Growth Performance of Green Oak, Red Oak, and Green Cos in a Deep Flow Technique Hydroponic System

Abstract

This study examined the growth performance and economic returns of three types of salad vegetables grown in a closed greenhouse using a deep flow technique (DFT) hydroponic system and adjusted to an electrical conductivity (EC) of 1.2–1.8 mS/cm and a pH of 5.6–6.5. The solution contained two balanced stock solutions: Stock A (N, P, K, Mg, S, Mo, B, Zn, Cu, and Mn) and Stock B (Ca and Fe). The study was conducted in Non Mak Khaeng, Watthana Nakhon, Sa Kaeo, Thailand, from March to April, 2024, utilizing a completely randomized design (CRD) with salad vegetable types as the treatment factor. Three lettuce varieties were tested: Green Oak, Red Oak, and Green Cos, with five replications of 10 plants each. The results revealed that Green Cos exhibited the highest growth performance in terms of root length (30.97 ± 0.32 cm), canopy height (19.33 ± 0.25 cm), and weight per plant (162.40 ± 5.29 g), with statistically significant differences (p<0.05) compared with Green Oak and Red Oak. However, Green Oak was recorded for the highest number of leaves (22.00 ± 1.00 leaves per plant). Survival rates were consistent at 100% across all three types. From an economic perspective, Green Cos yielded the highest profit of 4,872.54 THB, followed by Green Oak and Red Oak with profits of 4,526.94 THB and 3,867.88 THB, respectively. This research can be applied to the planning of salad vegetable production in a DFT hydroponic system to align with market goals. For example, it can help increase yields to meet the demands of health-conscious consumers, enhance competitiveness in the market, and ensure stable long-term income. Additionally, this approach supports the development of sustainable agricultural practice.