Effects of nutrient solution EC on plant growth and phytochemical accumulation in substrate-grown spinach

Abstract

Abstract The effects of nutrient solution electrical conductivity EC level on the plant growth, nitrates, total phenols, chlorophylls, riboflavin, and ascorbic acid content were evaluated in two cultivars of spinach (Spinacia oleracea L. cv. Manatee and Regia). Soil blocked spinach seedlings (five seedlings per block) were transplanted (on 25 January 2018) at 18 days after emergence into to Styrofoam planting boxes (100-cm long × 25-cm wide × 10-cm high) filled with 14 L of substrate. Each planting box was irrigated daily by drip and fertilized with nutrient solution. The nutrient solution was injected in the irrigation system at two different rates to reach two different ECs (1.7 and 1.2 dS m-1). The fresh yield was not affected by the EC of the nutrient solution or by the cultivar, nevertheless, leaf-blade and petiole dry weight percentage increased with EC. Leaf-blade NO3 concentration (1.58 mg/g fresh weight) was lower in the plants irrigated with low EC, while leaf–blade riboflavin content increased with the EC reaching 37.09 µg/100g fresh weight. Total phenols content in leaf-blade and petiole were affected neither by cultivar nor EC.