Controlled environments alter nutrient content of soybeans.

Information about compositional changes in plants grown in controlled environments is essential for developing a safe, nutritious diet for a Controlled Ecomological Life-Support System (CELSS). Information now is available for some CELSS candidate crops, but detailed information has been lacking for soybeans. To determine the effect of environment on macronutrient and mineral composition of soybeans, plants were grown both in the field and in a controlled environment where the hydroponic nutrient solution, photosynthetic flux (PPF), and CO2 level were manipulated to achieve rapid growth rates. Plants were harvested at seed maturity, separated into discrete parts, and oven dried prior to chemical analysis. Plant material was analyzed for proximate composition (moisture, protein, lipid, ash, and carbohydrate), total nitrogen (N), nonprotein N (NPN), nitrate, minerals, amino acid composition, and total dietary fiber. The effect of environment on composition varied by cultivar and plant part. Chamber-grown plants generally exhibited the following characteristics compared with field-grown plants: 1) increased total N and protein N for all plant parts, 2) increased nitrate in leaves and stems but not in seeds, 3) increased lipids in seeds, and 4) decreased Ca:P ratio for stems, pods, and leaves. These trends are consistent with data for other CELSS crops. Total N, protein N, and amino acid contents for 350 ppm CO2 and 1000 ppm CO2 were similar for seeds, but protein N and amino acid contents for leaves were higher at 350 ppm CO2 than at 1000 ppm CO2. Total dietary fiber content of soybean leaves was higher with 350 ppm CO2 than with 1000 ppm CO2. Such data will help in selecting of crop species, cultivars, and growing conditions to ensure safe, nutritious diets for CELSS.     

Excess nutrients in hydroponic solutions alter nutrient content of rice, wheat, and potato.

Environment has significant effects on the nutrient content of field-grown crop plants. Little is known, however, about compositional changes caused by controlled environments in which plants receive only artificial radiation and soilless, hydroponic culture. This knowledge is essential for developing a safe, nutritious diet in a Controlled Ecological Life-Support System (CELSS). Three crops that are candidates for inclusion in a CELSS (rice, wheat, and white potato) were grown both in the field and in controlled environments where the hydroponic nutrient solution, photosynthetic photon flux (PPF), and CO2 level were manipulated to achieve rapid growth rates. Plants were harvested at maturity, separated into discrete parts, and dried prior to analysis. Plant materials were analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate, minerals, and amino-acid composition. The effect of environment on nutrient content varied by crop and plant part. Total N and nonprotein N (NPN) contents of plant biomass generally increased under controlled-environment conditions compared to field conditions, especially for leafy plant parts and roots. Nitrate levels were increased in hydroponically-grown vegetative tissues, but nitrate was excluded from grains and tubers. Mineral content changes in plant tissue included increased phosphorus and decreased levels of certain micronutrient elements under controlled-environment conditions. These findings suggest that cultivar selection, genetic manipulation, and environmental control could be important to obtain highly nutritious biomass in a CELSS.     

Proximate composition of CELSS crops grown in NASA's Biomass Production Chamber.

Edible biomass from four crops of wheat (Triticum aestivum L.), four crops of lettuce (Lactuca sativa L.), four crops of potato (Solanum tuberosum L.), and three crops of soybean (Glycine max (L.) Merr.) grown in NASA's CELSS Biomass Production Chamber were analyzed for proximate composition. All plants were grown using recirculating nutrient (hydroponic) film culture with pH and electrical conductivity automatically controlled. Temperature and humidity were controlled to near optimal levels for each species and atmospheric carbon dioxide partial pressures were maintained near 100 Pa during the light cycles. Soybean seed contained the highest percentage of protein and fat, potato tubers and wheat seed contained the highest levels of carbohydrate, and lettuce leaves contained the highest level of ash. Analyses showed values close to data published for field-grown plants with several exceptions: In comparison with field-grown plants, wheat seed had higher protein levels; soybean seed had higher ash and crude fiber levels; and potato tubers and lettuce leaves had higher protein and ash levels. The higher ash and protein levels may have been a result of the continuous supply of nutrients (e.g., potassium and nitrogen) to the plants by the recirculating hydroponic culture.     

Proximate nutritional composition of CELSS crops grown at different CO2 partial pressures.

Two CELSS candidate crops, soybean (Glycine max) and potato (Solanum tuberosum), were grown hydroponically in controlled environments maintained at carbon dioxide (CO2) partial pressures ranging from 0.05 to 1.00 kPa (500 to 10,000 ppm at 101 kPa atmospheric pressure). Plants were harvested at maturity (90 days for soybean and 105 days for potato) and all tissues analyzed for proximate nutritional composition (i.e. protein, fat, carbohydrate, crude fiber, and ash content). Soybean seed ash and crude fiber were higher and carbohydrate was lower than values reported for field-grown seed. Potato tubers showed little difference from field-grown tubers. With the exception of increased crude fiber of soybean seed with increased CO2, no trends were apparent with regard to CO2 effects on proximate composition of soybean seed and potato tubers. Crude fiber of soybean stems and leaves increased with increased CO2, as did soybean leaf protein (total nitrogen). Potato leaf and stem (combined) protein levels also increased with increased CO2, while leaf and stem carbohydrates decreased. Values for leaf and stem protein and ash were higher than values generally reported for field-grown plants for both species. Results suggest that CO2 partial pressure should have little influence on proximate composition of potato tubers or soybean seed, but that high ash and protein levels might be expected from leaves and stems of crops grown in controlled environments of a CELSS.     

CO2 enrichment influences yields of 'Florunner,' 'Georgia Red' and 'New Mexico' peanut cultivars.

Three peanut cultivars, 'Florunner,' 'Georgia Red,' and 'New Mexico,' were grown in reach-in chambers to determine response to CO2 enrichment. CO2 treatments were ambient (400 micromol mol-1) and 700 micromol mol-1. Growth chamber conditions included 700 micromol m-2 s-1 photosynthetic photon flux (PPF), 28/22C, 7O% RH, and 12/12 h photoperiod. Growth media consisted of a 1:1 mixture (v/v) of vermiculite and sterilized sand. Six 10 L pots of each cultivar were fertilized three times per week with 250 mL of nutrient solution containing additional Ca (10 mM) and NO3 (25 mM) and watered well. Beginning 21 days after planting (DAP) and every three weeks thereafter up to 84 days, the second leaf from the growing axis (main stem) was detached to determine CO2 effect on leaf area, specific leaf area (SLA) and dry weight. Plants were harvested 97 DAP, at which time total leaf area, leaf number, plant and root weights and pod production data were taken. Numbers of pods per plant, pod fresh and dry weights, fibrous root and plant dry weights were higher for all cultivars grown at 700 micromol mol-1 than at ambient CO2. Also, leaf area for all cultivars was larger with CO2 enrichment than at ambient. SLA tended to decline with time regardless of CO2 treatment. Percentage of total sound mature kernels (%TSMK) was similar for both treatments. Plants grown at 700 micromol mol-1 CO2 had slightly more immature pods and seeds at final harvest.     

Quality characteristics of the radish grown under reduced atmospheric pressure

This study addresses whether reduced atmospheric pressure (hypobaria) affects the quality traits of radish grown under such environments. Radish (Raphanus sativus L. cv. Cherry Bomb Hybrid II) plants were grown hydroponically in specially designed hypobaric plant growth chambers at three atmospheric pressures; 33, 66, and 96 kPa (control). Oxygen and carbon dioxide partial pressures were maintained constant at 21 and 0.12 kPa, respectively. Plants were harvested at 21 days after planting, with aerial shoots and swollen hypocotyls (edible portion of the radish referred to as the “root” hereafter) separated immediately upon removal from the chambers. Samples were subsequently evaluated for their sensory characteristics (color, taste, overall appearance, and texture), taste-determining factors (glucosinolate and soluble carbohydrate content and myrosinase activity), proximate nutrients (protein, dietary fiber, and carbohydrate) and potential health benefit attributes (antioxidant capacity). In roots of control plants, concentrations of glucosinolate, total soluble sugar, and nitrate, as well as myrosinase activity and total antioxidant capacity (measured as ORAC_FL), were 2.9, 20, 5.1, 9.4, and 1.9 times greater than the amount in leaves, respectively. There was no significant difference in total antioxidant capacity, sensory characteristics, carbohydrate composition, or proximate nutrient content among the three pressure treatments. However, glucosinolate content in the root and nitrate concentration in the leaf declined as the atmospheric pressure decreased, suggesting perturbation to some nitrogen-related metabolism.     

Effect of elevated carbon dioxide on nutritional quality of tomato.

Tomato (Lycopersicon esculentum Mill.) cvs. Red Robin (RR) and Reimann Philipp (RP) were grown hydroponically for 105 d with a 12 h photoperiod, 26 degrees C/22 degrees C thermoperiod, and 500 micromol m-2 s-1 PPF at either 400, 1200, 5000, or 10,000 micromol mol-1 (0.04, 0.12, 0.50, 1.00 kPa) CO2. Harvested fruits were analyzed for proximate composition, total dietary fiber, nitrate, and elemental composition. No trends were apparent with regard to CO2 effects on proximate composition, with fruit from all treatments and both cultivars averaging 18.9% protein, 3.6% fat, 10.2% ash, and 67.2% carbohydrate. In comparison, average values for field-grown fruit are 16.6% protein, 3.8% fat, 8.1% ash, and 71.5% carbohydrate (Duke and Atchely, 1986). Total dietary fiber was highest at 10,000 micromol mol-1 (28.4% and 22.6% for RR and RP) and lowest at 1000 micromol mol-1 (18.2% and 15.9% for RR and RP), but showed no overall trend in response to CO2. Nitrate values ranged from 0.19% to 0.35% and showed no trend with regard to CO2. K, Mg, and P concentrations showed no trend in response to CO2, but Ca levels increased from 198 and 956 ppm in RR and RP at 400 micromol mol-1, to 2537 and 2825 ppm at 10,000 micromol mol-1. This increase in Ca caused an increase in fruit Ca/P ratios from 0.07 and 0.37 for RR and RP at 400 micromol mol-1 to 0.99 and 1.23 for RR and RP at 10,000 micromol mol-1, suggesting that more dietary Ca should be available from high CO2-grown fruit.     

Regulating plant/insect interactions using CO2 enrichment in model ecosystems.

The greenhouse environment is a challenging artificial ecosystem in which it is possible to study selected plant/insect interaction in a controlled environment. Due to a combination of "direct" and "indirect" effects of CO2 enrichment on plant photosynthesis and plant development, canopy productivity is generally increased. In this paper, we discuss the effects of daytime and nighttime CO2 enrichment protocols on gas exchange of pepper plants (Capsicum annuum L, cv Cubico) grown in controlled environments. In addition, we present the effects of thrips, a common Insect pest, on the photosynthetic and respiratory activity of these plant canopies. Carbon dioxide has diverse effects on the physiology and mortality of insects. However, our data indicate that thrips and whiteflies, at least, are not killed "directly" by CO2 levels used to enhance photosynthesis and plant growth. Together the data suggest that the insect population is affected "indirectly" by CO2 and that the primary effect of CO2 is via its effects on plant metabolism.     

Specific effects of irradiance and CO2 concentration doublings on productivity and mineral content in lettuce.

Experiments in growth chambers with controlled atmosphere were performed to compare the effects on the productivity of two treatments stimulating photosynthesis: the doubling of CO2 concentration, the doubling of irradiance; the combining of both was also tested. A large effect of light was noticed: (i) the accumulation of carbon was, contrarily to CO2 effect, amplified within time, and led to the most important dry matter production. (ii) the specific leaf weight was about two-fold increased. (iii) the nitrate content was 2-3 fold less. A significant positive effect of CO2 was detected on the fresh biomass production and the iron content of lettuce. A synergy was observed on dry matter production by the interaction of the two factors.     

Growth of soybean and potato at high CO2 partial pressures.

Soybean and potato plants were grown in controlled environments at carbon dioxide (CO2) partial pressures ranging from 0.05 to 1.00 kPa. The highest yields of edible biomass occurred at 0.10 kPa for both species, with higher CO2 levels being supraoptimal, but not injurious to the plants. Stomatal conductance rates of upper canopy leaves were lowest at 0.10 kPa CO2, while conductance rates at 0.50 and 1.00 kPa were significantly greater than 0.10 kPa. Total water use by the plants was greatest at the highest CO2 pressures (i.e. 0.50 and 1.00 kPa); consequently, water use efficiencies (biomass produced/water used) were low at the highest CO2 pressures. Based on previous CO2 studies in the literature, the increased conductance and water use at the highest CO2 pressures were surprising and pose interesting challenges for managing plants in a CELSS, where CO2 pressures may exceed optimal levels.     

The effects of CO2 on growth and transpiration of radish (Raphanus sativus) in hypobaria

Plants grown on long-term space missions will likely be grown in low pressure environments (i.e., hypobaria). However, in hypobaria the transpiration rates of plants can increase and may result in wilting if the water is not readily replaced. It is possible to reduce transpiration by increasing the partial pressure of CO₂ (pCO₂), but the effects of pCO₂ at high levels (>120 Pa) on the growth and transpiration of plants in hypobaria are not known. Therefore, the effects of pCO₂ on the growth and transpiration of radish (Raphanus sativus var. Cherry Bomb II) in hypobaria were studied. The fresh weight (FW), leaf area, dry weight (DW), CO₂ assimilation rates (C_A), dark respiration rates (DR), and transpiration rates from 26 day-old radish plants that were grown for an additional seven days at different total pressures (33, 66 or 101 kPa) and pCO₂ (40 Pa, 100 Pa and 180 Pa) were measured. In general, the dry weight of plants increased with CO₂ enrichment and with lower total pressure. In limiting pCO₂ (40 Pa) conditions, the transpiration for plants grown at 33 kPa was approximately twice that of controls (101 kPa total pressure with 40 Pa pCO₂). Increasing the pCO₂ from 40 Pa to 180 Pa reduced the transpiration rates for plants grown in hypobaria and in standard atmospheric pressures. However, for plants grown in hypobaria and high pCO₂ (180 Pa) leaf damage was evident. Radish growth can be enhanced and transpiration reduced in hypobaria by enriching the gas phase with CO₂ although at high levels leaf damage may occur.     

Integration of crop production with CELSS waste management.

Lettuce plants were grown utilizing water, inorganic elements, and CO2 inputs recovered from waste streams. The impact of these waste-derived inputs on the growth of lettuce was quantified and compared with results obtained when reagent grade inputs were used. Phytotoxicity was evident in both the untreated wastewater stream and the recovered CO2 stream. The toxicity of surfactants in wastewater was removed using several treatment systems. Harmful effects of gaseous products resulting from incineration of inedible biomass on crop growth were observed. No phytotoxicity was observed when inorganic elements recovered from incinerated biomass ash were used to prepare the hydroponic solution, but the balance of nutrients had to be modified to achieve near optimal growth. The results were used to evaluate closure potential of water and inorganic elemental loops for integrated plant growth and human requirements.     

Carbon balance and productivity of Lemna gibba, a candidate plant for CELSS.

The photosynthesis and productivity of Lemna gibba were studied with a view to its use in Controlled Ecological Life Support Systems (CELSS). Photosynthesis of L. gibba floating on the nutrient solution could be driven by light coming from either above or below. Light from below was about 75% as effective as from above when the stand was sparse, but much less so with dense stands. High rates of photosynthesis (ca. 800 nanomoles CO2 g dry weight (DW)-1 s-1) were measured at 750 micromoles m-2 s-1 PPF and 1500 micromoles mol-1 CO2. This was attained at densities up to 660 g fresh weight (FW) m-2 with young cultures. After a few days growth under these conditions, and at higher densities, the rate of photosynthesis dropped to less than 25% of the initial value. This drop was only partly alleviated by thinning the stand or by introducing a short dark period at high temperature (26 degrees C). Despite the drop in the rate of photosynthesis, maximum yields were obtained in batch cultures grown under continuous light, constant temperature and high [CO2]. Plant protein content was less than reported for field grown Lemna. When the plants were harvested daily, maintaining a stand density of 600 g FW m-2, yields of 18 g DW m-2 d-1 were obtained. The total dry weight of L. gibba included 40% soluble material (sugars and amino acids), 15% protein, 5% starch, 5% ash and 35% cellulose and other polymers. We conclude that a CELSS system could be designed around stacked, alternate layers of transparent Lemna trays and lamps. This would allow for 7 tiers per meter height. Based on present data from single layers, the yield of such a system is calculated to be 135 g DW m-3 d-1 of a 100% edible, protein-rich food.     

Soybean cultivation for Bioregenerative Life Support Systems (BLSSs): The effect of hydroponic system and nitrogen source

Soybean [Glycine max (L.) Merr.] is one of the plant species selected within the European Space Agency (ESA) Micro-Ecological Life Support System Alternative (MELiSSA) project for hydroponic cultivation in Biological Life Support Systems (BLSSs), because of the high nutritional value of seeds. Root symbiosis of soybean with Bradirhizobium japonicum contributes to plant nutrition in soil, providing ammonium through the bacterial fixation of atmospheric nitrogen. The aim of this study was to evaluate the effects of two hydroponic systems, Nutrient Film Technique (NFT) and cultivation on rockwool, and two nitrogen sources in the nutrient solution, nitrate (as Ca(NO₃)₂ and KNO₃) and urea (CO(NH₂)₂), on root symbiosis, plant growth and seeds production of soybean. Plants of cultivar ‘OT8914’, inoculated with B. japonicum strain BUS-2, were grown in a growth chamber, under controlled environmental conditions.     

Short-term and long-term effects of low total pressure on gas exchange rates of spinach.

In this study, spinach plants were grown under atmospheric and low pressure conditions with constant O2 and CO2 partial pressures, and the effects of low total pressure on gas exchange rates were investigated. CO2 assimilation and transpiration rates of spinach grown under atmospheric pressure increased after short-term exposure to low total pressure due to the enhancement of leaf conductance. However, gas exchange rates of plants grown at 25 kPa total pressure were not greater than those grown at atmospheric pressure. Stomatal pore length and width were significantly smaller in leaves grown at low total pressure. This result suggested that gas exchange rates of plants grown under low total pressure were not stimulated even with the enhancement of gas diffusion because the stomatal size and stomatal aperture decreased.     

Effects of long-term low atmospheric pressure on gas exchange and growth of lettuce

The objectives of this research were to determine photosynthesis, evapotranspiration and growth of lettuce at long-term low atmospheric pressure. Lettuce (Lactuca sativa L. cv. Youmaicai) plants were grown at 40 kPa total pressure (8.4 kPa _pO₂$p_{{\text{O}}_2}$) or 101 kPa total pressure (20.9 kPa _pO₂$p_{{\text{O}}_2}$) from seed to harvest for 35 days. Germination rate of lettuce seeds decreased by 7.6% at low pressure, although this was not significant. There was no significant difference in crop photosynthetic rate between hypobaria and ambient pressure during the 35-day study. The crop evapotranspiration rate was significantly lower at low pressure than that at ambient pressure from 20 to 30 days after planting (DAP), but it had no significant difference before 20 DAP or after 30 DAP. The growth cycle of lettuce plants at low pressure was delayed. At low pressure, lettuce leaves were curly at the seedling stage and this disappeared gradually as the plants grew. Ambient lettuce plants were yellow and had an epinastic growth at harvest. The shoot height, leaf number, leaf length and shoot/root ratio were lower at low pressure than those at ambient pressure, while leaf area and root growth increased. Total biomass of lettuce plants grown at two pressures had no significant difference. Ethylene production at low pressure decreased significantly by 38.8% compared with ambient pressure. There was no significant difference in microelements, nutritional phytochemicals and nitrate concentrations at the two treatments. This research shows that lettuce can be grown at long-term low pressure (40 kPa) without significant adverse effects on seed germination, gas exchange and plant growth. Furthermore, ethylene release was reduced in hypobaria.     

Carbon dioxide exchange of lettuce plants under hypobaric conditions.

Growth of plants in a Controlled Ecological Life Support System (CELSS) may involve the use of hypobaric pressures enabling lower mass requirements for atmospheres and possible enhancement of crop productivity. A controlled environment plant growth chamber with hypobaric capability designed and built at Ames Research Center was used to determine if reduced pressures influence the rates of photosynthesis (Ps) and dark respiration (DR) of hydroponically grown lettuce plants. The chamber, referred to as a plant volatiles chamber (PVC), has a growing area of about 0.2 m2, a total gas volume of about 0.7 m3, and a leak rate at 50 kPa of <0.1%/day. When the pressure in the chamber was reduced from ambient to 51 kPa, the rate of net Ps increased by 25% and the rate of DR decreased by 40%. The rate of Ps increased linearly with decreasing pressure. There was a greater effect of reduced pressure at 41 Pa CO2 than at 81 Pa CO2. This is consistent with reports showing greater inhibition of photorespiration (Pr) in reduced O2 at low CO2 concentrations. When the partial pressure of O2 was held constant but the total pressure was varied between 51 and 101 kPa, the rate of CO2 uptake was nearly constant, suggesting that low pressure enhancement of Ps may be mainly attributable to lowered partial pressure of O2 and the accompanying reduction in Pr. The effects of lowered partial pressure of O2 on Ps and DR could result in substantial increases in the rates of biomass production, enabling rapid throughput of crops or allowing flexibility in the use of mass and energy resources for a CELSS.     

Carbon dioxide exchange of lettuce plants under hypobaric conditions.

Growth of plants in a Controlled Ecological Life Support System (CELSS) may involve the use of hypobaric pressures enabling lower mass requirements for atmospheres and possible enhancement of crop productivity. A controlled environment plant growth chamber with hypobaric capability designed and built at Ames Research Center was used to determine if reduced pressures influence the rates of photosynthesis (Ps) and dark respiration (DR) of hydroponically grown lettuce plants. The chamber, referred to as a plant volatiles chamber (PVC), has a growing area of about 0.2 m2, a total gas volume of about 0.7 m3, and a leak rate at 50 kPa of <0.1%/day. When the pressure in the chamber was reduced from ambient to 51 kPa, the rate of net Ps increased by 25% and the rate of DR decreased by 40%. The rate of Ps increased linearly with decreasing pressure. There was a greater effect of reduced pressure at 41 Pa CO2 than at 81 Pa CO2. This is consistent with reports showing greater inhibition of photorespiration (Pr) in reduced O2 at low CO2 concentrations. When the partial pressure of O2 was held constant but the total pressure was varied between 51 and 101 kPa, the rate of CO2 uptake was nearly constant, suggesting that low pressure enhancement of Ps may be mainly attributable to lowered partial pressure of O2 and the accompanying reduction in Pr. The effects of lowered partial pressure of O2 on Ps and DR could result in substantial increases in the rates of biomass production, enabling rapid throughput of crops or allowing flexibility in the use of mass and energy resources for a CELSS.     

Incineration of biomass and utilization of product gas as a CO2 source for crop production in closed systems: gas quality and phytotoxicity.

This study addressed the recycle of carbon from inedible biomass to CO2 for utilization in crop production. Earlier work identified incineration as an attractive approach to resource recovery from solid wastes because the products are well segregated. Given the effective separation of carbon into the gaseous product stream from the incinerator in the form of CO2 we captured the gaseous stream produced during incineration of wheat inedible biomass and utilized it as the CO2 source for crop production. Injection rate was based on maintenance of CO2 concentration in the growing environment. The crop grown in the closed system was lettuce. Carbon was primarily in the form of CO2 in the incinerator product gas with less than 8% of carbon compounds appearing as CO. Nitrogen oxides and organic compounds such as toluene, xylene, and benzene were present in the product gas at lower concentrations (< 4 micromol mol-1); sulfur containing compounds were below the detection limits. Direct utilization of the gaseous product of the incinerator as the CO2 source was toxic to lettuce grown in a closed chamber. Net photosynthetic rates of the crop was suppressed more than 50% and visual injury symptoms were visible within 3 days of the introduction of the incinerator gas. Even the removal of the incinerator gas alter two days of crop exposure and replacement with pure CO2 did not eliminate the toxic effects. Both organic and inorganic components of the incinerator gas are candidates for the toxin.     

Production characteristics of the “higher plants–soil-like substrate” system as an element of the bioregenerative life support system

The study addresses the possibility of long-duration operation of a higher plant conveyor, using a soil-like substrate (SLS) as the root zone. Chufa (Cyperus esculentus L.), radish (Raphanus sativus L.), and lettuce (Lactuca sativa L.) were used as study material. A chufa community consisting of 4 age groups and radish and lettuce communities consisting of 2 age groups were irrigated with a nutrient solution, which contained mineral elements extracted from the SLS. After each harvest, inedible biomass of the harvested plants and inedible biomasses of wheat and saltwort were added to the SLS. The amounts of the inedible biomasses of wheat and saltwort to be added to the SLS were determined based on the nitrogen content of the edible mass of harvested plants. CO₂ concentration in the growth chamber was maintained within the range of 1100–1700 ppm. The results of the study show that higher plants can be grown quite successfully using the proposed process of plant waste utilization in the SLS. The addition of chufa inedible biomass to the SLS resulted in species-specific inhibition of growth of both cultivated crops and microorganisms in the “higher plants – SLS” system. There were certain differences between the amounts of some mineral elements removed from the SLS with the harvested edible biomass and those added to it with the inedible biomasses of wheat and saltwort.