaf color kept RUE high. The equations of the relationship between RUE and air temperature, and the leaf color value, express the influence of high temperature and leaf color on dry matter production. DMG of Hinohikari was successfully calculated by the same equation with an additional parameter. DMGHN for Hinohikari was plotted for the incidence of milky white rice kernels. The coefficient of determination between milky white rice kernels and DMGHN was high (r2 = 0.65). The following model used to predict the incidence of milky white rice kernels was obtained:
IMWK = 52.3 exp(-599.9 × DMGHN)
where IMWK was the incidence of milky white rice kernels (%).View full abstractDownload PDF (1139K) -
Toshikazu ASAKURA, Hiroyoshi SUGIURA, Daisuke SAKAMOTO, Toshihiko SUGI ...2010 Volume 66 Issue 4 Pages 269-277
Published: March 10, 2010
Released on J-STAGE: April 04, 2011
JOURNAL FREE ACCESSFull bloom dates of the ‘Someiyoshino’ flowering cherry (Prunus×yedoensis Matsum.) and hourly temperature data at 46 observatories across Japan were used to develop a universal model for predicting the phenology without site specific calibration. The prediction model consisted of three sub models for endodormancy and ecodormancy stages respectively, as well as their transient dormancy stage. The chill unit model of the endodormancy stage was expressed as a concave-low parabolic equation with a maximum chill unit value of 1.0 optimal temperature. In ecodormancy, the effective temperature curve for bud growth to accumulate the growing degree hours (GDH) was expressed as a sigmoid function at temperatures exceeding 0°C. Usually temperatures below 0°C are excluded for GDH accumulation; however, in this model a positive constant was included assuming the promotive effects on bud growth under successively higher temperatures. Since the transition from endodormancy to ecodormancy should be a gradual response, the GDH was weighted by another sigmoid curve of growth competence which determined the growth ability of buds to forcing temperatures. The growth competence was zero during the initial stage of endodormacny and started gradually climbing before the end of endodormancy. The model parameters were evaluated by examining the deviation of accumulated GDH and RMSE between the observed and predicted dates. First, the model was fitted to different climate sites, Aomori and Fukuoka, and then tested at other sites nationwide. The selected model required an accumulated chill unit of 1450 for endodormancy completion with an effective temperature range from -6 to 14°C, and then the accumulated development of 6000 GDH to reach full bloom. The model, based on hourly temperature data only, succeeded in expressing the trends of full bloom dates for almost all sites except for southern Kyushu region, with the RMSE between observed and predicted dates of 2.33 days.View full abstractDownload PDF (3575K) -
Yo SHIMIZU, Kenji OMASA2010 Volume 66 Issue 4 Pages 279-288
Published: March 10, 2010
Released on J-STAGE: April 04, 2011
JOURNAL FREE ACCESSThe flowering of the Japanese apricot (Prunus mume Sieb. et Zucc.), which is representative of phenological events in winter, is widely observed in Japan. Shifts in the flowering date are related to climate change such as global warming and the urban heat island effect. In the present study, we analyzed trends in the flowering date of the Japanese apricot to clarify temporal and spatial variation from 1961 to 2007 using statistical methods. Phenological and meteorological data were recorded by the Japan Meteorological Agency at 34 meteorological stations in Japan. By linear regression analysis of the flowering date (expressed as the day of the year, DOY) against the year, mean trends of this parameter were shown to be significantly negative (i.e. advancing flowering) at 15 stations (44% of the total), with no significant positive trends. Comparison of the mean flowering dates in the 2000s with those in the four subintervals (the 1960s-1990s) indicated that the number of stations showing significant negative trends decreased from the 1960s to the 1990s. In a few phenological stations, the flowering date was delayed. The first principal component of the trends accounted for 55% of the variation in the flowering date for the period 1961 to 2007 at 34 stations and reflected chronological progression in the flowering. In particular, a recent trend since the mid-1990s contributed to advancing trends during the period 1961-2007. From the mid-1980s, the flowering date was delayed at the Owase station and several stations in south-eastern Japan, located in warm areas. Conversely, a few stations in cold regions indicated that recent flowering dates were earlier than those in the 1970s and 1980s, in addition to the trends shown by the first principal component.View full abstractDownload PDF (1431K) -
Taku M. SAITOH, Ichiro TAMAGAWA, Hiroyuki MURAOKA, Hiroshi KOIZUMI2010 Volume 66 Issue 4 Pages 289-298
Published: March 10, 2010
Released on J-STAGE: April 04, 2011
Advance online publication: September 30, 2010JOURNAL FREE ACCESSThis study evaluated heat storage flux or released flux due to biotic activity (SC) in forests. First, as a case study, we investigated diurnal pattern of SC over an evergreen coniferous forest via a three-year continuous eddy-covariance CO2 flux measurement. We clarified that (1) in some case, SC reached over 15% of total heat storage flux during the snow-free period (May-October), (2) SC was 4.3 W m-2 on average and reached 4.9-7.0% of average sensible and latent heat fluxes during the snow-free period. Second, we estimated SC by using net ecosystem exchange over several forest ecosystems as reported by previous studies. During the snow-free period over several forest ecosystems, the maximum Sc and daily amplitude exceed 3-12 and 4-17 W m-2 respectively. Those values were comparable to those of the latent heat storage flux in the air layer from the ground surface to the level of eddy-covariance measurement over several forest ecosystems as shown by previous reports. Our findings suggest that SC cannot be always ignored. We would need to examine whether SC can be ignored based on the circumstances of the targeted research.View full abstractDownload PDF (823K)
Short Papers (in Japanese)
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Kae MIYAZAWA, Masumi OKADA2010 Volume 66 Issue 4 Pages 299-304
Published: March 10, 2010
Released on J-STAGE: April 04, 2011
JOURNAL FREE ACCESSThe authors investigated the effects of CO2 concentration and temperature on the eating quality of komatsuna (Brassica rapa var. peruviridis). The komatsuna was grown in two temperature-gradient chambers at three temperature levels averaging 18.9, 21.9, and 23.0°C. One of the chambers was used to produce an elevated ambient atmospheric CO2 concentration of 200 ppm. Among the six sensory quality factors evaluated by a ten-member panel, the sweetness rating and overall rating were significantly lower in samples grown under elevated CO2 compared to those grown under ambient CO2, regardless of the temperature regime. It is possible that the taste and nutritional quality of leafy vegetables could decline in future CO2 concentrations.View full abstractDownload PDF (796K)
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