Effect of Fruit Growth and Physiological Behavior of Highbush Blueberries in a Plastic House

Abstract

In Japan, the harvesting time for highbush blueberry cultivars coincide with the rainy season. Fruits quality has been low due to cloudy and rainy conditions. Fruits cracking can be a problem with very wet soil following rain.
To protect fruits from the rain, we try to grow five cultivars of highbush blueberry, under artificial condition in a plastic house; included varieties were Weymouth, Earliblue, Collins, Darrow and Coville.
1) In 1994 and 1995 the plants in the plastic house were covered with vinyl sheets from March to the harvesting time. In 1996 the vinyl sheets were removed from the plastic house after flower fell.
2) The maximum daily temperature within the plastic house was 10°C-15°C higher than temperature in the open field. Due to these higher temperature, the plants sprouting date, leaf opening date, and first blooming date advanced by about 10 dats. Because of this advanced growth, harvest time in the plastic house began before the rainy season.
3) The fruit sets from trees in the plastic house yielded a higher percentage than those tested in the open field. In 1994 and 1995 fruits sets from trees in the open field yielded varying berries of weight and size than those grown in the plastic house. In 1996, fruits grown in the plastic house tended to be larger.
4) The experiment of 1996 showed that the plants protected by the plastic house resulted well with early ripning, in yield, in size and quality.