NEWS WEEK 10 - LESS GROWTH IN SPRING DUE TO DIFFERENT CLIMATE MANAGEMENT

This spring, Ruud van Schie can handle the available cold economically. Whilst in 2006, growing tomatoes under a double screen, the air treatment units were regularly used to dehumidify, now with peppers under a single moisture-permeable screen, this is not necessary. Nevertheless, the screen holds heat in very well and saves a lot of energy (see graph).

Heat control using air treatment units in the bio-optimised greenhouse is different than with pipe heating. This led to the greenhouse temperature in the bio-optimised greenhouse being 1 to 2 degrees higher than in the reference greenhouse. These high night temperatures have led to a somewhat shorter plant in the bio-optimised greenhouse. The growth in length is around 15 cm shorter than in the reference greenhouse. In addition, the plant is now less lush and seems to be more resistant to sudden changes in radiation intensity.

The first setting was measured in week 8. This is later than last year, which is ascribed to the darker weather. In the bio-optimised greenhouse, 1 fruit/m2 less has set than in the reference greenhouse. This is not a large difference and can be explained by the higher night temperature maintained in the bio-optimised greenhouse.

top

NEWS WEEK 4 - RH COMPENSATES FOR LIGHT SHORTAGE

Since 29 December 2006, peppers have been planted in Ruud van Schie’s bio-optimised greenhouse. He has chosen the yellow Fiero species.

There are four air treatment units suspended in the bio-optimised greenhouse 1100 m2 in size, which can be used to heat, dehumidify and cool. In addition, there is a misting system and different fans, to level out horizontal and vertical temperature distribution. A new screen has been fitted as well, while there is an older screen and a fixed film in the reference greenhouse. Wageningen UR Glastuinbouw is comparing the bio-optimised greenhouse with this Van Schie reference greenhouse.

In January, cooling, dehumidification or misting have not been used yet. The different screens do result in a different greenhouse climate though. From the illustration, it looks like the RH in the reference greenhouse (light green line) is a bit higher than in the bio-optimised greenhouse (blue line).
The light level was lower in the reference greenhouse than in the bio-optimised greenhouse due to the double screen, but the average plant weights and leaf surfaces after five weeks of growing were the same in both greenhouses. This shows that a higher RH in the reference house is compensating for the loss of light.

top