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.

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.

Comparisons of gas exchange parameters and shoot water relations of interior spruce (Picea glauca (Moench) Voss times Picea engelmannii Parry ex Engelm.) clones under repeated soil drought

1998 ◽  
Vol 28 (6) ◽  
pp. 820-830 ◽  
Author(s):  
Shihe Fan ◽  
Steven C Grossnickle
Keyword(s):  
Water Relations ◽  
Picea Glauca ◽  
Net Photosynthesis ◽  
Picea Engelmannii ◽  
Soil Drought ◽  
Gas Exchange Parameters ◽  
Tissue Water ◽  
Shoot Tissue ◽  
Interior Spruce ◽  
Exchange Parameters

Physiological response of interior spruce (Picea glauca (Moench) Voss x Picea engelmannii Parry ex Engelm.) to drought conditions was compared for somatic seedlings from clones G351, T703, N366, and W460. Seedlings were subjected to four cycles of progressive soil drought by withholding water. Changes in net photosynthesis (Pn), stomatal conductance (gwv), and predawn water potentials ( psi pd) were measured during and after each drought cycle. Shoot tissue water relations parameters were measured using pressure-volume analysis at the beginning and end of the fourth drought cycle. When comparing drought cycle 1 with drought cycle 4, clones G351, N366, and T703 showed significantly reduced Pn, but gwv of all clones was not affected. Net photosynthesis and gwv decreased with psi pd more rapidly in clone W460 than in the remaining clones. When rewatered after drought, clone T703 had the most rapid Pn and gwv recovery whereas clone G351 had the slowest recovery of Pn and gwv. Over four drought cycles, all clones photosynthesized at progressively lower psi pd, but adjustments in tissue water relations parameters were marginal. These results implied that gas exchange parameters were more sensitive than shoot tissue water relations parameters in detecting clonal variation in the physiological response of interior spruce under simulated drought conditions.

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.

scholarly journals Gas Exchange, Water Relations, and Dry Weight Partitioning during Root Initiation and Development of Poinsettia Cuttings

1995 ◽  
Vol 120 (3) ◽  
pp. 454-459 ◽  
Author(s):  
Sven E. Svenson ◽  
Fred T. Davies ◽  
Sharon A. Duray
Keyword(s):  
Gas Exchange ◽  
Water Relations ◽  
Adventitious Roots ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Dry Mass ◽  
Root Primordia ◽  
Root Numbers ◽  
Relative Water ◽  
Dry Weight Partitioning

Gas exchange, water relations, and dry weight partitioning of shoot tip cuttings of `Eckespoint Lilo Red' (`Lilo') and `Gutbier V-10 Amy Red' (`Amy') poinsettia (Euphorbia pulcherrima Wind. ex Klotzsch) were studied during the initiation and development of adventitious roots. Net photosynthesis (A) and stomatal conductance (g) of cuttings were initially low and remained low until root primordia formation. Foliar relative water content (RWC) and osmotic potential (ψπ) increased upon formation of root primordia. Following formation of root primordia (2 days before visible root emergence) and concurrent with increasing RWC and ψπ, g increased. As roots initially emerged, A and g increased rapidly and continued to increase with further root primordia development and subsequent emergence of adventitious roots. Cutting stem and leaf dry mass and leaf area increased during the first few days after sticking cuttings. During primordium development and initial root emergence, the highest percent increase in dry weight was accounted for by basal stem sections. AU cuttings of both cultivars rooted and had similar root numbers after 23 days, but `Lilo' cuttings had 15% better rooting and 44% more roots than `Amy' after 15 days. This research supports the hypothesis that formation and elongation of root primordia coincides with increased gas exchange in poinsettia cuttings, and that gas exchange can be used as a nondestructive indicator of adventitious root development.

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

Mechanisms of Impairment of the Photosynthetic Apparatus in Intact Leaves by Ozone

1999 ◽  
Vol 54 (9-10) ◽  
pp. 824-829 ◽  
Author(s):  
Thomas Gerhard Reichenauer ◽  
Harald Romuald Bolhàr-Nordenkampf
Keyword(s):  
Plant Growth ◽  
Calvin Cycle ◽  
Photosynthetic Apparatus ◽  
Net Photosynthesis ◽  
Major Effect ◽  
Photochemical Reactions ◽  
Early Event ◽  
Lag Phase ◽  
Limiting Factor ◽  
Negative Consequences

Tropospheric ozone has been recognised as a limiting factor for plant growth since late fifties of our century. The decrease in the rate of light saturated net photosynthesis (Asat) was shown to be the major effect of ozone in leaves with negative consequences for plant growth and the development of plant communities. The reasons for the ozone-induced decrease in Asat are still under investigation. Possible mechanisms are an increasing stomatal limitation, an increase in mesophyll limitation including a reduction of the CO2 fixation in the Calvin cycle and an impairment of the photochemical reactions in the grana membranes of chloroplasts. We conclude from the reviewed literature and from our own experiments that a decrease in carboxylation efficiency (CE) seems to be an early event caused by ozone leading to a decrease in Asat. The loss in current photochemical capacity (Fv/Fm) appears with a lag phase of many days and therefore the loss is thought to be a secondary effect due to a decreased demand of ‘assimilatory power’

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