ISHS Acta Horticulturae 644: International Symposium on Growing Media and Hydroponics
ENZYME ACTIVITY IN NUTRIENT SOLUTION OF CLOSED HYDROPONIC SYSTEMS WITH INTEGRATED SLOW FILTERS |
| Authors: | T. Brand, B.W. Alsanius |
| Keywords: | cellulase, chitinase,  -1,3-glucanase, protease, tomato, Lycopersicon esculentum L., nutrient film technique (NFT) |
| Abstract:
The phenomenon of suppressiveness in closed growing systems has been shown in recent years. Hitherto, basic mechanisms were discussed, but not investi-gated. Enzymes capable of degrading fungal cell walls, such as chitinases, cellulases, -1,3-glucanases and proteases may be one fac-tor responsible for natural disease control.
Investigating cell wall-degrading en-zymes in closed hydroponic systems (NFT) with integrated slow filters revealed natural occurrence of the tested enzymes in two tomato crops during fall 2000 and spring 2001. Protease was detected throughout the tests.
Variable rates of enzyme activity were observed during the first three weeks, but after this time a level of about 0.1 mU was attained in the hydroponic systems of both crops.
Highest prote-ase activity was found in the top layer of slow filters.
Chitinolytic enzyme activity was detected nearly consistently in the spring-crop, but not in the one growing in the fall.
Cellulase and -1,3-glucanase were found only occasionally.
Further investigations are needed to study the dynamics of cell wall-degrading enzymes and their significance for crop production in hydroponic systems.
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