ISHS Acta Horticulturae 548: International Symposium on Growing Media and Hydroponics
EFFECT OF THE NUTRIENT SOLUTION POTASSIUM CONCENTRATION ON TOMATOES GROWN ON NEW OR REUSED PUMICE |
| Authors: | C. Economakis, A. Daskalaki, A. Bitsaki |
| Keywords: | pumice, hydroponics, tomato, potassium |
| Abstract:
Tomato plants were grown over a 5 month period (from October till February) under unheated glasshouse conditions in double-faced (black and white) polyethylene bags containing 20 l of pumice, new or reused. On each bag two tomato plants were placed, while the bags were laid in paired rows giving a plant density of 2.7 plants/m2. Complete nutrient solution with three modified levels of potassium concentration (K1=200ppm, K2=290ppm and K3=340ppm) were applied. Each potassium treatment was applied on 36 bags containing pumice as new material and on 36 bags with pumice used for second consecutive tomato cultivation period. Total yield/plant was affected by K concentration only for the reused pumice plants, while the new material gave considerably higher yield than that of the reused one only for the higher potassium treatments (K2 and K3). The yield of first class fruits (over 150g of weight) increased significantly with increasing K concentration for the new substrate plants, while the opposite was found for the reused ones. Early yield increased with increasing solution K concentration, but only for the new substrate plants. | |
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