Temporal variability of dew in a transition morpho-climaticzone in Southern Brazil

Abstract

The period in which leaves are exposed to dew is of extreme importance for epidemiological aspects, which affects the health and the final biomass production of plants. The objective of this study was to determine the main temporal characteristics of the dew occurrence in a preserved point of the transition morphoclimatic zone between the Pampa Biome and the Atlantic Forest Biome in Santa Maria, Rio Grande do Sul State, Brazil. Data were collected from June 2016 to May 2018 by a LWS-L sensor. Number of days with dew per month and the frequency histograms of the dew onset and dry-off times per season were determined. The leaf wetness duration (LWD, h) was calculated. Mean LWD per month and its monthly variability was determined. The minimum number of occurrences by month was 4 (January 2017), and the maximum was 29 (April 2018). The preferred onset and dryoff times were 6-9 PM, and 7-10 AM, respectively, although there were diferences between seasons. The LWD tended to decrease during the warmer seasons (9.00-9.54h), compared to the colder seasons (10.58-11.12 h), and presented a significantly monthly variability.