Development and Yield of Vegetables Cultivated on Substrate Heated by Geothermal Waters Part I: Bell Pepper, Slicing Cucumber, Tomato

Polyethylene pipes were buried in the soil at a depth of 0.4 m and spaced at 0.5 and 0.25 m apart in covered tunnels. Geothermal waters with temperatures between 30–45°C, from the final phase of a process that utilized geothermal energy, were pumped through the pipes. The impact of heating by geothermal energy, and the spacing of the heating grid on the growth, development, and productivity of bell pepper, slicing cucumber and tomato was investigated. Acceleration in time to harvest and an increase in yield of vegetables were observed. Heating the tunnels caused yields to be significantly higher than in the unheated tunnels. The 0.25 m spacing of the heating grid sometimes contributed to lowered cucumber and pepper yield, while tomato yield was increased.