EFFECT OF THE NUTRIENT SOLUTION POTASSIUM CONCENTRATION ON TOMATOES GROWN ON NEW OR REUSED PUMICE

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.

International Symposium on Growing Media and Hydroponics

C. Economakis, A. Daskalaki, A. Bitsaki

pumice, hydroponics, tomato, potassium

https://doi.org/10.17660/ActaHortic.2001.548.61