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Volume 68, Issue 4
Displaying 1-4 of 4 articles from this issue
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Full Paper
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Fumiyoshi KONDO, Osamu TSUKAMOTO2012 Volume 68 Issue 4 Pages 183-194
Published: March 10, 2012
Released on J-STAGE: December 12, 2012
JOURNAL FREE ACCESSWe experimentally validated the density correction (called WPL or Webb correction) over the dry asphalt surface by simultaneously measuring CO2 fluxes by closed-path eddy covariance and closed-chamber techniques, which is inescapable for evaluating the surface CO2 flux by the open-path eddy covariance technique. The total CO2 flux with WPL correction by the open-path eddy covariance technique was evaluated as a systematically small upward flux, which was consistent with that of our previous study. The instrumental error of the sonic anemometers and the additional heating correction for the open-path gas analyzer were not potential sources of total upward CO2 fluxes. The CO2 flux by the closed-chamber technique was also an upward flux; however, it was three orders of magnitude smaller than the total CO2 flux by the open-path eddy covariance technique. The CO2 flux calculated from the CO2 mixing ratio by the closed-path eddy covariance technique was almost zero. Our results suggest the possible upward overestimation of the total CO2 flux with the WPL correction by the open-path eddy covariance technique.View full abstractDownload PDF (992K) -
Hiroyuki MATSUDA, Tsuyoshi HAYASAKA, Takahiro KONTA, Masumi ASANO, Shi ...2012 Volume 68 Issue 4 Pages 195-204
Published: March 10, 2012
Released on J-STAGE: December 12, 2012
JOURNAL FREE ACCESSIn the southern part of the relatively cool Tohoku region of Japan, the mean temperature during the rice cropping season rose at Shonai and Murayama from 1974 to 2004, yet the amount of solar radiation showed no significant trend. Higher mean temperature and solar radiation during the first half of the cropping season advanced the heading date, exposing ripening rice to higher temperatures and more solar radiation. These meteorological influences on paddy rice were different at every site. At Shonai, the heading date advanced with the increase of mean temperature from transplanting to heading after 1980. Other sites did not show these phenomena. The mean temperatures during the latter half of the ripening period increased over time at Shonai and Murayama. Those during the first half of the ripening period exceeded 27°C several times at Shonai and Murayama, increasing the rate of white immature grains at Shonai. The amount of solar radiation during the ripening period showed no trend, but that at Natori was lower than that at Shonai and Murayama.View full abstractDownload PDF (837K) -
Hiroyuki SHIMONO, Ayako ISHII2012 Volume 68 Issue 4 Pages 205-214
Published: March 10, 2012
Released on J-STAGE: December 12, 2012
JOURNAL FREE ACCESSPoor grain growth caused by high temperatures during the ripening stage is a critical problem for rice production. However, the magnitude of the reduction in grain growth also depends on the temperatures before the ripening stage. We hypothesized that the water temperature (Tw) during vegetative growth can affect grain growth under high temperatures during the ripening stage. We exposed the japonica cultivar ‘Hitomebore’ to four levels of Tw during vegetative growth, ranging from 20 to 30°C, and examined grain growth under subsequent high temperatures during the ripening stage in a 3-year experiment using plants having only main stems produced by removing all tillers. We measured green leaf area, chlorophyll content, spikelet number per panicle, hull length, and grain size. To investigate the contribution of the sink-source balance to grain growth, we examined the effect of the interaction between Tw during vegetative growth and a partial sink-removal treatment on grain weight. High air temperature during the ripening stage decreased grain weight, and low Tw during vegetative growth significantly decreased grain weight under both normal and high air temperatures during the ripening stage, without a significant interaction. The responses of grain weight to Tw during vegetative growth were observed even in plants with partial sink removal. The reduced grain growth under lower Tw during vegetative growth resulted from decreased hull length of the grains. Our results support the hypothesis that low Tw during vegetative growth can decrease grain growth in rice at high air temperatures during the ripening stage. It affects the hull size rather than the sink-source balance.View full abstractDownload PDF (659K)
Short Paper
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Maricar M. AGUILOS, Kentaro TAKAGI, Hiroyuki TAKAHASHI, Junko HASEGAWA ...2012 Volume 68 Issue 4 Pages 215-224
Published: March 10, 2012
Released on J-STAGE: December 12, 2012
JOURNAL FREE ACCESSWe determined the interannual variation of annual litterfall rate in cool-temperate forests [three mixed-forests (Mx1-Mx3), an evergreen coniferous forest (Ec), and a deciduous conifer plantation (Dc)] of northern Hokkaido over a 16-year observation period (1996-2011) and evaluated the effect of meteorological and phenological variables on the annual litterfall production. Total solar radiation during spring (from March to May) positively correlated with the annual litterfall rate in the current year at three mixed forests with statistical significance. A warm spring advanced the day of snow melt and the day of leaf expansion, however, the early leaf expansion did not enhance the annual litter production at any of the studied forests. In conclusion, spring solar radiation was the best explanatory factor among the studied factors that determines the interannual variation of the annual litterfall rate at cool-temperate mixed forests, although the mechanisms behind this relationship remain unknown. The early snowmelt and leaf expansion caused by a warm spring did not directly link to the enhancement of the litterfall rate. This implies that global warming or changing rainfall patterns do not necessarily affect the annual litterfall amount in these forests, at least within the range observed during the 16 years.View full abstractDownload PDF (644K)
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