scholarly journals Southeastern Rear Edge Populations of Quercus suber L. Showed Two Alternative Strategies to Cope with Water Stress

Forests ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1344
Author(s):  
Hana Ghouil ◽  
Domingo Sancho-Knapik ◽  
Amira Ben Mna ◽  
Nabil Amimi ◽  
Youssef Ammari ◽  
...  
Keyword(s):  
Water Stress ◽  
Osmotic Adjustment ◽  
Common Garden ◽  
Dry Mass ◽  
Quercus Suber ◽  
Species Variation ◽  
Change Models ◽  
Rear Edge ◽  
Elastic Adjustment ◽  
Water Stress Tolerance

Climate change models predict an increase in aridity, especially in the regions under Mediterranean-type climates such as the Mediterranean Basin. However, there is a lack of ecophysiological studies supporting the selection of the more drought-adapted ecotypes for reforestation programs. In this study, we analyzed the anatomical and functional adaptations of 18-month-old seedlings to drought on 16 Quercus suber L. populations from the southeastern rear edge of the species distribution in northern Tunisia growing in a common garden, in order to identify the most appropriate material to use in reforestations. The results evidenced that populations from more xeric habitats displayed the highest leaf dry mass per area (LMA) and lowest leaf area (LA) values, together with the largest increase in the bulk modulus of elasticity (Δε) in response to drought (i.e., elastic adjustment). On the other hand, some populations with intermediate values of aridity, LMA and LA displayed the sharpest increase in proline concentration (ΔPro), with a concomitant increase in osmotic potential at full turgor (Δπo) (i.e., osmotic adjustment). Therefore, two different strategies seem to drive the within-species variation of the studied Q. suber populations in response to water scarcity: (i) a water saver strategy for improving water stress tolerance through the maximization of the elastic adjustment; and (ii) a water spender strategy for maintaining water absorption and photosynthetic activity under moderate water stress through the maximization of the osmotic adjustment. We concluded that the higher elastic adjustment, together with reduced LA and increased LMA, implied a better performance under drought stress in the populations of Q. suber from more xeric habitats, which can be considered the most drought-adapted ecotypes and, consequently, the most appropriate for reforestation programs under an eventual increase in aridity.

Fertilization and water stress interactions in young Eucalyptus grandis plants

2006 ◽  
Vol 36 (4) ◽  
pp. 1028-1034 ◽  
Author(s):  
Corina Graciano ◽  
Juan J Guiamet ◽  
Juan F Goya
Keyword(s):  
Water Stress ◽  
Osmotic Adjustment ◽  
Eucalyptus Grandis ◽  
Field Capacity ◽  
Dry Mass ◽  
Stress Conditions ◽  
P Fertilization ◽  
Water Stress Tolerance ◽  
Mass Allocation

We determined whether fertilization with N and P affects water relations, and thereby water-stress tolerance, in young Eucalyptus grandis plants. To assess whether fertilization enhances osmotic adjustment under drought, 3-month-old E. grandis were planted in pots and fertilized with either N (1 g of urea) or P (12 g of calcium super phos phate). The soil was watered to attain one of two conditions: field capacity and –0.8 MPa. P fertilization when plants were well watered conditions increased solute accumulation, which might confer better performance under water stress. However, under water-stress conditions, nonfertilized and N-fertilized plants showed osmotic adjustment, while P-fertilized plants did not. P fertilization increased dry-mass allocation to leaves and decreased allocation to roots even under water-stress conditions. N-fertilized plants increased allocation to roots and maintained allocation to leaves under water-stress conditions in comparison with control plants, so they were not affected by water stress as much as P-fertilized plants were. This may explain why P fertilization increased growth when water was not limiting but had no effect under drought conditions. In the long term, changes in dry-mass allocation caused by P fertilization might increase susceptibility to water deficit.

Water-stress tolerance and late-season organic solute accumulation in hybrid poplar

1989 ◽  
Vol 67 (6) ◽  
pp. 1681-1688 ◽  
Author(s):  
T. J. Tschaplinski ◽  
T. J. Blake
Keyword(s):  
Water Stress ◽  
Stress Tolerance ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Soluble Sugar ◽  
Hybrid Poplar ◽  
Turgor Loss Point ◽  
Water Stress Tolerance ◽  
Organic Solute ◽  
The Relationship

Organic solute concentrations of five hybrid poplar cultivars were compared to determine the relationship between water-stress tolerance, tissue solute concentration, and growth rate under field conditions. In the expanding foliage of the faster growing Populus deltoides Bartr. × P. balsamifera L. (Jackii 4), the saturated osmotic potential and turgor loss point osmotic potential were 0.18 MPa and 0.47 MPa lower, respectively, than in the slower growing P. deltoides × P. balsamifera (Jackii 7). The expanding foliage of Jackii 4 had higher (ca. 50%) concentrations of organic solutes, attributable mainly to salicyl alcohol, salicin, sucrose, and an unidentified compound. The coupling of high productivity and stress tolerance in Jackii 4 suggests that these may be compatible rather than competing attributes. Water-stress studies on P. deltoides Bartr. × P. nigra L. (DN 22) under greenhouse conditions demonstrated that stressed trees accumulated 4 times the soluble sugar concentrations of well-watered trees, lowering the saturated osmotic potential by 0.55 MPa and turgor loss point osmotic potential by 1.0 MPa. Leaves were the primary site of osmotic adjustment to water stress and roots showed no adjustment. The use of repeated drying cycles in planting stock may aid survival of postplanting stress in species capable of osmotic adjustment. The relationship between stress tolerance and solute concentrations in the greenhouse water-stress study paralleled that of the field study.

Water-stress tolerance of black and eastern cottonwood clones and four hybrid progeny. I. Growth, water relations, and gas exchange

1994 ◽  
Vol 24 (2) ◽  
pp. 364-371 ◽  
Author(s):  
T.J. Tschaplinski ◽  
G.A. Tuskan ◽  
C.A. Gunderson
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Stress Tolerance ◽  
Soil Water ◽  
Osmotic Adjustment ◽  
Soil Water Potential ◽  
Hybrid Progeny ◽  
Black Cottonwood ◽  
Eastern Cottonwood ◽  
Water Stress Tolerance

Water-stress tolerance of six clones in a pedigree consisting of black cottonwood (Populustrichocarpa Torr. & Gray, female) and eastern cottonwood (Populusdeltoides Bartr., male) parental clones and four hybrid progeny was investigated. Trees were grown outdoors in pots; well-watered trees were kept moist (soil water potential greater than −0.03 MPa), and stressed trees (soil water potential less than −2.0 MPa) were subjected to repeated cyclical stress of 1 or 2 days duration over the 14-week study. Male P. deltoides and the male clone 242 displayed the greatest degree of stress tolerance, as evidenced by greater osmotic adjustment at saturation (0.25 MPa) and maintenance of relative growth rate of the main stem under water stress at 100 and 69% of that of well-watered trees, respectively, compared with reductions to 50–58% for the other hybrid clones. However, differences in total plant dry weight under water stress were less obvious, with female clones allocating more carbon to branch production under well-watered conditions, which was further increased under water stress. Three of the four hybrids displayed some degree of osmotic adjustment at saturation after bud set, which was likely conferred by male P. deltoides. Screening clones of Populus for drought tolerance should take into account the segregating tendency of hybrids to allocate carbon to lateral meristems under stress.

scholarly journals Planting orientation of Portulacaria afra cuttings for thicket restoration: vertical versus horizontal

2019 ◽  
Author(s):  
Mutakusi B Ragimana ◽  
Alastair J Potts
Keyword(s):  
Water Stress ◽  
Photosynthetic Efficiency ◽  
Plant Stress ◽  
Common Garden ◽  
Dry Mass ◽  
Main Stem ◽  
Vertical Orientation ◽  
Total Size ◽  
Horizontal Orientation ◽  
Establishment Phase

Aim. The re-establishment of Portulacaria afra in the landscape-scale Subtropical Thicket Restoration Programme has exclusively used vertically-orientated truncheons (i.e. large cuttings with the main stem planted 10-20 cm into the ground). Despite the planting of millions of truncheons, the rates of survival, growth and restoration are low. This may be driven by browsing pressure and/or drought conditions during the truncheon establishment phase. Here we conduct a common garden experiment to explore the establishment of horizontal versus vertically orientated truncheons. Horizontal truncheons have their main stem buried in the soil and only a few side branches exposed above ground — these truncheons may experience reduced water stress. Here we compared the levels of water stress during the establishment phase of truncheons with different orientation. Location. Eastern Cape, South Africa. Methods. Our experiment involved three planting treatments for truncheons: vertical orientation, horizontal orientation, and horizontal orientation with exposed side branches clipped. Truncheons were grown for two months and plants were well-watered. On two occasions during the experiment, photosynthetic efficiency was measured on all plants to ascertain levels of plant stress. After the experiment, the root, stem and leaf dry mass were recorded for each replicate, as well as leaf moisture. Results. The root mass proportion (of the total plant) was not significantly different among treatments. Despite this, leaf-level photosynthetic efficiency was recorded as significantly lower in vertical truncheons versus horizontal truncheons. Main conclusions. Smaller horizontally-orientated truncheons do not grow roots at a faster rate (relative to their total size) than the larger vertically-orientated truncheons that have more leaf material to support. Nonetheless, under well-watered conditions, the larger truncheons experienced stress evidenced by lowered leaf photosynthetic efficiency values. Thus, we suggest that horizontal buried truncheons may have a higher likelihood of survival under seasonal drought-stress conditions. It remains to be tested whether horizontally-orientated truncheons (with less above-ground biomass) experience lower rates of herbivory than the standard vertical cuttings.

scholarly journals Planting orientation of Portulacaria afra cuttings for thicket restoration: vertical versus horizontal

2019 ◽  
Author(s):  
Mutakusi B Ragimana ◽  
Alastair J Potts
Keyword(s):  
Water Stress ◽  
Photosynthetic Efficiency ◽  
Plant Stress ◽  
Common Garden ◽  
Dry Mass ◽  
Main Stem ◽  
Vertical Orientation ◽  
Total Size ◽  
Horizontal Orientation ◽  
Establishment Phase

Aim. The re-establishment of Portulacaria afra in the landscape-scale Subtropical Thicket Restoration Programme has exclusively used vertically-orientated truncheons (i.e. large cuttings with the main stem planted 10-20 cm into the ground). Despite the planting of millions of truncheons, the rates of survival, growth and restoration are low. This may be driven by browsing pressure and/or drought conditions during the truncheon establishment phase. Here we conduct a common garden experiment to explore the establishment of horizontal versus vertically orientated truncheons. Horizontal truncheons have their main stem buried in the soil and only a few side branches exposed above ground — these truncheons may experience reduced water stress. Here we compared the levels of water stress during the establishment phase of truncheons with different orientation. Location. Eastern Cape, South Africa. Methods. Our experiment involved three planting treatments for truncheons: vertical orientation, horizontal orientation, and horizontal orientation with exposed side branches clipped. Truncheons were grown for two months and plants were well-watered. On two occasions during the experiment, photosynthetic efficiency was measured on all plants to ascertain levels of plant stress. After the experiment, the root, stem and leaf dry mass were recorded for each replicate, as well as leaf moisture. Results. The root mass proportion (of the total plant) was not significantly different among treatments. Despite this, leaf-level photosynthetic efficiency was recorded as significantly lower in vertical truncheons versus horizontal truncheons. Main conclusions. Smaller horizontally-orientated truncheons do not grow roots at a faster rate (relative to their total size) than the larger vertically-orientated truncheons that have more leaf material to support. Nonetheless, under well-watered conditions, the larger truncheons experienced stress evidenced by lowered leaf photosynthetic efficiency values. Thus, we suggest that horizontal buried truncheons may have a higher likelihood of survival under seasonal drought-stress conditions. It remains to be tested whether horizontally-orientated truncheons (with less above-ground biomass) experience lower rates of herbivory than the standard vertical cuttings.

Water-stress tolerance of black and eastern cottonwood clones and four hybrid progeny. II. Metabolites and inorganic ions that constitute osmotic adjustment

1994 ◽  
Vol 24 (4) ◽  
pp. 681-687 ◽  
Author(s):  
T.J. Tschaplinski ◽  
G.A. Tuskan
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Osmotic Adjustment ◽  
Soil Water Potential ◽  
Inorganic Ions ◽  
Male Parent ◽  
Hybrid Progeny ◽  
Eastern Cottonwood ◽  
Water Stress Tolerance ◽  
Male Hybrid

The biochemical bases of water-stress tolerance in a pedigree consisting of black cottonwood (Populustrichocarpa Torr. & Gray female) and eastern cottonwood (Populusdeltoides Bartr. male) parental clones and four hybrid progeny were investigated. Trees were grown outdoors in pots; well-watered trees (soil water potential greater than −0.03 MPa) were kept moist in trays, and stressed trees (soil water potential less than −2.0 MPa) were subjected to repeated cyclical stress of 1 or 2 days duration over the 14-week study. Analysis of the major metabolites and ions in fully expanded leaves demonstrated that the greatest degree of osmotic adjustment was displayed by male hybrid 242, the P. deltoides male parent, and male hybrid 239 to a lesser extent. Osmotic adjustment in leaves of both hybrid 242 and the P. deltoides male parent was primarily constituted by malic acid, K, sucrose, and glucose, with the same metabolites also increasing in fine roots of hybrid 242, the only clone to display osmotic adjustment in roots. Female clone 240 and P. deltoides displayed organic solute-based adjustments to water stress that were offset by declines in inorganic ions, particularly Na and Mg. Given that the P. trichocarpa female parent did not display osmotic adjustment in either tissue, the hybrids' capacity for adjustment was likely conferred by the P. deltoides male parent.

scholarly journals Expansion and Osmotic Adjustment of Strawberry Fruit during Water Stress

1997 ◽  
Vol 122 (2) ◽  
pp. 183-189 ◽  
Author(s):  
Kirk W. Pomper ◽  
Patrick J. Breen
Keyword(s):  
Water Stress ◽  
Osmotic Adjustment ◽  
Turgor Pressure ◽  
Fold Increase ◽  
Dry Mass ◽  
Pressure Transducers ◽  
Control Fruit ◽  
Relative Water ◽  
Cell Elasticity

Expansion of green-white and red fruit in control (watered) and water-stressed greenhouse-grown strawberry (Fragaria ×ananassa Duch. `Brighton') plants was monitored with pressure transducers. Expansion of green-white fruit in control plants was rapid, showing little diurnal variation; whereas in water-stressed plants, fruit expansion occurred only during dark periods and shrinkage during the day. Red fruit were mature and failed to show net expansion. The apoplastic water potential (ψaw), measured with in situ psychrometers in control plants was always higher in leaves than in green-white fruit. In stressed plants, ψaw of leaves was higher than that of green-white fruit only in the dark, corresponding to the period when these fruit expanded. To determine the ability of fruit to osmotically adjust, fruit were removed from control and water-stressed plants, and hydrated for 12 hours; then, solute potential at full turgor (ψs100) was measured. Water-stressed green-white fruit showed osmotic adjustment with a ψs100 that was 0.28 MPa lower than that of control fruit. Mature leaves of water-stressed plants showed a similar level of osmotic adjustment, whereas water stress did not have a significant effect on the ψs100 of red fruit. Fruit also were severed to permit rapid dehydration, and fruit solute potential (ψs) was plotted against relative water content [RWC = (fresh mass - dry mass ÷ fully turgid mass - dry mass) × 100]. Water-stressed, green-white fruit had a lower ψs for a given RWC than control fruit, further confirming the occurrence of osmotic adjustment in the stressed fruit tissue. The lack of a linear relationship between turgor pressure and RWC prevented the calculation of cell elasticity or volumetric elastic modulus. Osmotic adjustment resulted in about a 2.5-fold increase in glucose and sucrose levels in water-stressed green-white fruit. Although green-white fruit on water-stressed plants showed osmotic adjustment, it was not sufficient to maintain fruit expansion during the day.

Osmotic adjustment and its use as a selection criterion in Eucalyptus seedlings

1994 ◽  
Vol 24 (12) ◽  
pp. 2404-2408 ◽  
Author(s):  
Jorge H. Lemcoff ◽  
Ana B. Guarnaschelli ◽  
Ana M. Garau ◽  
María E. Bascialli ◽  
Claudio M. Ghersa
Keyword(s):  
Water Stress ◽  
Drought Stress ◽  
Stress Tolerance ◽  
Osmotic Adjustment ◽  
Developmental Stages ◽  
Selection Criterion ◽  
Field Capacity ◽  
Water Stress Tolerance ◽  
Early Developmental Stages ◽  
Early Developmental

Osmotic adjustment was studied in 6-month-old seedlings of Eucalyptuscamaldulensis Dehnh., Eucalyptustereticornis Smith, Eucalyptusviminalis Labill., and Eucalyptusgrandis Hill ex Maiden. Because osmotic adjustment is related to water-stress tolerance, it can be used as a selection criterion of material adapted to drought. Half of the individuals of each species were submitted gradually to water stress, while the rest were maintained in soil at field capacity. Twenty-five days later the effect of stress on the development of osmotic adjustment was analyzed. All species had adjusted osmotically. The lowest osmotic adjustment was observed in E. camaldulensis and E. grandis (14.1% and 15.2%, respectively). Eucalyptusviminalis and E. tereticornis had values of 32.3% and 41.9%, respectively. Our results demonstrate that species differ significantly in their extent of osmotic adjustment under drought stress, and that it is possible to use this inductive plant feature as one of the criteria to select, during early developmental stages, Eucalyptus genotypes adapted to drought-prone environments. Some phylogenetic considerations are presented.

Rhizosphere Symbionts Improve Water Stress Tolerance in Moldavian balm through Modulation of Osmolytes

Rhizosphere ◽  
2021 ◽  
pp. 100367
Author(s):  
Zohreh Ghanbarzadeh ◽  
Hajar Zamani ◽  
Sasan Mohsenzadeh ◽  
Łukasz Marczak ◽  
Maciej Stobiecki ◽  
...  
Keyword(s):  
Water Stress ◽  
Stress Tolerance ◽  
Water Stress Tolerance
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