Water quality, climatic environment and mineral nutrition of tomato grown on substrate with fully recirculated nutrient solution

摘要

A tomato crop (Lycopersicum esculentum Mill. cv. Recento) grown on rockwool with fully recirculated nutrient solution yielded 33,1 kg/m~2 (2,2 pl./m~2) within 130 days. Nutrient concentration and balance adjustements were based on solution and tap water analyses. The latter's electrical conductivity (EC - 0,3 mS/cm) showed stfght variation and was sufficient in supplying for Ca, Mg and SO_4 for most of the growing period. NO_3, SO_4, Ca and Mg concentrations in the recirculated solution increased from the end of May and to the beginning of July; plant uptake resumed by the end of July. K uptake was weak from the beginning of July through the end of August as shown by accumulation in the solution; plant uptake increased then strongly for a short period in September. Nutrient solution's electrical conductivity fluctuated from a minimum of 1,4 (May) to a maximum of 3,13 mS/cm (mid-August). Mineral contents of fruits showed too high K/Ca+Mg ratio. Fruit blossom-end rot occurred increasingly from the end of August, the main causes of which being high day and night air humidity, poor root renewal and excess K to the cost of Ca and Mg uptake.