The effect of shade upon seedling growth in groundsel bush (Baccharis halimifolia L.)

1977 ◽  
Vol 28 (4) ◽  
pp. 681 ◽  
Author(s):  
FD Panetta
Keyword(s):  
Seedling Growth ◽  
Reproductive Output ◽  
Experimental Period ◽  
Height Growth ◽  
Light Conditions ◽  
Baccharis Halimifolia ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Treatment Comparisons ◽  
Reduced Light

Analysis of seedling growth of groundsel bush (Baccharis halimifolia L.) under different glasshouse light conditions indicated that seedlings growing in light shade (24% daylight) maintained relative growth rates equal to those of seedlings grown unshaded (57% daylight) for up to 11 weeks after germination. Compensation for reduced light was effected through increased leaf area rather than through increased photosynthetic efficiency. Although markedly less than in unshaded or light shade treatments, growth was maintained throughout the experimental period under the lowest radiant flux employed (17% daylight). Root systems developed more slowly and were smaller in shaded than in unshaded seedlings. Increased stem allocation (height growth) followed a peak in root allocation, and did not occur until 11 weeks after germination in any treatment. Comparisons of seed weight and seedling relative growth rate with associated pasture species indicate that groundsel is at a disadvantage in terms of both parameters. It appears that the success of this woody weed is due largely to a combination of high reproductive output and effective dispersal, which enables it to colonize relatively open microsites which occur in cultivated as well as natural field situations.

Seedling growth responses to water and nutrient augmentation in the understorey of a lowland moist forest, Panama

2008 ◽  
Vol 24 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Joseph B. Yavitt ◽  
S. Joseph Wright
Keyword(s):  
Seedling Growth ◽  
Growth Rates ◽  
Height Growth ◽  
Dry Season ◽  
Wet Season ◽  
Soil Resources ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Moist Forest ◽  
Number Of Leaves

Abstract:We irrigated and fertilized (with nutrients) seedlings of Doliocarpus olivaceus (Dilleniaceae, a shade-tolerant liana), Faramea occidentalis (Rubiaceae, a shade-tolerant understorey tree) and Tetragastris panamensis (Burseraceae, a shade-tolerant canopy tree) growing in the understorey of an old-growth tropical moist forest in Panama to assess the impact of seasonal water availability and nutrient-poor soils on seedling growth rates. In control plots, height growth rates were greater in the dry season than in the wet season for Doliocarpus (21%) and for Faramea (89%), whereas Tetragastris had similar seasonal rates. For numbers of leaves, Faramea had 3.5-fold greater relative growth rates in the dry season than in the wet season, while Doliocarpus and Tetragastris lost leaves (semi-deciduous) during the same period. Irrigation and nutrient augmentation increased height growth rates for all three species (45% to 272%). For Doliocarpus, irrigation and nutrient augmentation prevented leaf fall during the dry season. For Faramea in the dry season, irrigation and nutrient augmentation when applied independently reduced the growth of new leaves by 65% to 87%, but relative growth rates for number of leaves were the same as the control rates in the combined irrigation and nutrient augmentation treatment. The growth of new leaves for Tetragastris responded to dry-season irrigation but not nutrient augmentation. Although all measurements occurred beneath the forest canopy, during the dry season, Tetragastris had a negative relationship between canopy openness and relative growth rate for number of leaves, whereas the other two species had a positive relationship. Our results show that soil resources influence growth rates even in the deep shade of the forest understorey, and demonstrate different responses to soil resources among species that might contribute to niche differentiation and species coexistence.

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.

Growth responses of six bryophyte species to different light intensities

1993 ◽  
Vol 71 (5) ◽  
pp. 661-665 ◽  
Author(s):  
Emmanuel Rincón
Keyword(s):  
Growth Rate ◽  
Light Intensity ◽  
Growth Rates ◽  
Growth Analysis ◽  
Total Chlorophyll ◽  
Light Conditions ◽  
Growth Responses ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Plastic Responses

The growth responses of Brachythecium rutabulum, Eurhynchium praelongum, Lophocolea bidentata, Plagiomnium undulatum, Pseudoscleropodium purum, and Thuidiurn tamariscinum, growing under seven different light conditions, were determined in a 36-day laboratory experiment. Biomass production, relative growth rate, chlorophyll content, and morphological plastic responses (bending of the shoots) were determined following initial and final harvests. All species achieved greater biomass as irradiance increased. This trend was also observed in the relative growth rates, which were higher as irradiance increased, for all the bryophytes investigated. All species except L. bidentata showed an increased elevation of the shoot as irradiance decreased. Total chlorophyll was higher in all species at the lowest irradiance level, but no clear differences were observed in the ratios of chlorophyll a to b for all the species. Key words: grassland bryophytes, light intensity, growth analysis, plasticity.

Responses of Pinusbanksiana and Pinusresinosa seedlings to flooding

1983 ◽  
Vol 13 (4) ◽  
pp. 633-639 ◽  
Author(s):  
Z. C. Tang ◽  
T. T. Kozlowski
Keyword(s):  
Shoot Growth ◽  
Dry Weight ◽  
Root Systems ◽  
Height Growth ◽  
Drastic Reduction ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Plant Parts ◽  
Weight Increment ◽  
Growth Production

Flooding of soil for 45 days severely inhibited growth of 115-day-old Pinusbanksiana Lamb, and P. resinosa Ait. seedlings, with significant effects apparent within 15 days after initiation of flooding. Both species adapted poorly to flooding of soil but P. banksiana was more adversely affected than P. resinosa as shown by earlier and more drastic reduction of growth in the former species. In both species flooding decreased the rate of height growth, production of secondary needles, dry weight increment, and relative growth rates of various plant parts. Root growth of both species was reduced more than shoot growth. The reduction in dry weight increment of root systems of both species reflected arrested branching and elongation of roots as well as decay of roots, mainly the very small nonwoody roots. Flooding slightly stimulated ethylene production by submerged stems.

Variation in growth and reproduction of Bolomys lasiurus (Rodentia: Muridae) in an Amazonian savanna

1995 ◽  
Vol 11 (3) ◽  
pp. 419-428 ◽  
Author(s):  
Angelo De Lima Francisco ◽  
William E. Magnusson ◽  
Tânia M. Sanaiotti
Keyword(s):  
Direct Effect ◽  
Growth Rates ◽  
Reproductive Output ◽  
Dry Season ◽  
Consistent Pattern ◽  
Wet Season ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Lactating Females ◽  
Growth And Reproduction

ABSTRACTReproduction by Bolomys lasiurus is strongly seasonal in the Amazonian savanna of Alter do Chāo, Pará, Brazil. No pregnant or lactating females were recorded during the early dry season (July-September). Relative growth rates showed a similar though less consistent pattern. These patterns do not appear to be due to a direct effect of rainfall as high reproduction and growth were recorded during the late dry season (October-November), even though rainfall and the availability of fruits of shrubs were low during that period. It is likely that reinitiation of reproduction during the dry season is due to an increase in the availability of invertebrates and/ or wind-dispersed seeds. Fire at the end of the dry season appears to affect the diet of the rats, causing an increase in the ingestion of invertebrates during the following wet season. However, our data do not indicate that fire affects individual reproductive output or growth.

scholarly journals Diameter and height growth analysis for individual White Pine trees in the area of Kostelec nad Černými lesy 

2012 ◽  
Vol 49 (No. 12) ◽  
pp. 544-551 ◽  
Author(s):  
C. Y Liao ◽  
V. V Podrázský ◽  
G. B Liu
Keyword(s):  
Growth Analysis ◽  
Tree Height ◽  
Height Growth ◽  
Growth Data ◽  
White Pine ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Growth Functions ◽  
Pine Trees ◽  
Best Fit

Four theoretical growth functions, Mitscherlich, Logistic, Gompertz and Korf functions, were applied to the growth data on dbh and tree height of individual Eastern White Pine (Pinus strobus) trees to model their growth. The current increments, mean increments and relative growth rates of dbh and height as functions of age were given by derivation from the best fit growth functions. The growth processes of dbh and height were divided into three periods by the inflexion points of the corresponding current increment curves.

Effects of Photoperiods on the Growth Performance of Juvenile Trichogaster lalius (Hamilton, 1822)

2017 ◽  
Vol 65 ◽  
pp. 16-21 ◽  
Author(s):  
Madhu Awasthi ◽  
Pragya Gupta ◽  
Farah Bano ◽  
Mohammad Serajuddin
Keyword(s):  
Body Weight ◽  
Growth Performance ◽  
Growth Rates ◽  
Juvenile Fish ◽  
Maximum Growth ◽  
Light Conditions ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Light Duration ◽  
The Mean

Juvenile of Trichogaster lalius was reared under three photoperiod conditions (0L:24D, 12L:12D, 16L:08D) for 60 days to examine the growth performance under laboratory conditions. The maximum growth was observed in the juvenile of T. lalius exposed to 16:00 hrs. light. The mean body weight of different groups of juvenile fish exposed to different light conditions were significantly different (p<0.05) from each other which was observed from 20thday of the experiment. The absolute, specific, and relative growth rates were found to be maximum in the group exposed to 16:00 hrs. light duration. The present study indicated that 16:00 hrs. light duration was considered to be better for the growth of juvenile of T. lalius under controlled condition.

A Measure of Economic Growth in East and in West Pakistan

1961 ◽  
Vol 1 (2) ◽  
pp. 49-54
Author(s):  
S. U. Khan
Keyword(s):  
Regional Planning ◽  
National Income ◽  
Future Planning ◽  
Correct Evaluation ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
National Planning ◽  
Income Data ◽  
Regional Basis ◽  
The Difference

It is sometimes said that "national planning will simply have no meaning if it completely ignores the economic disparities between the two wings and fails to evolve a sensible pattern of regional planning"2. The lack of much essential data on a regional basis, however, renders any precise estimate of the relative growth rates almost impossible. Data either are not available or are inadequate on such important variables as production, income, consumption and trade, so that even a correct evaluation of past development efforts is not possible. The implications of such a situation for future planning are not difficult to understand. In this article an attempt is made to estimate the absorption of specified commodities in East and West Pakistan separately3. This will indicate the pattern of consumption and also give a rough idea about the growth rate of the two wings. With this purpose in view, quantity indices of absorption are prepared for each wing separately, taking data on availability of goods and prices from the Institute's monograph on Inflation. The quantity indi¬ces, however, are not of course strictly comparable with national income estimates because of the difference in coverage of the two series. National income data include government, services, trade, etc., while the quantity indices cover only specified goods available for each region.

Sign in / Sign up

Export Citation Format

Share Document