Transport of Tritiated Water and 14C-Labelled Assimilate Into Grains of Wheat. II. Independence of Entry of 14c-Labelled Assimilate and THO

1985 ◽  
Vol 12 (6) ◽  
pp. 587 ◽  
Author(s):  
CF Jenner
Keyword(s):  
Mass Flow ◽  
Tritiated Water ◽  
Grain Filling ◽  
Transport Mechanisms ◽  
Hot Wire ◽  
Wheat Grain ◽  
Pressure Driven

The mechanism involved in the transport of assimilates through the stalk by which the grain is attached to the rachilla has been investigated. Based on the presumption of pressure-driven mass flow, treatments designed to inhibit the import of assimilates would be expected to inhibit also the entry of water into the grain. Detached ears were supplied with solutions of [14C]sucrose in tritiated water (THO), and ears attached to the plant were watered with THO and supplied with 14CO2. The rachilla was heated by contact with a hot wire, and the stalk by steam-girdling. In addition, dinitrophenol (DNP) was used as an inhibitor of metabolically linked transport mechanisms. Heating or treatment with DNP reduced the transport of [14C]sucrose or [14C]-labelled assimilate into the grain, but the entry of THO was not reduced even by treatments which abolished altogether the transport of 14C into the grain. These results cannot be reconciled with mass flow as the means of transporting assimilates through the stalk of the wheat grain during grain filling.

Transport of Tritiated Water and 14c-Labelled Assimilate Into Grains of Wheat. III. Diffusion of Tho Through the Stalk

1985 ◽  
Vol 12 (6) ◽  
pp. 595 ◽  
Author(s):  
CF Jenner
Keyword(s):  
Mass Flow ◽  
Short Distance ◽  
Vascular System ◽  
Tritiated Water ◽  
The Self ◽  
Wheat Grain ◽  
Physical Processes ◽  
Self Diffusion ◽  
Separate System ◽  
Flow Through

Measuring the rate at which tritiated water is transported by diffusion through the stalk of the wheat grain is the main purpose of this paper. Diffusion of THO through the stalk is much slower than expected on the basis of the self-diffusion of THO in water, demonstrating that there are substantial resistances to diffusion of water in the stalk. Entry of THO into the grain by physical processes alone (diffusion), as measured in assemblies in which the grain (stripped of its bracts) is sealed into an impermeable capsule, is fast enough to account for the observed rate of transport of THO into normally functioning grains. Metabolically linked transport of water through the stalk is not detectable. Either the volume of water involved in mass flow through the stalk is too low to be detectable - which would require the concentration of sucrose to be about 2 M, or the entry of assimilate is not accompanied by water. Short-distance transfer of solute (only) from the plant's vascular system to a separate system servicing the grain seems the simplest explanation on the basis of the available evidence.

Variation in the wheat intake of individual sheep measured by use of labelled grain: behavioural influences

1981 ◽  
Vol 21 (111) ◽  
pp. 395 ◽  
Author(s):  
E Juwarini ◽  
B Howard ◽  
BD Siebert ◽  
JJ Lynch ◽  
RL Elwin
Keyword(s):  
Dominance Hierarchy ◽  
Tritiated Water ◽  
Supplementary Feeding ◽  
Previous Experience ◽  
Feed Consumption ◽  
Wheat Grain ◽  
Accurate Calculation ◽  
Early Introduction

A preliminary experiment with sheep in pens demonstrated that wheat grain could be labelled with tritiated water so that when fed it could provide data that would allow accurate calculation of individual feed consumption. This techinque was used with two groups of sheep fed supplementary wheat grain in paddocks. Half of the animals had previous experience of grain feeding some eight months earlier and the others had not eaten grain. Individual diversity of intake could be estimated usefully by tritium labelling of wheat, which was fed to the sheep in a group. The experiment showed that there was a threefold difference in the amount of wheat eaten between the lowest and highest intakes. Further, animals with previous experience of grain feeding consumed the entire ration initially, but those without previous experience did not consume all of the ration until two weeks after wheat feeding began. Over the period of measurement the experienced sheep consumed about 13% more wheat than the non-experienced group. There were insufficient aggressive acts to establish a dominance hierarchy in either group, although the experienced sheep were more aggressive than the others. Aggressiveness by one sheep towards other sheep did not result in higher wheat intakes by the former compared with other sheep in the group. The results are discussed in terms of the variability in acceptance of such supplements by animals, and of the value, later in life, of early introduction of supplementary feeding.

Diffusion of Water in the Wheat Grain: Nuclear Magnetic Resonance and Radioisotopic Methods Provide Complementary Information

1990 ◽  
Vol 17 (2) ◽  
pp. 107 ◽  
Author(s):  
CF Jenner ◽  
GP Jones
Keyword(s):  
Diffusion Coefficient ◽  
Tritiated Water ◽  
Free Water ◽  
Wheat Grain ◽  
Freezing And Thawing ◽  
Complementary Information ◽  
Average Diffusion Coefficient ◽  
Average Diffusion ◽  
Polymeric Component ◽  
Developing Grains

Diffusion of water within developing grains of wheat has been evaluated by two independent methods: by kinetic analysis of the movement of tritiated water (THO) through the grain, and by n.m.r. procedures. Both methods provided different but complementary information. Movement of THO basipetally through grains attached to the ear was faster than diffusion could explain, and a reversal of the gradient of THO at the base of the grain also could not be accounted for by diffusion. These observations are adduced as evidence for recirculation of water within the grain. The average diffusion coefficient measured by both methods indicated that the diffusive motion of water was substantially hindered. Freezing and thawing resulted in an increase in diffusion but did not increase diffusion to values expected of free water. Starch, the major polymeric component of the grain, was not responsible for the residual reduction in diffusion coefficient in frozen and thawed tissue.

Mass flow-rate control unit to calibrate hot-wire sensors

2007 ◽  
Vol 44 (2) ◽  
pp. 189-197 ◽  
Author(s):  
F. Durst ◽  
K. Haddad ◽  
A. Al-Salaymeh ◽  
Shadi Eid ◽  
B. Ünsal
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rate Control ◽  
Control Unit ◽  
Hot Wire ◽  
Flow Rate Control

scholarly journals Simulation of wheat yield by nitrogen and nonlinearity of environmental conditions

2020 ◽  
Vol 24 (1) ◽  
pp. 44-51
Author(s):  
Ana P. B. Trautmann ◽  
José A. G. da Silva ◽  
Manuel O. Binelo ◽  
Antonio C. Valdiero ◽  
Luana Henrichsen ◽  
...  
Keyword(s):  
Fuzzy Logic ◽  
Air Temperature ◽  
Block Design ◽  
Wheat Yield ◽  
Grain Filling ◽  
Phenological Stage ◽  
Southern Brazil ◽  
Wheat Grain ◽  
Nitrogen Use ◽  
Randomized Block Design

ABSTRACT Fuzzy logic can simulate wheat productivity by assisting crop predictability. The objective of the study is the use of fuzzy logic to simulate wheat yield in the conditions of nitrogen use, together with the effects of air temperature and rainfall, in the main cereal succession systems in Southern Brazil. The study was conducted in the years 2014, 2015 and 2016, in Augusto Pestana, RS, Brazil. The experimental design was a randomized block design with four repetitions in a 4 x 3 factorial scheme for N-fertilizer doses (0, 30, 60, 120 kg ha-1) and nutrient supply forms [100% in phenological stage V3 (third expanded leaf); (70%/30%) in the phenological stage V3/V6 (third and sixth expanded leaf) and; fractionated (70%/30%) at the phenological stage V3/E (third expanded leaf and beginning of grain filling)], respectively, in the soybean/wheat and corn/wheat systems. The pertinence functions and the linguistic values established for the input and output variables are adequate for the use of fuzzy logic. Fuzzy logic simulates wheat grain yield efficiently in the conditions of nitrogen use with air temperature and rainfall in crop systems.

scholarly journals Localization, Gene Expression, and Functions of Glutamine Synthetase Isozymes in Wheat Grain (Triticum aestivum L.)

2021 ◽  
Vol 12 ◽  
Author(s):  
Yihao Wei ◽  
Shuping Xiong ◽  
Zhiyong Zhang ◽  
Xiaodan Meng ◽  
Lulu Wang ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Metabolism ◽  
Glutamate Synthase ◽  
Grain Filling ◽  
Maximum Activity ◽  
Transfer Cells ◽  
Aleurone Layer ◽  
Wheat Grain ◽  
Plant Nitrogen ◽  
Endosperm Transfer Cells

Glutamine synthetase (GS) plays a major role in plant nitrogen metabolism, but the roles of individual GS isoforms in grains are unknown. Here, the localization and expression of individual TaGS isozymes in wheat grain were probed with TaGS isoenzyme-specific antibodies, and the nitrogen metabolism of grain during the grain filling stage were investigated. Immunofluorescence revealed that TaGS1;1, TaGS1;3, and TaGS2 were expressed in different regions of the embryo. In grain transporting tissues, TaGS1;2 was localized in vascular bundle; TaGS1;2 and TaGS1;1 were in chalaza and placentochalaza; TaGS1;1 and TaGS1;3 were in endosperm transfer cells; and TaGS1;3 and TaGS2 were in aleurone layer. GS exhibited maximum activity and expression at 8 days after flowering (DAF) with peak glutamine content in grains; from then, NH4+ increased largely from NO3- reduction, glutamate dehydrogenase (GDH) aminating activity increased continuously, and the activities of GS and glutamate synthase (GOGAT) decreased, while only TaGS1;3 kept a stable expression in different TaGS isozymes. Hence, GS-GOGAT cycle and GDH play different roles in NH4+ assimilation of grain in different stages of grain development; TaGS1;3, located in aleurone layer and endosperm transfer cells, plays a key role in Gln into endosperm for gluten synthesis. At 30 DAF, grain amino acids are mainly transported from maternal phloem.

Transport of Tritiated Water and 14C-Labelled Assimilate Into Grains of Wheat. I. Entry of Tho Through and in Association With the Stalk of the Grain

1985 ◽  
Vol 12 (6) ◽  
pp. 573 ◽  
Author(s):  
CF Jenner
Keyword(s):  
Water Potential ◽  
Dry Matter ◽  
Tritiated Water ◽  
Potential Gradient ◽  
Grain Filling ◽  
Vapour Phase ◽  
Reasonable Estimate ◽  
Intact Plants ◽  
Water Potential Gradient ◽  
Negligible Contribution

Dry matter is transported through the stalk of the wheat grain, and during grain filling is accumulated within it with no change in the quantity of water in the grain, and with little or no net transfer of water through the stalk. Accumulation of dry matter is also independent of the magnitude and the direction of a water potential gradient imposed between the plant and the atmosphere surrounding the grain. A procedure is described, based on sealing the grain (minus its bracts) within an impermeable capsule, for measuring the total net influx of radioactive water into the grain (FT). Tritiated water, THO, is used as a tracer for water. FT is assumed to comprise transport in the liquid phase and transport in the vapour phase, by mass flow and by diffusion. Apoplastic flow makes a negligible contribution in the system described because the water potential gradient is minimized. FT was obtained by adding to the quantity of THO accumulating in the encapsulated assemblies an estimate of the amount of THO lost from the assemblies by leakage. Two types of ears were compared: ears on intact plants assimilating 14CO2 and growing in small pots watered with THO, and detached ears cultured on [14C]sucrose in a solution of THO. Both types gave similar results but the detached ear system probably furnished the most reasonable estimate, a rate of 10.1 �l of THO per assembly per day.

scholarly journals Effect of allele combinations at Ppd‐1 loci on durum wheat grain filling at contrasting latitudes

2019 ◽  
Vol 206 (1) ◽  
pp. 64-75 ◽  
Author(s):  
Jose M. Arjona ◽  
Conxita Royo ◽  
Susanne Dreisigacker ◽  
Karim Ammar ◽  
Joan Subirà ◽  
...  
Keyword(s):  
Durum Wheat ◽  
Grain Filling ◽  
Wheat Grain

scholarly journals Co-ordinated expression of amino acid metabolism in response to N and S deficiency during wheat grain filling

2008 ◽  
Vol 59 (13) ◽  
pp. 3675-3689 ◽  
Author(s):  
Jonathan R. Howarth ◽  
Saroj Parmar ◽  
Janina Jones ◽  
Caroline E. Shepherd ◽  
Delia-Irina Corol ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Grain Filling ◽  
Wheat Grain ◽  
S Deficiency
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