Abstract
The performance of foam-formed cellulose substrates developed for lettuce cultivation in hydroponics was investigated. Material development stages were run in parallel with a range of lettuce cultivation campaigns performed to investigate applicability of the fabricated substrates as root supports in hydroponic cultivation of lettuce in a deep-water culture experimental setup. Material composition, original density, and microbial control methods were adjusted based on observed mechanical integrity and degradation resistance of the substrates in cultivations. Management of the lettuce cultivation, including the nutrient and environmental regimes, was the same for each of the performed cultivation campaigns. Special considerations concerning potential applications of similar hydroponic systems in lunar environments have been considered. During harvests, fresh plant weight and the ratio of the dry root to dry plant weight were recorded for each plant to assess biomass distribution and overall growth performance for individual plants and selected plant groups based on substrate properties or applied substrate treatments. The effects of the substrate properties on plant growth and development indicated that plants generally thrived in cellulose-based substrates. However, treatment strategies needed to be implemented and refined to effectively control microbial growth that originated because of the organic nature of cellulose. The most effective approach involved a combination of hydrogen peroxide treatment and elevating the substrates and successfully inhibited microbial growth.