Growth and net assimilation rates in thinned and unthinned stands of balsam fir

1988 ◽  
Vol 18 (9) ◽  
pp. 1205-1210 ◽  
Author(s):  
M. B. Lavigne
Keyword(s):  
Growth Rates ◽  
Stem Growth ◽  
Balsam Fir ◽  
Competitive Position ◽  
Stem Respiration ◽  
Photosynthetic Rates ◽  
Respiration Rates ◽  
Net Assimilation ◽  
Lower Ratio

Current annual stem growth rates per hectare of unthinned young stands of balsam fir (Abiesbalsamea (L.) Mill.) were 2–3 times greater than in adjacent stands thinned 4–6 years earlier, largely because unthinned stands contained 2.5–4.0 times more foliar weight per hectare. Stem growth rates per tree in thinned stands were 3–8 times greater than those in unthinned stands because of the reduced competition and the lower ratio of heterotrophic to autotrophic tissues (S/F). However, the foliar efficiencies, as measured by annual stem growth per unit of foliar weight (E), of thinned plots were not significantly greater than those of unthinned plots, in spite of the reduced competition and lower S/F ratio. The lack of response of foliar efficiency to thinning is discussed in relation to published information about photosynthetic rates and stem respiration rates. In all stands, the E values of dominant trees were equal to, or less than, those of subordinate trees, in spite of their superior competitive position and lower S/F ratio. The lack of correlation between competitive position and foliar efficiency is also discussed.

Stem growth and respiration of young balsam fir trees in thinned and unthinned stands

1988 ◽  
Vol 18 (5) ◽  
pp. 483-489 ◽  
Author(s):  
M. B. Lavigne
Keyword(s):  
Surface Area ◽  
Stem Growth ◽  
Balsam Fir ◽  
Maintenance Respiration ◽  
Beneficial Effects ◽  
Respiration Rates ◽  
Rate Of Photosynthesis ◽  
Stem Surface Area ◽  
Highly Correlated ◽  
Lower Stem

Average respiration rate per square decimetre of stem surface area was greater in a thinned stand of balsam fir (Abiesbalsamea (L.) Mill.) than in an unthinned stand. While respiration rates of internodes were highly correlated to their rates of stem growth, the differences in respiration among internodes and stands could not be explained by the unequal use of respiration products to support synthesis alone. Maintenance respiration rates were greater for internodes with higher rates of stem growth, and consequently the efficiency of using photosynthates for growth was reduced in the thinned stand. In addition, breast-height internodes respired at higher rates than upper stem internodes with equal growth rates. It is argued that lower stem internodes expended more respiration products for translocation than upper stem internodes. The rate of stem growth per unit of foliar weight was less in the thinned than in the unthinned stand, indicating that the higher rate of respiration per unit of stem surface area counteracted the beneficial effects of thinning on the rate of photosynthesis per unit of foliar weight.

Studies on the sowing dates of cotton in the Sudan Gezira: I. The influence of date of sowing on plant growth and development

1967 ◽  
Vol 69 (3) ◽  
pp. 305-315 ◽  
Author(s):  
J. E. Jackson
Keyword(s):  
Growth Rates ◽  
Slow Growth ◽  
Seasonal Pattern ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Research Division ◽  
Sowing Dates ◽  
Net Assimilation ◽  
State Growth ◽  
Sudan Gezira

Growth analysis of cotton crops sown in the Sudan Gezira at monthly intervals between August and May revealed a marked seasonal pattern of growth. Irrespective of plant age and fruiting state growth of non-senescent plants was slowest during the cool winter months. Relative growth rates of young plants were highest in August, September and early October due to the high specific leaf areas and fairly high net assimilation rates found then. They were lowest when minimum temperatures were lowest. Net assimilation rates were also lowest in the coolest months, probably as a result of restricted growth. High temperatures in the spring reduced fruiting. It is concluded that low minimum temperatures and high evaporation rates are both associated with slow growth, and play a large part in determining the characteristic decline of growth rates of cotton sown at the usual date in August.I wish to thank the Chief of the Research Division, Ministry of Agriculture, Sudan, for permission to publish this paper and to record my gratitude to the team of field and laboratory assistants, especially Salih Saad and Hassan Osman, who helped in the work.

Growth, morphology, and gas exchange in white spruce (Picea glauca) seedlings acclimated to different humidity conditions

2001 ◽  
Vol 31 (6) ◽  
pp. 1038-1045 ◽  
Author(s):  
Jessica J Roberts ◽  
Janusz J Zwiazek
Keyword(s):  
Relative Humidity ◽  
Growth Rates ◽  
Picea Glauca ◽  
White Spruce ◽  
Physiological Characteristics ◽  
Growth Morphology ◽  
Early Seedling Growth ◽  
Second Growth ◽  
Early Seedling ◽  
Net Assimilation

The study examined the effects of different relative humidity conditions at germination, early growth, and following cold storage on morphological and physiological characteristics of white spruce (Picea glauca (Moench) Voss) seedlings. Seedlings that were grown for 18 weeks following seed germination at the lower, 30% RH (RHinitial) treatments were shorter and had smaller stem diameters, shorter needles with more epicuticular wax, and a greater density of needles per centimetre stem, compared with the 80% RHinitial seedlings. After 18 weeks of growth under 30, 50, and 80% RH, the seedlings were hardened off, stored for 8 weeks at 3°C and planted in pots in growth chambers under 42 and 74% relative humidity (RHsubsequent). Under 74% RHsubsequent conditions, the lower RHinitial seedlings flushed sooner and had higher growth rates compared with the higher RHinitial seedlings. When the higher RHinitial seedlings were placed under 42% RHsubsequent conditions, their bud flush was delayed, and subsequent growth rates were lower compared with the lower RHinitial seedlings. When measured at 40% RH, seedlings subjected to lower RHinitial had higher net assimilation rates and stomatal conductance compared with the seedlings acclimated to higher RHinitial humidity. It was concluded that the humidity conditions present during early seedling growth following germination significantly affect their morphological and physiological characteristics during the second growth season.

scholarly journals Tolerance to water stress in boron-deficient tea (Camellia sinensis) plants

2012 ◽  
Vol 24 (1) ◽  
pp. 41-51 ◽  
Author(s):  
Roghieh Hajiboland ◽  
Soodabe Bastani
Keyword(s):  
Water Stress ◽  
Camellia Sinensis ◽  
Stress Conditions ◽  
Assimilation Rate ◽  
Antioxidant Defence System ◽  
Young Leaves ◽  
Net Assimilation ◽  
Single Stress ◽  
Tea Plants ◽  
Lower Ratio

Tolerance to water stress in boron-deficient tea (Camellia sinensis) plantsThe effects of boron (B) deficiency and water stress were studied in tea plants (Camellia sinensis[L.] O. Kuntze) grown in growth chambers in perlite irrigated with a nutrient solution. Dry matter production was reduced significantly by both low B supply and water stress. Shoot-root translocation of B declined in water-stressed plants. In addition, the re-translocation of B was impaired under drought, which was reflected in a significantly lower ratio of B content of young to old leaves in both B-deficient and B-sufficient plants. Leaf photochemical parameters were negatively influenced by B deficiency and water stress in the old but not in the young leaves. Although B-deficient plants were more conservative in relation to water loss following elevated stomatal limitation, their water potential was lower than in B-sufficient plants irrespective of the watering regime. Under the combined effects of B deficiency and water stress, the reduction in the CO2assimilation rate was more prominent than that under a single stress factor. The reduction of the net assimilation rate (A) in B-deficient plants due to water stress and in water-stressed plants due to low B supply were not accompanied by significant changes in the stomatal conductance, suggesting an involvement of non-stomatal factors. The activity of antioxidant enzymes and proline content increased under B deficiency and water stress conditions. Our results suggested that, in young leaves that have been developed under water stress, an acclimation to water stress conditions occurred that was well reflected in their more stable photochemistry, water relations and an efficient antioxidant defence system compared with the older leaves.

The impact of endophyte on the health and productivity of sheep grazing ryegrass-based pastures

1999 ◽  
Vol 7 ◽  
pp. 11-17
Author(s):  
L.R. Fletcher ◽  
B.L. Sutherland ◽  
C.G. Fletcher
Keyword(s):  
Perennial Ryegrass ◽  
Growth Rates ◽  
Plasma Prolactin ◽  
Sheep Grazing ◽  
Wild Type ◽  
Lower Plasma ◽  
Lower Growth ◽  
Respiration Rates ◽  
Neotyphodium Lolii ◽  
The Impact

The health and production of sheep grazing perennial ryegrass with and without wild-type endophyte (Neotyphodium lolii) has been studied in several trials over a number of years. Lambs/ hoggets grazing predominantly perennial ryegrass swards with endophyte developed moderate to severe ryegrass staggers in summer and autumn, while those grazing endophyte-free ryegrass did not. Lambs/hoggets grazing ryegrass with endophyte also had more dags, lower growth rates, lower plasma prolactin levels, higher body temperatures and respiration rates under warm humid conditions. Most of these adverse responses were more severe in summer and autumn when endophyte toxin concentrations were highest. Many of these symptoms are similar to those described for the "autumn ill thrift" syndrome in New Zealand. Keywords: dags, endophyte, flystrike, growth rates, hyperthermia, Neotyphodium, perennial ryegrass, prolactin, ryegrass staggers, sheep

scholarly journals Application of brassinosteroid to Tabebuia alba (Bignoniaceae) plants

2000 ◽  
Vol 12 (3) ◽  
pp. 187-194 ◽  
Author(s):  
ELIZABETH ORIKA ONO ◽  
TERUKO NAKAMURA ◽  
SÍLVIA RODRIGUES MACHADO ◽  
JOÃO DOMINGOS RODRIGUES
Keyword(s):  
Growth Rates ◽  
Indoleacetic Acid ◽  
Anatomical Study ◽  
Stem Growth ◽  
Spongy Parenchyma ◽  
Petiole Length ◽  
Water Control ◽  
Plastic Bags ◽  
Fertilized Soil ◽  
Palisade And Spongy Parenchyma

The objective of this study was to observe the effects of brassinosteroid, gibberelin, and auxin application on the development and foliar anatomy of Tabebuia alba (Cham.) Sandw. seedlings. T. alba seedlings were grown in plastic bags with fertilized soil and treated with the following: 1- water (control); 2- brassinolide (BR1) 0.104 mM; 3- BR1 0.208 mM; 4- 3-indoleacetic acid (IAA) 0.2854 mM; 5- IAA 0.5708 mM; 6- GA3 (gibberellin A3) 0.1443 mM; 7- GA3 0.2887 mM; 8- GA3 0.072 mM + IAA 0.1427 mM; 9- GA3 0.1443 mM + IAA 0.2854 mM; 10- GA3 0.072 mM + BR1 0.052 mM; and 11- GA3 0.1443 mM + BR1 0.104 mM. Plant height and petiole length were measured before the treatments and 21 days after application of the growth regulators. These data allowed the calculation of stem and petiole growth rates. The results showed that GA3 + brassinolide produced the highest stem and petiole growth rates and brassinolide application stimulated petiole growth but not stem growth. The anatomical study of leaves showed alterations in blade and petiole thickness, palisade and spongy parenchyma height, and epidermis cells.

A Comparison of the Respiratory Processes and Growth Rate of Selected Australian Alpine and Related Lowland Plant Species

1990 ◽  
Vol 17 (5) ◽  
pp. 517 ◽  
Author(s):  
OK Atkin ◽  
DA Day
Keyword(s):  
Growth Rates ◽  
Alternative Oxidase ◽  
Geographical Origin ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Alternative Pathways ◽  
Respiration Rates ◽  
Whole Plant ◽  
Two Temperatures ◽  
Plant Respiration

Respiratory processes and growth rates of alpine and lowland species of three genera (Ranunculus, Plantago and Luzula) were compared. Relative growth rates were determined for the first 14 weeks of growth at two temperatures (7-10°C and 12-15°C). Generally, the relative growth rates of the alpine species were lower than those of their lowland relatives. Whole-plant respiration rates were measured and leaf slices from each species were used for a detailed analysis of respiratory pathways. Major differences were found between genera, particularly in their alternative oxidase activity, but respiratory patterns (both whole-plant respiration rates and the relative rates of cytochrome and alternative pathways in leaf slices) were maintained within a given genus, independent of the environmental or geographical origin of each species from that genus. The lack of correlation between growth rates and respiration rates suggests that the alpine plants used their respiratory products less efficiently than did the lowland species.

Thermal Adaptation of Pennisetum: Leaf Photosynthesis and Photosynthate Translocation

1977 ◽  
Vol 4 (5) ◽  
pp. 763 ◽  
Author(s):  
CJ Pearson ◽  
GA Derrick
Keyword(s):  
Low Temperature ◽  
Growth Rates ◽  
Thermal Adaptation ◽  
Leaf Photosynthesis ◽  
Photosynthetic Rates ◽  
Photosynthate Translocation

Leaf photosynthetic rates, loss of photosynthate 14C, sucrose concentrations and invertase activities were measured in three genotypes of Pennisetum growing at daylnight temperatures that ranged from 18/13 to 33/28°C. Leaves at low temperature had low photosynthetic rates, exported 14C more slowly, retained a higher proportion of photosynthate 14C, had higher sucrose concentrations and aged (physiologically) more slowly than did leaves growing at higher temperatures. The genotype that retained most photosynthate in the source leaves was the most cold-intolerant whereas there was no correlation between photosynthetic rates and previously observed growth rates.

Seasonally varying relationship between stem respiration, increment and carbon allocation of Norway spruce trees

2020 ◽  
Vol 40 (7) ◽  
pp. 943-955
Author(s):  
Eva Darenova ◽  
Petr Horáček ◽  
Jan Krejza ◽  
Radek Pokorný ◽  
Marian Pavelka
Keyword(s):  
Cell Wall ◽  
Norway Spruce ◽  
Carbon Allocation ◽  
Stem Growth ◽  
Wall Thickening ◽  
Radial Increment ◽  
Stem Respiration ◽  
Energy Demands ◽  
The Relationship ◽  
Stem Radial Increment

Abstract Stem respiration is an important component of an ecosystem’s carbon budget. Beside environmental factors, it depends highly on tree energy demands for stem growth. Determination of the relationship between stem growth and stem respiration would help to reveal the response of stem respiration to changing climate, which is expected to substantially affect tree growth. Common measurement of stem radial increment does not record all aspects of stem growth processes, especially those connected with cell wall thickening; therefore, the relationship between stem respiration and stem radial increment may vary depending on the wood cell growth differentiation phase. This study presents results from measurements of stem respiration and increment carried out for seven growing seasons in a young Norway spruce forest. Moreover, rates of carbon allocation to stems were modeled for these years. Stem respiration was divided into maintenance (Rm) and growth respiration (Rg) based upon the mature tissue method. There was a close relationship between Rg and daily stem radial increment (dSRI), and this relationship differed before and after dSRI seasonal maximum, which was around 19 June. Before this date, Rg increased exponentially with dSRI, while after this date logarithmically. This is a result of later maxima of Rg and its slower decrease when compared with dSRI, which is connected with energy demands for cell wall thickening. Rg reached a maxima at the end of June or in July. The maximum of carbon allocation to stem peaked in late summer, when Rg mostly tended to decrease. The overall contribution of Rg to stem CO2 efflux amounted to 46.9% for the growing period from May to September and 38.2% for the year as a whole. This study shows that further deeper analysis of in situ stem growth and stem respiration dynamics is greatly needed, especially with a focus on wood formation on a cell level.

Dormancy, germination and seedling growth of two Kalaharian perennials of the genus Harpagophytum (Pedaliaceae)

1988 ◽  
Vol 4 (2) ◽  
pp. 185-198 ◽  
Author(s):  
W. H. O. Ernst ◽  
T. Tietema ◽  
E. M. Veenendaal ◽  
R. Masene
Keyword(s):  
Gibberellic Acid ◽  
High Temperatures ◽  
Seedling Growth ◽  
Seed Coat ◽  
Growth Rates ◽  
Natural Conditions ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Respiration Rates ◽  
Drought Avoidance

ABSTRACTDormancy and germination ecology of two Harpagophytum species (Pedaliaceae) from an open Acacia savanna in Botswana were investigated. The maintenance of dormancy is governed partly by the seed coat but mainly by the endosperm and the embryo itself, as demonstrated by removal of the endosperm. Dissemination of the seed from the fruit can be delayed for several years without affecting the viability of the embryo, due to very low respiration rates.Germination can be enhanced slightly by high temperatures under natural conditions, and by gibberellic acid or removal of the endosperm under laboratory conditions. Relative growth rates for both Harpagophytum species are lower than for subtropical grasses and legumes, due to a strong investment in root and tuber biomass. Germination and seedling growth is discussed in relation to the drought avoidance syndrome and the animal disperser syndrome.

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