Influence of nitrogen source and concentrations on wheat growth and production inside “Lunar Palace-1”

Minimizing nitrogen (N) consumption and maximizing crop productivity are major challenges to growing plants in Bioregenerative Life Support System (BLSS) for future long-term space mission. Plants cultivated in the controlled environments are sensitive to the low recyclable N (such as from the urine). The purpose of this study is to investigate the effects of nitrogen fertilizer (NH4+-N and NO3−-N) disturbance on growth, photosynthetic efficiency, antioxidant defence systems and biomass yield and quality of wheat (Triticum aestivum L.) cultivars during ontogenesis. Experiments were divided into 4 controlled groups,Ⅰ: NO3−-N: NH4+-N = 7:1 mmol L−1; Ⅱ: NO3−-N: NH4+-N = 14:0.5 mmol L−1; Ⅲ: NO3−-N: NH4+-N = 7:0.5 mmol L−1 and CK: NO3−-N: NH4+-N = 14:1 mmol L−1, and other salt concentrations were the same. The results showed that heading and flowering stages in spring wheat are sensitive to low N concentration, especially NO3−-N in group Ⅰ and Ⅲ. NO3− is better to root growth than to shoot growth. The plants were spindling and the output was lower 21.3% when spring wheat was in low N concentration solution. Meanwhile, photosynthetic rate of low N concentrations is worse than that of CK. The soluble sugar content of the edible part of wheat plants is influenced with NO3−: NH4+ ratio. In addition, when N concentration was lowest in group Ⅲ, the lignin content decreased to 2.58%, which was more beneficial to recycle substances in the processes of the environment regeneration.