Effects of clonal integration on response to sand burial and defoliation by the dune plant Ipomoea pes-caprae (Convolvulaceae)

2000 ◽  
Vol 48 (2) ◽  
pp. 159 ◽  
Author(s):  
Catherine E. Bach
Keyword(s):  
Stem Growth ◽  
Physiological Integration ◽  
Clonal Integration ◽  
Leaf Production ◽  
Sand Burial ◽  
Negative Effect ◽  
Dune Plant ◽  
Effect On Growth

This study examined the importance of clonal integration on the growth and mortality of a tropical dune plant, Ipomoea pes-caprae L. (Roth), in response to two stresses: sand burial and defoliation. Sand burial and artificial defoliation treatments were applied to one shoot on daughter ramets, some of which were connected to other ramets and some of which were not connected to other ramets. Sand burial significantly enhanced both stem growth and leaf production of the buried shoots, both for connected and unconnected ramets. Defoliation decreased stem growth of shoots other than the defoliated shoot, but only for unburied ramets. Defoliation also had a greater negative effect on growth of other shoots on connected ramets than on unconnected ramets. At the level of the entire ramet, burial stimulated both stem growth and leaf production for connected ramets, but not for unconnected ramets. These results support the hypothesis that physiological integration between ramets mediates the response to both sand burial and defoliation in Ipomoea pes-caprae.

scholarly journals Influence of the constituents of Izatison, DMSO and PEG400, on the growth and the grain productivity of the oat cultivar Nezlamny during two generations after the seed treatment

2021 ◽  
Vol 29 ◽  
pp. 41-46
Author(s):  
V. A. Katsan ◽  
A.I. Potopalsky ◽  
B.O. Zadorozhnii
Keyword(s):  
Seed Treatment ◽  
First Generation ◽  
Negative Influence ◽  
Stem Growth ◽  
Panicle Length ◽  
Stem Height ◽  
Grain Productivity ◽  
Two Generations ◽  
Negative Effect ◽  
Stimulation Of

Aim. The investigation of the influence of the constituents of Izatison, DMSO and PEG400, on the oat growth and its grain productivity during 2 generations after the seed treatment became the aim of this study for the elucidation of mechanism of Izatison stimulant influence. Methods. The broad scale of the concentrations of the solvents composition in the proportion, to be as in Izatison, was used. The plants were grown in the field. The growth processes were evaluated by the stem height on the tubing stage. The grain productivity was characterized by the panicle length, the grains number in the panicle and of theirs weight. Results. The dependence of influence of the solvents composition on the stem growth from its concentration was detected in the first generation. In some variants the negative influence was revealed on the grains number in the panicle and on theirs weight. The stimulation of the growth regardless from the solvents concentration was observed in the second generation and the more pronounced negative effect on the grain productivity. Conclusions. The solvents DMSO and PEG400 are able to influence on the oat growth and its productivity, and that effect was manifested also in 2 generation after the seed treatment. Keywords: Izatison, DMSO, PEG400, oat growth and grain productivity.

scholarly journals CLONAL INTEGRATION MODIFIES RESPONSES OF HEDYSARUM LAEVE TO LOCAL SAND BURIAL IN MU US SANDLAND

2006 ◽  
Vol 30 (2) ◽  
pp. 278-285 ◽  
Author(s):  
LIU Feng-Hong ◽  
◽  
YE Xue-Hua ◽  
YU Fei-Hai ◽  
DONG Ming
Keyword(s):  
Clonal Integration ◽  
Sand Burial ◽  
Hedysarum Laeve

scholarly journals External debt and economic growth in Tunisia

2014 ◽  
Vol 61 (6) ◽  
pp. 669-689 ◽  
Author(s):  
Samir Abdelhafidh
Keyword(s):  
Economic Growth ◽  
External Debt ◽  
Distributed Lag ◽  
Autoregressive Distributed Lag ◽  
Negative Effect ◽  
Short Run ◽  
Empirical Methodology ◽  
Effect On Growth

This paper investigates the external debt effect on economic growth in Tunisia. Our empirical methodology is based on the autoregressive distributed lag approach. We find that in the long- as well as in the short-run, external debt had a negative effect on growth over the 1970-2010 period. The longrun effect was slightly higher in the period before the Ben Ali?s presidency than in the period after. However, during his period, the external debt short-run effect was the double of that observed during the period before. These results suggest that an external debt reduction should favor economic growth in Tunisia.

Response of Mitchell grasses (Astrebla F. Muell.) to photoperiod and temperature

1970 ◽  
Vol 21 (3) ◽  
pp. 395 ◽  
Author(s):  
FX Jozwik
Keyword(s):  
Growth And Development ◽  
Effect Of Temperature ◽  
Controlled Environment ◽  
Floral Initiation ◽  
Leaf Production ◽  
Number Of Leaves ◽  
Main Tiller ◽  
Effect On Growth

Controlled environment experiments were carried out to determine the effect of temperature and photoperiod on Astrebla pectinata, A. lappacea, A. elymoides, and A. squarrosa. Photoperiod had little effect on growth and development of tillers and on floral initiation, but did affect numbers of emergent inflorescences. Usually, inflorescence production increased with decreasing photoperiod. Temperature had significant effects on all parameters measured (number of main tillers and emergent inflorescences, elongation of main tillers, and number of leaves and axillary tillers per main tiller). Growth per tiller and leaf production increased with temperature (up to 30/25�C) but for tiller numbers the optimum was about 28/23�, Geographically separated strains of A. pectinata generally exhibited similar responses to photoperiod and temperature while different species from the same location differed in their response.

scholarly journals Hierarchical organization of a Sardinian sand dune plant community

2016 ◽  
Author(s):  
Valentina Cusseddu ◽  
Giulia Ceccherelli ◽  
Mark Bertness
Keyword(s):  
Plant Community ◽  
Sand Dune ◽  
Seedling Recruitment ◽  
Interspecific Interactions ◽  
Abiotic Factors ◽  
Hierarchical Organization ◽  
Foundation Species ◽  
Dune Sand ◽  
Sand Burial ◽  
Dune Plant

Coastal sand dunes have attracted the attention of plant ecologists for over a century, but they have largely relied on correlations to explain dune plant community organization. We experimentally examined longstanding hypotheses that sand binding, interspecific interactions, abiotic factors and seedling recruitment are drivers of sand dune plant community structure in Sardinia, Italy. Removing foundation species from the fore, middle and back dune habitats over 3 years led to erosion and habitat loss on the fore dune and limited plant recovery that increased with dune elevation. Reciprocal species removals in all zones suggested that interspecific competition is common, but that dominance is transient, particularly due to sand burial disturbance in the middle dune. A fully factorial 2-year physical factor manipulation of water, nutrient availability and substrate stability revealed no significant proximate response to these abiotic factors in any dune zone. In the fore and middle dune, plant seeds are trapped under adult plants during seed germination, and seedling survivorship and growth generally increase with dune height in spite of increased herbivory in the back dune. Sand and seed erosion lead to limited seed recruitment on the fore dune while high summer temperatures and allelopathy lead to competitive dominance of woody plants in the back dune. Our results suggest that Sardinian sand dune plant communities are hierarchically organized, structured by sand binding foundation species on the fore dune, sand burial in the middle dune and increasingly successful seedling recruitment, growth and competitive dominance in the back dune.

Variations in Growth, Clonal and Sexual Reproduction ofSpartina alternifloraResponding to Changes in Clonal Integration and Sand Burial

2015 ◽  
Vol 43 (7) ◽  
pp. 1100-1106 ◽  
Author(s):  
Yan Xiao ◽  
Hui Zhao ◽  
Wen Yang ◽  
Hua Qing ◽  
Changfang Zhou ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Clonal Integration ◽  
Sand Burial

Tobacco or not tobacco: predicting farming households’ income in Indonesia

2020 ◽  
pp. tobaccocontrol-2019-055274 ◽  
Author(s):  
Gumilang Aryo Sahadewo ◽  
Jeffrey Drope ◽  
Qing Li ◽  
Nigar Nargis ◽  
Firman Witoelar
Keyword(s):  
Household Income ◽  
Economic Losses ◽  
Leaf Production ◽  
Tobacco Leaf ◽  
Economic Decisions ◽  
Tobacco Control Policies ◽  
Negative Effect ◽  
Household Labour ◽  
Farming Households ◽  
Current Tobacco

BackgroundRecent research in several countries has demonstrated that small-holder tobacco farming is typically not a profitable enterprise. Many farming households report losing money in this economic endeavour, even without incorporating the value of their household labour. Losses are typically considerably worse when household labour is considered. We take advantage of panel data that include information about both current and former tobacco farming households’ characteristics and economic decisions to be the first to rigorously estimate the effects of both tobacco and non-tobacco farming on income.MethodsWe designed and implemented a two-wave economic survey of current and former tobacco farming households in Indonesia’s two largest tobacco-growing regions. We use regression analysis to estimate the effects of tobacco farming on household income per farming area in both survey waves.ResultsWe find that former tobacco farming households are typically generating profits from their non-tobacco farming, while current tobacco farming households experience greater variability, including experiencing economic losses. Former tobacco farming households’ income were comparable to current tobacco farming households’ even in the period in which tobacco leaf production and prices of tobacco leaf were relatively high. We find a negative and significant effect of tobacco farming on household income.ConclusionsOne of the main arguments from those opposing tobacco control policies—especially increasing cigarette excise taxes—is their alleged effect on tobacco farming households’ livelihoods through a lower demand for tobacco leaves. Our finding that there is a negative effect of tobacco farming on household income shows that the narrative is grossly inaccurate. Shifting to non-tobacco farming would allow farming households to reallocate their resources to other more lucrative economic opportunities.

Influence of fish density on the energy allocation pattern of juvenile brook trout (Salvelinus fontinalis)

1998 ◽  
Vol 55 (4) ◽  
pp. 796-805 ◽  
Author(s):  
François Marchand ◽  
Daniel Boisclair
Keyword(s):  
Aggressive Behavior ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Energy Allocation ◽  
Fish Density ◽  
Allocation Pattern ◽  
Consumption Rates ◽  
Negative Effect ◽  
Activity Costs ◽  
Effect On Growth

Our objectives were (i) to assess the influence of fish density on the energy allocation pattern of juvenile brook trout (Salvelinus fontinalis) and (ii) to define the mechanism by which this influence occurs. We estimated growth, consumption, and activity rates of brook trout held in 8-m3 enclosures characterized by two different densities (four or eight fish per enclosure; D4 and D8 enclosures, respectively). Eight experiments designed to estimate these variables were performed during a 27-day period. Fish from D4 enclosures ( DELTA W bar = 0.46 g) grew twice as much as those from D8 enclosures ( DELTA W bar = 0.24 g). For any given experiment, consumption rates were not significantly different between the two fish densities (0.434-1.09 g dry ·100 g wet-1 ·day-1). However, fish stocked in D8 enclosures displayed more aggressive behavior, executed 5.5 times more movements, and swam at speeds 13% faster than fish in D4 enclosures. These differences resulted in activity rates fourfold higher in D8 enclosures than in D4 enclosures. Empirical analyses combining our results with published values of growth, consumption, and activity rates supported the hypothesis that competition can have a negative effect on growth through a decrease in consumption rates and an increase in activity costs.

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