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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Through form to function: root hair development and nutrient uptake

Root hairs project from the surface of the root to aid nutrient and water uptake and to anchor the plant in the soil. Their formation involves the precise control of cell fate and localized cell growth. We are now beginning to unravel the complexities of the molecular interactions that underlie this developmental regulation. In addition, after years of speculation, nutrient transport by root hairs has been demonstrated clearly at the physiological and molecular level, with evidence for root hairs being intense sites of H(+)-ATPase activity and involved in the uptake of Ca(2+), K(+), NH(4)(+), NO(3)(-), Mn(2+), Zn(2+), Cl(-) and H(2)PO(4)(-).

Review, Tutorial↗
NASA NTRS2024

Substrate Matters: Ionic Silver Alters Lettuce Growth, Nutrient Uptake, and Root Microbiome in a Hydroponics System

Ionic silver (Ag+) is being investigated as a residual biocide for use in NASA spacecraft potable water systems on future crewed missions. This water will be used to irrigate future spaceflight crop production systems. We have evaluated the impact of three concentrations (31 ppb, 125 ppb, and 500 ppb) of ionic silver biocide solutions on lettuce in an arcillite (calcinated clay particle substrate) and hydroponic (substrate-less) growth setup after 28 days. Lettuce plant growth was reduced in the hydroponic samples treated with 31 ppb silver and severely stunted for samples treated at 125 ppb and 500 ppb silver. No growth defects were observed in arcillite-grown lettuce. Silver was detectable in the hydroponic-grown lettuce leaves at each concentration but was not detected in the arcillite-grown lettuce leaves. Specifically, when 125 ppb silver water was applied to a hydroponics tray, Ag+ was detected at an average amount of 7 μg/g (dry weight) in lettuce leaves. The increase in Ag+ corresponded with a decrease in several essential elements in the lettuce tissue (Ca, K, P, S). In the arcillite growth setup, silver did not impact the plant root zone microbiome in terms of alpha diversity and relative abundance between treatments and control. However, with increasing silver concentration, the alpha diversity increased in lettuce root samples and in the water from the hydroponics tray samples. The genera in the hydroponic root and water samples were similar across the silver concentrations but displayed different relative abundances. This suggests that ionic silver was acting as a selective pressure for the microbes that colonize the hydroponic water. The surviving microbes likely utilized exudates from the stunted plant roots as a carbon source. Analysis of the root-associated microbiomes in response to silver showed enrichment of metagenomic pathways associated with alternate carbon source utilization, fatty-acid synthesis, and the ppGpp (guanosine 3′-diphosphate 5′-diphosphate) stringent response global regulatory system that operates under conditions of environmental stress. Nutrient solutions containing Ag+ in concentrations greater than 31 ppb in hydroponic systems lacking cation-exchange capacity can severely impact crop production due to stunting of plant growth.

lettuce↗
NASA NTRS1986

Nitrogen uptake and utilization by intact plants

The results of experiments support the proposed conceptual model that relates nitrogen uptake activity by plants as a balanced interdependence between the carbon-supplying function of the shoot and the nitrogen-supplying function of the roots. The data are being used to modify a dynamic simulation of plant growth, which presently describes carbon flows through the plant, to describe nitrogen uptake and assimilation within the plant system. Although several models have been proposed to predict nitrogen uptake and partitioning, they emphasize root characteristics affecting nutrient uptake and relay on empirical methods to describe the relationship between nitrogen and carbon flows within the plant. Researchers, on the other hand, propose to continue to attempt a mechanistic solution in which the effects of environment on nitrogen (as well as carbon) assimilation are incorporated through their direct effects on photosynthesis, respiration, and aging processes.

Raper, C. D., Jr.↗
NASA NTRS1997

Physiological Response of Plants Grown on Porous Ceramic Tubes

This research involves the manipulation of the root-zone water potential for the purposes of discriminating the rate limiting step in the inorganic nutrient uptake mechanism utilized by higher plants. This reaction sequence includes the pathways controlled by the root-zone conditions such as water tension and gradient concentrations. Furthermore, plant based control mechanisms dictated by various protein productions are differentiated as well. For the nutrients limited by the environmental availability, the kinetics were modeled using convection and diffusion equations. Alternatively, for the nutrients dependent upon enzyme manipulations, the uptakes are modeled using Michaelis-Menten kinetics. In order to differentiate between these various mechanistic steps, an experimental apparatus known as the Porous Ceramic Tube - Nutrient Delivery System (PCT-NDS) was used. Manipulation of the applied suction pressure circulating a nutrient solution through this system imposes a change in the matric component of the water potential. This compensates for the different osmotic components of water potential dictated by nutrient concentration. By maintaining this control over the root-zone conditions, the rate limiting steps in the uptake of the essential nutrients into tomato plants (Lycopersicon esculentum cv. Cherry Elite) were differentiated. Results showed that the uptake of some nutrients were mass transfer limited while others were limited by the enzyme kinetics. Each of these were adequately modeled with calculations and discussions of the parameter estimations provided.

Tsao, David↗
NASA NTRS1990

Root-zone acidity affects relative uptake of nitrate and ammonium from mixed nitrogen sources

Soybean plants (Glycine max [L.] Merr. cv Ransom) were grown for 21 days on 4 sources of N (1.0 mM NO3-, 0.67 mM NO3- plus 0.33 mM NH4+, 0.33 mM NO3- plus 0.67 mM NH4+, and 1.0 mM NH4+) in hydroponic culture with the acidity of the nutrient solution controlled at pH 6.0, 5.5, 5.0, and 4.5. Dry matter and total N accumulation of the plants was not significantly affected by N-source at any of the pH levels except for decreases in these parameters in plants supplied solely with NH4+ at pH 4.5. Shoot-to-root ratios increased in plants which had an increased proportion [correction of proporiton] of NH4(+)-N in their nutrient solutions at all levels of root-zone pH. Uptake of NO3- and NH4+ was monitored daily by ion chromatography as depletion of these ions from the replenished hydroponic solutions. At all pH levels the proportion of either ion that was absorbed increased as the ratio of that ion increased in the nutrient solution. In plants which were supplied with sources of NO3- plus NH4+, NH4+ was absorbed at a ratio of 2:1 over NO3- at pH 6.0. As the pH of the root-zone declined, however, NH4+ uptake decreased and NO3- uptake increased. Thus, the NH4+ to NO3- uptake ratio declined with decreases in root-zone pH. The data indicate a negative effect of declining root-zone pH on NH4+ uptake and supports a hypothesis that the inhibition of growth of plants dependent on NH4(+)-N at low pH is due to a decline in NH4+ uptake and a consequential limitation of growth by N stress.

NASA Discipline Life Support Systems↗
NASA NTRS1994

Diurnal changes in net uptake rate of nitrate are associated with changes in estimated export of carbohydrates to roots

The rate of NO3- uptake by soybean (Glycine max [L.] Merrill) roots generally declines during the night in association with progressive depletion of the nonstructural carbohydrate pool in the shoot as well as the concentration of carbohydrates in roots. To determine if NO3- uptake rate changes in response to variations in translocation rate of carbohydrates from shoot to roots per se or to carbohydrate status of the roots, the night period was interrupted with a low light level from incandescent lamps to alter the diurnal pattern of NO3- uptake by roots and export of carbohydrate from shoots of nonnodulated soybean. Depletion of NO3- from replenished, complete nutrient solutions containing 1 mM NO3- was measured by ion chromatography and rates of NO3- uptake were calculated. Changes in export of carbohydrates from shoot to roots during intervals of the night period were calculated as the differences between rates of disappearance in contents of nonstructural carbohydrates and their estimated rates of utilization in shoot respiration and growth. A positive, significant correlation occurred between changes in calculated rates of carbohydrate export from shoots and NO3- uptake rates. Conversely, there was no significant correlation between concentrations of nonstructural carbohydrates in roots and NO3- uptake rates. These results support the hypothesis that carbohydrate flux from shoot to roots has a direct role in regulation of nitrogen uptake by the whole plant.

Non-NASA Center↗
NASA NTRS1988

Nitrogen uptake by wheat seedlings, interactive effects of four nitrogen sources: NO3-, NO2-, NH4+, and urea

The net influx (uptake) rates of NO3-, NH4+, NO2-, and urea into roots of wheat (Triticum aestivum cv Yecora Rojo) seedlings from complete nutrient solutions containing all four compounds were monitored simultaneously. Although urea uptake was too slow to monitor, its presence had major inhibitory effects on the uptake of each of the other compounds. Rates of NO3-, NH4+, and NO2- uptake depended in a complex fashion on the concentration of all four N compounds. Equations were developed which describe the uptake rates of each of the compounds, and of total N, as functions of concentrations of all N sources. Contour plots of the results show the interactions over the range of concentrations employed. The coefficients of these equations provide quantitative values for evaluating primary and interactive effects of each compound on N uptake.

NASA Discipline Number 61-10↗
NASA NTRS1996

Nutrient management effects on sweetpotato genotypes under controlled environment

Sweetpotato is one of several crops recommended by National Aeronautics and Space Administration (NASA) for bioregenerative life support studies. One of the objectives of the Tuskegee University NASA Center is to optimize growth conditions for adaptability of sweetpotatoes for closed bioregenerative systems. The role of nutrient solution management as it impacts yield has been one of the major thrusts in these studies. Nutrient solution management protocol currently used consists of a modified half Hoagland solution that is changed at 14-day intervals. Reservoirs are refilled with deionized water if the volume of the nutrient solution was reduced to 8 liters or less before the time of solution change. There is the need to recycle and replenish nutrient solution during crop growth, rather than discard at 14 day intervals as previously done, in order to reduce waste. Experiments were conducted in an environmental growth room to examine the effects of container size on the growth of several sweetpotato genotypes grown under a nutrient replenishment protocol. Plants were grown from vine cuttings of 15cm length and were planted in 0.15 x 0.15 x 1.2m growth channels using a closed nutrient film technique system. Nutrient was supplied in a modified half strength Hoagland's solution with a 1:2.4 N:K ratio. Nutrient replenishment protocol consisted of daily water replenishment to a constant volume of 30.4 liters in the small containers and 273.6 liters in the large container. Nutrients were replenished as needed when the EC of the nutrient solution fell below 1200 mhos/cm. The experimental design used was a split-plot with the main plot being container size and genotypes as the subplot. Nine sweetpotato genotypes were evaluated. Results showed no effect of nutrient solution container size on storage root yield, foliage fresh and dry mass, leaf area or vine length. However, plants grown using the large nutrient solution container accumulated more storage root dry mass than those with the small containers. Although plants grown with the smaller containers showed greater water uptake, plant nutrient uptake was lower than with the larger container. All genotypes evaluated showed variation in their responses to all parameters measured.

Solanaceae/genetics/growth & development↗
NASA NTRS1993

A data base of crop nutrient use, water use, and carbon dioxide exchange in a 2O square meter growth chamber: I. Wheat as a case study

A data set is given describing the daily nutrient uptake, gas exchange, environmental conditions, and carbon (C), and nutrient partitioning at harvest for the entire canopy and root system of a wheat crop (Triticum aestivum, cv. Yecora Rojo). The data were obtained from a 20 m2 stand of wheat plants grown from planting to maturity in a closed, controlled environment, and include daily nutrient uptake [macronutrients, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S); and micronutrients, iron (Fe), boron (B), manganese (Mn), zinc (Zn), copper (Cu), and molybdenum (Mo)], canopy carbon dioxide (CO2) exchange rates, and transpiration. Environmental factors such as relative humidity, air temperature, nutrient solution temperature, pH and electrical conductivity, and photoperiod were controlled in the chamber to specific set points. A detailed description of biomass yield for each of the 64 plant growth trays comprising the 20 m2 of growth area is also provided, and includes dry weights of grain, straw, chaff, and roots, along with the concentration of nutrients in different plant tissues and the percent carbohydrate, fat, and protein. To our knowledge, this information represents one of the most extensive data sets available for a canopy of wheat grown from seed to maturity under controlled environmental and nutritional conditions, and thus may provide useful information for model development and validation. A methods section is included to qualify any assumptions that might be required for the use of the data in plant growth models, along with a daily event calendar indicating when adjustments in set points and occasional equipment or sensor failures occurred.

NASA Discipline Number 61-20↗
NASA NTRS1993

A Data Base of Crop Nutrient Use, Water Use, and Carbon Dioxide Exchange in a 20 Square Meter Growth Chamber: Wheat as a Case Study - Part 1

A data set is given describing the daily nutrient uptake, gas exchange, environmental conditions, and carbon (C), and nutrient partitioning at harvest for the entire canopy and root system of a wheat crop (Triticum aestivum, cv. Yecora Rojo). The data were obtained from a 20 sq m stand of wheat plants grown from planting to maturity in a closed, controlled environment, and include daily nutrient uptake [macronutrients, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S); and micronutrients, iron (Fe), boron (B), manganese (Mn), zinc (Zn), copper (Cu), and molybdenum (Mo)], canopy carbon dioxide (CO2) exchange rates, and transpiration. Environmental factors such as relative humidity, air temperature, nutrient solution temperature, pH and electrical conductivity, and photoperiod were controlled in the chamber to specific set points. A detailed description of biomass yield for each of the 64 plant growth trays comprising the 20 sq m of growth area is also provided, and includes dry weights of grain, straw, chaff, and roots, along with the concentration of nutrients in different plant tissues and the percent carbohydrate, fat, and protein. To our knowledge, this information represents one of the most extensive data sets available for a canopy of wheat grown from seed to maturity under controlled environmental and nutritional conditions, and thus may provide useful information for model development and validation. A methods section is included to qualify any assumptions that might he required for the use of the data in plant growth models, along with a daily event calendar indicating when adjustments in set points and occasional equipment or sensor failures occurred.

Wheeler, Raymond M.↗
NASA NTRS1986

Utilization of ammonium as a nitrogen source: effects of ambient acidity on growth and nitrogen accumulation by soybean

Dry matter accumulation of plants utilizing NH4+ as the sole nitrogen source generally is less than that of plants receiving NO3- unless acidity of the root-zone is controlled at a pH of about 6.0. To test the hypothesis that the reduction in growth is a consequence of nitrogen stress within the plant in response to effects of increased acidity during uptake of NH4+ by roots, nonnodulated soybean plants (Glycine max [L.] Merr. cv Ransom) were grown for 24 days in flowing nutrient culture containing 1.0 millimolar NH4+ as the nitrogen source. Acidities of the culture solutions were controlled at pH 6.1, 5.1, and 4.1 +/- 0.1 by automatic additions of 0.01 N H2SO4 or Ca(OH)2. Plants were sampled at intervals of 3 to 4 days for determination of dry matter and nitrogen accumulation. Rates of NH4+ uptake per gram root dry weight were calculated from these data. Net CO2 exchange rates per unit leaf area were measured on attached leaves by infrared gas analysis. When acidity of the culture solution was increased from pH 6.1 to 5.1, dry matter and nitrogen accumulation were reduced by about 40% within 14 days. Net CO2 exchange rates per unit leaf area, however, were not affected, and the decreased growth was associated with a reduction in rates of appearance and expansion of new leaves. The uptake rates of NH4+ per gram root were about 25% lower throughout the 24 days at pH 5.1 than at 6.1. A further increase in solution acidity from pH 5.1 to 4.1 resulted in cessation of net dry matter production and appearance of new leaves within 10 days. Net CO2 exchange rates per unit leaf area declined rapidly until all viable leaves had abscised by 18 days. Uptake rates of NH4+, which were initially about 50% lower at pH 4.1 than at 6.1 continued to decline with time of exposure until net uptake ceased at 10 days. Since these responses also are characteristic of the sequence of responses that occur during onset and progression of a nitrogen stress, they corroborate our hypothesis.

NASA Discipline Number 61-10↗
NASA NTRS1989

Effects of NaCl on metabolic heat evolution rates by barley roots

The effect of salinity stress on metabolic heat output of barley (Hordeum vulgare L.) root tips was measured by isothermal microcalorimetry. Several varieties differing in tolerance to salinity were compared and differences quantified. Two levels of inhibition by increasing salt were found. Following the transition from the initial rate of the first level, inhibition remained at about 50% with further increases in salt concentration up to 150 millimolar. The concentration of salt required to inhibit to this level was cultivar dependent. At highter concentrations (>150 millimolar) of salt, metabolism was further decreased. This decrease was not cultivar dependent. The decreased rate of metabolic heat output at the first transition could be correlated with decreases in uptake of NO3-, NH4+, and Pi that occurred as the salt concentration was increased. The high degree of dependence of the inhibition of metabolic heat output on NaCl concentration points to a highly cooperative reaction responsible for the general inhibition of metabolism and nutrient uptake. The time required to attain the first level of salt inhibition is less than 20 minutes. Inhibition of root tips was not reversible by washing with salt free solutions. In addition to revealing these features of salt inhibition, isothermal microcalorimetry is a promising method for convenient and rapid determination of varietal differences in response to increasing salinity.

NASA Discipline Life Support Systems↗
NASA NTRS2001

Beneficial effects of humic acid on micronutrient availability to wheat

Humic acid (HA) is a relatively stable product of organic matter decomposition and thus accumulates in environmental systems. Humic acid might benefit plant growth by chelating unavailable nutrients and buffering pH. We examined the effect of HA on growth and micronutrient uptake in wheat (Triticum aestivum L.) grown hydroponically. Four root-zone treatments were compared: (i) 25 micromoles synthetic chelate N-(4-hydroxyethyl)ethylenediaminetriacetic acid (C10H18N2O7) (HEDTA at 0.25 mM C); (ii) 25 micromoles synthetic chelate with 4-morpholineethanesulfonic acid (C6H13N4S) (MES at 5 mM C) pH buffer; (iii) HA at 1 mM C without synthetic chelate or buffer; and (iv) no synthetic chelate or buffer. Ample inorganic Fe (35 micromoles Fe3+) was supplied in all treatments. There was no statistically significant difference in total biomass or seed yield among treatments, but HA was effective at ameliorating the leaf interveinal chlorosis that occurred during early growth of the nonchelated treatment. Leaf-tissue Cu and Zn concentrations were lower in the HEDTA treatment relative to no chelate (NC), indicating HEDTA strongly complexed these nutrients, thus reducing their free ion activities and hence, bioavailability. Humic acid did not complex Zn as strongly and chemical equilibrium modeling supported these results. Titration tests indicated that HA was not an effective pH buffer at 1 mM C, and higher levels resulted in HA-Ca and HA-Mg flocculation in the nutrient solution.

Non-NASA Center↗
NASA NTRS2007

Plant Productivity and Characterization of Zeoponic Substrates after Three Successive Crops of Radish (Raphanus sativus L.)

The National Aeronautics and Space Administration (NASA) has developed a zeolite-based synthetic substrate, termed zeoponics. The zeoponic substrate (consisting of NH4(-) and K-exchanged clinoptilolite, synthetic apatite, and dolomite) provides all of the plant-essential nutrients through mineral dissolution and ion exchange, with only the addition of water. Previous studies have shown high productivity of wheat in zeoponic substrates; however, no experiments have been conducted on other crops. The objective of this study was to determine the productivity and nutrient uptake of radish (Raphanus sativus L.) grown in zeoponic substrates with three successive crops in the same substrate. Radish was chosen because of its sensitivities to NH4(+). Average fresh weights of edible roots were similar for radish grown in zeoponic substrates watered with deionized H2O (10.97 g/plant) and in potting mix control substrate irrigated with nutrient solution (10.92 g/plant). Average fresh weight production of edible roots for radish grown in same zeoponic substrate increased in yield over time with the lowest yield in the first crop (7.10 g/plant) and highest in the third crop (13.90 g/plant). The Ca plant tissue levels in radishes (1.8-2.9 wt. %) grown in zeoponic substrates are lower than the suggested sufficient range of 3.0-4.5 wt. % Ca; however, the Ca level is highest (2.9 wt. %) in radishes grown in the third crop in the same zeoponic substrates. The higher radish yield in the third crop was attributed to a reduction in an NH4(-) induced Ca deficiency that has been previously described for wheat grown in zeoponic substrates. The P levels in plant tissues of radish grown in the zeoponic substrates ranged from 0.94-1.15 wt. %; which is slightly higher than the sufficient levels of 0.3-0.7 wt. %. With the exception of Ca and P, other macronutrient and micronutrient levels in radish grown in zeoponic substrates were well within the recommended sufficient ranges. After three successive crops of radish growth, the zeoponic substrates had 52% of the original NH4(-)N and 78% of the original K remaining on zeolite exchange sites. Zeoponic substrates are capable of long-term productivity of radishes for space.

Gruener, J. E.↗
NASA NTRS1981

Winter wheat: A model for the simulation of growth and yield in winter wheat

The basic ideas and constructs for a general physical/physiological process level winter wheat simulation model are documented. It is a materials balance model which calculates daily increments of photosynthate production and respiratory losses in the crop canopy. The partitioning of the resulting dry matter to the active growing tissues in the plant each day, transpiration and the uptake of nitrogen from the soil profile are simulated. It incorporates the RHIZOS model which simulates, in two dimensions, the movement of water, roots, and soluble nutrients through the soil profile. It records the time of initiation of each of the plant organs. These phenological events are calculated from temperature functions with delays resulting from physiological stress. Stress is defined mathematically as an imbalance in the metabolite supply; demand ratio. Physiological stress is also the basis for the calculation of rates of tiller and floret abortion. Thus, tillering and head differentiation are modeled as the resulants of the two processes, morphogenesis and abortion, which may be occurring simulaneously.

Baker, D. N.↗
NASA NTRS1982

Plant Growth in Controlled Environments in Response to Characteristics of Nutrient Solutions

Emphasis was given to environmental factors that alter the flux of carbohydrate from the shoot to the root system to support the absorption of nitrogen and the subsequent interaction between nitrogen uptake and whole plant growth. Only the nitrate form of nitrogen was utilized in order to establish base line responses for evaluation of future studies utilizing both ammonium and nitrate.

Raper, C. D., Jr.↗
NASA NTRS1986

The uptake of NO3-, NO2-, and NH4+ by intact wheat (Triticum aestivum) seedlings. I. Induction and kinetics of transport systems

The inducibility and kinetics of the NO3-, NO2-, and NH4+ transporters in roots of wheat seedlings (Triticum aestivum cv Yercora Rojo) were characterized using precise methods approaching constant analysis of the substrate solutions. A microcomputer-controlled automated high performance liquid chromatography system was used to determine the depletion of each N species (initially at 1 millimolar) from complete nutrient solutions. Uptake rate analyses were performed using computerized curve-fitting techniques. More precise estimates were obtained for the time required for the extent of the induction of each transporter. Up to 10 and 6 hours, respectively, were required to achieve apparent full induction of the NO3- and NO2- transporters. Evidence for substrate inducibility of the NH4+ transporters requiring 5 hours is presented. The transport of NO3- was mediated by a dual system (or dual phasic), whereas only single systems were found for transport of NO2- and NH4+. The Km values for NO3-, NO2-, and NH4+ were, respectively, 0.027, 0.054, and 0.05 millimolar. The Km for mechanism II of NO3- transport could not be defined in this study as it exhibited only apparent first order kinetics up to 1 millimolar.

NASA Program CELSS↗