Comparative growth and quality performance of lettuce cultivars under hydroponic and soil systems

Abstract Traditional soil-based lettuce cultivation is limited by constrained space, soil-borne pathogens, variable produce quality and difficulties in achieving year-round production. Hydroponic systems present a viable alternative; however, comparative data on system–cultivar interactions under Nepalese conditions are limited. This study aims to identify an efficient hydroponic system for improving lettuce growth and quality. The experiment was conducted to evaluate the growth performance and biochemical quality of four lettuce cultivars (‘Green Span’, ‘New Red Fire’, ‘Lollo Rossa’ and ‘Black Rose’) under three production systems: nutrient film technique (NFT), deep-water culture (DWC) and soil-based cultivation for off-season production in Nepal. The experiment was conducted at Khumaltar, Lalitpur, from July to September 2023 using a combined randomized complete block design with four replications. Growth parameters and biochemical traits were assessed at 28 and 42 days after transplanting. The NFT system significantly enhanced vegetative growth, recording the highest fresh weight (90.5 g) at 28 DAT compared to DWC (47.4 g) and soil-based cultivation (17.1 g). ‘Green Span’ exhibited superior biomass accumulation and vegetative vigour across all systems. At 42 DAT, the interaction between production system and cultivar significantly affected lettuce fresh weight. ‘Green Span’ grown under the soil-based system recorded the highest fresh weight, followed by plants grown under the NFT system, indicating a cultivar-specific response during post-harvest regrowth. While hydroponic systems maximized growth parameters, soil-based cultivation resulted in higher total soluble solids and titratable acidity. Anthocyanin accumulation was highest in ‘Black Rose’ and ‘Lollo Rossa’, particularly under soil conditions, whereas ‘Green Span’ and ‘Lollo Rossa’ showed higher vitamin C content. Overall, the results demonstrate significant cultivar × production-system effects, highlighting the importance of selecting suitable combinations for off-season lettuce production. Significance of this study What is already known on this subject? Hydroponic systems are widely recognized for improving lettuce growth and productivity compared with conventional soil cultivation. Continuous nutrient availability and favourable root-zone conditions in hydroponics enhance nutrient uptake and plant development. Lettuce performance is also known to vary among cultivars due to genetic differences in growth and resource-use efficiency. What are the new findings? The study provides novel comparative information on NFT, DWC and soil-based lettuce production under off-season conditions in Nepal , including post-harvest regrowth. It provides a basis for improving off-season and potentially year-round lettuce production. The results further identified cultivar-specific responses, highlighting differences in adaptability to hydroponic environments. What are the expected impacts on horticulture? The findings provide practical guidance for selecting suitable lettuce cultivars and hydroponic systems to maximize productivity and quality. Adoption of NFT technology can improve resource-use efficiency, shorten production cycles and increase yield. These outcomes can support the expansion of sustainable, year-round leafy vegetable production, particularly in regions with limited arable land and water resources.