RECENT DEVELOPMENTS IN GREENHOUSE CROP IRRIGATION IN THE MEDITERRANEAN REGION

In recent years, there has been a rapid expansion of Greenhouse crops growing in the Mediterranean Region of Turkey. Together with the expansion of greenhouse growing, new irrigation techniques have also been introduced in greenhouses.

The newest and the most important techniques introduced in the greenhouses of the region was the "Drip or Trickle Irrigation".

At the same time, tensiometers have been widely used for determining irrigation timing for vegetables. But, it was understood by the researchers of the region that tensiometers are not directly useful for accurate measurement of water content of the soil. However, they are good indicators of soil water status in the active root zone, and thus, can be used for irrigation scheduling of protected cultivation.

It is also known by many researchers that irrigation scheduling for conventional soil-grown greenhouse crops depends on ET rates and the readily available water (about 50 % of the total available) in the top 30 cm soil layer (most active root zone under localized irrigation systems). This should be determined from soil-water retention curves. The tensiometer reading range of 0–80 centibars should be adequate for drip-irrigated crops and most soils under greenhouse production, as non-stress conditions are usually required for high yields.

Results of some case studies of drip irrigation under greenhouse conditions are discussed.