巻号一覧
58 巻 (2002)
- 4 号 p. 171-
- 3 号 p. 115-
- 2 号 p. 63-
- 1 号 p. 1-
58 巻, 4 号
選択された号の論文の4件中1～4を表示しています
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カマラ S., クルプアラッキ T., ラナトゥンゲ E.R., 林 陽生, 横沢 正幸, 西森 基貴, 三上 岳彦2002 年 58 巻 4 号 p. 171-183
発行日: 2002/12/10
公開日: 2010/02/25
ジャーナル フリー多変数分類法を用いて, 西アフリカの熱帯湿潤山岳地域における降水機構の季節的構造を解析し, 高湿潤から半湿潤レジームにおける降水量変動を明らかにした。すなわち, 主成分分析によって3成分モデルを構築し, 対象地域の季節的な降水量変動の特徴を解析した。3つの成分は, 乾季 (12月～4月), 雨季 (6月～9月), および移行期 (雨季から乾季への移行は10月～11月, 乾季から雨季への移行は5月) であり, 乾季成分によって, 降水量変動のほとんどは説明できた。また, これら3成分および階層的クラスター法を用いて, 降水レジームを表現する7つのクラスター群が特定した。このような地域的な降水量特性を深く理解することは, 経済活動のほとんどを, 降水によってその活動が左右される農業およびその関連産業に依存している西アフリカ諸国にとって重要である。抄録全体を表示PDF形式でダウンロード (3015K) -
脇山 恭行2002 年 58 巻 4 号 p. 185-194
発行日: 2002/12/10
公開日: 2010/02/25
ジャーナル フリーInfrared remote sensing is used for crop monitoring, for example evaluation of water stress, detection of infected crops and estimation of transpiration and photosynthetic rates. This study was conducted to show another application of remote sensing information. The relationship between rice leaf temperature and chlorophyll content in the leaf blade was investigated by using thermography during the ripening period. The canopy of a rice community fertilized by top dressing was cooler than that not fertilized in a 1999 field experiment. In an experiment using thermocouples to measure leaf temperature, a rice leaf with high chlorophyll content was also cooler than that with a low chlorophyll content. Transpiration resistance and transpiration rate were measured with a porometer. Transpiration rate was higher with increasing chlorophyll content in the leaf blade. Stomatal aperture is related to chlorophyll content in the leaf blade. High degree of stomatal aperture is caused by high chlorophyll content in the leaf blade. As degree of stomatal aperture increases, transpiration rate increases. Therefore the rice leaf got cooler with increasing chlorophyll content in leaf blade. Paddy rice communities with different chlorophyll contents were provided with fertilization of different nitrogen levels on basal and top dressing in a 2000 field experiment. Canopy temperature of the rice community with high chlorophyll content was 0.85°C cooler than that of the rice community with low chlorophyll content. Results of this study revealed that infrared remote sensing could detect difference in chlorophyll contents in rice communities and could be used in fertilizer management in paddy fields.抄録全体を表示PDF形式でダウンロード (1290K) -
横山 仁, 木曽 雅昭, 原薗 芳信2002 年 58 巻 4 号 p. 195-206
発行日: 2002/12/10
公開日: 2010/02/25
ジャーナル フリーLeaves of leather fern are used as a foliage plant and Mottled Yellowing Syndrome (MYS) has been occurring on leaves cultivated in protected greenhouses at Hachijo Island since the 1990s. Experiments with different shading levels and soil moisture levels were carried out to develop cultivation methods that will prevent the occurrence of MYS. Relationships between the greenhouse environment and the occurrence of MYS were examined and the following results were obtained.
The temperature of air, the canopy surface, and soil in the greenhouses were affected not only by shading levels but also by the color of the shading net. Air and canopy surface temperature decreased with an increase of shading rate with blue nets, however, temperatures under black nets were quite high due to the high surface temperature of the nets, which caused a high occurrence of MYS.
Numbers of leaves decreased with an increase of shading level, but the leaf size increased. Chlorophyll content of the leaves increased with shading levels too.
An optimum greenhouse environment to increase leaf size, leaf number, and chlorophyll content was obtained by a using a blue net with a 55% shading rate and the soil water potential controlled to less than 0.016MPa.
MYS occurrence is increased by high temperature stress of the plant rather than high solar radiation in greenhouses. Also, MYS occurrence was decreased by frequent irrigation.
MYS occurrence (%) can be estimated by degree days over 34°C of maximum air temperature for well-irrigated greenhouses, and by 1.5 times the degree days over 32°C for less-irrigated greenhouses. Farmers can manage the greenhouse environment to reduce MYS damage by applying these results.
Greenhouses devoted to leather fern cultivation should be shaded (around half the amount of sunlight compared to outside) and should be controlled to keep good ventilation and soil moisture by frequent irrigation, which provides a desirable canopy surface-, air- and soil temperature, resulting in reduction of MYS damage and improvement in productivity and quality.抄録全体を表示PDF形式でダウンロード (5076K) -
細野 達夫, 細井 徳夫2002 年 58 巻 4 号 p. 207-216
発行日: 2002/12/10
公開日: 2010/02/25
ジャーナル フリーInformation on water uptake by plants is useful for management in greenhouse cultivation (e.g. irrigation control). In this paper, we continuously measured water uptake by long-term tomatoes grown in a re-circulating hydroponic system in a glasshouse through two entire cultivation periods (Each cultivation period was 9-10 months long, from mid-winter to mid-summer). Amount of water uptake by plants was measured by monitoring the amount of water supplied to the hydroponic system. Over 95% of total water uptake by the plants throughout cultivation period was passed through the plants as transpiration. Daily amount of water uptake increased with the increase of leaf area until LAI reached 1.5, then was not significantly affected by LAI. Day-by-day change of daily water uptake amount was primarily associated with change of daily-accumulated solar radiation. Daily water uptake amount by long-term tomatoes was well estimated by a multiple regression equation including daily-averaged air temperature and water vapor pressure deficit in glasshouse in addition to daily-accumulated solar radiation as independent variables.抄録全体を表示PDF形式でダウンロード (1331K)
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