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Volume 67, Issue 4
Displaying 1-11 of 11 articles from this issue
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Preface
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Kazuhiko KOBAYASHI, Tsuneo KUWAGATA, Mayumi YOSHIMOTO, Masayuki YOKOZA ...2011 Volume 67 Issue 4 Pages 205-207
Published: March 10, 2011
Released on J-STAGE: February 07, 2012
JOURNAL FREE ACCESSDownload PDF (582K)
Original Paper
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Yasushi ISHIGOOKA, Tsuneo KUWAGATA, Motoki NISHIMORI, Toshihiro HASEGA ...2011 Volume 67 Issue 4 Pages 209-224
Published: March 10, 2011
Released on J-STAGE: February 07, 2012
JOURNAL FREE ACCESSThe spatiotemporal characteristics of high summertime temperatures, which can cause high-temperature injuries to rice, during the recent period of climatic variability (1978-2010) in Japan were analyzed and quantified by using daily gridded meteorological data with high spatial resolution and GIS data. Several indices based on heat-dose (defined as the cumulative temperature exceeding a certain threshold) were introduced to assess the impact of heat stress on rice production and quality. Specifically, we examined the utility of these indices for evaluating quality declines in rice. Time series of heat-dose indices based on maximum and minimum summertime temperatures showed that heat stress intensity increased remarkably from 1994. Moreover, high values of a heat-dose index based on a daily mean temperature exceeding 26°C during the 20 days after the heading date of rice showed a clear association with a decline in observed rice quality, whereas no clear relationship was apparent between decreased rice quality due to heat stress and average temperature. We also examined the effect of heat stress on spikelet fertility and ripening in the rice cultivar Koshihikari in four representative regions of Japan by using two indices, a heat-dose index based on a daily maximum temperature exceeding 35°C during 7 days around the heading date, and one based on a daily mean temperature exceeding 26°C during the 20 days after heading. The first index showed large interannual variability in the four regions because of its high dependence on the timing of heading.View full abstractDownload PDF (1241K) -
Toshihiro HASEGAWA, Tsutomu ISHIMARU, Motohiko KONDO, Tsuneo KUWAGATA, ...2011 Volume 67 Issue 4 Pages 225-232
Published: March 10, 2011
Released on J-STAGE: February 07, 2012
JOURNAL FREE ACCESSHeat-induced spikelet sterility is one of the major threats to rice production from global warming. Previous chamber experiments have shown that even a short exposure to heat can induce spikelet sterility, but actual damage to a crop in the open field has rarely been reported. In the mid-summer of 2007, the Kanto and Tokai regions in Japan experienced record high temperatures above 40°C. We examined whether this extreme heat event induced sterility in open fields. We collected panicle samples from 132 fields in 5 prefectures in the Kanto and Tokai regions. Maximum air temperature averaged over a 5-day period around the heading stage exceeded the threshold for sterility (35°C) in more than 40% of the crops surveyed. Spikelet sterility ranged from 2% to 23%, and was more than 10% in 20% of the crops studied. Spikelet sterility in 2007 was apparently higher than that in the normal summer of 2008 and peaked with the heat wave, which confirms for the first time that extreme heat in midsummer induced sterility under open field conditions in Japan, but to a lesser extent than what was predicted from previous chamber experiments. The lesson from this survey is that air temperature per se is not sufficient to predict the occurrence of heat-induced sterility and that factors influencing the heat budget of the panicles are needed to account for the crop damage. Crop management practices such as selection of tolerant cultivars and optimizing the timing and amount of nitrogen application could moderate the occurrence of heat induced spikelet sterility which can help to develop adaptation measures to climate change.View full abstractDownload PDF (663K) -
Mayumi YOSHIMOTO, Minehiko FUKUOKA, Toshihiro HASEGAWA, Misako UTSUMI, ...2011 Volume 67 Issue 4 Pages 233-247
Published: March 10, 2011
Released on J-STAGE: February 07, 2012
JOURNAL FREE ACCESSProjected global warming is expected to increase the occurrence of heat-induced spikelet sterility (HISS) of rice (Oryza sativa L.). Previous chamber experiments have shown that HISS can occur where temperature at flowering time exceeds the threshold temperature of around 35°C. The occurrence of HISS is, however, difficult to predict because the thermal conditions of rice canopy can be different from the air temperature under field condition. To cope with this, we developed a simple micrometeorology model focusing canopy and panicle temperatures; IM2PACT (Integrated Micrometeorology Model for Panicle And Canopy Temperature) as a tool to be incorporated into general meteorology databases. The IM2PACT was validated by leaf transpiration retarding (RT) experiment. During their flowering stage, leaf temperature elevated by RT treatment, which caused warming and drying of the air inside the canopy, resulting in the elevation of the panicle temperature (Tp). The IM2PACT well simulated the RT experiment, and was proved to simulate not only the Tp magnitude but also the effects on Tp of leaf transpiration characteristics via changes in micrometeorology inside the canopy. The IM2PACT was applied to the meteorology dataset based on ANEMOS in order to analyse the Tp at Kanto and Tokai regions of extremely hot summer in 2007. There was a great gap in spatial distributions between the Tp and the daily maximum air temperature which is commonly used as a measure of HISS, because the difference of meteorology, especially relative humidity, among areas altered the panicle-air temperature difference. This strongly suggests that we must refer to the Tp instead of the air temperature in daily maximum, as a measure variable for HISS. The IM2PACT is a powerful tool to elucidate the Tp in the climate change impact study to bridge between the responses of crop susceptible to heat and the meteorological data.View full abstractDownload PDF (2479K) -
Atsuko TANAKA, Kazunobu TORIYAMA, Kazuhiko KOBAYASHI2011 Volume 67 Issue 4 Pages 249-258
Published: March 10, 2011
Released on J-STAGE: February 07, 2012
JOURNAL FREE ACCESSIn 2010, rice growth and yield were compared between farmer's fields under different fertilization practices: application of rice straw and bran for 11 years (O-11), the same but for 2 years (O-2), and a combination of synthetic fertilizer and cow manure (F). With the daily maximum air temperature reaching 34.5°C on average across the flowering period, the rice plants showed spikelet sterility at 5.5%, 14.5%, and 21.8% in O-11, O-2, and F fields, respectively. The lower spikelet sterility in O-11 could be attributed to the slower decrease in the SPAD value, which was realized by higher soil fertility in O-11. The slower decline in SPAD value in O-11 could also have helped the rice plants to maintain the fraction of imperfectly filled grain which was comparable or smaller (20.4%) than that for F (28.9%). The poor performance of the plants in O-2 (25.4%) was ascribed to the earlier decline in SPAD value and commencement of lodging. Further studies are warranted into the mechanisms of reduced heat-induced yield loss under organic fertilizer management.View full abstractDownload PDF (701K) -
Seiji SHIMODA2011 Volume 67 Issue 4 Pages 259-267
Published: March 10, 2011
Released on J-STAGE: February 07, 2012
JOURNAL FREE ACCESSIn western Japan, rice grain damage from high temperatures has recently been severe. The adverse effects of high temperature on rice ripening can be accentuated by water management practices. In field experiments carried out under different weather conditions, the early drainage decreased yield, grain weight, and quality in 2008, but early drainage had no effect on brown rice yield in 2009 or 2010. Decreases in grain weight, yield, and the percentage of perfect grain in the dry regime in 2008 compared with the wet regime of the years can be explained by the early drainage during the early grain-filling period. In 2010, the mean daily temperature averaged over the 20 days after heading was 29°C, and the percentage of perfect grains was low. The combination of high temperature and abundant radiation during the grain-filling period may explain the low proportion of perfect grains without a decrease in grain weight in 2010. The effect of drainage was smaller in 2010, when the high temperatures caused rapid senescence and shortened the grain-filling period. Thus, grain filling may have been completed before the water shortage could reduce the availability of CO2 to a critical level.View full abstractDownload PDF (679K) -
Manabu NEMOTO, Takahiro HAMASAKI, Hiroyuki SHIMONO2011 Volume 67 Issue 4 Pages 269-274
Published: March 10, 2011
Released on J-STAGE: February 07, 2012
JOURNAL FREE ACCESSThe summer temperature in Hokkaido in 2010 was the hottest on meteorological record and caused the crop index of rice (Oryza sativa L.) to drop below average. The mean temperature was 2.2°C higher than normal (based on the period 1981-2010) and was coincident with climate change predictions for the end of the 21st century. To investigate possible measures against the hot conditions projected in Hokkaido and the resulting reductions in yield, we tested Hitomebore, a cultivar from the Tohoku region of Japan. Although local cultivars had been used in accordance with conventional procedures, 2010 was the first year in which Hokkaido's rice yield was decreased by factors other than cold injury or strong winds. The extremely high temperature in June probably shortened the basic vegetative growth period, thus reducing the number of tillers and number of grains. However, Hitomebore grown at our experimental paddy field in Sapporo under the hot conditions of 2010 reached the heading stage during a period when it was safe from cold-induced injury, and it ripened fully to give a yield of 6300 kg/ha. Introduction of new cultivars with properties similar to those of Hitomebore will be one way of adapting to the expected climate change.View full abstractDownload PDF (609K) -
Manabu NEMOTO, Takahiro HAMASAKI, Ryoji SAMESHIMA, Etsushi KUMAGAI, Hi ...2011 Volume 67 Issue 4 Pages 275-284
Published: March 10, 2011
Released on J-STAGE: February 07, 2012
JOURNAL FREE ACCESSImpact assessment and adaptation planning to enable growth of paddy rice (Oryza sativa L.) under conditions of ongoing climate change are necessary in the Hokkaido region of northern Japan because of the intensive climate warming (+2-3°C in summer) projected to occur during the 21st century. Most previous studies have been based on extrapolation of results from past and present experimental data on unexperienced warming conditions under projected climatic change. These facts motivated us to use an assessment method known as an open-field day-length-extension (ODE) experiment. First, we confirmed the feasibility of an ODE experiment, which involves artificially extending day length with supplemental lighting. ODE treatment was performed in Morioka in 2009 (treatment ODE09M), where the summer temperature was 2.5°C higher than the current average summer temperature in Sapporo, and the results were compared with those obtained in Sapporo, Hokkaido, in 2010 (treatment C10S), which had an extraordinarily hot summer (mean daily temperature 2.3°C higher than normal). The difference in heading date between ODE09M and C10S was small, i.e., 4 days for the three cultivars Koshihikari, Hitomebore, and Akitakomachi. Second, by comparing previous temperature gradient chamber (TGC) results with those from the ODE experiment, we found that a TGC experiment system was likely to overestimate the effect of temperature on heading date by up to 7 days. Finally, we calculated paddy rice cultivation under projected climate change conditions in Sapporo in terms of three critical dates for stable rice cultivation: the early limit for transplanting, the early limit for heading, and the late limit for heading. The warmer climate condition at Morioka formed by the ODE experiment that is an analog of future climate (2.5°C higher than the current average) at an northern site, Sapporo, would allow successful cultivation of Hitomebore and Akitakomachi, but not Koshihikari, in Sapporo.View full abstractDownload PDF (1105K) -
Masashi OKADA, Toshichika IIZUMI, Yousay HAYASHI, Masayuki YOKOZAWA2011 Volume 67 Issue 4 Pages 285-295
Published: March 10, 2011
Released on J-STAGE: February 07, 2012
Advance online publication: November 04, 2011JOURNAL FREE ACCESSThis study examined the impacts of climate change both on rice quality and yield using a climatologically empirical rice quality model together with a process-based rice growth model. The target area is Kyushu in the western part of Japan, where the decline in rice quality already occurs at the present time. After confirming the model reproducibility, we made simulations to project the changes of rice quality under climate change scenarios. All the projections suggested that the rice quality would significantly deteriorate. We analyzed the results by distinguishing the direct and indirect effects of climate based on simulations with changing weather data. It suggested that the indirect effect induced by the shift of the grain-filling period is relatively larger than the direct effect by temperature rise. We also examined the effects of adaptation measure shifting the date of transplanting on rice quality and yield. It is shown that rice quality is more sensitive to the shifting transplanting date than rice yield; consequently, shifting the transplanting date later might be an appropriate measure for the adaptation to climate change.View full abstractDownload PDF (1124K)
Research Note
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Tsuneo KUWAGATA, Mayumi YOSHIMOTO, Yasushi ISHIGOOKA, Toshihiro HASEGA ...2011 Volume 67 Issue 4 Pages 297-306
Published: March 10, 2011
Released on J-STAGE: February 07, 2012
JOURNAL FREE ACCESSAn agro-meteorological database coupled with crop models (MeteoCrop DB) has been developed for studying the impacts of climate change on rice (Oryza sativa L.) in Japan (http://MeteoCrop.dc.affrc.go.jp). MeteoCrop DB consists of daily meteorological data at the Automated Meteorological Data Acquisition System (AMeDAS) stations (about 850 sites across Japan) from 1980 to 2011 and those at the about 160 surface meteorological observatories from 1961 to 2011. These stations cover the whole of Japan and are the main components of the meteorological observation network of the Japan Meteorological Agency. The daily meteorological information in the database consists of both general meteorological elements (air temperature, wind speed, precipitation, sunshine duration etc.) and agro-meteorological elements (solar radiation, humidity, downward longwave radiation, potential evaporation etc.). Since the latter elements are critical for studying rice production but are not measured at the AMeDAS stations, they are estimated for each AMeDAS location from the observed sunshine duration and the observed elements at the neighboring surface meteorological observatory. The models of micro-meteorology in crop canopy and rice growth are run in combination with the agro-meteorological information to estimate the daily mean water temperature in a rice paddy during the growth period, the diurnal change in rice panicle temperature during the flowering period, and phenological stages of the rice plants.View full abstractDownload PDF (1601K) -
Ryoji SAMESHIMA, Takahiro HAMASAKI, Manabu NEMOTO, Etsushi KUMAGAI, Hi ...2011 Volume 67 Issue 4 Pages 307-312
Published: March 10, 2011
Released on J-STAGE: February 07, 2012
JOURNAL FREE ACCESSWe developed an open-field day-length-extension method for estimating the effect of a temperature increase on crop growth. We chose a pair of experimental sites (Sapporo and Morioka) with the necessary difference in air temperature. To estimate the temperature effect alone, day length at the southern site was extended to equal that at the northern site by supplemental light treatment. In the day-length-extension treatment, the start time of the lighting at dawn and the end time at dusk were set on the basis of the threshold light intensity at the northern site (the threshold light intensity at which the crop senses light and shows a photoperiodic response). We used the threshold solar altitude corresponding to the threshold light intensity to determine the start and end times of supplemental lighting. The threshold solar altitude, however, depends on weather conditions. To cancel the effect of weather, we used the threshold solar altitude of a fine day even on cloudy or rainy days. Measurement of photon flux density at the two sites showed that the difference in the threshold solar altitude on a fine day between the sites was small, suggesting that the same threshold value can be widely used.View full abstractDownload PDF (717K)
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