Root connections can trigger physiological responses to defoliation in nondefoliated aspen suckers

Botany ◽  
2011 ◽  
Vol 89 (11) ◽  
pp. 753-761 ◽  
Author(s):  
Matthieu Baret ◽  
Annie DesRochers
Keyword(s):  
Stomatal Conductance ◽  
Populus Tremuloides ◽  
Forest Dynamics ◽  
Physiological Responses ◽  
Stand Dynamics ◽  
High Humidity ◽  
High Moisture ◽  
Maximum Capacity ◽  
Root Suckering ◽  
Moisture Conditions

In species such as aspen ( Populus tremuloides Michx.), trees are interconnected through their root system owing to their regeneration mode by root suckering. These root connections challenge classic notions of forest dynamics that consider trees as individuals competing for resources, because root connections allow trees to share water, minerals, and carbohydrates. The purpose of this study was to demonstrate that trees can directly influence the physiology of other nearby trees through root connections. In the summers of 2007 and 2008, pairs of aspen suckers (i.e., two suckers connected by a parental root) were selected and divided into three height classes and compared with each other (dominant, codominant, suppressed). Suckers distally positioned on the parental root were manually defoliated, and the effects of defoliation on photosynthesis, stomatal conductance, and specific leaf area (SLA) were measured on connected but nondefoliated suckers. Results showed that defoliation caused physiological responses in the interconnected trees in summer 2007, which was drier than summer 2008. Defoliation of a connected sucker had a greater effect on suppressed suckers, for which mean photosynthesis rate increased by 17% compared with that of controls. The effect was less important for codominant (14% increase) and dominant (12%) trees. SLA of suppressed suckers also increased, while the increase in SLA values was smaller for codominant and dominant suckers. In summer 2008, no defoliation effect was observed, probably owing to high moisture conditions that resulted in much higher stomatal conductance values compared with those in 2007 (+55%). Under high humidity conditions, leaf specific hydraulic conductance does not constrain stomatal conductance, so the rate of CO2 assimilation was probably at its maximum capacity. This study demonstrated that trees could physiologically interact through root connections, and these interactions should thus be considered in studies of stand dynamics.

scholarly journals Effects of shading on the growth, development and yield of winged bean (Psophocarpus tetragonolobus)

2020 ◽  
Vol 50 (2) ◽  
Author(s):  
Murthazar Naim Raai ◽  
Nurul Amalina Mohd Zain ◽  
Normaniza Osman ◽  
Nur Ardiyana Rejab ◽  
Nurul Amylia Sahruzaini ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Physiological Responses ◽  
Canopy Cover ◽  
Winged Bean ◽  
Psophocarpus Tetragonolobus ◽  
Photosynthetic Gas Exchange ◽  
Growth Development ◽  
The Tropics ◽  
Protein Rich

ABSTRACT: An experiment was conducted to investigate the effects of different shading regimes [i.e., 60% (heavy), 30% (moderate), and 0% (control)] on 25 traits associated with the morphological features, photosynthetic gas exchange and agronomic characteristics of winged bean (Psophocarpus tetragonolobus), an underutilized protein-rich legume from the tropics. Collectively, 80% of the studied variables displayed significant differences (P<0.05) between at least two shade treatments. Shading generally showed most pronounced effect on the physiological traits of the legume, whereby the stomatal conductance, photosynthetic and transpiration rate differed significantly among plants for all treatments. The non-shaded plants were observed to have superior growth and physiological responses than the shaded plants. Interestingly, the moderately shaded plants exhibited the highest yield per plant, which significantly differed from the non-shaded and heavily shaded plants. This indicated that winged bean can adapt to partial canopy cover, making it a potential nitrogen-fixing cash crop which can be planted together with fruit or oil trees in commercial plantations.

scholarly journals The influence of the timing and methods of harvesting the seed grass of the eastern goat’s rue (Galega orientales Lam.) on the yield and sowing quality of seeds

2021 ◽  
Vol 901 (1) ◽  
pp. 012042
Author(s):  
V N Zolotarev
Keyword(s):  
Comparative Assessment ◽  
Optimal Harvesting ◽  
High Humidity ◽  
Yield Losses ◽  
High Moisture Content ◽  
High Moisture ◽  
Green Beans ◽  
Grass Stand ◽  
Light Green

Abstract Eastern goat’s rue (Galega orientales Lam.) possesses high fodder productivity and accumulates a large amount of vegetative mass with high humidity for harvesting for seeds. This greatly complicates the harvesting of grass stand for seeds. One of the ways to solve this problem is to carry out desiccation of the grass stand. A complicating factor in choosing the optimal harvesting period is the extended flowering and ripening period of goat’s rue beans, the duration of which reaches 25-35 days. The use of the drug Reglon Super based on diquat is a highly effective agrotechnical method that allows increasing the collection of seeds by 24%. The desiccation of the herbage contributes to the production of seeds with high sowing qualities. The seeds with the best sowing qualities are found in beans with yellow, brown, brown or dark brown color of the beans. In light green beans, the seeds are fully formed, but have a high moisture content. Goat’s rue beans do not crack or crumble at the onset of the full ripeness phase. This allows the seed to be harvested when most of the beans are ripe. A comparative assessment of the timing and method of harvesting the seed herbage of the goat’s rue showed that with a ripening of 39% and the presence of 47% of light green and yellow beans, the yield losses ranged from 26 to 56%. The highest seed yield in one confidence interval of 422-453 kg / ha and 444 kg / ha was obtained, respectively, by direct threshing with preliminary desiccation of the grass stand in the ripening phase of 74-97% of beans or by separate harvesting when mowing into swaths during ripening 74 % beans.

Heat

2020 ◽  
pp. 1687-1689
Author(s):  
Michael A. Stroud
Keyword(s):  
Physical Activity ◽  
Body Temperature ◽  
Supportive Care ◽  
Physiological Responses ◽  
Heat Stroke ◽  
Heat Exposure ◽  
High Humidity ◽  
Heat Exhaustion ◽  
Clinical Presentations ◽  
Cold Core

Rising body temperature triggers behavioural and physiological responses including reduction in physical activity, alterations of clothing, skin vasodilatation, and sweating. Heat-related illness is relatively common, especially with high humidity or prolonged physical activity. Risk can be reduced by acclimatization with repeated heat exposure, but some individuals seem to be particularly susceptible. Clinical presentations of heat-related illness include (1) ‘heat exhaustion’—the commonest manifestation, with symptoms including nausea, weakness, headache, and thirst. Patients appear dehydrated, complain of being hot, and are flushed and sweaty. Treatment requires rest and fluids, given orally or (in severe cases) intravenously. (2) ‘Heat stroke’ victims often complain of headache, may be drowsy or irritable, and may claim to feel cold. Core temperature is usually 38–41°C, but the patient is shivering with dry, vasoconstricted skin. Treatment requires (a) aggressive rapid cooling; (b) close biochemical monitoring; (c) supportive care for organ failure. There is significant mortality.

Multidecadal decline and recovery of aspen experiencing contrasting fire regimes: long-unburned, infrequent and frequent mixed-severity wildfire

2020 ◽  
Author(s):  
Cerena J. Brewen ◽  
John-Pascal Berrill ◽  
Martin W. Ritchie ◽  
Kevin Boston ◽  
Christa M. Dagley ◽  
...  
Keyword(s):  
Populus Tremuloides ◽  
Spatial Dynamics ◽  
Minor Component ◽  
Fire Regimes ◽  
Quaking Aspen ◽  
Aerial Photos ◽  
Wide Range ◽  
Fire Exclusion ◽  
Time Periods ◽  
Root Suckering

AbstractQuaking aspen (Populus tremuloides) is a valued, minor component on western landscapes. It provides a wide range of ecosystem services and has been in decline throughout the arid west for the last century. This decline may be explained partially by the lack of fire on the landscape as aspen benefit from fire that eliminates conifer competition and stimulates reproduction through root suckering. Managers are interested in aspen restoration but there is a lack of knowledge about their spatial dynamics in response to fire. Our study area in northeastern California on the Lassen, Modoc and Plumas National Forests has experienced recent large mixed-severity wildfires where aspen was present, providing an opportunity to study the re-introduction of fire. We observed two time periods; a 54-year absence of fire from 1941 to 1993 preceding a 24-year period of wildfire activity from 1993 to 2017. We utilized aerial photos to delineate aspen stand size, location and succession to conifers. We chose aspen stands in areas where wildfires overlapped (twice-burned), where only a single wildfire burned, and areas that did not burn within the recent 24-year period. We looked at these same stands within the first period of fire exclusion for comparison (i.e., 1941-1993). In the absence of fire, all aspen stand areas declined and all stands experienced increases in conifer composition. After wildfire, stands that burned experienced a release from conifer competition and increased in stand area. Stands that burned twice or at high severity experienced a larger removal of conifer competition than stands that burned once at low severity, promoting aspen recovery and expansion. Stands with less edge:area ratio also expanded more with fire present. Across both time periods, stand movement, where aspen stand footprints were mostly in new areas compared to footprints of previous years, was highest in smaller stands. In the fire exclusion period, smaller stands exhibited greater changes in area and location (movement), highlighting their vulnerability to loss in the absence of disturbances that provide adequate growing space for aspen over time.

scholarly journals Juvenile response to conifer release alternatives on aspen-white spruce boreal mixedwood sites.Part II: Quality of aspen regeneration

2005 ◽  
Vol 81 (4) ◽  
pp. 548-558 ◽  
Author(s):  
Sylvia Greifenhagen ◽  
Douglas G Pitt ◽  
Monique C Wester ◽  
F. Wayne Bell
Keyword(s):  
Populus Tremuloides ◽  
Block Design ◽  
Ground Level ◽  
Fibre Production ◽  
Post Treatment ◽  
Stem Volume ◽  
Randomized Block Design ◽  
Stump Sprouting ◽  
Root Suckering

This study, a component of the Fallingsnow Ecosystem Project, was designed to investigate the effects of conifer release alternatives on the quality of regenerating trembling aspen (Populus tremuloides Michx.). A randomized block design was used to compare untreated aspen with aspen growing in areas treated with two broadcast cutting treatments (brushsaw and Silvana Selective) and two broadcast herbicide treatments (glyphosate and triclopyr). The glyphosate treatment virtually eliminated aspen, whereas triclopyr tended to top-kill aspen, resulting in lateral dominance. Both fall cutting treatments generated prolific aspen root suckering and stump sprouting. Stain was common in aspen across the study site in damaged, untreated, and post-treatment stems, indicating that stain develops rapidly in young aspen suckers. Stems damaged by the treatments had higher incidences of decay (33% of cut stems and 10% of herbicide-damaged stems) than untreated aspen (8% of stems); however, decay volume was low for all treatments (1–4% of total stem volume affected). The location of decay (e.g., near ground level in cut stems) and presence of stem crooks in herbicide-treated aspen are important effects of the treatments on aspen quality. Armillaria root disease, which was found throughout the study site, was more prevalent in roots of treatment-damaged and untreated aspen than in suckers that originated post-treatment. These differences can be attributed to proximity to parent stumps, prevalence of root wounds, and older age of damaged and untreated stems. Key words: aspen quality, decay, conifer release, vegetation management, fibre production

Studies of lignin degradation in mound material of the termite Nasutitermes exitiosus

Soil Research ◽  
1992 ◽  
Vol 30 (2) ◽  
pp. 189 ◽  
Author(s):  
LJ Cookson
Keyword(s):  
Populus Tremuloides ◽  
Lignin Degradation ◽  
Co2 Evolution ◽  
Adjacent Soil ◽  
Moisture Conditions

Lignin degradation in the mound material of the enteric lignin degrading termite Nasutitermes exitiosus (Hill) was studied under normal and wet moisture conditions during incubation with C-14-(lignin)-Populus tremuloides Michx. There was negligible 14(CO2) evolution from mound material incubated for five weeks. However, adjacent soil when wet produced a 6.8% degradation of the 14C-(lignin)-lignocellulose.

scholarly journals Physiological responses of two halophytic grass species under drought stress environment

2016 ◽  
Vol 75 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Zamin Shaheed Siddiqui ◽  
Huda Shahid ◽  
Jung-Il Cho ◽  
Sung-Han Park ◽  
Tae-Hun Ryu ◽  
...  
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Water Deficit ◽  
Physiological Responses ◽  
Biomass Accumulation ◽  
Photosynthetic Performance ◽  
Grass Species ◽  
Free Proline ◽  
Relative Water ◽  
Halophytic Grasses

AbstractThe physiological responses of two halophytic grass species, Halopyrum mucronatum (L.) Staph. and Cenchrus ciliaris (L.), under drought stress were evaluated. Biomass accumulation, relative water content, free proline, H2O2content, stomatal conductance, photosynthetic performance and quantum yield (Fv/Fmratio) were studied. Under drought conditions, these halophytic plants expressed differential responses to water deficit. Stomatal conductance and free proline content were higher in H. mucronatum than in C. ciliaris, while H2O2content in H. mucronatum was substantially lower than in C. ciliaris. Performance index showed considerable sensitivity to a water deficit condition, more so in C. ciliaris than in H. mucronatum. Results were discussed in relation to comparative physiological performance and antioxidant enzymes activity of both halophytic grasses under drought stress.

The effect of ectomycorrhizae on water relations in aspen (Populus tremuloides) and white spruce (Picea glauca) at low soil temperatures

2002 ◽  
Vol 80 (6) ◽  
pp. 684-689 ◽  
Author(s):  
Simon M Landhäusser ◽  
Tawfik M Muhsin ◽  
Janusz J Zwiazek
Keyword(s):  
Stomatal Conductance ◽  
Soil Temperature ◽  
Water Uptake ◽  
Water Relations ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
White Spruce ◽  
Hydraulic Conductance ◽  
Root Hydraulic Conductance ◽  
Soil Temperatures

Low soil temperatures, common during the growing season in northern forests, have the potential to impede plant growth. In this study, water uptake, water relations, and growth characteristics were examined in aspen (Populus tremuloides) and white spruce (Picea glauca) seedlings that were inoculated with ectomycorrhizal fungi and grown at 20°C daytime air temperatures and low soil temperatures of 4°C and 8°C. Mycorrhizal associations had little effect on root and shoot biomass at both soil temperatures. Root hydraulic conductance (Kr) was higher in both mycorrhizal plant species compared to nonmycorrhizal plants, but there was no soil temperature effect on Kr in either species. Mycorrhizae also increased shoot water potential (Ψw) in Populus tremuloides but had no effect on Ψw in Picea glauca. The increases in Kr and Ψw were not reflected by changes in stomatal conductance (gs) and transpiration rates (E), suggesting that the reduction of water flow in seedlings exposed to low soil temperature was not likely the factor limiting gs in both plant species.Key words: boreal forest, root hydraulic conductance, root growth, stomatal conductance, water uptake.

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