Articles
FERTILIZATION OF GREENHOUSE TOMATOES GROWN IN SUBIRRIGATION METHOD
The idea of this method consists in growing plants in bottomless or bottom-perforated 400–450 mm height plastic containers filled with peat or peat-bark substrata.
Containers are placed in shallow layer of stagnant nutrient solution.
Distribution of tomato root system depends from air to water relationship.
When optimum – 400 mm high column of substrate was used the best air to water ratio was established in the 100 to 300 mm layer above the surface of nutrient solution.
About 70% of the total fine roots were present in this area and only 8% of the roots were found outside container, directly in the nutrient solution.
Relative activity of the root system – measured by oxygen uptake was similar in substrate and in the nutrient solution.
Therefore highest nutrient uptake took place in the area where root growth was most prolific.
It has been concluded that optimum salt concentration in the nutrient solution should be equal to the equivalent of 1 g KC1 per liter.
Due to capilary movement inside substrate column this results in optimum concentration in most active root zone equal to c. 3 g KCl equivalent per liter of nutrient solution.