Comparative Response of Lettuce (Lactuca sativa L.) Varieties to Nutrient Film Technique (NFT) Hydroponics in an Advanced Greenhouse Setup: Impacts on Yield and Quality

In the face of rapidly changing climatic conditions that are increasingly threatening the stability of the present agricultural economy, it has now become mandatory to evaluate the response of different plants varieties to conventional greenhouse conditions versus artificially controlled environments, particularly under LED lighting. Present study was carried out to evaluate the comparative response of four lettuce (Lactuca sativa L.) varieties to Nutrient Film Technique (NFT) hydroponics under precisely controlled LED lighting versus conventional greenhouse conditions, with the aim of optimizing yield and quality. A randomized complete block design with four varieties (V1-Lugano, V2-Aleppo, V3-Carmesi, V4-Kineta), five repetitions, and two blocks was implemented over two years (2023–2024) in the Plant Factory research greenhouse of USAMV Bucharest. Plants were grown in an NFT system at EC 1.2–2.2 mS cm⁻¹ and pH 6.0, comparing natural sunlight (average 274.3 µmol m⁻² s⁻¹) with LED lighting (181.7 µmol m⁻² s⁻¹, 18 h photoperiod, red + blue spectrum). Morphometric parameters (fresh mass, rosette diameter, leaf number), sugar content, and nitrate levels were measured and analyzed by two-way ANOVA and Tukey’s HSD test. The LED Plant Factory system (LED) significantly outperformed the conventional greenhouse across all varieties (p < 0.0001), increasing fresh biomass by 16.9–68.4 % (highest in Kineta: 238.41 g plant⁻¹ vs. 141.56 g plant⁻¹), enlarging rosette diameter, and elevating soluble sugar content (4.23 vs. 3.71 °Brix). A highly significant variety × growing-system interaction (p < 0.0001) revealed genotype-specific responses, with Kineta showing the strongest positive reaction. Nitrate accumulation was higher under LED (1243.3 vs. 811.4 mg kg⁻¹), remaining below critical thresholds. These results demonstrate that LED-supplemented NFT hydroponics, when matched to cultivar-specific responses, substantially improves lettuce productivity and nutritional quality while highlighting the need for integrated spectral and varietal optimization in controlled-environment agriculture.