ISHS Acta Horticulturae 554: World Congress on Soilless Culture: Agriculture in the Coming Millennium
DISINFECTION SYSTEMS OF RECYCLED EFFLUENTS IN FLOWER CROPS |
| Authors: | C. Poncet, M. Offroy, C. Antonini, A. Bettachini, G. Bonnet, J.M. Drapier, D. Hericher, P. Julien |
| Keywords: | recycling, irrigation water, chlorine, soilless culture, thermodisinfection |
| Abstract:
In soilless cultures, the process of recycling drainage water is a good way to implement the laws with regard to water-saving and limiting polluting effluents. Nevertheless, it is possible that this process could favour the dissemination of pathogens. To avoid potential risks for plant health, the disinfection of irrigation water is an alternative. Different systems were tested i.e. U.V, thermodisinfection and chlorination. In the experimental conditions, insufficient efficiency was shown in the U.V. system. Due to the fact that thermodisinfection would mean too high an investment, it was not implemented even if results obtained by this technique were very satisfactory. Having taken into consideration the characteristics of the floricultural farms of the south of France (size, means of investment…), a cost-effective methodology was searched for. With reference to drinking water, chlorine disinfection was examined. Feasibility studies were carried out in the laboratory to evaluate the sensitivity of pathogens likely to be disseminated in recycled water (Agrobacterium tumefaciens, Phytophthora cryptogea…). It was demonstrated in these studies that an amount of 4 mg/l of active chlorine applied over 30 minutes was necessary and sufficient to obtain disinfection of bacteria and fungal spores. Systems using sodium hypochlorite or chlorine gas were installed in experimental sites on rose and gerbera crops as well as in a rose floricultural farm. No phytotoxicity symptoms were detected. The reliability of a chlorine gas system installed in a rose culture for 4 years was proven. Consequently, the producers could use this technique as a routine mean of disinfection. | |
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