Evaluation of Alternative Water Input Modes for Space-Based Plant Culture Applications

Wheat seeds were automatically imbibed and germinated within a Porous Tube Insert Module (PTIM) apparatus developed to support both porous tube and substrate-based nutrient delivery systems (PTNDS, SNDS) in space. The PTIM was operated under both; (1) a programmable fixed feed mode, and (2) a moisture sensor feedback control mode. For the former, increased levels of water use efficiency were evident within the PTNDS component of the study. For the latter, moisture sensors within the SNDS were evaluated at setpoints of 65-85% relative water content. Data demonstrating the ability of this approach to control moisture levels and the vertical moisture distribution patterns obtained over an 18 d grow-out interval are presented.