关键词: 干热河谷区, 露水持续时间, 气象因子, 露水量

Abstract: Clarifying the characteristics of dew events and the main controlling environmental factors of dew formation in orange orchards in the dry-hot valley region can provide scientific basis for assessing drought mitigation by dew resources in agriculture. Dew, soil water content and meteorological data were analyzed during July 8, 2020 to November 13, 2022 in an orange orchard of Yuanjiang dry-hot valley region. At the daily scale, dew events with an amount range of 0.2-0.4 mm·d^-1 happened most frequently. The highest occurrence chance was observed for dew events with a duration of 0-2 h and 2-4 h per day. At the seasonal scale, dew events mainly concentrated in July to November. Moreover, the coefficients of variation of dew amount across all seasons were significantly smaller than those of precipitation amount. Dew occurrence frequency reached the maximum under the following conditions: wind speed of 0-1 m·s^-1, relative humidity of more than 80%, vapor pressure deficit of 0-0.4 kPa, and temperature-dew point difference within 1-2 ℃. Furthermore, the wind direction interval of 150° to 310° was beneficial to dew formation. Relative humidity and temperature-dew point difference had the greatest influence on dew formation, being the common main controlling environmental factors in different seasons. Dew was more stable than rainfall, and was an important source of moisture for orange orchards in the dry-hot valley region. Especially in the dry season with limited rainfall, dew occurred at the highest frequency, which has a potential role in alleviating the impacts of drought in orange orchards. Additionally, the considerable amount of dew in the rainy season can provide additional water replenishment to orange orchards during the short intermittent drought periods.

Key words: dry-hot valley region, dew duration, meteorological factor, dew amount