Effects of water stress preconditioning on gas exchange and water relations of Populusdeltoides clones

1993 ◽  
Vol 23 (7) ◽  
pp. 1291-1297 ◽  
Author(s):  
G. Michael Gebre ◽  
Michael R. Kuhns

The effect of water stress preconditioning on gas exchange was investigated in greenhouse-grown eastern Cottonwood (Populusdeltoides Bartr.). Two clones from southern Ohio (Ohio Red) and eastern Nebraska (Platte) were selected based on their differences in dehydration tolerance. Plants were either watered every day (control) or preconditioned by watering every 3 (TRT 1) or 4 days (TRT 2). After three dry–wet cycles (TRT 2), predawn leaf water potential (Ψw) of Ohio Red was −0.32 MPa; net photosynthesis and stomatal conductance were reduced to 13 and 9% of control, respectively. Eighteen hours after rewatering, photosynthesis recovered (103% of control), while stomatal conductance was 60% of control. Net photosynthesis of Platte was reduced to 43% and stomatal conductance to 32% of control (Ψw−0.21 MPa), and neither recovered fully when rewatered. After six dry–wet cycles (TRT 2), net photosynthesis of Ohio Red was reduced by 50%, though Ψw was −0.48 MPa. Clones showed an osmotic adjustment of −0.2 MPa after three (Platte) and six cycles (Ohio Red). When all preconditioned plants were stressed for 10 days, Ψw was −1.05 MPa and plants had negative net photosynthesis and no osmotic adjustment. Net photosynthetic rate of Ohio Red recovered (100% of control) on the second day of rewatering (stomatal conductance 68%), while Platte had not recovered (71%) by the fourth day (stomatal conductance 95%). These differences suggest that recovery of photosynthesis was limited mainly by stomatal factors in Ohio Red and nonstomatal factors in Platte. The preconditioning treatment also seems to have benefitted Ohio Red.

2009 ◽  
Vol 45 (2) ◽  
pp. 189-198 ◽  
Author(s):  
F. P. GOMES ◽  
M. A. OLIVA ◽  
M. S. MIELKE ◽  
A-A. F. DE ALMEIDA ◽  
H. G. LEITE ◽  
...  

SUMMARYAbscisic acid (ABA) accumulation in leaves of drought-stressed coconut palms and its involvement with stomatal regulation of gas exchange during and after stress were investigated. Two Brazilian Green Dwarf coconut ecotypes from hot/humid and hot/dry environments were submitted to three consecutive drying/recovery cycles under greenhouse conditions. ABA accumulated in leaflets before significant changes in pre-dawn leaflet water potential (ΨPD) and did not recover completely in the two ecotypes after 8 days of rewatering. Stomatal conductance was influenced by ABA under mild drought and by ΨPD under severe drought. There were no significant differences between the ecotypes for most variables measured. However, the ecotype from a hot/dry environment showed higher water use efficiency after repeated cycles of water stress.


1994 ◽  
Vol 24 (2) ◽  
pp. 364-371 ◽  
Author(s):  
T.J. Tschaplinski ◽  
G.A. Tuskan ◽  
C.A. Gunderson

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.


HortScience ◽  
2005 ◽  
Vol 40 (5) ◽  
pp. 1529-1533 ◽  
Author(s):  
J. Ryan Stewart ◽  
Roger Kjelgren ◽  
Paul G. Johnson ◽  
Michael R. Kuhns

Although transplanted trees typically establish and grow without incident in frequently irrigated turfgrass, their performance in precisely irrigated turfgrass in an arid climate is not known. We investigated the effect of precision irrigation scheduling on growth and water relations of balled-and-burlapped littleleaf linden (Tilia cordata Mill. `Greenspire') planted in buffalograss (Buchloë dactyloides [Nutt.] Engelm. `Tatanka') and kentucky bluegrass (Poa pratensis L.). Over 2 years, trees in turfgrass were irrigated either by frequent replacement based on local reference evapotranspiration, or precision irrigated by estimating depletion of soil water to the point of incipient water stress for each turfgrass species. Predawn leaf water potential and stomatal conductance of trees were measured during first-year establishment, and predawn leaf water potential was measured during a mid-season water-deficit period during the second year. Trunk diameter growth and total tree leaf area were measured at the end of each year. Values of predawn leaf water potential and stomatal conductance of trees in precision-irrigated buffalograss were lower (–0.65 MPa, 25.3 mmol·m–2·s–1) than those of trees in the other treatments near the end of the first growing season. The longer interval between precision irrigations resulted in mild water stress, but was not manifested in growth differences among trees across treatments during the first season. During the water-deficit period of the second year, there was no evidence of stress among the trees regardless of treatment. At the end of the second season, total leaf area of trees grown in precision-irrigated kentucky bluegrass (1.10 ± 0.34 m2) was 46% of that of trees grown in buffalograss (2.39 ± 0.82 m2) that were irrigated frequently. Trunk diameter growth of trees in frequently irrigated kentucky bluegrass (1.91 ± 2.65 mm) was 29% of that of the trees grown in buffalograss (6.68 ± 1.68 mm), regardless of irrigation treatment, suggesting a competition effect from kentucky bluegrass. We conclude that frequent irrigation of balled-and-burlapped trees in turfgrass, particularly buffalograss, is more conducive to tree health during establishment than is maximizing the interval between turfgrass irrigation. Regardless of irrigation schedule, kentucky bluegrass appears to impact tree growth severely during establishment in an arid climate.


Weed Science ◽  
1987 ◽  
Vol 35 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Philip H. Munger ◽  
James M. Chandler ◽  
J. Tom Cothren

Greenhouse experiments were conducted to elucidate the effects of water stress on photosynthetic parameters of soybean [Glycine max(L.) Merr. ‘Hutton′] and velvetleaf (Abutilon theophrastiMedik. # ABUTH). Stomatal conductance of both species responded curvilinearly to reductions in leaf water potential. At leaf water potentials less negative than −2.5 MPa, stomatal conductance, net photosynthetic rate, and transpiration rate were greater in velvetleaf than in soybean. Soybean photosynthetic rate was linearly related to stomatal conductance. Velvetleaf photosynthetic rate increased linearly with stomatal conductances up to 1.5 cm s–1; however, no increase in photosynthetic rate was observed at stomatal conductances greater than 1.5 cm s–1, indicating nonstomatal limitations to photosynthesis. As water stress intensified, stomatal conductance, photosynthetic rate, and transpiration of velvetleaf declined more rapidly than in soybean.


1986 ◽  
Vol 16 (6) ◽  
pp. 1371-1375 ◽  
Author(s):  
G. Scarascia-Mugnozza ◽  
T. M. Hinckley ◽  
R. F. Stettler

Results are presented on the decline of net photosynthesis during the application of rapid water stress to excised shoots of different Populus L. clones. Six clones were selected from the species Populustrichocarpa Torr. & Gray, Populusdeltoides Bartr., and from the hybrid Populustrichocarpa × Populusdeltoides, taking into account the differences in stomatal behaviour between and within these species. The two most productive P. trichocarpa clones and the hybrid clone, characterized by a reduced ability to close stomata during leaf desiccation, showed, nevertheless, a sharp reduction of net photosynthesis at water potentials lower than −1.5 MPa. In contrast, the inhibition of net assimilation in the P. deltoides clone, caused by water stress, was accompanied by a reduction in stomatal conductance. In all studied clones the decrease in net photosynthetic rate followed closely the point of turgor loss of the leaves, indicating a possible relationship between nonstomatal inhibition of photosynthesis and protoplast volume shrinkage.


1994 ◽  
Vol 24 (4) ◽  
pp. 681-687 ◽  
Author(s):  
T.J. Tschaplinski ◽  
G.A. Tuskan

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.


1980 ◽  
Vol 7 (3) ◽  
pp. 299 ◽  
Author(s):  
MM Ludlow ◽  
TT Ng ◽  
CW Ford

Net photosynthesis of the last fully expanded leaf of P. maximum var. trichoglume was able to recover from leaf water potentials as low as -92 bar. The degree of stress experienced during the single drying cycle did not influence the maximum net photosynthetic rate attained during recovery, but the time taken to reach the maximum increased with the degree of stress experienced. During the first 24 h, the rate of recovery of net photosynthesis was mainly determined by the rate at which the water status improved. Leaves which experienced water potentials less than c. -40 bar had a slower rate of recovery of water potential than less stressed leaves. This was partially offset by higher rates of net photosynthesis. Furthermore, the relationship between leaf water potential and net photosynthesis recorded during the drying cycle was different from those measured during recovery. Thus different relationships must be used in models simulating behaviour during water stress and subsequent recovery. Stomatal resistance exerted greater control than intracellular resistance over net photosynthesis in the recovery phase, irrespective of the water potential before rewatering or whether plants were preconditioned to stress. Although abscisic acid concentration was positively related to leaf water potential and stomatal resistance during the drying cycle, the relationship between abscisic acid concentration and stomatal resistance during recovery was poor or absent. Sucrose and amino-acid nitrogen accumulated during stress and decreased during recovery. However, the level of non- structural carbohydrates or nitrogen compounds in the recovery phase did not appear to influence net photosynthetic rate or its components. In fact, the reverse appeared to occur: the rate of photosynthesis and growth seemed to determine the levels of these compounds.


2006 ◽  
Vol 131 (6) ◽  
pp. 709-715 ◽  
Author(s):  
Jun Ying Zhao ◽  
Li Jun Wang ◽  
Pei Ge Fan ◽  
Zhan Wu Dai ◽  
Shao Hua Li

Half or whole root systems of micropropagated `Gala' apple (Malus ×domestica Borkh.) plants were subjected to drought stress by regulating the osmotic potential of the nutrient solution using polyethylene glycol (20% w/v) to investigate the effect of root drying on NO3- content and metabolism in roots and leaves and on leaf photosynthesis. No significant difference in predawn leaf water potential was found between half root stress (HRS) and control (CK), while predawn leaf water potential from both was significantly higher than for the whole root stress (WRS) treatment. However, diurnal leaf water potential of HRS was lower than CK and higher than WRS during most of the daytime. Neither HRS nor WRS influenced foliar NO3- concentration, but both significantly reduced NO3- concentration in drought-stressed roots as early as 4 hours after stress treatment started. This reduced NO3- concentration was maintained in HRS and WRS roots to the end of the experiment. However, there were no significant differences in NO3- concerntation between CK roots and unstressed roots of HRS. Similar to the effect on root NO3- concentration, both HRS and WRS reduced nitrate reductase activity in drought-stressed roots. Moreover, leaf net photosynthesis, stomatal conductance and transpiration rate of HRS plants were reduced significantly throughout the experiment when compared with CK plants, but the values were higher than those of WRS plants in the first 7 days of stress treatment though not at later times. Net photosynthesis, stomatal conductance and transpiration rate were correlated to root NO3- concentration. This correlation may simply reflect the fact that water stress affected both NO3- concentration in roots and leaf gas exchange in the same direction.


HortScience ◽  
2000 ◽  
Vol 35 (4) ◽  
pp. 763-768
Author(s):  
Thayne Montague ◽  
Roger Kjelgren ◽  
Larry Rupp

Gas exchange and growth of transplanted and nontransplanted, field-grown Norway maple (Acer platanoides L. `Schwedleri') and littleleaf linden (Tilia cordata Mill. `Greenspire') trees were investigated in an arid climate. In the spring of 1995, three trees of each species were moved with a tree spade to a new location within a field nursery and three nontransplanted trees were selected as controls. Predawn leaf water potential, morning-to-evening stomatal conductance and leaf temperature, leaf-to-air vapor pressure difference, midday stomatal conductance and photosynthetic rate, and growth data were collected over a 2-year period. After transplanting, weekly predawn leaf water potential indicated that transplanted trees were under greater water stress than were nontransplanted (control) trees. However, predawn leaf water potential of maple trees recovered to control levels 18 weeks after transplanting, while that of transplanted linden trees remained more negative than that of controls. In 1995, stomatal conductance and photosynthetic rates were lower throughout the day for transplanted trees. In 1996, gas exchange rates of transplanted maple trees recovered to near control levels while rates for transplanted linden trees did not. Sensitivity of stomata to leaf-to-air vapor pressure difference varied with species and with transplant treatment. Each year transplanted trees of both species had less apical growth than did control trees. Although gas exchange and apical growth of transplanted trees was reduced following transplanting, recovery of gas exchange to control rates differed with species.


1994 ◽  
Vol 24 (5) ◽  
pp. 954-959 ◽  
Author(s):  
L.J. Samuelson ◽  
J.R. Seiler

The interactive influences of ambient (374 μL•L−1) or elevated (713 μL•L−1) CO2, low or high soil fertility, well-watered or water-stressed treatment, and rooting volume on gas exchange and growth were examined in red spruce (Picearubens Sarg.) grown from seed through two growing seasons. Leaf gas exchange throughout two growing seasons and growth after two growing seasons in response to elevated CO2 were independent of soil fertility and water-stress treatments, and rooting volume. During the first growing season, no reduction in leaf photosynthesis of seedlings grown in elevated CO2 compared with seedlings grown in ambient CO2 was observed when measured at the same CO2 concentration. During the second growing season, net photosynthesis was up to 21% lower for elevated CO2-grown seedlings than for ambient CO2-grown seedlings when measured at 358 μL•L−1. Thus, photosynthetic acclimation to growth in elevated CO2 occurred gradually and was not a function of root-sink strength or soil-fertility treatment. However, net photosynthesis of seedlings grown and measured at an elevated CO2 concentration was still over 2 times greater than the photosynthesis of seedlings grown and measured at an ambient CO2 concentration. Growth enhancement by CO2 was maintained, since seedlings grown in elevated CO2 were 40% larger in both size and weight after two growing seasons.


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