Effect of regulated irrigation water temperature on hydroponics production of Spinach (Spinacia oleracea L.)

Abstract

The effects of different temperature regimes of irrigation water on the growth rate of Spinacia oleracea L. were 
determined in the greenhouse for 8 weeks. The spinach seedlings were irrigated with water heated to various 
temperatures (24, 26 and 28°C) via pumps connected to 4 sets of water tanks each maintained at the experimental 
temperatures using Dolphin aquarium heaters. Unheated water from the tap supplied from the fourth tank served as 
control. All the plants were supplied with a mixture of Ocean HYDROGRO and Ocean HORTICAL nutrient solutions 
containing all essential elements. After 8 weeks of growth, results showed that leaf length (mm), leaf number and total 
fresh and dry weights (g per plant) was higher in plants grown at elevated temperatures compared with the control 
plants with optimum growth being recorded at 28°C. These results suggest that controlled production of spinach 
during winter seasons is possible by irrigation with heated water in a greenhouse.