Journal of Agricultural Meteorology
Online ISSN : 1881-0136
Print ISSN : 0021-8588
ISSN-L : 0021-8588
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Volume 59, Issue 3
September
Displaying 1-6 of 6 articles from this issue
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Invited Review Papers
  • Thermal Imaging for the Study of Plant Water Relations
    Hamlyn G. JONES, Ilkka LEINONEN
    Article type: Others
    Subject area: Others
    2003 Volume 59 Issue 3 Pages 205-217
    Published: 2003
    Released on J-STAGE: September 29, 2004
    DOIhttps://doi.org/10.2480/agrmet.59.205
    JOURNAL FREE ACCESS
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    The use of infrared thermography for the study of plant water relations is reviewed. Increases in leaf temperature detected by thermography largely reflect stomatal closure as a measure of “stress.” Increases in leaf temperature can therefore be used as an indicator for irrigation scheduling. Most other uses of thermography in plant and crop science, for example as a diagnostic tool for a number of plant diseases and environmental pollutants, also depend on the indirect effects of these stressors on stomatal aperture and transpiration rate. Advances in digital image analysis are providing new ways automating image collection and analysis of specific areas within images and for large numbers of images. In spite of the power of infrared thermography, its value for diagnosis and quantification of plant stress will be greatly aided by its use in combination with other sensing techniques such as spectral reflectance or fluorescence imaging.
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Full Papers
  • Reduction of Lettuce Tipburn by Shortening Day/night Cycle
    Eiji GOTO, Tadashi TAKAKURA
    Article type: Others
    Subject area: Others
    2003 Volume 59 Issue 3 Pages 219-225
    Published: 2003
    Released on J-STAGE: September 29, 2004
    DOIhttps://doi.org/10.2480/agrmet.59.219
    JOURNAL FREE ACCESS
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    Lettuce tipburn is a calcium-related physiological disorder. Tipburn occurs mainly in inner developing leaves which have lower calcium concentrations and release of latex accompanied by rupture of laticifier in the leaves is responsible for tipburn. Shortening day/night cycles was tested to reduce injury of lettuce tipburn. Growth experiment was carried out to compare development of tipburn under 3- and 24-hour day/night cycles with the same total integrated light intensities in the cultivating period. The 24-hour cycle had a 14-hour light period and a 10-hour dark period and the 3-hour cycle had a 105-minute light period and a 75-minute dark period. Lettuce plants were exposed to the different day/night cycles from the 21st day to harvesting time. Air temperatures in the light period and dark period were 24°C and 20°C, respectively, and RHs were 85% and 90%. PPFD was 264μmol m-2s-1, and CO2 concentration was 1, 500μmol mol-1. Tipburn development was slower at the 3-hour cycle than at the 24-hour cycle though growth rate was the same for both cycles. Time course in turgor pressure in laticifiers in young leaves was measured using the thermocouple psychrometer technique under the two day/night cycles. Maximum turgor pressure in the light period was significantly lower at the 3-hour cycle than at the 24-hour cycle. The results show that frequent repetitions of shorter light and dark periods without changing the total light period decrease the accumulation of metabolites in the latex, lower excessive turgor pressure in laticifiers, and as a result, reduce tipburn without sacrificing a rapid growth rate.
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  • Estimates of Snowfall Depth, Maximum Snow Depth, and Snow Pack Environments under Global Warming in Japan from Five Sets of Predicted Data
    Satoshi INOUE, Kotaro YOKOYAMA
    Article type: Others
    Subject area: Others
    2003 Volume 59 Issue 3 Pages 227-236
    Published: 2003
    Released on J-STAGE: September 29, 2004
    DOIhttps://doi.org/10.2480/agrmet.59.227
    JOURNAL FREE ACCESS
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    Snowfall depth, maximum snow depth, and snow pack environments under global warming are estimated over all of Japan by using 5 sets of predicted data. The input data used for the estimation were interpolated monthly mean air temperatures and amounts of monthly precipitation under a gradually increasing concentration of CO2 for 100 years from present conditions as predicted by 5 different institutes.
    The predicted trends varied according to geographic location. In Hokkaido and in the highlands of Honshu, no significant change was found, but the maximum snow depth decreased. In the Tohoku district (northeastern Honshu), except for in the highlands, snowfall and maximum snow depth decreased considrably. Snow pack environments changed from “dry” to “wet”. At low elevations on the side of the Sea of Japan of Honshu south of the Hokuriku district, no snowfall occurred and no snow pack of consequence was present by the mid-21st century. Although details among the 5 sets of predicted global warming data are different for air temperature and precipitation, the results predicted for snow conditions are very similar. For the influences of precipitation, the decrease observed in Canadian Centre for Climate Modelling and Analysis, and the large fluctuations of Australia’s Commonwealth Scientific and Industrial Research Organization, are limited to the winter snowfall depth in Hokkaido and in the highlands of Honshu. In contrast, the influence of the late temperature rising of Meteorological Research Institute (Japan) affects all aspects of snow. Airtemperature is a more important predictor of snow than is precipitation.
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Full Papers (in Japanese)
  • Studies on the Environmental Control for Curing Storage of Konjak Tubers
    Ippei MIYAGAWA, Tetsuo FUJIWARA, Kazuyoshi KOSAKAI, Yoichi SHIGA
    Article type: Others
    Subject area: Others
    2003 Volume 59 Issue 3 Pages 237-244
    Published: 2003
    Released on J-STAGE: September 29, 2004
    DOIhttps://doi.org/10.2480/agrmet.59.237
    JOURNAL FREE ACCESS
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    Study was conducted on the environmental conditions in the curing treatment for konjak tubers (Amorphophallus konjac K. Koch) in which development of soft rot bacteria (Erwina carotovora) was controlled by drying.
    1. For the purpose of curing, tubers inoculated with soft-rot bacteria were kept in an environment at 55-70%RH, 30°C and with 0.5m/sec of ventilation air-flow for five days. These curing conditions resulted in wound cork formation that protected the tubers from rotting disease.
    2. Tubers inoculated with soft-rot bacteria were kept in an environment at 50-80% RH, 15°C and 1-2m/sec of ventilation for 24h or less. The infected tubers treated by this method were cured and preserved from rotting disease.
    3. Two batches of freshly harvested konjak tubers were dried: the first only on the days of harvest and the other for a period of seven days. Both were then cured in an environment at 60-75% RH, 30°C, with less than 3% CO2 concentration and 1-2m/sec of ventilation for five days. Subsequently, they were stored in a high humidity environment (95-100% RH).
    This storage method prevented tubers from rot and reduced the weight loss of tubers during the storage period. Furthermore, high-quality konjak food can be produced from even the tubers which were stored for nine months. Seed tubers stored by this storage method brought better yield than normal.
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Short Papers (in Japanese)
  • Effect of Heat Storage Flux on Energy Balance in a Larch Forest
    Masataka MIURA, Takashi HIRANO, Ryuichi HIRATA, Jun-ichi MOGAMI, Koh I ...
    Article type: Others
    Subject area: Others
    2003 Volume 59 Issue 3 Pages 245-250
    Published: 2003
    Released on J-STAGE: September 29, 2004
    DOIhttps://doi.org/10.2480/agrmet.59.245
    JOURNAL FREE ACCESS
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    Sum of sensible and latent heat fluxes measured by the eddy covariance technique is systematically smaller than available energy in many terrestrial ecosystems, which includes forests. This energy imbalance is an essential issue for the flux measurement. In this study, we evaluated heat storage flux and investigated its effect on energy balance in a larch plantation developing on a flat terrain. Above-ground biomass was the largest component producing the heat storage flux of the forest ecosystem; about 70-80% of the heat storage flux was generated in above-ground biomass for summer and fall. Moreover, the heat storage flux of topsoil over heat plates had a considerable bearing on the evaluation of soil heat flux. Adding these heat storage fluxes improved energy balance by 6-10%; it increased the slope of the ordinary least square between eddy energy fluxes and available energy, which was used as an index of energy balance closure, from 0.83 to 0.88 in summer and from 0.93 to 1.03 in fall. This suggests that we have to measure and consider heat storage flux when we investigate the energy balance of forest ecosystems.
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Research Notes (in Japanese)
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