scholarly journals Regulation of Nitrogen Uptake at the Whole-plant Level: A Study in Almond Trees

1999 ◽  
Vol 9 (4) ◽  
pp. 598-600 ◽  
Author(s):  
Farbod Youssefi ◽  
Patrick H. Brown ◽  
Steve A. Weinbaum
Keyword(s):  
N Uptake ◽  
Prunus Dulcis ◽  
Inhibitory Effect ◽  
Tree Level ◽  
Soil N ◽  
Phloem Sap ◽  
Whole Plant ◽  
Soil N Uptake ◽  
Almond Trees ◽  
Plant Level

It has been proposed that a pool of amino N, whose size is determined by aboveground N demand, cycles in the plant and regulates soil N uptake by exerting an inhibitory effect at the root level. Several experiments were carried out to study this hypothesis in almond trees [Prunus dulcis (Mill.) D.A. Webb]. Based on the evidence found, there is an association, at the whole tree level, between sap N content and soil N uptake. The data are consistent with the possibility that increased phloem sap amino acids result in decreased uptake of soil N.

The Regulation of N Uptake at the Whole-plant Level in Tree Crops

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 556d-556
Author(s):  
Farbod Youssefi ◽  
Patrick H. Brown ◽  
Steve A. Weinbaum
Keyword(s):  
N Uptake ◽  
Xylem Sap ◽  
Soil N ◽  
N Content ◽  
Whole Plant ◽  
Soil N Uptake ◽  
Almond Trees ◽  
Plant Level ◽  
N Demand ◽  
N Status

Coordinating fertilization practices with tree N uptake is important for reduction of groundwater contamination with nitrate. To reach this goal, the regulation of nitrogen uptake at the whole-plant level must be further understood. A theory that has been proposed on this subject is that a pool of amino-N, whose size is determined by above-ground N demand, cycles in the plant and regulates soil N uptake by exerting an inhibitory effect at the root level. Several experiments were carried out to study this hypothesis in fruit trees. First, foliar applications of N were made in almond trees, which led to the observation that soil N uptake was reduced in treated trees. In these trees, foliar-applied N was present in the roots when uptake was reduced; further, amino-N content of leaf and bark phloem sap was increased after several hours in the treated tree. In another experiment, amino-N content of phloem and xylem sap of almond trees of varying N status was determined. Several trees under each N status were given a pulse of abundant N fertilizer, so that their N uptake would be compared. Trees of higher N status, with greater amounts of amino-N cycling in their sap, did not take up more N than equivalent control plants, whereas lower N status trees did. To complete this series of experiments, it was observed that fruit-bearing shoots in walnut trees exported smaller proportions of foliar-applied N than non-bearing shoots, indicating that above-ground N demand may regulate the pool of N that moves down in the plant. These results and the principles that regulate N uptake will be discussed.

scholarly journals Inhibition of N2 Fixation by N Fertilization of Common Bean (Phaseolus vulgaris L.) Plants Grown on Fields of Farmers in the Eastern Cape of South Africa, Measured Using 15N Natural Abundance and Tissue Ureide Analysis

2021 ◽  
Vol 3 ◽  
Author(s):  
Simon J. Habinshuti ◽  
Sipho T. Maseko ◽  
Felix D. Dakora
Keyword(s):  
South Africa ◽  
Single Dose ◽  
Phaseolus Vulgaris ◽  
N Uptake ◽  
N Fertilizer ◽  
Double Dose ◽  
Soil N ◽  
Eastern Cape ◽  
Bean Plants ◽  
Soil N Uptake

Inhibition of N2 fixation in N-fertilized common bean (Phaseolus vulgaris L.) plants growing on the fields of farmers in the Eastern Cape of South Africa was measured using 15N natural abundance and tissue ureide analysis. The N-fertilized bean plants revealed greater soil N uptake, higher concentrations of nitrate in organs, low tissue ureide levels, and much lower percent relative ureide-N abundance when compared with unfertilized plants. In contrast, the unfertilized plants showed greater nodule fresh weight, higher N derived from fixation (e.g., 84.6, 90.4, and 97.1% at Lujecweni fields 2, 3, and 4, respectively), increased amount of N-fixed (e.g., 163.3, 161.3, and 140.3 kg ha−1 at Lujecweni fields 2, 3, and 4, respectively), greater ureide concentration in stems and petioles, higher % relative ureide-N abundance, and low soil N uptake. We also found that the percent N derived from fixation (%Ndfa) was very high for some bean plants receiving a double dose of N fertilizer [e.g., Lujecweni field 1 (51.8%) and Tikitiki field 1 (53.3%], and quite high for others receiving a single dose of N fertilizer [e.g., Tikitiki field 2 (50.1%), Mfabantu fields 1 and 2 (45.5 and 79.9%, respectively), and St. Luthberts field 1 (58.9%)]. Though not assessed in this study, it is likely that the rhizobia that effectively nodulated the N-fertilized bean plants and fixed considerable amounts of symbiotic N had constitutive and/or inducible nitrate reductase genes for reducing nitrate in nodules and bacteroids, hence their ability to form root nodules and derived high %Ndfa in bean with added N. While single- and double-dose N fertilizer applications increased plant growth and grain yield compared to unfertilized bean plants, the single-dose N fertilizer application produced much greater grain yield than the double dose. This indicates that farmers should stop using a double dose of N fertilizers on bean production, as it decreases yields and can potentially pollute the environment. This study has however shown that government supply of free N fertilizers to resource-poor farmers in South Africa increased bean yields for food/nutritional security.

scholarly journals Contribution of previous year’s leaf N and soil N uptake to current year’s leaf growth in sessile oak

2016 ◽  
Author(s):  
Stephane Bazot ◽  
Chantal Fresneau ◽  
Claire Damesin ◽  
Laure Barthes
Keyword(s):  
Leaf Growth ◽  
N Uptake ◽  
Soil N ◽  
Rhizospheric Soil ◽  
Growing Seasons ◽  
Soil N Uptake ◽  
Previous Autumn ◽  
Leaf N ◽  
N Pool

Abstract. The origin of the N which contributes to the synthesis of N reserves of in situ forest trees in autumn, and to the growth of new organs the following spring, is currently poorly documented. To characterize the metabolism of various possible N sources (plant N and soil N), six distinct 20 year-old sessile oaks were 15N labelled by spraying 15NH415NO3: (i) on leaves in May, to label the N pool remobilized in the autumn for synthesis of reserves; (ii) on soil in the autumn, to label the N pool taken up from soil; (iii) on soil at the beginning of the following spring, to label the N pool taken up from soil in the spring. The partitioning of 15N in leaves, twigs, phloem, xylem, fine roots, rhizospheric soil and microbial biomass was followed during two growing seasons. Results showed a significant incorporation of 15N in the soil-tree system; more than 30 % of the administered 15N was recovered. Analysis of the partitioning clearly revealed that in autumn, roots’ N reserves were formed from foliage 15N (73 %) and to a lesser extent from soil 15N (27 %). The following spring, 15N used for the synthesis of new leaves came first from 15N stored during the previous autumn, mainly from 15N reserves formed from foliage (95 %). Thereafter, when leaves were fully expanded, 15N uptake from soil during the previous autumn and before budburst contributed to the formation of new leaves (60 %).

scholarly journals 614 Nitrogen Uptake Efficiency of Apple Rootstocks and Scions

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 553C-553
Author(s):  
Paula B. Aguirre ◽  
Teryl R. Roper ◽  
Armand R. Krueger
Keyword(s):  
Ammonium Nitrate ◽  
Nitrogen Uptake ◽  
N Uptake ◽  
Soil N ◽  
Apple Rootstocks ◽  
Total N ◽  
Wood Tissue ◽  
Nitrogen Uptake Efficiency ◽  
Uptake Efficiency ◽  
Soil N Uptake

The uptake efficiency of apple scions and rootstocks has not been studied in the field. Using 15N (ammonium nitrate, 1 atom % 15N) we compared nitrogen uptake efficiency of 12 rootstocks grafted to one scion (Gala) and of 20 scions on the same clonal rootstock (M.9 EMLA) in orchards located in northeastern Wisconsin. Trees were treated in either Fall or Spring 1998 with 40 g actual N per tree applied as a liquid to the soil. N uptake was assessed by measuring 15N in leaf and wood tissue taken monthly from June to Oct. 1998. Tissues were oven-dried and analized using a ratio mass spectrometer. Treatment differences were greater among scions with the same rootstocks than among rootstocks with the same scion. Total N and 15N content differences were found between roostocks and these values were inversely related to tree size.

scholarly journals Contribution of previous year's leaf N and soil N uptake to current year's leaf growth in sessile oak

2016 ◽  
Vol 13 (11) ◽  
pp. 3475-3484 ◽  
Author(s):  
Stephane Bazot ◽  
Chantal Fresneau ◽  
Claire Damesin ◽  
Laure Barthes
Keyword(s):  
Leaf Growth ◽  
N Uptake ◽  
Soil N ◽  
Rhizospheric Soil ◽  
Growing Seasons ◽  
Soil N Uptake ◽  
Previous Autumn ◽  
Leaf N ◽  
N Pool

Abstract. The origin of N which contributes to the synthesis of N reserves of in situ forest trees in autumn and to the growth of new organs the following spring is currently poorly documented. To characterize the metabolism of various possible N sources (plant N and soil N), six distinct 20-year-old sessile oaks were 15N labelled by spraying 15NH415NO3: (i) on leaves in May, to label the N pool remobilized in the autumn for synthesis of reserves, (ii) on soil in the autumn, to label the N pool taken up from soil and (iii) on soil at the beginning of the following spring, to label the N pool taken up from soil in the spring. The partitioning of 15N in leaves, twigs, phloem, xylem, fine roots, rhizospheric soil and microbial biomass was followed during two growing seasons. Results showed a significant incorporation of 15N into the soil–tree system; more than 30 % of the administered 15N was recovered. Analysis of the partitioning clearly revealed that in autumn, roots' N reserves were formed from foliage 15N (73 %) and to a lesser extent from soil 15N (27 %). The following spring, 15N used for the synthesis of new leaves came first from 15N stored during the previous autumn, mainly from 15N reserves formed from foliage (95 %). Thereafter, when leaves were fully expanded, 15N uptake from the soil during the previous autumn and before budburst contributed to the formation of new leaves (60 %).

Fertilizer response of barley silage in southern and central Alberta

2004 ◽  
Vol 84 (1) ◽  
pp. 133-147 ◽  
Author(s):  
R. H. McKenzie ◽  
A. B. Middleton ◽  
J. DeMulder ◽  
E. Bremer
Keyword(s):  
N Uptake ◽  
N Fertilizer ◽  
Fertilizer Efficiency ◽  
N Availability ◽  
Soil N ◽  
Fertilizer Response ◽  
Southern Alberta ◽  
Soil N Uptake ◽  
Barley Silage ◽  
N Demand

Barley (Hordeum vulgare L.) silage is the foundation for cattle production on the Canadian prairies, but few studies have evaluated fertilizer requirements for the range of cultivars, soil types and environmental conditions in which it is grown. The objectives of this study were (1) to determine optimum N fertilizer rates for a range of barley cultivars when used for silage in southern and central Alberta and (2) to determine the frequency and impact of P, K and S deficiencies. Thirty-two field experiments were conducted from 1994 to 1996; 20 in southern Alberta under irrigated (8) or dryland (12) conditions and 12 in central Alberta under dryland conditions. Two semi-dwarf (CDC Earl, Tukwa) and three conventional (AC Lacombe, Leduc and Seebe) cultivars were tested. Fertilizer treatments included six rates of N (0 to 200 kg ha-1) and one rate each of P (13 kg ha-1), K (50 kg ha-1) and S (20 or 30 kg ha-1), compared to an appropriate unfertilized control. Optimum rates of N fertilizer ranged from 0 to 172 kg N ha-1. Irrigated sites had the highest N demand but the lowest economic optimum rate of N fertilizer (NFopt) due to high fertilizer N efficiency and high soil N availability. Dryland sites in southern Alberta had a lower N demand than irrigated sites, but NFopt was higher due to lower soil N availability. Sites in central Alberta had the least demand for N, but NFopt was similar to irrigated sites due to low N fertilizer efficiency. Nitrogen fertilizer efficiency frequently exceeded 80% in southern Alberta, particularly under irrigation. Soil N uptake increased with optimum barley yield, indicating that factors that increased crop growth also increased net mineralization and/or efficiency of soil N uptake. A good fit of NFopt was obtained in southern Alberta based on spring soil NO3-N levels and optimum yield. The best estimate of NFopt in central Alberta was the mean due to the lack of a relationship between soil N uptake and spring soil NO3-N. Barley response to P fertilizer was greatest in central Alberta and least in southern Alberta under irrigation. Few responses to K or S fertilizer were observed due to the generally adequate levels of these nutrients in Alberta soils. Fiber concentrations were not strongly affected by fertilizer treatment, while protein concentrations varied with the availability of N relative to demand. Improvements in prediction of fertilizer response for barley silage require better predictors of N fertilizer efficiency and soil N uptake, particularly in central Alberta. Key words: Hordeum vulgare, nitrogen fertilizer use efficiency, protein, fiber

scholarly journals Direct uptake of soil nitrogen by mosses

2006 ◽  
Vol 2 (2) ◽  
pp. 286-288 ◽  
Author(s):  
Edward Ayres ◽  
René van der Wal ◽  
Martin Sommerkorn ◽  
Richard D Bardgett
Keyword(s):  
Wet Deposition ◽  
Higher Plants ◽  
N Uptake ◽  
Terrestrial Ecosystems ◽  
Soil N ◽  
Arctic Ecosystems ◽  
Moss Species ◽  
Wide Range ◽  
Soil N Uptake ◽  
First Time

Mosses are one of the most diverse and widespread groups of plants and often form the dominant vegetation in montane, boreal and arctic ecosystems. However, unlike higher plants, mosses lack developed root and vascular systems, which is thought to limit their access to soil nutrients. Here, we test the ability of two physiologically and taxonomically distinct moss species to take up soil- and wet deposition-derived nitrogen (N) in natural intact turfs using stable isotopic techniques ( 15 N). Both species exhibited increased concentrations of shoot 15 N when exposed to either soil- or wet deposition-derived 15 N, demonstrating conclusively and for the first time, that mosses derive N from the soil. Given the broad physiological and taxonomic differences between these moss species, we suggest soil N uptake may be common among mosses, although further studies are required to test this prediction. Soil N uptake by moss species may allow them to compete for soil N in a wide range of ecosystems. Moreover, since many terrestrial ecosystems are N limited, soil N uptake by mosses may have implications for plant community structure and nutrient cycling. Finally, soil N uptake may place some moss species at greater risk from N pollution than previously appreciated.

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