Salt tolerance of flower crops grown in soilless culture

Gerbera, carnation, rose, aster, bouvardia, and lily were grown in a hydrop onic system at different levels of salinity. The EC and sodium (Na) and chl oride (Cl) concentrations maintained in the root environment solution were tuned at the expected salt sensitivity of the crops grown. The target value s for the EC were between 1.7 and 5.2 dS m(-1) (25 degrees C) and the Na an d Cl concentrations between 0 and 30 mmol L-1. All experiments had one trea tment in which the EC was increased through addition of nutrients instead o f sodium chloride (NaCl). The calculated salinity threshold values were bet ween 1.1 and 4.3 dS m(-1) and the salinity yield decrease (SYD) values betw een 2.1 and 16.8% per dS m(-1). For aster no values could be calculated, be cause the highest EC value of 4.2 in this experiment did not affect the pro duction level. However, the regrowth of this crop after the first harvest w as strongly hindered by the EC in the root environment, especially when the EC was increased with NaCl. The flower production of the bouvardia crop wa s specifically decreased by the addition of Na. Postharvest quality charact eristics of the flower crops were not affected by the treatments. The relat ionships between the Na and Cl concentrations in solution and the uptake co ncentrations of these elements was determined for the different crops. Most ly, a linear relationship was found, for Cl sometimes a curvilinear relatio nship showed a better fit.