Studies on the Status of Unburnt Eucalyptus Woodland at Ocean Grove, Victoria. III. Comparative Water Relations of the Major Tree Species.

1978 ◽  
Vol 26 (6) ◽  
pp. 819 ◽  
Author(s):  
JR Withers
Keyword(s):  
Water Relations ◽  
Drought Resistance ◽  
Water Saturation ◽  
Field Trials ◽  
High Rate ◽  
Rapid Decline ◽  
Tissue Water ◽  
Differential Survival ◽  
Relative Water ◽  
The Status

At Ocean Grove, unburnt Eucalyptus woodland is being replaced by Casuarina scrub. Autecological studies were initiated to study aspects of the mechanism of replacement. C. littoralis seedlings are more drought-resistant than E. ovata seedlings. The drought resistance of C. littoralis is largely due to desiccation avoidance facilitated by efficient reduction of stomatal and cuticular transpiration. C. littoralis seedlings reduced their transpiration rate at high relative water contents and water potentials, and maintained a turgid condition for several days longer than E. ovata seedlings. Although there was a high rate of water loss from detached E. ovata leaves, the induced water saturation deficits were reversible over a wider range of water deficits than in C. littoralis. Hence E. ovata may be more desiccation-tolerant than C. littoralis. The greater desiccation-avoiding capacity of C. littoralis is partly due to its more xeromorphic foliage, its slower growth rates and to differences in tissue water relations. Both adult and juvenile cladodes of C. littoralis exhibited a more rapid decline in shoot water potential with decreasing water content than did E. ovata leaves. In field trials, more Eucalyptus than Casuarina seedlings died during the hot dry summers. Hence the differential survival of E. ovata and C. littoralis seedlings in the field may be partly due to differences in their drought resistance.

Relative Drought Resistance of Tristaniopsis laurina and Acmena smithii From Riparian Warm Temperate Rainforest in Victoria

1990 ◽  
Vol 38 (4) ◽  
pp. 361 ◽  
Author(s):  
DR Melick
Keyword(s):  
Drought Tolerance ◽  
Water Relations ◽  
Drought Resistance ◽  
Leaf Abscission ◽  
Tissue Water ◽  
Temperate Rainforest ◽  
Direct Observations ◽  
Pressure Bomb ◽  
Warm Temperate ◽  
Adult Plants

The drought tolerances of the warm temperate rainforest species Tristaniopsis laurina and Acmena smithii were examined. Using pressure bomb techniques the tissue water relations of hardened juvenile and adult material were measured. T. laurina showed relatively little physiological drought tolerance in either the juvenile or adult plants, whereas A. smithii showed an increase in physiological drought tolerance in adult plants. Direct observations of droughted hardened 9-month-old seedlings revealed a relatively high leaf conductance in T. laurina seedlings with wilting becoming generalised after 9 days of droughting. All T. laurina plants rehydrated after 15 days of drought survived albeit with significant leaf abscission, but only 2 of the 5 plants rehydrated after 20 days of drought recovered and these were defoliated. Stomatal resistances were higher in droughted A. smithii seedlings and wilting did not become generalised until after 14 days of droughting. All A. smithii plants recovered when rehydrated after 20 days of droughting with little or no sign of leaf abscission. Leaves of T. laurina and A. smithii became scorched when subjected to temperatures of 50°C and 60°C respectively. The extent to which these differences delimit the distribution of these species in the relatively dry warm temperate rainforest communities of Gippsland in Victoria is discussed.

Tissue water relations for Brigalow and Mulga

1968 ◽  
Vol 16 (3) ◽  
pp. 487 ◽  
Author(s):  
DJ Connor ◽  
BR Tunstall
Keyword(s):  
Drought Tolerance ◽  
Water Potential ◽  
Water Content ◽  
Water Relations ◽  
Relative Water Content ◽  
Arid Zone ◽  
Tissue Water ◽  
Relative Water ◽  
The Relationship ◽  
Arid Zone Plants

The relationship between the relative water content and the water potential of the phyllodes in brigalow and mulga is compared. It is shown that brigalow phyllode tissue is more resistant to desiccation than that of mulga. This is of interest because mulga has previously been considered to represent an extreme in drought tolerance of Australian arid zone plants.

Leaf and root osmotic adjustment in drought-stressed Quercusalba, Q. macrocarpa, and Q. stellata seedlings

1988 ◽  
Vol 18 (1) ◽  
pp. 1-5 ◽  
Author(s):  
William C. Parker ◽  
Stephen G. Pallardy
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Water Relations ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Root Tissue ◽  
Tissue Elasticity ◽  
Tissue Water ◽  
Before And After ◽  
Relative Water

The leaf and root tissue water relations of Quercusalba L., Quercusmacrocarpa Michx., and Quercusstellata Wang. seedlings before and after drought were examined to evaluate the occurrence and comparative extent of osmotic adjustment in seedlings of these species. Drought resulted in active osmotic adjustment in leaves of all three species, with decreases in osmotic potential at full tissue hydration and at the turgor loss point from 0.25 to 0.60 MPa. Active osmotic adjustment in Q. stellata, and increased root tissue elasticity in Q. macrocarpa and Q. alba, resulted in turgor loss of roots occurring at a water potential 0.36 to 0.66 MPa lower in drought-stressed than in well-watered seedlings. Species differed in tissue water relations only before drought, with Q. stellata exhibiting lower osmotic potentials than Q. alba and Q. macrocarpa. Estimates of the osmotic potential at full saturation were generally lower in leaves than in roots, but the osmotic potential at turgor loss was similar. Roots exhibited turgor loss at lower values of relative water content and experienced a more gradual decrease in water potential per unit water content during dehydration than did leaves. This response indicates greater relative tissue capacitance in roots than in leaves in these species.

Photosynthesis, water relations, and leaf morphology of xeric versus mesic Quercusrubra ecotypes in central Pennsylvania in relation to moisture stress

1992 ◽  
Vol 22 (9) ◽  
pp. 1402-1407 ◽  
Author(s):  
Mark E. Kubiske ◽  
Marc D. Abrams
Keyword(s):  
Water Relations ◽  
Leaf Morphology ◽  
Photosynthetic Apparatus ◽  
Morphological Characteristics ◽  
Net Photosynthesis ◽  
Moisture Stress ◽  
Tissue Water ◽  
Central Pennsylvania ◽  
Relative Water ◽  
Mesic Site

Differences in photosynthesis and water relations during drought, and in leaf morphology, were evaluated in 1-year-old greenhouse-grown Quercusrubra L. seedlings from neighboring mesic and xeric sites in central Pennsylvania, U.S.A. Xeric seedlings had higher photosynthetic rates and stomatal conductance to water vapor than mesic seedlings during well-watered conditions. During a drought cycle, xeric seedlings maintained positive net photosynthesis at significantly lower predawn leaf water potential and relative water content. Mesic seedlings exhibited greater intrasource variation in gas exchange during drought, which may be related to reduced selection pressure for drought tolerance characteristics on the mesic site or to gene flow from the adjacent, upslope xeric site. Nonstomatal limitations to photosynthesis increased during drought and accounted for 98% of the reduction in photosynthesis as both sources approached incipient wilting. Xeric seedlings exhibited less nonstomatal inhibition of photosynthesis during early and midstages of drought, suggesting a greater tolerance of the photosynthetic apparatus for tissue water deficit. Xeric seedlings also exhibited the expected leaf morphological characteristics, which included smaller leaf area and greater leaf thickness and specific leaf mass. These results indicate that Q. rubra growing on adjacent sites in central Pennsylvania exhibit ecotypic differences in ecophysiology that are consistent with site moisture conditions.

scholarly journals Experts’ moral views on gene drive technologies: a qualitative interview study

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
N. de Graeff ◽  
Karin R. Jongsma ◽  
Annelien L. Bredenoord
Keyword(s):  
Invasive Species ◽  
Epistemic Uncertainty ◽  
Field Trials ◽  
Interview Study ◽  
Gene Drive ◽  
Agricultural Pests ◽  
Stepping Stones ◽  
Vector Borne Diseases ◽  
Qualitative Interview Study ◽  
The Status

Abstract Background Gene drive technologies (GDTs) promote the rapid spread of a particular genetic element within a population of non-human organisms. Potential applications of GDTs include the control of insect vectors, invasive species and agricultural pests. Whether, and if so, under what conditions, GDTs should be deployed is hotly debated. Although broad stances in this debate have been described, the convictions that inform the moral views of the experts shaping these technologies and related policies have not been examined in depth in the academic literature. Methods In this qualitative study, we interviewed GDT experts (n = 33) from different disciplines to identify and better understand their moral views regarding these technologies. The pseudonymized transcripts were analyzed thematically. Results The respondents’ moral views were principally influenced by their attitudes towards (1) the uncertainty related to GDTs; (2) the alternatives to which they should be compared; and (3) the role humans should have in nature. Respondents agreed there is epistemic uncertainty related to GDTs, identified similar knowledge gaps, and stressed the importance of realistic expectations in discussions on GDTs. They disagreed about whether uncertainty provides a rationale to refrain from field trials (‘risks of intervention’ stance) or to proceed with phased testing to obtain more knowledge given the harms of the status quo (‘risks of non-intervention’ stance). With regards to alternatives to tackle vector-borne diseases, invasive species and agricultural pests, respondents disagreed about which alternatives should be considered (un)feasible and (in)sufficiently explored: conventional strategies (‘downstream solutions’ stance) or systematic changes to health care, political and agricultural systems (‘upstream solutions’ stance). Finally, respondents held different views on nature and whether the use of GDTs is compatible with humans’ role in nature (‘interference’ stance) or not (‘non-interference stance’). Conclusions This interview study helps to disentangle the debate on GDTs by providing a better understanding of the moral views of GDT experts. The obtained insights provide valuable stepping-stones for a constructive debate about underlying value conflicts and call attention to topics that deserve further (normative) reflection. Further evaluation of these issues can facilitate the debate on and responsible development of GDTs.

scholarly journals Licorice (Glycyrrhiza glabra)—Growth and Phytochemical Compound Secretion in Degraded Lands under Drought Stress

2021 ◽  
Vol 13 (5) ◽  
pp. 2923
Author(s):  
Botir Khaitov ◽  
Munisa Urmonova ◽  
Aziz Karimov ◽  
Botirjon Sulaymonov ◽  
Kholik Allanov ◽  
...  
Keyword(s):  
Drought Stress ◽  
Water Deficit ◽  
Background Field ◽  
Field Trials ◽  
Glycyrrhiza Glabra ◽  
Agricultural System ◽  
Positive Effects ◽  
Relative Water ◽  
Moderate Drought ◽  
Four Levels

Water deficiency restricts plant productivity, while excessive soil moisture may also have an adverse impact. In light of this background, field trials were conducted in secondary saline soil (EC 6.5 dS m−1) at the experimental station of Tashkent State Agrarian University (TSAU), Uzbekistan to determine drought tolerance of licorice (Glycyrrhiza glabra) by exposure to four levels of water deficit, namely control (70–80%), moderate (50–60%), strong (30–40%) and intense (10–20%) relative water content (WC) in the soil. The moderate drought stress exhibited positive effects on the morphological and physiological parameters of licorice, and was considered to be the most suitable water regime for licorice cultivation. Plant growth under the 50–60% WC treatment was slightly higher as compared to 70–80% WC treatment, exhibiting weak water deficit promotes licorice growth, root yield and secondary metabolite production. In particular, secondary metabolites i.e., ash, glycyrrhizic acid, extractive compounds and flavonoids, tended to increase under moderate water deficit, however further drought intensification brought a sharp decline of these values. These results contribute to the development of licorice cultivation technologies in arid regions and the most important consideration is the restoration of ecological and economical functions of the dryland agricultural system.

Facing drought in a Mediterranean post-fire community: tissue water relations in species with different life traits

2004 ◽  
Vol 25 (1-2) ◽  
pp. 67-72 ◽  
Author(s):  
Marco Borghetti ◽  
F. Magnani ◽  
A. Fabrizio ◽  
A. Saracino
Keyword(s):  
Water Relations ◽  
Tissue Water ◽  
Life Traits

scholarly journals Evaluating and Differentiating Ankle Instability

2019 ◽  
Vol 54 (6) ◽  
pp. 617-627 ◽  
Author(s):  
Phillip A. Gribble
Keyword(s):  
Ankle Instability ◽  
Chronic Ankle Instability ◽  
High Rate ◽  
Diagnostic Tools ◽  
Ankle Sprains ◽  
Lateral Ankle ◽  
The Status ◽  
History Of ◽  
Ankle Complex

Given the prevalence of lateral ankle sprains during physical activity and the high rate of reinjury and chronic ankle instability, clinicians should be cognizant of the need to expand the evaluation of ankle instability beyond the acute time point. Physical assessments of the injured ankle should be similar, regardless of whether this is the initial lateral ankle sprain or the patient has experienced multiple sprains. To this point, a thorough injury history of the affected ankle provides important information during the clinical examination. The physical examination should assess the talocrural and subtalar joints, and clinicians should be aware of efficacious diagnostic tools that provide information about the status of injured structures. As patients progress into the subacute and return-to-activity phases after injury, comprehensive assessments of lateral ankle-complex instability will identify any disease and patient-oriented outcome deficits that resemble chronic ankle instability, which should be addressed with appropriate interventions to minimize the risk of developing long-term, recurrent ankle instability.

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