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| Nitrogen Productivity Studies. a Measured areal biomass and MEC model curve calculated with Φ γ = 225 μmol γ m −2 s −1 and c CO2 = 525 ppm. b Measured fresh weight percentage of total nitrogen in plants over time. A single measurement was performed for each condition at 20 d AE . c Nitrogen productivity calculated from measured biomass and nitrogen content. Error bars represent propagated error. a-c Time range highlighted in gray is specified harvest time, t M , plus 5 d 11 . Error bars represent one SD. For each data point, 5 ≤ N ≤ 10. d-f Concentration and change in concentration of nitrogen measured in the NSS over time by experimental condition (deficient, normal, excess). Error bars represent 1 SD. N = 3 for each data point. g-i Photos of lettuce crops during main growth phase at 35 d AE grown in deficient, normal, and excess nitrogen conditions, respectively.
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Food production and pharmaceutical synthesis are posited as essential biotechnologies for facilitating human exploration beyond Earth. These technologies not only offer critical green space and food agency to astronauts but also promise to minimize mass and volume requirements through scalable, modular agriculture within closed-loop systems, offeri...
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Context 1
... 71%, 81%, and 62% for deficient, normal, and excess N levels, respectively. The particular hydroponic system used shows an average germination percentage of 85% for lettuce given normal N. The biomass data were compared to the output of the MEC model (Eq. (2)) with inputs of the average values of Φ γ and c CO2 observed in the hydroponic system (Fig. 4a); see Fig. S6a, b for the growth rate [g DW d −1 ] and relative growth rate 42 ...
Context 2
... all conditions, the average fresh weight percentage of N decreased over time (Fig. 4b). Toward t M , the average mass fraction of plant N in the normal condition was smaller than that of the excess condition, yet the plants in the normal condition achieved greater average biomass, indicating that excess ammonium may have induced growth-inhibiting stresses. In the deficient condition, the average plant N content was lower ...
Context 3
... productivity ( _ Y N ) was calculated from measured biomass and nitrogen content data (Fig. 4c). The overall average nitrogen productivity under the normal N condition was 1:33 ± 0:79 g DW d À1 g À1 N ; under the deficient and excess conditions, it was 1.49 ± 0.99 and 1:90 ± 1:32 g DW d À1 g À1 N , respectively. The average of _ Y N across all conditions was 1:47 ± ...
Context 4
... molar concentrations of nitrate and ammonium in the NSS reservoirs, c [mM], were measured from 2-40 d after sowing (d AS , preceding d AE by 3 d). The concentrations and changes in concentrations over time are shown in Fig. 4d, e, f for each N condition. The concentrations over time grouped by molecular form of N are shown in Fig. S7, and the relative changes of the concentrations from the initial values are shown in Fig. S8. In the deficient N condition, the rate at which both forms of N were depleted from the NSS did not show any large fluctuations over ...
Context 5
... vascular plants can effectively take up nitrogen even when concentration is relatively low 44 . In all conditions, the depletion of nitrogen continued even as a number of plants were harvested and removed from the system every 5 days (Fig. S9). Representative photos of plants from each condition at the end of the harvest period are shown in Fig. ...
