Soybean cultivar selection for Bioregenerative Life Support Systems (BLSSs) – Hydroponic cultivation Original Research Article

Four soybean cultivars (‘Atlantic’, ‘Cresir’, ‘Pr91m10’ and ‘Regir’), selected through a theoretical procedure as suitable for cultivation in BLSS, were evaluated in terms of growth and production. Germination percentage and Mean Germination Time (MGT) were measured. Plants were cultivated in a growth chamber equipped with a recirculating hydroponic system (Nutrient Film Technique). Cultivation was performed under controlled environmental conditions (12 h photoperiod, light intensity 350 μmol m−2 s−1, temperature regime 26/20 °C light/dark, relative humidity 65–75%). Fertigation was performed with a standard Hoagland solution, modified for soybean specific requirements, and EC and pH were kept at 2.0 dS m−1 and 5.5 respectively.The percentage of germination was high (from 86.9% in ‘Cresir’ to 96.8% in ‘Regir’)and the MGT was similar for all the cultivars (4.3 days). The growing cycle lasted from 114 in ‘Cresir’ to 133 days on average in the other cultivars. Differences in plant size were recorded, with ‘Pr91m10’ plants being the shortest (58 vs 106 cm). Cultivars did not differ significantly in seed yield (12 g plant−1) and in non edible biomass (waste), water consumption and biomass conversion efficiency (water, radiation and acid use indexes). ‘Pr91m10’ showed the highest protein content in the seeds (35.6% vs 33.3% on average in the other cultivars).