Growth and biomass yield of 25 crops in the 4-subject 180-day integrated experiment

Abstract

To support human life during deep space exploration, the cultivation of higher plant plays a critical role in sustaining gas, water, and nutrient cycles in Controlled Ecological Life Support System (CELSS). This study aimed to develop crop co-cultivation and highly efficient production techniques, explore diverse plant growth patterns, and evaluate the capability of continuous production in a long-term closed environment. Twenty-five crops, including 1 grain, 2 tubers, 2 oil plants, 2 fruits, 3 functional plants, and 15 vegetables, were selected for their nutrient content, growth cycle, and environmental requirement. Depending on their requirements of light source, photoperiod, nutrient solution, and temperature, 25 crops were distributed in 4 separate cabins, which spanned 195.36 square meters in total. Most wheat were grown in a nutrient solution, whereas a small portion of wheat and the other crops were grown in a solid substrate, in order to recycle solution and solid wastes properly. Throughout the trial period, most of these crops adapted to the closed environment and completed the whole growth and development cycle normally. The results showed that the crop cultivation system could continuously provide a variety of vegetables and fruits at a rate of 1.43 kg d−1 (fresh weight) for 4 crews in the 180-day experiment and at a rate of 1.30 kg d−1 (dry weight) grains and tubers in the last 60 days. The harvest index of sweet potato was higher than that of wheat and potato, whereas its yield per unit area was similar to that of wheat. Since the harvest of the first batch of grains and tubers, crops grown in the cabins gradually became the main source of crews' diet. In addition, various cultivars displayed distinct differences in growth and yield under the same conditions. Further research in crop cultivation in CELSS should focus on the adaptability and adaptation mechanisms of the cultivated varieties.