EFFECTS OF ROOT-ZONE NUTRIENT CONCENTRATION ON CUCUMBER GROWN IN ROCKWOOL

We applied a new method to control root-zone salinity in rockwool, to investigate the effects of two constant levels of nutrient concentration in the rhizosphere (3.2 and 7.0 dS m^-1) on growth, yield as well as water and nutrient uptake of cucumber (cv.
Activa); the cultivation cycle lasted from July (transplanting) to October (93 days). The method is based on switching between two nutrient solutions (1.7 and 3.8 dS m^-1), the latter obtained by adding extra nutrients at the same ionic concentration ratio as in the basic nutrient solution.
In this way we managed to maintain the root-zone EC constant and around the prefixed values in both treatments; the mean EC were 3.54±0.08 and 6.87±0.11 in low EC and high EC respectively.
Nutrient concentration had no effect on the dry matter production in cucumber plants nor on its partitioning.
However, the fresh biomass, particularly the marketable yield was significantly reduced at high nutrient concentration.
This reduction was the result of a decline in fruit number and a larger incidence of unmarketable fruits.
The high nutrient treatment resulted in a significant decrease of leaf area and SLA. The dry matter percentage of high concentration fruits was always higher.
The extra nutrient concentration in the root zone reduced of about 11 % the uptake of water.
As regard nutrient, the uptake concentration of single ions was not influenced by ion content in the root zone at least at our EC levels.

International Symposium on High Technology for Greenhouse System Management: Greensys2007

F. Giuffrida, E. Heuvelink, C. Stanghellini

soilless, substrate, rhizosphere, electrical conductivity, salinity, transpiration

https://doi.org/10.17660/ActaHortic.2008.801.126