The tournament No 6 seed won their match 6-4, 6-4 last night.
Watson had entered the tournament as a wildcard this year, having made the semi-finals last summer.
With grass her favourite playing surface, she seemed to have found her feet with a second set defeat of American Kayla Day just 24 hours earlier.
However, she then fell to Pliskova of the Czech Republic.
Pliskova is currently ranked 50th in the world, and is a former world No. 1.
Wimbledon is the next tournament on the tennis schedules.
Watson – currently ranked 158th in the world – is on the alternate entry list for the Ladies’ Singles meaning she is not guaranteed a place in the draw.
She’ll have to qualify through the preliminary rounds or be granted a wild card to take part. She is currently listed to take part in the qualifiers.
Pictured top: Heather Watson in action earlier this year at the Billie Jean King cup.
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Watson finds her identity in win back on the grass courts of Nottingham
