scholarly journals GROWTH SUBSTANCE CURVATURES OF AVENA IN LIGHT AND DARK

1936 ◽  
Vol 20 (2) ◽  
pp. 283-309 ◽  
Author(s):  
J. Van Overbeek
Keyword(s):  
Growth Hormone ◽  
Growth Rate ◽  
Growth Response ◽  
Growth Substance ◽  
Continuous Exposure ◽  
Growth Responses ◽  
Section 8 ◽  
Oxidative Inactivation

An attempt has been made to analyze the base response, one of the light growth responses of Avena coleoptiles, by means of growth substance curvatures. The decrease in growth rate (first part of the base response) after exposure to light does not show if hetero-auxin is substituted for auxin-a (Sections 5, 6, and 10). This decreased growth after exposure very likely is due to an oxidative inactivation of auxin-a (Sections 8 and 9). Hetero-auxin can be inactivated too but in a much lesser degree than auxin-a (Section 9). The increase in growth rate following on the decreased growth (second part of the base response) is due to an increase in response of the plant to growth hormone which is independent of the type of hormone (Sections 1, 2, 7, 8, and 10). Under conditions of continuous exposure to light, however, the inactivation of the auxin-a under influence of the light is superimposed on this increased response to growth hormone. This inactivation can be eliminated from the light growth response by replacing the auxin-a by hetero-auxin. More detailed information on this subject can be found in Section 10. A review of the experiments and their results can be obtained from the scheme in Section 8. In Section 11 it is shown that light inhibits the formation of growth hormone in the decapitated coleoptile (regeneration). Very small amounts of light (25 m.c.s.) inhibit the regeneration markedly.

scholarly journals Testing a New Approach to Quantify Growth Responses to Pruning Among Three Temperate Tree Species

2016 ◽  
Vol 42 (3) ◽  
Author(s):  
Matt Follett ◽  
Charles Nock ◽  
Christian Buteau ◽  
Christian Messier
Keyword(s):  
Growth Rate ◽  
Growth Response ◽  
Abiotic Factors ◽  
Growth Conditions ◽  
Accurate Estimation ◽  
Cycle Duration ◽  
Growth Responses ◽  
Laser Measurements ◽  
Branch Growth ◽  
Highly Correlated

In settled areas, electrical line safety is maintained by pruning encroaching trees. Identifying key predictors of branch elongation growth rate following pruning would assist in developing predictive models and optimizing pruning cycles. However, measuring branches in trees near electrical lines is complex and challenging. This paper describes an innovative approach using a handheld laser rangefinder to safely and accurately estimate growth from the ground. In-tree and ground-based laser measurements were highly correlated. This was followed by testing for correlations between branch growth response over a number of years after pruning and many biotic and abiotic factors for Fraxinus pennsylvanica, Acer platanoides, and Acer saccharinum, in the city of Montreal, Canada. In a sample of 59 trees, A. saccharinum had the greatest branch growth, followed by F. pennsylvanica, and finally A. platanoides. Branch growth increased following pruning and subsequently strongly declined, with A. platanoides declining the fastest. Branch inclination angle was positively correlated with growth rate for two species, but not for A. saccharinum. Among the types of pruning used, directional pruning techniques resulted in the least branch regrowth rate. Tree diameter was weakly related to branch growth rates. These results suggest that while growth conditions for street trees may be perceived as homogenous, there is substantial variation in branch growth response. This variation may be related to pruning history, or unmeasured abiotic or biotic variables. Estimating pruning cycle duration is a complex task and further work is needed to develop a predictive model for more accurate estimation of return times.

scholarly journals Sprucing up the mixedwoods: growth response of white spruce (Picea glauca) to partial cutting in the eastern Canadian boreal forest

2016 ◽  
Vol 46 (10) ◽  
pp. 1205-1215 ◽  
Author(s):  
Jessica Smith ◽  
Brian D. Harvey ◽  
Ahmed Koubaa ◽  
Suzanne Brais ◽  
Marc J. Mazerolle
Keyword(s):  
Growth Rate ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
Growth Response ◽  
Volume Growth ◽  
White Spruce ◽  
Growth Responses ◽  
Eastern Canada ◽  
Partial Cutting ◽  
Mixed Effect

Mixed-species stands present a number of opportunities for and challenges to forest managers. Boreal mixedwood stands in eastern Canada are often characterized by a dominant canopy of shade-intolerant aspen (Populus tremuloides Michx.) with more shade-tolerant conifers in the mid- to sub-canopy layers. Because the aspen and conifer components often attain optimal merchantable sizes at different moments in stand development, there is an interest in developing silvicultural practices that allow partial or total removal of aspen and favour accelerated growth of residual conifers. We tested four partial harvesting treatments in mixed aspen – white spruce (Picea glauca (Moench.) Voss) stands in which different proportions of aspen (0%, 50%, 65%, and 100% basal area) were removed. Ten years after treatments, 72 spruce stems representing dominant, co-dominant, and suppressed social classes were destructively sampled for stem analysis. Using linear mixed effect models, we analyzed growth as a function of treatment intensity, time since treatment, social status, pretreatment growth rate, and neighbourhood competition. Relative to control stands, radial and volume growth responses were detected only in the extreme treatment of 100% aspen removal. In relative terms, suppressed trees showed the greatest magnitude of cumulative growth increase. Compared with control trees, average annual radial and volume increments were, respectively, 23.5% and 7.1% higher for dominant trees, 67.7% and 24.1% higher for co-dominant trees, and 115.8% and 65.6% higher for suppressed trees over the 10 years after treatment. Growth response was proportional to pretreatment growth rate, and among neighbouring trees, only coniferous neighbours had a negative effect on white spruce growth. Our results suggest that in similar mixed-stand conditions, relatively heavy removal of overstory aspen accompanied by thinning of crowded conifers would result in greatest growth response of residual spruce stems.

Increased growth rate following transfer to daily sc administration from three weekly im injections of hGH in growth hormone deficient children

1983 ◽  
Vol 104 (2) ◽  
pp. 148-152 ◽  
Author(s):  
K. W. Kastrup ◽  
J. Sandahl Christiansen ◽  
J. Koch Andersen ◽  
H. Ørskov
Keyword(s):  
Growth Hormone ◽  
Growth Rate ◽  
Growth Response ◽  
Pubertal Development ◽  
Human Growth ◽  
Bone Age ◽  
Hormone Deficiency ◽  
First Year ◽  
Weekly Dose ◽  
Second Year

Abstract. The effect of more frequent (daily) injections of human growth hormone (hGH) on growth rate was studied in 16 growth hormone deficient children (12 boys, 4 girls) during 2 years. All had previously been treated with im injection of hGH 2–3 times weekly and in the majority of the patients a waning growth response was observed. For a total weekly dose of 12 IU hGH a daily dose of 2 IU was injected sc at night before sleep. This dosage has been shown by us to imitate the average nocturnal hGH profile in plasma. Growth response on the im treatment was 5.2 ± 1.2 cm/year (sd) in boys and 5.4 ± 0.9 cm/year in girls. A significant increase was seen during the first year of sc treatment to 7.9 ± 2.7 cm in boys and 6.3 ± 2cm in girls. During the second year the growth response was still significantly increased in boys (7.2 ± 1.9 cm). Bone age was more advanced and the period of previous im treatment was longer in girls (6.7 vs 3.6 years) which may be the main cause of the waning second year response (4.7 ±1.3 cm/year). Pubertal development occurred in 9 children during treatment. However, the highest growth rates were not found in these children. Absence of antibodies against hGH and local reactions at the injection site is evidence of the safety of the treatment, which was very well accepted by the children. Daily sc injections thus represent an effective alternative to conventional im injections ensuring high acceptance in children with growth hormone deficiency.

A cadmium-tolerant strain of Neocosmospora vasinfecta shows reduced cadmium influx

1991 ◽  
Vol 69 (6) ◽  
pp. 1296-1301 ◽  
Author(s):  
K. Budd
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Growth Response ◽  
Specific Growth ◽  
Cadmium Toxicity ◽  
Recovery Phase ◽  
Growth Responses ◽  
Cadmium Level ◽  
Key Words Cadmium ◽  
Net Uptake

Neocosmospora vasinfecta was grown in a defined liquid medium and its growth responses to CdSO4 were measured. The specific growth rate of mycelium not previously exposed to cadmium was reduced to 50% by 51 μM cadmium. The growth response to concentrations of cadmium above 50 μM was complex, showing declining and then recovery phases. Inoculum taken from a culture grown to the recovery phase in presence of 100 μM cadmium was cadmium tolerant; a cadmium level of 420 μM was required to reduce its specific growth rate by 50%. Tolerance was not lost by growth in the absence of cadmium. The tolerant mycelium showed markedly reduced net uptake of cadmium as compared with the normal (cadmium sensitive) mycelium. This reduction was due to a decrease in the unidirectional influx of cadmium, with little or no change in efflux. Cadmium toxicity in the normal mycelium was strongly antagonized by calcium but only weakly by manganese or zinc. Calcium also inhibited the uptake of cadmium. Key words: cadmium, calcium, Neocosmospora, tolerance, toxicity, transport.

Growth hormone treatment in children with idiopathic short stature: correlation of growth response with peripheral thyroid hormone action

2011 ◽  
Vol 74 (3) ◽  
pp. 346-353 ◽  
Author(s):  
Sebastián Susperreguy ◽  
Liliana Muñoz ◽  
Natalia Y. Tkalenko ◽  
Ivan D. Mascanfroni ◽  
Vanina A. Alamino ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Thyroid Hormone ◽  
Short Stature ◽  
Growth Response ◽  
Growth Hormone Treatment ◽  
Hormone Treatment ◽  
Idiopathic Short Stature ◽  
Hormone Action ◽  
Thyroid Hormone Action

scholarly journals THE ACTION OF THE PLANT GROWTH HORMONE

1933 ◽  
Vol 17 (1) ◽  
pp. 63-76 ◽  
Author(s):  
James Bonner
Keyword(s):  
Growth Hormone ◽  
Plant Growth ◽  
Growth Substance ◽  
Plant Growth Hormone ◽  
High Concentrations ◽  
Normal Respiration

1. Sections of Avena coleoptiles are found to show a considerable elongation when suspended in solutions of growth substance. 2. This elongation does not take place in the absence of O2 and is inhibited by KCN and phenylurethane. 3. The rate of respiration of sections of coleoptiles is increased by the addition of growth substance in concentrations which cause growth. High concentrations of growth substance inhibit growth and also respiration. 4. The increase in respiration is inhibited by KCN and phenylurethane in the concentrations which inhibit normal respiration. These concentrations are the same as those which inhibit growth. 5. From 2, 3, and 4, it seems possible that the increase in respiration caused by growth substance may be an essential part of its action in growth.

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