Climate in Biosphere
Online ISSN : 2185-7954
Print ISSN : 1346-5368
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Volume 16
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  • HIROYUKI OHNO, KAORI SASAKI, GENJI OHARA, KOU NAKAZONO
    Volume 16 (2016) Pages 71-79
    Released: March 01, 2016
    JOURNALS FREE ACCESS
    We developed a method for determining nationwide 1 km-grid square values of daily mean, maximum and minimum air temperature, and daily precipitation in Japan. The data were obtained using the JMA's nationwide observations, numerical forecasts, and climatic normal values. RMSE values for these elements in the past were 0.66 °C, 0.98 °C, 1.10 °C, and 5.9 mm/day, while those for one-day future were 1.18 °C, 1.65 °C, 2.00 °C, and 11.0 mm/day, respectively. The improvement in accuracy by introducing the forecasts was recognized even for values six-day future, though errors tended to increase with forecast range. The data are intended for use in the management of currently growing crops with a combination of crop models.
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  • Tatsuo HOSONO, Katsuyuki KATAYAMA
    Volume 16 (2016) Pages 80-85
    Released: March 05, 2016
    JOURNALS FREE ACCESS
    To develop new indices for optimal harvest timing of edamame (green soybeans), pod thickness increase rate, relative pod thickness against the maximum and relative seed dry weight against the value at maturity as soybean, in addition to pod thickness, were correlated with the timing of when soluble sugar content in seed per fresh weight peaked. Two cultivars of edamame were used, ‘Niigata-chamame’ and ‘Yuagarimusume’.
    Edamame is usually harvested during the mid to late pod filling stage of the soybean. During this stage, pod thickness increase rate gradually decreases and pod thickness against time is fitted by the quadratic function. Thus, the pod thickness increase rate linearly decreases with time during the period. At the optimal harvest timing, when sugar content in seed per fresh weight peaks, pod thickness increase rate, relative pod thickness, and relative seed dry weight are estimated to be around 0.15-0.20 mm/d, 90 % and 50 %, respectively.
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  • Toshiaki SHIMOTAKA, Satsuki OGAWA, Yoko SHINOHARA, Masashi HISHIIKE, W ...
    Volume 16 (2016) Pages 86-93
    Released: May 11, 2016
    JOURNALS FREE ACCESS
    Since approximately 1976, soil solarization has been implemented in order to address the continuous cropping damage and soil blight in farmlands, and many methods have been considered. We evaluated the effect of soil sterilization because soil borne pathogens been shown to perish over elapsed times at a more-than-specific temperature at the spot stage. As for soil temperature, however, it is thought that the sterilization effect cannot be evaluated in the elapsed time due to greatly changing weather conditions during the processing period. Therefore, the positive heat-load index, which includes the heat capacity of soil's temperature rise, was proposed for the construction of a model for the sterilization effect factor with multiplication-level quantity for the rise in soil temperature above the constant temperature. This study examined the method of estimating the modeling of the solar-heating load index in order to determine the land criteria for soil solarization.
    The solar-heating load index (SHLI(°C・hrs)), which indicates the effect of soil solarization, provided the model that could be estimated from the daily maximum soil temperature during a sterilization period (τ). The model is defined by the following equation:
    SHLI = AΔTB ΔT = TsmaxTc
    where A and B are constant, Tsmax is the daily maximum soil temperature (°C), and Tc is 40
    °C, based on the literature.
    Constant A showed a tendency to increase linearly as the measurement depth of the soil temperature increased, while constant B did not show any change in difference regarding the measurement depth of the soil temperature. Therefore, the SHLI that incorporated the measurement depth of the soil temperature is expressed by the following equation.
    SHLI=(0.0746×Dr+0.7317)ΔT(0.0033×Dr+1.5878)
    where Dr is the measurement depth from the surface of the ground (cm).
    Our findings showed that when the SHLI of the soil solarization period exceeds 500 °C・hrs, there is little evidence of the onset of common scab of potato.
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