Gas and ion exchanges in wheat roots after nitrogen supply

Barneix, Atilio J.; Breteler, H.; Geijn, S.C. van de

doi:10.1111/j.1399-3054.1984.tb06340.x

Cited by 42 publications

(28 citation statements)

References 24 publications

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“…Owing to the higher demand for energy and Cskeletons, root respiration is thought to be generally higher with ammonium than with nitrate supply (Barneix et al, 1984, Peuke & Jeschke, 1993. In the present study, however, root respiration rates in non-mycorrhizal plants tended to be higher in nitrate-than in ammonium-supplied plants (Table 3).…”

Section: Table 5 Concentrations (Mg G'^ D Wt) Of Starch and Solublecontrasting

confidence: 62%

“…This might be because the site of nitrate reduction and assimilation in conifer seedlings, in contrast to many annual plants, is located mainly in the roots (.-Vlexander, 1983;Scheromm & Plassard, 1988). Accordingly, the demand for energy and C-skeletons in the roots is also high w ith nitrate supply and the CO., release in roots increases with increasing nitrate uptake (Barneix et al, 1984;Sasakawa & LaRue, 1986;van der Werf et al, 1988). Lower root respiration rates in nitrate-than in ammoniumsupplied plants might therefore be found mainly in plants which reduce nitrate predominantly in the shoots, like many annual crop plants.…”

Section: Table 5 Concentrations (Mg G'^ D Wt) Of Starch and Solublementioning

confidence: 99%

“…Supply of ammonium stimulates root respiration more than does supply of nitrate in Triticum vidgare and Ricinus communis (Barneix, Breteler & van de Geijn, 1984, Peuke & Jeschke, 1993 as well as in excised beech ectomycorrhiza (Harley, McCready & Geddes, 1954). Root respiration rates are also increased by mycorrhizal infection (Barnard & Jorgenseii, 1977;Reid et al, 1983).…”

Section: Introductionmentioning

confidence: 99%

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Growth and mineral nutrition of non‐mycorrhizal and mycorrhizal Norway spruce (Picea abies) seedlings grown in semi‐hydroponic sand culture

Eltrop

Marschner

1996

New Phytologist

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S U M M A R YIn seedlings of Norway spruce {Picea abies (L.) Karst.), grown in semi-hydroponic sand culture, mycorrhizal infection decreased grow-th (Eltrop & Marschner, 1996). Possible reasotis for this growth depression were investigated in the present study by comparing the plant and fungal biomass distribution and carbon partitioning between non-mycorrhizal and mycorrhizal {Pisolithus tinctorius) plants supplied with ammonium or nitrate as source of N.Despite the high mycorrhizal infection rate (55-71 '\, of total root tips), the amount of fungal btomass in roots and extramatrical mycelium of mycorrhizal plants accounted for less than 3°o of plant dry matter and was significantly lower in nitrate-than in ammonium-supplied plants.The CO., assimilation rates were higher in mycorrhizal thari in non-mycorrhizal plants supplied with ammonium as well as those supplied with nitrate. High light intensity considerably increased CO., assimilation rates. The respiration rates of the intact root systems were significantly increased in ammonium-supplied mycorrhizal plants compat-ed with non-mycorrhizal plants. The amount of CO., lost in root respiration as a percentage of the amount of CO., gained in photosynthesis (respiratory quotient), ranged from 49-3 "o at 30 °C root zone temperature and low light intensity (290/(mol m"'s"') to ll-7"o at 10 °C and high light intensity (990//mol m~" s"'). In ammonium-supplied plants grown at 22 °C and low light intensity, the proportion of carbon lost by root respiration was significantly higher in mycorrhizal than in non-m\xorrhizal plants. This increase in root respiration was of the same order of magnitude (7-4 "o) as the decrease in dry matter production by mycorrhizal plants (10-1 °"). In nitrate-supplied plants, no significant difference in the respiratory quotient was found between non-mycorrhizal and mycorrhizal plants. The respiration rate per unit d. wt of the fungal mycelium was estimated to account for 31-3 °o (ammonium supply) and 8-3 "o (nitrate supply) of that of the total mycorrhizal root system although the dry weight accounted for only 4-0 "" (ammonium supply) and 2-5 °o (nitrate supply). Accordingly, the respiration rate was calculated to be 11-1 times higher with ammonium supply, and 3-4 times higher with nitrate supply, than that of the root tissue. The carbohydrate coi-icentrations in shoots and roots were not consistently different between non-mycorrhizal and mycorrhizal plants.It was concluded that increased root respiration was mainly responsible for the growth reduction in mycorrhizal compared with non-mycorrhizal plants, whereas the production of fungal biomass in the extramatrical t-nycelium of mycorrhizal plants was of minor importance.

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Section: Table 5 Concentrations (Mg G'^ D Wt) Of Starch and Solublecontrasting

confidence: 62%

Section: Table 5 Concentrations (Mg G'^ D Wt) Of Starch and Solublementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Growth and mineral nutrition of non‐mycorrhizal and mycorrhizal Norway spruce (Picea abies) seedlings grown in semi‐hydroponic sand culture

Eltrop

Marschner

1996

New Phytologist

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“…These values are consistent with the 1.3 Amol CO2 g-1 min-' estimated for root maintenance respiration (21); consequently, it seems appropriate to use the net CO2 evolution that we measured under nitrogen deprivation as a gauge of maintenance respiration. Maintenance respiration might vary with nitrogen source because of different contributions to altemative pathway respiration (2,12,16), but alternative pathway respiration is negligible in barley roots (4) and, thus, need not be considered here.…”

Section: Respiration Under Nitrogen Deprivationmentioning

confidence: 99%

“…Vol. 99,1992 and 0.35 Amol CO2 g-1 min-' = 0.88 ,umol N03-absorbed g-1 min-' x (2) + 0.13 ,umol N03-assimilated g-1 min-' y.…”

mentioning

confidence: 99%

Root Respiration Associated with Ammonium and Nitrate Absorption and Assimilation by Barley

Bloom

Sukrapanna²,

Warner³

1992

Plant Physiol.

414

224

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We examined nitrate assimilation and root gas fluxes in a wildtype barley (Hordeum vulgare L. cv Steptoe), a mutant (narla) deficient in NADH nitrate reductase, and a mutant (narla;nar7w) deficient in both NADH and NAD(P)H nitrate reductases. Estimates of in vivo nitrate assimilation from excised roots and whole plants indicated that the narla mutation influences assimilation only in the shoot and that exposure to N03-induced shoot nitrate reduction more slowly than root nitrate reduction in all three genotypes.When plants that had been deprived of nitrogen for several days were exposed to ammonium, root carbon dioxide evolution and oxygen consumption increased markedly, but respiratory quotient-the ratio of carbon dioxide evolved to oxygen consumed did not change. A shift from ammonium to nitrate nutrition stimulated root carbon dioxide evolution slightly and inhibited oxygen consumption in the wild type and narla mutant, but had negligible effects on root gas fluxes in the narla;nar7w mutant. These results indicate that, under NH4' nutrition, 14% of root carbon catabolism is coupled to NH4' absorption and assimilation and that, under N03-nutrition, 5% of root carbon catabolism is coupled to N03-absorption, 15% to N03-assimilation, and 3% to NH4+ assimilation. The additional energy requirements of N03-assimilation appear to diminish root mitochondrial electron transport. Thus, the energy requirements of NH4' and N03-absorption and assimilation constitute a significant portion of root respiration.Nitrogen assimilation is among the most energy-intensive processes in plants, requiring the transfer of two electrons per N03 converted to NO2, six electrons per N02 converted to NH4', and two electrons and one ATP per NH4' converted to glutamate. To provide sufficient electrons for these reactions, plants may divert reductant from mitochondrial electron transport. During dark N03-assimilation, shoots of a higher plant (8) and algae (18, 29) evolved CO2 significantly faster than they consumed O2, presumably because the TCA cycle or the oxidative pentose phosphate pathway catabolized substrates and transferred some electrons to N03-and N02-rather than to O2. These results indicate that, in the dark, shoots expend up to 25% of their respiratory energy on nitrogen assimilation (8).Plants from 5 to 95% of the N03-absorbed from the rhizosphere (1, 20). Estimates of root nitrogen acquisition and the associated energy transfers have been limited (2, 4, 5, 10, 12, 14-16, 23, 26, 27), and these could not distinguish among expenditures for tissue maintenance, root growth, NH4' and NO3-absorption, and NH4' and N03-assimilation. Root respiration is usually determined from net 02 uptake, yet N03-, N02-, and NH4' can substitute for 02 as electron acceptors during nitrogen assimilation. Root carbon catabolism might be a more pertinent measure, but analysis of dissolved CO2 has required discontinuous sampling (24,29) or elevated CO2 concentrations (17). The present study employed an instrumentation system that simultaneously mo...

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Alternative pathways and phosphate and nitrogen nutrition

Rychter

Szal

2015

Alternative Respiratory Pathways in Higher Plants

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Gas and ion exchanges in wheat roots after nitrogen supply

Cited by 42 publications

References 24 publications

Growth and mineral nutrition of non‐mycorrhizal and mycorrhizal Norway spruce (Picea abies) seedlings grown in semi‐hydroponic sand culture

Growth and mineral nutrition of non‐mycorrhizal and mycorrhizal Norway spruce (Picea abies) seedlings grown in semi‐hydroponic sand culture

Root Respiration Associated with Ammonium and Nitrate Absorption and Assimilation by Barley

Alternative pathways and phosphate and nitrogen nutrition

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