Cultivation of Microgreens in a Nutrient-Substrate-Soil-less Microsystem Under Simulated Lunar Gravity: Growth Patterns, Morphological Traits, and Physiological Responses

The successful cultivation of fresh vegetables in space as a dietary supplement is critical for supporting long-duration missions, where the degradation of nutrients in pre-packaged foods could damage astronaut health. This study explores the growth patterns, morphological traits, and physiological responses of 5 (five) microgreen varieties - Broccoli (Brassica rapa var cymosa ), Radish ( Raphanus sativus var sativus ), Mustard ( Sinapis alba ), Alfalfa (Medicago sativa ), and Mungbean ( Vigna radiata ) - under simulated lunar gravity (lun-g) conditions using a Random Positioning Machine (RPM) and a minimalistic Nutrient-Substrate-Soil-less Microsystem (NSLM), comparing these development performance features with terrestrial controls. The results demonstrated that all selected microgreen varieties successfully developed in the system proposed. The samples exposed to lun-g exhibited accelerated growth compared to the terrestrial controls, achieving full maturity in only four days. Additionally, increased fresh mass of 107.32% for Broccoli (Brassica rapa var cymosa ) and 9.30% for Mungbean ( Vigna radiata ) as maximum and minimum values were observed. A significant increase in stem length was observed in the NSLM samples under lun-g, namely, 309.65% Mustard ( Sinapis alba ) and 62.13% Mungbean ( Vigna radiata ) - maximum and minimum values - compared to their respective terrestrial controls. No other significant morphological alterations were observed, indicating that the five (5) selected varieties of microgreens can effectively adapt to low-resource environments and lun-g gravity conditions. The findings of this study demonstrate the potential of minimal-growing systems to cultivate fresh leafy vegetables in space, eliminating the need for complex substrates and nutrient management, reducing the cultivation area and optimizing the need for irrigation water, as well as minimizing the related logistical challenges.