M. BÖHME, L.T. HOANG and R. VORWERK
Humboldt University of Berlin, Department of Horticultural Sciences, Lentzeallee 75, D-14195 Berlin, Germany
BÖHME, M., L.T. HOANG and R. VORWERK, 2003. Comparison of organic and mineral nutrient solution for cucumbers cultivated in closed substrate systems. Bulg. J. Agric. Sci., 9: 291–296
The investigations started out from the desire of achieving a well-balanced nutrient supply in substrate culture. An experiment with greenhouse cucumber and different kinds of substrate (perlite, rockwool, coconut fibre, and compost) was used to show the effect of mineral as well as organic nutrition on plant growth and yield. Application of metal chelates may contribute to better nutrient uptake by the crop plants. LACTOFOL®(lactic acid salts) turned out to enter into stable chemical bonds with metal ions. According to preliminary investigations with tomato, LACTOFOL® was expected to produce beneficial effects both as a leaf fertiliser and as a component of nutrient solutions in substrate culture. A closed system run on a standard mineral solution was compared with a system using the organic LACTOFOL®. Deficient nutrients were supplied by adding suitable salts and acids, so that finally both test groups received the same amount of plant nutrients. Moreover, in both variants LACTOFOL® and humic acid were applied in different concentrations as leaf fertilisers.
Plant development and crop yield were significantly higher in the variants with LACTOFOL®-O in the solution, particularly when grown in perlite, rockwool or compost. Significantly higher yields were also achieved in the variants with leaf application of LACTOFOL®-O and humic acid. In some cases humic acid treatments produced the same yield increase. Against the background of identical basic fertilisation, nitrogen concentrations in the drain water were higher in the LACTOFOL® group, a fact that seems to indicate a better nitrogen utilisation efficiency of cucumber plants in those variants.