ISHS Acta Horticulturae 511: XXV International Horticultural Congress, Part 1: Culture Techniques with Special Emphasis on Environmental Implications - Nutrient Management
REUSE OF DRAINAGE WATER FOR THE PRODUCTION OF HIGH QUALITY FRUITS IN SINGLE-TRUSS TOMATO GROWN IN A CLOSED HYDROPONIC SYSTEM |
| Authors: | K. Okano, Y. Sakamoto, S. Watanabe |
| Abstract:
A closed hydroponic system was established in the cultivation of single-truss tomato, where drainage was utilized for improving the fruit quality. Plants were grown in a “wet-sheet culture (WSC)” bed, where a water-retaining sheet (non-woven fabric) was used as a growing medium. No aeration device was needed because the roots developed on the wet sheet and were directly exposed to the atmosphere. Nutrient solution with EC 1.2 dS m-1 was applied by tube irrigation. Supply of the solution was controlled with a level sensor, and surplus solution was overflowed from the bed and collected into a reservoir tank. Tomato (Lycopersicon esculentum Mill) seedlings were transplanted to the WSC beds in a density of 10,400 plants 10a-1 at early June in 1997, and main shoots were pinched after the anthesis of the first truss leaving two leaves above the truss. On an average, 20 to 30% of daily-supplied nutrient solution was overflowed as drainage. At the final stage of ripening, the preserved drainage in the tank was concentrated to EC 5.0 dS m-1, and re-supplied to the bed instead of the fresh solution. Until the end of the harvest, all the preserved drainage have been exhausted by the plants, and no waste solution was drained out of the greenhouse. Moreover, a fruit cracking frequently occurred under the condition of high temperature could be completely prevented by the application of the concentrated drainage maybe due to the salinity effect. | |
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