• 作者： 徐森雄
• 作者服務機構： 國立屏東農業專科學校水土保持科
• 中文摘要： 本文以屏東代表臺灣西南部地區，進行觀測冬季乾旱期問內，常見旱作葉面之結露情形，並以壓克力板為代替性觀測試材，比較兩者結露量之關係。 在1981年11月至1982年4月，結露日數達120天，壓克力板之露量19.4mm。同期間內常見旱作如玉米、大豆、花生、紅豆及甘藷等之葉面露量平均在4.42~6.41 mg cm day 間，惟當壓克力板露量少於4.9 mg cm day 時，葉面即未能測得露水。作物正反兩葉面之露量對壓克力板露量之比值，平均言之，其大小順序為玉米67%，大豆61%，紅豆及甘藷58%，花生54%。若以X為百葉箱內相對濕度 90%之時間（hr.），Y為結露時間（hr．）時，結露時間可從Y＝1.9734＋0.8065X推估。
• 英文摘要： This study deals with the phenomenon ofdew on several crops (maize, soybean, peanut, adzukii bean and sweet potato) underwinter-dry climate in southwest region ofTaiwan (represented by Pingtung area). Thedew amount on leaves and acrylic plate weremeasured by means of weighing method withfilter paper, and the time of dew durationwas recorded by an improved Taylor typedew duration recorder. From November 1981to April 1982, the observed records of dewwere summarized as follows： 1. The total dew amount on leaves and its total dewy days in respective investiga- tion period were 6.69 mm（53 days) on maize，5.40 mm (48 days) on soybean, 7.21 mm (73 days) on peanut, 4.92 mm (46 days) on adzukii bean and 3.72 mm (36 days) on sweet potato·2. Acrylic plate is a proper substitute material for dew measurment on leaves that had been ascertained in previous study by the author. In this study the ratio of dew amount on leaves to that on acrylic plate in the same period was 67% for maize, 61% for soybean, 54% for peanut, 58% for adzukii bean and sweet potato. If the dew amount on acrylic plate less than 4.9 mg/cm /day, dew can not be measured on leaves.3. The total dew amount on acrylic plate was 19.4 mm within 120 dewy days in the period from November to April, and the average dew duration was 10 hours daily．4 ．Dew duration can be estimated from the following equation： Y＝1.9734＋0.8065X Where, Y is dew duration in hours and X is the hours for relative humidity 90% in the shelter.
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