Lettuce Screening for Growth, Quality, and Water Use Efficiency in a Hydroponic Culture System

Field production of lettuce (Lactuca sativa L.) in southwest Texas is limited due to adverse environmental conditions, especially high temperatures and drought during the growing season. In addition, due to strict restrictions for surface and underground water resources, the vegetable industry is increasingly interested in maximizing water use efficiency (WUE) when growing high value leafy vegetables. Recirculated hydroponic culture offers several advantages over open field production. This study evaluated WUE, growth components and overall product quality of Bibb (cvs. Buttercrunch, Bibb), loose leaf (cvs. Bellatrix, Ezatrix, Caipira, Kremlin Red Leaf, Progreen 76, Ezfrill, Ezfilan, Pearl Gem) and Romaine (cvs. Sunbelt, Chabi) lettuce grown in a hydroponic culture system (NFT) at the Texas A&M AgriLife Research and Extension Center, Uvalde. Plants were grown in three cycles, October 2014, December 2014, and February 2015, for 57, 46, and 46 days, respectively, from seeding to harvest. Within the  Bibb group, greatest fresh weight, leaf length, leaf number, Brix and WUE [0.22-0.58 L.g^-1 dry weight (DW)] were recorded for Buttercrunch. Within the Romaine group, greatest fresh weight, leaf length, leaf chlorophyll (SPAD) and WUE (0.28-0.70 L.g^-1 DW) were recorded for Sunbelt. Conversely, these cultivars expressed moderate leaf tipburn injury during the first cycle. Within the loose leaf group, highest growth and WUE (0.66, 0.75, 0.72, and 0.59 L.g^-1 DW) were recorded for Ezatrix, Caipira, Kremlin Red and Pearl Gem, respectively. Expanded screening and selection of lettuce cultivars for reduced leaf tip burn, high WUE and leaf quality in hydroponic culture is important to improve water productivity, extend the production season, and improve the final product quality with minimum pesticides and nitrate leaching to the environment.