Seed Germination in Ruzizi Grass (Brachaaria ruziziensis Germain & Evrard)

1976 ◽  
Vol 24 (4) ◽  
pp. 437 ◽  
Author(s):  
C Renard ◽  
P Capelle
Keyword(s):  
Hydrogen Peroxide ◽  
Seed Germination ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Oxidizing Agents ◽  
Brachiaria Ruziziensis

Sowing is the most common way of establishing Brachiaria ruziziensis in pastures, but seed germi- nation is poor as a result of dormancy. The mechanism of dormancy is clearly located in the hull, for removing the hull or cutting at the base of the spikelet stimulates germination. No leachable inhibitor seems to be the cause of dormancy. However, the action of oxidizing agents such as hydrogen peroxide and the measurement of oxygen uptake by full or empty spikelets suggest that a restriction of gas exchange by the hull is responsible.

Mechanisms Controlling Dormancy in the Arid Zone Grass Aristida contorta. I. Physiology and Mechanisms of Dormancy

1974 ◽  
Vol 22 (4) ◽  
pp. 635 ◽  
Author(s):  
JJ Mott
Keyword(s):  
Gas Exchange ◽  
Oxygen Uptake ◽  
High Temperatures ◽  
Arid Zone ◽  
Ambient Temperatures ◽  
Oxidizing Agents

Two dormancy mechanisms are evident in young A. contorta grain. One is an after-ripening requirement of the embryo, and can be satisfied by storage at ambient temperatures; the second is associated with the hull and requires prolonged periods of high temperatures before germination can take place. The dormancy imposed by the hull is not controlled by a leachable inhibitor, but germination can be stimulated by oxidizing agents or by the removal of small sections of the hull directly over the embryo. The oxygen uptake of dormant grain is very low, but non-dormant grain, or dormant grain with the hull removed, shows a much higher uptake. The possibility remains that there is a mechanical restriction of gas exchange by the hull, the hull of non-dormant grain being more permeable than that of dormant grain.

Pulmonary Gas Exchange and Oxygen Uptake During Exercise in Patients with Type 1 Diabetes Mellitus

1992 ◽  
Vol 9 (3) ◽  
pp. 252-257 ◽  
Author(s):  
Th. Wanke ◽  
D. Formanek ◽  
M. Auinger ◽  
H. Zwick ◽  
K. Irsigler
Keyword(s):  
Diabetes Mellitus ◽  
Type 1 Diabetes ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Type 1 Diabetes Mellitus ◽  
Pulmonary Gas Exchange

scholarly journals Coca chewing for exercise: hormonal and metabolic responses of nonhabitual chewers

1996 ◽  
Vol 81 (5) ◽  
pp. 1901-1907 ◽  
Author(s):  
Roland Favier ◽  
Esperanza Caceres ◽  
Laurent Guillon ◽  
Brigitte Sempore ◽  
Michel Sauvain ◽  
...  
Keyword(s):  
Heart Rate ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Metabolic Responses ◽  
Physiological Data ◽  
Respiratory Gas Exchange ◽  
Gum Chewing ◽  
Arterial Blood ◽  
Before And After ◽  
Exercise Induced

Favier, Roland, Esperanza Caceres, Laurent Guillon, Brigitte Sempore, Michel Sauvain, Harry Koubi, and Hilde Spielvogel. Coca chewing for exercise: hormonal and metabolic responses of nonhabitual chewers. J. Appl. Physiol. 81(5): 1901–1907, 1996.—To determine the effects of acute coca use on the hormonal and metabolic responses to exercise, 12 healthy nonhabitual coca users were submitted twice to steady-state exercise (∼75% maximal O2 uptake). On one occasion, they were asked to chew 15 g of coca leaves 1 h before exercise, whereas on the other occasion, exercise was performed after 1 h of chewing a sugar-free chewing gum. Plasma epinephrine, norepinephrine, insulin, glucagon, and metabolites (glucose, lactate, glycerol, and free fatty acids) were determined at rest before and after coca chewing and during the 5th, 15th, 30th, and 60th min of exercise. Simultaneously to these determinations, cardiorespiratory variables (heart rate, mean arterial blood pressure, oxygen uptake, and respiratory gas exchange ratio) were also measured. At rest, coca chewing had no effect on plasma hormonal and metabolic levels except for a significantly reduced insulin concentration. During exercise, the oxygen uptake, heart rate, and respiratory gas exchange ratio were significantly increased in the coca-chewing trial compared with the control (gum-chewing) test. The exercise-induced drop in plasma glucose and insulin was prevented by prior coca chewing. These results contrast with previous data obtained in chronic coca users who display during prolonged submaximal exercise an exaggerated plasma sympathetic response, an enhanced availability and utilization of fat (R. Favier, E. Caceres, H. Koubi, B. Sempore, M. Sauvain, and H. Spielvogel. J. Appl. Physiol. 80: 650–655, 1996). We conclude that, whereas coca chewing might affect glucose homeostasis during exercise, none of the physiological data provided by this study would suggest that acute coca chewing in nonhabitual users could enhance tolerance to exercise.

Boron Supply and Water Deficit Consequences in Young Paricá (Schizolobium parahyba var. amazonicum) Plants

2016 ◽  
Vol 44 (1) ◽  
pp. 250-256 ◽  
Author(s):  
Bianca do Carmo SILVA ◽  
Pêola Reis de SOUZA ◽  
Daihany Moraes CALLEGARI ◽  
Vanessa Ferreira ALVES ◽  
Allan Klynger da Silva LOBATO ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Deficit ◽  
Water Use ◽  
Electrolyte Leakage ◽  
Tolerance Mechanism ◽  
Schizolobium Parahyba ◽  
Use Efficiency

Boron (B) is a very important nutrient required by forest plants; when supplied in adequate amounts, plants can ameliorate the negative effects of abiotic stresses. The objective of this study was to (i) investigate gas exchange, (ii) measure oxidant and antioxidant compounds, and (iii) respond how B supply acts on tolerance mechanism to water deficit in young Schizolobium parahyba plants. The experiment employed a factorial that was entirely randomised, with two boron levels (25 and 250 µmol L-1, simulating conditions of sufficient B and high B, respectively) and two water conditions (control and water deficit). Water deficit induced negative modifications on net photosynthetic rate, stomatal conductance and water use efficiency, while B high promoted intensification of the effects on stomatal conductance and water use efficiency. Hydrogen peroxide and electrolyte leakage of both tissues suffered non-significant increases after B high and when applied water deficit. Ascorbate levels presented increases after water deficit and B high to leaf and root. Our results suggested that the tolerance mechanism to water deficit in young Schizolobium parahyba plants is coupled to increases in total glutathione and ascorbate aiming to control the overproduction of hydrogen peroxide and alleviates the negative consequences on electrolyte leakage and gas exchange. In relation to B supply, this study proved that sufficient level promoted better responses under control and water deficit conditions.

scholarly journals Different Modes of Hydrogen Peroxide Action During Seed Germination

2016 ◽  
Vol 7 ◽  
Author(s):  
Łukasz Wojtyla ◽  
Katarzyna Lechowska ◽  
Szymon Kubala ◽  
Małgorzata Garnczarska
Keyword(s):  
Hydrogen Peroxide ◽  
Seed Germination

Hydrogen Peroxide and Di(hydroperoxy)propane Adducts of Phosphine Oxides as Stoichiometric and Soluble Oxidizing Agents

2015 ◽  
Vol 127 (45) ◽  
pp. 13539-13543 ◽  
Author(s):  
Shin Hye Ahn ◽  
Kyle J. Cluff ◽  
Nattamai Bhuvanesh ◽  
Janet Blümel
Keyword(s):  
Hydrogen Peroxide ◽  
Phosphine Oxides ◽  
Oxidizing Agents

Some Aspects of Gas Exchange in Tuna

1972 ◽  
Vol 56 (3) ◽  
pp. 809-823
Author(s):  
E. D. STEVENS
Keyword(s):  
Hydrostatic Pressure ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Average Rate ◽  
Oxygen Removal ◽  
Skipjack Tuna ◽  
Partial Pressure Of Oxygen ◽  
Free Swimming ◽  
Flow Rates ◽  
Theoretical Predictions

1. Some aspects of gas exchange in restrained skipjack tuna were analysed. 2. The average rate at which water flowed over the gills was 2.81/min. kg. 3. The concentration of oxygen in water entering and leaving the gills was measured and used to calculate oxygen uptake (692 mg/h.kg) and utilization (0.71). 4. The drop in hydrostatic pressure as water flowed over the gills was 1.9 cm water and agrees favourably with theoretical predictions. 5. The partial pressure of oxygen was measured in blood afferent and efferent to the gills and used to calculate effectiveness of oxygen removal from the water (90%) and the transfer factor for oxygen (0.12 ml/min.kg.mmHg). 6. The average utilization measured in free-swimming tuna was 0.56. 7. The extraordinary ability of tuna to efficiently extract oxygen from the water at high gill water flow rates is discussed.

Ventilation and gas exchange in lizards during treadmill exercise.

1997 ◽  
Vol 200 (20) ◽  
pp. 2629-2639
Author(s):  
T Wang ◽  
D R Carrier ◽  
J W Hicks
Keyword(s):  
Exchange Rate ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Minute Ventilation ◽  
Oxygen Demand ◽  
Lung Ventilation ◽  
Iguana Iguana ◽  
Maximal Aerobic Speed ◽  
Gas Exchange Rate ◽  
Treadmill Locomotion

The extent to which lizards ventilate their lungs during locomotion is controversial. Direct measurements of airflow across the nostrils suggest a progressive reduction in tidal volume and minute ventilation with increased running speed, while other studies have demonstrated that arterial PO2 remains constant during exercise. To resolve these conflicting findings, we measured minute ventilation and gas exchange rate in five specimens of Varanus exanthematicus and five specimens of Iguana iguana during treadmill locomotion at speeds between 0.14 and 1.11ms-1 at 35 degrees C. These speeds are much lower than maximal running speeds, but are greater than the maximal aerobic speed. In both species, the ventilatory pattern during locomotion was highly irregular, indicating an interference between locomotion and lung ventilation. In Varanus exanthematicus, treadmill locomotion elicited a six- to eightfold increase in minute ventilation from a pre-exercise level of 102mlkg-1min-1, whereas the rate of oxygen uptake increased approximately threefold (from 3.9 to 12.6mlkg-1min-1). After exercise, both minute ventilation and gas exchange rate decreased immediately. Because minute ventilation increased more than did oxygen consumption, an increase in lung PO2 during exercise is predicted and, thus, Varanus exanthematicus appears effectively to ventilate its lungs to match the increased metabolic rate during locomotion at moderate speed. In Iguana iguana, both minute ventilation and gas exchange rate increased above resting values during locomotion at 0.28ms-1, but both decreased with further increases in locomotor speed. Furthermore, following exercise, both minute ventilation and oxygen uptake rate increased significantly. Iguana iguana, therefore, appears to be unable to match the increased oxygen demand with adequate ventilation at moderate and higher speeds.

Sign in / Sign up

Export Citation Format

Share Document