The influence of nitrogen supply on growth and internal recycling of nitrogen in young Nothofagus fusca trees

2001 ◽  
Vol 28 (3) ◽  
pp. 249 ◽  
Author(s):  
David W. Stephens ◽  
Peter Millard ◽  
Matthew H. Turnbull ◽  
David Whitehead
Keyword(s):  
Total Nitrogen ◽  
Growth Cycle ◽  
Nitrogen Supply ◽  
Low Fertility ◽  
Nitrogen Storage ◽  
Dormant Period ◽  
Nitrogen Acquisition ◽  
Low Nitrogen ◽  
Nutrient Solutions ◽  
Nitrogen Remobilisation

The effect of nitrogen supply on biomass, and nitrogen storage and remobilisation, was investigated in young Nothofagus fusca (Hook f.) Oerst. trees growing in pots while irrigated with nutrient solutions containing 0.5 (low nitrogen, LN), 3 (medium nitrogen, MN) and 6 (high nitrogen, HN) mM nitrogen. During the first annual growth cycle, nitrogen supply was labelled with 15 N. By mid-autumn of the second annual cycle, dry weights of whole tree, stem, leaves and roots for trees in the HN and MN treatments were over 10-fold greater than the weights for trees in the LN treatment. Nitrogen was stored in roots and remobilised for new leaf and stem growth during spring. In summer, remobilised nitrogen comprised approximately 40% of the total nitrogen in leaves and stems for trees in all treatments. Nitrogen uptake for trees in the HN and MN treatments continued during the winter dormant period, and accounted for approximately half the total nitrogen acquired during the first cycle. Storage of nitrogen in roots (a deciduous characteristic), and the independence of nitrogen remobilisation from leaf senescence and significant winter uptake of nitrogen (both evergreen characteristics), suggest that the leaf phenology of N. fusca allows the species to maximise nitrogen acquisition from low fertility soils to enhance productivity.

Factors Influencing the Calibration of near Infrared Reflectometry Applied to the Assessment of Total Nitrogen in Potato. II. Operator, Moisture and Maturity Class

1995 ◽  
Vol 3 (3) ◽  
pp. 167-174 ◽  
Author(s):  
Mark W. Young ◽  
Donald K.L. MacKerron ◽  
Howard V. Davies
Keyword(s):  
Field Experiment ◽  
Spectral Data ◽  
Total Nitrogen ◽  
Near Infrared ◽  
Nitrogen Concentration ◽  
Moisture Contents ◽  
Factors Influencing ◽  
Maturity Class ◽  
The One ◽  
Low Nitrogen

Oven dried samples of leaf stem and tuber material taken from a nitrogen field experiment were analysed by Dumas combustion when fresh and by near infrared (NIR) then, and in the next two years, by a number of operators who made estimates of nitrogen concentration, [N]NIR, with differing degrees of error. The errors differed between years in the case of the one operator who made estimates in two years. Leaf, stem and tuber material of high and low nitrogen concentration were treated to produce samples at various moisture contents. These samples were scanned by NIR and the spectral data were examined. Higher moisture was found to decrease the reflectance at all the wavelengths used and would, therefore, introduce error into [N]NIR estimates. The NIR calibration used was found to be applicable to cultivars in a range of maturity classes. Several recommendations are made that will help to minimise the error introduced into [N]NIR estimates from various sources.

The influence of diet on the nitrogenous components passing to the duodenum and through the lower ileum of sheep

1966 ◽  
Vol 166 (1002) ◽  
pp. 63-79 ◽  
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Nitrogen Content ◽  
Aspartic Acid ◽  
Total Nitrogen ◽  
Amino Nitrogen ◽  
Terminal Part ◽  
High Nitrogen ◽  
Low Nitrogen ◽  
Lower Ileum

Analyses of the alimentary contents flowing to the duodenum of sheep during 24 h show that when the sheep are consuming a low-nitrogen diet more total nitrogen and amino nitrogen pass to the duodenum than are eaten daily in the food whereas when the sheep are eating high nitrogen diets, less total nitrogen and less amino nitrogen pass to the duodenum. The disparity between the total nitrogen and amino nitrogen content of the diets largely disappeared by the time the alimentary contents reached the terminal part of the ileum. From 64 to 68% of the nitrogen entering the duodenum and 54 to 64% of the nitrogen in the ileal contents was in the form of amino nitrogen. Proportionately more of the amino nitrogen was in solution in the ileal contents than in the duodenal contents. Losses of amino acids in the stomach when a high-nitrogen diet was consumed were especially large for glutamic acid, aspartic acid, proline, arginine and leucine. They were least for cystine and threonine. Gains of amino acids in the stomach when low nitrogen diets were consumed were all substantial except for proline, where a loss was found when hay and flaked maize were given. When these changes are considered as proportions of the quantities eaten then trends are similar for all acids. Changes in the molar proportions of the amino acids present in hydrolysates of the duodenal and ileal contents are discussed together with the significance of these changes in relation to the nutrition of the sheep.

scholarly journals Low Crown Root Number Enhances Nitrogen Acquisition from Low-Nitrogen Soils in Maize

2014 ◽  
Vol 166 (2) ◽  
pp. 581-589 ◽  
Author(s):  
P. Saengwilai ◽  
X. Tian ◽  
J. P. Lynch
Keyword(s):  
Root Number ◽  
Nitrogen Acquisition ◽  
Crown Root ◽  
Low Nitrogen

scholarly journals Unexpectedly low nitrogen acquisition and absence of root architecture adaptation to nitrate supply in a Medicago truncatula highly branched root mutant

2014 ◽  
Vol 65 (9) ◽  
pp. 2365-2380 ◽  
Author(s):  
Virginie Bourion ◽  
Chantal Martin ◽  
Henri de Larambergue ◽  
Françoise Jacquin ◽  
Grégoire Aubert ◽  
...  
Keyword(s):  
Medicago Truncatula ◽  
Root Architecture ◽  
Nitrogen Acquisition ◽  
Nitrate Supply ◽  
Low Nitrogen

Physiological and ecological studies on the oestrogenic isoflavones in subterranean clover (T. subterraneum L.) VII. Effects of nitrogen supply

1969 ◽  
Vol 20 (6) ◽  
pp. 1043 ◽  
Author(s):  
RC Rossiter
Keyword(s):  
Protein Synthesis ◽  
Nitrogen Deficiency ◽  
Subterranean Clover ◽  
Nitrogen Supply ◽  
The Other ◽  
Biochanin A ◽  
Ecological Studies ◽  
Carbon Substrates ◽  
Low Nitrogen ◽  
Practical Implications

In experiments with young plants of the Dwalganup strain of subterranean clover, nitrogen deficiency was associated with increased concentrations of isoflavones in the expanded leaves and cotyledons. In the first trifoliate leaves the concentration of total isoflavones (formononetin+genistein+ biochanin A) was approximately doubled at low nitrogen supply. Biochanin A was much less affected than the other two isoflavones. The increase in isoflavone contents of nitrogen-deficient leaves was associated with decreased protein synthesis, but not always with increased sugar contents. The supply of carbon substrates for isoflavone synthesis may depend on starch as well as sugar contents. Practical implications of the results are considered briefly.

Competition between skeleton weed (Chondrila juncea L) and cereals in relation to nitrogen supply

1958 ◽  
Vol 9 (1) ◽  
pp. 1 ◽  
Author(s):  
LF Myers ◽  
J Lipsett
Keyword(s):  
Crop Yields ◽  
Nitrogen Supply ◽  
Weed Competition ◽  
Nitrogen Application ◽  
High Nitrogen ◽  
Nitrogen Levels ◽  
Grain Nitrogen ◽  
Low Nitrogen ◽  
Yield Of Oats ◽  
Plant Growth Regulating Substances

The effect of skeleton weed competition on the yield of wheat and oats was investigated in seasons when rainfall was plentiful. Nitrogen was found to be the major factor limiting crop yields. In soils with comparable nitrogen-supplying powers, skeleton weed density governed the crop's response to applied nitrogen. Competition between skeleton weed and crop was severe at low nitrogen levels, but minor at the high nitrogen levels achieved either by nitrogen application, or when the crop followed a legume-rich pasture. Competition had its effect early in the crop's growth. Temporary removal of competition, by spraying with plant growth regulating substances (JICPA) at different times, was used to determine when competition was critical, and measure its effects. Skeleton weed reduced nitrogen supply early in the crop's growth, and so depressed yield. An application of 1 lb MCPA per acre in the fallow 54 days before sowing, or 10 days after crop emergence, increased the yield of oats from 710 to 1350 lb grain per acre: a response equal to that from 32 lb nitrogen per acre applied at planting in the same experiment. In each case, the response to spraying at the different times was analogous to the effect of a nitrogen application at these times. Early spraying gave responses in yield; later spraying gave responses in grain nitrogen. The results provide a new estimate of the reduction in crop yield due to skeleton weed.

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