Natalia Tikhomirova

Effect of photosynthetically active radiation, salinization, and type of nitrogen nutrition on growth of Salicornia europaea plants

Effects of various combinations of nutrient solution salinity (0.3, 171, and 342 mM NaCl), photosynthetically active radiation (PAR) of 600 or 1150 μmol/(m2 s), and type of nitrogen nutrition (amide-N or nitrate-N) on the productivity and the content of accumulated mineral nutrients and free amino acids were studied in Salicornia europaea plants. At PAR of 600 μmol/(m2 s), plant productivity increased with elevation of salinity level; at 1150 μmol/(m2 s), the maximum productivity was observed in the plants grown at 171 mM of NaCl. The content of free amino acids in shoots, regardless of PAR, decreased with growing salinity level, whereas Na content, on the opposite, increased. Glutamic acid, rather than proline, was shown to be the main organic osmolyte in this plant species. Comparison of the productivity of plants grown on solutions with amide (urea) or nitrate nitrogen showed that higher biomass accumulation was achieved in the former case.

Production process in Salicornia europaea plants as a prospective phototrophic constituent in bioregenerative life support systems

Plant productivity of a common glasswort Salicornia europaea L. was investigated in relation to the type of nitrogen nutrition and as a function of macronutrient concentrations mimicking the mineral composition of human urine. The source of nutrient nitrogen had no substantial effect on productivity of Salicornia europaea. In plants grown on media with amide as a nitrogen source, the content of nitrogenous substances, including glutamic and aspartic amino acids, was higher than in plants grown with nitrate. In plants grown on media with mineral composition analogous to that of human urine, the shoots accumulated Na and K in almost equally high amounts, on the background of high and nearly equal Na and K concentrations in the nutrient media.

A Small Test Closed Ecosystem with An Estimated Portion of Human Metabolism

The study describes a small closed ecosystem used to test technologies to be further employed in full-scale manned closed ecosystems. The experimental ecosystem is designed to use a certain portion of human metabolism, which is included in the gas, water, and organic waste loops of the system. In this experimental ecosystem, gas and water loops are fully closed, and the model enables processing of human waste and plant inedible biomass. A physicochemical method is used to remove pollutants from the air in the system. A human takes part in the gas exchange of the system through its respiration loop. This experimental ecosystem can be used for testing and improving new technologies to be further used in the future space stations.

Effects of PAR intensity and NaCl concentration on growth of Salicornia europaea plants as relevant to artificial ecological systems

Effects of variable levels of photosynthetically active radiation (PAR) and NaCl concentrations, typical of closed ecological life support systems, on growth of Salicornia europaea L. plants, CO2 exchange, mineral composition, and the content of malondialdehyde (MDA) and photosynthetic pigments were investigated. The plants were grown for 25 days at different salinities of nutrient Knop solution (171, 342, and 513 mM NaCl) under two PAR levels (690 and 1150 μmol/(m2 s)). At PAR of 690 μmol/(m2 s), the plant productivity did not show significant changes at increasing salinities; at 1150 μmol/(m2 s), the maximal productivity was observed at NaCl concentrations of 171 and 342 mM. The increase in NaCl concentration from 171 to 513 mM in the nutrient solution led to a substantial increase in the relative Na content in aboveground organs at PAR level of 1150 μmol/(m2 s). The MDA content in aboveground organs by the end of the growth period was independent of PAR intensity. The content of photosynthetic pigments in the assimilatory tissue decreased with the increase in salinity from 342 to 513 mM NaCl at PAR level of 1150 μmol/(m2 s) but not at the lower irradiance. The combination of 1150 μmol/(m2 s) PAR intensity with the salinity as high as 342 mM NaCl was found to be the most effective for optimal productivity of S. europaea plants.