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1
Kriedemann, P. E. "TREE WATER RELATIONS." Acta Horticulturae, no. 175 (March 1986): 343–50. http://dx.doi.org/10.17660/actahortic.1986.175.51.
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Measham, P. F., S. J. Wilson, A. J. Gracie, and S. A. Bound. "Tree water relations: Flow and fruit." Agricultural Water Management 137 (May 2014): 59–67. http://dx.doi.org/10.1016/j.agwat.2014.02.005.
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Renquist, A. Richard, Horst W. Caspari, and David J. Chalmers. "ASIAN PEAR (NASHI) TREE WATER RELATIONS IN LYSIMETERS." HortScience 27, no. 6 (1992): 572f—572. http://dx.doi.org/10.21273/hortsci.27.6.572f.
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Nashi pear (Pyrus serotina Rehder, cv. Hosui) trees were planted in 12 computerized 1m-wide drainage lysimeters in September 1987. During the 1990 season tree water use was monitored via lysimeter and neutron probe readings. Diurnal leaf water relations were studied using a pressure chamber for water potential (ψ) and a porometer for leaf conductance (gs). Xylem sap trunk flow velocities were measured with an experimental heat pulse device and converted to xylem flux. Close agreement existed between 24 hr xylem flux and lysimeter water use when comparing trees with different soil water content. Xylem flux also was very sensitive to changes in evaporative demand. During 9–13 day drying cycles pre-dawn ψ became progressively lower, morning decline more rapid, and afternoon recovery slower. The diurnal gs pattern also shifted during drying cycles, such that gs of water stressed trees always decreased from time of first measurement of sunlit leaves rather than increasing during the morning as on non-stressed trees. Late afternoon was the best time to distinguish between fully irrigated and stressed trees using gs measurements.
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Kjelgren, Roger, and Brenda Cleveland. "Growth and Water Relations of Kentucky Coffee Tree and Silver Maple Following Transplanting." Journal of Environmental Horticulture 12, no. 2 (1994): 96–99. http://dx.doi.org/10.24266/0738-2898-12.2.96.
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Abstract Following transplanting we monitored growth and water relations over two years in Kentucky coffee tree (Gymnocladus dioica (L.) C. Koch) and silver maple (Acer saccharinum L.). Field-grown, well-established trees transplanted in place were compared to nontransplanted control trees. Predawn water potential was measured twice each month for two growing seasons, as well as midday stomatal conductance and water potential. Shoot elongation, leaf size, diameter growth, and total leaf area were determined both years. Less total leaf area as a result of transplanting apparently moderated total tree transpiration in both species. Reduced tree transpiration allowed stomatal conductance and predawn water potential to reach levels equal to non-transplanted trees in both species during periods of high rainfall. During low-rainfall periods water relations of transplanted Kentucky coffee tree (KCT) declined more than silver maple (MAP) relative to the control trees. Compared to non-transplanted trees, transplanting reduced growth of KCT more than that of MAP the first year. In the second year, when growing-season rainfall was less than half of the first year, the relative effect of transplanting on growth of the two species was reversed, indicating that KCT was more drought tolerant. These results suggested that deciduous balled-and-burlapped trees transplanted while dormant self-regulate water loss by reducing transpiring leaf area the following growing season.
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Junttila, Samuli, Mariana Campos, Teemu Hölttä, et al. "Tree Water Status Affects Tree Branch Position." Forests 13, no. 5 (2022): 728. http://dx.doi.org/10.3390/f13050728.
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Physiological processes cause movements of tree stems and branches that occur in a circadian rhythm and over longer time periods, but there is a lack of quantitative understanding of the cause-and-effect relationships. We investigated the movement of tree branches in a long-term drought experiment and at a circadian time scale using time-series of terrestrial laser scanning measurements coupled with measurements of environmental drivers and tree water status. Our results showed that movement of branches was largely explained by leaf water status measured as leaf water potential in a controlled environment for both measured trees (R2 = 0.86 and R2 = 0.75). Our hypothesis is that changes in leaf and branch water status would cause branch movements was further supported by strong relationship between vapor pressure deficit and overnight branch movement (R2 = [0.57–0.74]). Due to lower atmospheric water demand during the nighttime, tree branches settle down as the amount of water in leaves increases. The results indicate that the quantified movement of tree branches could help us to further monitor and understand the water relations of tree communities.
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Caplan, Joshua S., Russell C. Galanti, Stuart Olshevski, and Sasha W. Eisenman. "Water relations of street trees in green infrastructure tree trench systems." Urban Forestry & Urban Greening 41 (May 2019): 170–78. http://dx.doi.org/10.1016/j.ufug.2019.03.016.
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Barij, Nadia, Jan Čermák, and Alexia Stokes. "Azimuthal variations in xylem structure and water relations in cork oak (Quercus suber)." IAWA Journal 32, no. 1 (2011): 25–40. http://dx.doi.org/10.1163/22941932-90000040.
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Azimuthal variations in xylem conductivity and transpiration can occur in trees and may be due to heterogeneity in environmental factors. In cork oak (Quercus suber L.), it can be hypothesized that such modifications may be more pronounced because the insulating layer of bark is harvested every 9–10 years, thus cambial cells will be exposed to fluctuations in the microenvironment. To investigate whether xylem structure and water relations differed around the stems of mature cork oak, sap flow per section and xylem structure were measured on the northern (N) and southern (S) sides of nine trees during three months in Portugal, using the Trunk Sector Heat Balance method. Crown size was measured on both sides of each tree and increment wood cores were extracted from the sites where sap flow was measured in five trees. Wood moisture content, earlywood (EW) vessel size and density were measured and theoretical hydraulic conductivity for individual vessels (Lth) was calculated along the N and S stem radial profiles. No significant differences in crown size between the two sides of the tree were found, but sap flow was higher on the S side of the tree in May only. No differences in wood moisture content were observed along the length of each wood core throughout the heartwood. Significant differences in vessel size occurred, with a greater diameter and surface area on the N side of the tree, and consequently Lth was significantly greater. These conduit diameters on the S facing side of the tree may be smaller in response to a combination of signals and trade-offs due to the heterogeneous air and soil environment around the tree.
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Moravec, C. M., K. J. Bradford, and E. A. Laca. "Water relations of drumstick tree seed (Moringa oleifera): imbibition, desiccation, and sorption isotherms." Seed Science and Technology 36, no. 2 (2008): 311–24. http://dx.doi.org/10.15258/sst.2008.36.2.05.
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Skov, Kjerstin R., Thomas E. Kolb, and Kimberly F. Wallin. "Tree Size and Drought Affect Ponderosa Pine Physiological Response to Thinning and Burning Treatments." Forest Science 50, no. 1 (2004): 81–91. http://dx.doi.org/10.1093/forestscience/50.1.81.
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Abstract Thinning and burning treatments based on presettlement (prior to Euro-American settlement) stand conditions have been proposed for improving the vigor and growth of Pinus ponderosa. No study has examined effects of different levels of such thinning treatments on tree water, carbon, and nitrogen relations, or compared effects between postsettlement (trees established after Euro-American settlement) and presettlement (established before Euro-American settlement) trees. We investigated responses of presettlement and postsettlement trees to three levels of thinning and burning (unthinned/unburned control, light thinning/burning, heavy thinning/burning) over 2 yr that differed in precipitation in northern Arizona. Both thinning treatments consistently increased predawn water potential of both tree sizes compared with the control. Effects of thinning on leaf gas exchange varied between tree sizes and measurement times. Thinning increased net photosynthetic rate and stomatal conductance only when soil water availability was lowest, and increases were greater for postsettlement than presettlement trees. In contrast, thinning had no effect on foliar nitrogen concentration.Our results suggest greater positive effects of restoration thinning on tree water and carbon relations for postsettlement versus presettlement trees, and under drought versus nondrought conditions. Photosynthetic response to thinning in old trees may be constrained by physiological factors associated with large size such as low soil-to-leaf hydraulic conductance. FOR. SCI. 50(1):81–91.
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Wolken, J. M., P. V. Blenis, and M. F. Dyck. "Whole-tree water relations of western gall rust infected lodgepole pine trees." Canadian Journal of Plant Pathology 31, no. 3 (2009): 330–39. http://dx.doi.org/10.1080/07060660909507607.
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Kjelgren, Roger, and Mike Foutch. "GROWTH OF KENTUCKY COFFEE TREE SEEDLINGS IN PROTECTIVE SHELTERS DURING FIELD ESTABLISHMENT." HortScience 27, no. 6 (1992): 569e—569. http://dx.doi.org/10.21273/hortsci.27.6.569e.
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Growth and water relations of seedlings grown in protective tree shelters were investigated during establishment in a field nursery. Shelters, 1.2 m high, were placed over 0.5 m Kentucky coffee tree seedlings following spring transplanting in a field experiment. Predawn leaf water potential (ψ) and stomatal conductance (gs) were monitored periodically through the season and growth was measured in late summer. In a second experiment diurnal microclimate, and seedling water relations and use, in the shelters were studied under controlled conditions. In the shelters, leaf and air temperature, humidity, and gs exceeded non-sheltered levels while solar radiation was 70% lower. Despite greater gs, normalized water use was 40% lower in the sheltered trees. While midday gs was similarly high in the field-grown trees, no differences in predawn ψ were detected through the season. Sheltered trees in the field had four times more shoot growth but 40% less caliper growth. Sheltered trees had leaf thickness lower than control trees, and together with the growth and radiation pattern, indicated that they were shade acclimated. Shelters can improve height growth and reduce water loss during establishment, but may not allow sufficient trunk development or taper for upright support
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Stewart, J. Ryan, Roger Kjelgren, Paul G. Johnson, and Michael R. Kuhns. "Growth and Water Relations of Littleleaf Linden Trees Established in Irrigated Buffalograss and Kentucky Bluegrass." HortScience 40, no. 5 (2005): 1529–33. http://dx.doi.org/10.21273/hortsci.40.5.1529.
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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.
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Kjelgren, Roger, and James Clark. "Water Relations of Sweetgum in an Urban Canyon and Park." Arboriculture & Urban Forestry 19, no. 5 (1993): 266–70. http://dx.doi.org/10.48044/jauf.1993.042.
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Water use and water relations of sweetgum growing in an urban canyon were investigated. Predawn water potential, dawn-to-dusk stomatal conductance, and leaf morphology were measured over a two-year period at a downtown site in Seattle, Washington. Trees received four hours of direct midsummer sunlight during midday. This was compared to similar-aged sweetgum street trees growing in a neighboring park-like setting. Specific leaf area and leaf presentation angle of the canyon trees were characteristic of shade acclimation. Stomata of the canyon trees quickly opened in response to light during the morning shade period, but closed rapidly in response to low humidity during the sunlit period, and remained closed through the afternoon shaded period. Overall lower conductances and leaf temperatures in the canyon trees resulted in transpiration rates that were lower than the park trees. The data suggest that trees growing in urban canyons will deplete soil water less rapidly due to the effects of reduced irradiance on tree transpiration.
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Barton, Amy J., and Christopher S. Walsh. "Transplanting Shock and Water Relations in Urban Tree Species." HortScience 33, no. 3 (1998): 540b—540. http://dx.doi.org/10.21273/hortsci.33.3.540b.
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Large-caliper trees transplanted into urban settings show low survivability. A 1-year transplanting experiment was conducted using Acer ginnala and Acer truncatum. Trees were blocked by species and size, with three blocks of four trees per species. Three trees of each species were left in their original location for purpose of comparison. A 2 × 2 factorial was used to assign treatments (water, water and top prune, top prune, and transplanted control). Using a Schollander Pressure Bomb, predawn and midday water potential measurements were recorded biweekly from early May through September. The first 8 weeks following transplant, all transplanted trees of both species had significantly (P ≥ 0.05) more negative midday water potentials than those not transplanted. During periods of stress, predawn water potentials of transplanted trees did not recover overnight. By September, irrigated trees had water potentials not significantly different from those of trees not transplanted. Canopy closure was measured on the same schedule using a Li-Cor Canopy Analyzer. Leaf area index of transplanted trees was nearly half that of non-transplanted trees. Trees treated with water did have slight, but significantly greater leaf area indexes than those of other treatments. It appears that the most notable effect of transplanting is the inhibition of leaf expansion resulting from early spring water stress. This leads to an open canopy for the whole season following transplant.
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Close, Richard, J. James Kielbaso, Phu Nguyen, and Robert Schutzki. "Urban vs. Natural Sugar Maple Growth: II. Water Relations." Arboriculture & Urban Forestry 22, no. 4 (1996): 187–92. http://dx.doi.org/10.48044/jauf.1996.028.
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Physiologic measurements of the internal water relations of sugar maple in a natural forest and along an urban street in Michigan were performed as a complement to a companion site characterization study. Investigations were carried out to determine how street trees are affected by the urban habitat, and to confirm through correlation analysis that siterelated water stress adversely influences tree growth and vitality. Significant water relations differences exist between the street site sugar maples and those in natural habitats. Predawn water potential, osmotic potential, and stomatal conductance were significantly lower in the street trees, and were significantly correlated with the low soil moisture levels and high atmospheric demands of the street site. Findings of this study, in conjunction with the site characterization data, can be of value in selecting appropriate remedial treatments for stressed urban trees, as well as to reiterate the need for further screening of drought-tolerant cultivars for urban sites.
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Fredericksen, T. S., K. C. Steiner, J. M. Skelly, et al. "Diel and Seasonal Patterns of Leaf Gas Exchange and Xylem Water Potentials of Different-Sized Prunus serotina Ehrh. Trees." Forest Science 42, no. 3 (1996): 359–65. http://dx.doi.org/10.1093/forestscience/42.3.359.
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Abstract Leaf gas exchange and xylem water potentials were measured in the field throughout the 1994 growing season on leaves in the upper crown of seedling, sapling, and forest canopy black cherry trees (Prunus serotina Ehrh.) in northcentral Pennsylvania. Rates of gas exchange and xylem water potentials generally decreased with increasing tree size. Rates of dark respiration also decreased with increasing tree size. Differences among tree size classes were consistent throughout the growing season for xylem water potentials, but not for leaf gas exchange measurements. In May and June, seedling net photosynthesis and stomatal conductance were approximately 2 x that of larger trees, but their values tended to be similar to or lower than those of larger trees in July and August. Averaged over the entire season, seedlings had higher leaf gas exchange rates than saplings, which had higher rates than canopy trees. Regardless of tree size, stomatal conductance and net photosynthetic rates reached a maximum near mid to late morning. Stomatal conductance and net photosynthesis decreased steadily during the afternoon for larger trees, but seedling rates remained high until late afternoon. Seedlings consistently had the highest predawn and midday xylem water potentials and leaf-to-air water vapor pressure deficits, while canopy trees had the lowest. The results of this study indicate that tree size is an important factor influencing foliar gas exchange and water relations. For. Sci. 42(3):359-365.
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Raffelsbauer, Volker, Franz Pucha-Cofrep, Simone Strobl, et al. "Trees with anisohydric behavior as main drivers of nocturnal evapotranspiration in a tropical mountain rainforest." PLOS ONE 18, no. 3 (2023): e0282397. http://dx.doi.org/10.1371/journal.pone.0282397.
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This study addresses transpiration in a tropical evergreen mountain forest in the Ecuadorian Andes from the leaf to the stand level, with emphasis on nocturnal plant-water relations. The stand level: Evapotranspiration (ET) measured over 12 months with the Eddy-Covariance (ECov) technique proved as the major share (79%) of water received from precipitation. Irrespective of the humid climate, the vegetation transpired day and night. On average, 15.3% of the total daily ET were due to nocturnal transpiration. Short spells of drought increased daily ET, mainly by enhanced nighttime transpiration. Following leaf transpiration rather than air temperature and atmospheric water vapor deficit, ET showed its maximum already in the morning hours. The tree level: Due to the humid climate, the total water consumption of trees was generally low. Nevertheless, xylem sap flux measurements separated the investigated tree species into a group showing relatively high and another one with low sap flux rates. The leaf level: Transpiration rates of Tapirira guianensis, a member of the high-flux-rate group, were more than twice those of Ocotea aciphylla, a representative of the group showing low sap flux rates. Representatives of the Tapirira group operated at a relatively high leaf water potential but with a considerable diurnal amplitude, while the leaves of the Ocotea group showed low water potential and small diurnal fluctuations. Overall, the Tapirira group performed anisohydrically and the Ocotea group isohydrically. Grouping of the tree species by their water relations complied with the extents of the diurnal stem circumference fluctuations. Nighttime transpiration and hydrological type: In contrast to the isohydrically performing trees of the Ocotea group, the anisohydric trees showed considerable water vapour pressure deficit (VPD)-dependent nocturnal transpiration. Therefore, we conclude that nighttime ET at the forest level is mainly sourced by the tree species with anisohydric performance.
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Rings, J., T. Kamai, M. Kandelous, et al. "Bayesian Inference of Tree Water Relations Using a Soil-Tree-Atmosphere Continuum Model." Procedia Environmental Sciences 19 (2013): 26–36. http://dx.doi.org/10.1016/j.proenv.2013.06.004.
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Ping Lu. "WHOLE-TREE WATER RELATIONS AND IRRIGATION SCHEDULING FOR MANGO." Acta Horticulturae, no. 992 (May 2013): 115–22. http://dx.doi.org/10.17660/actahortic.2013.992.13.
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Kjelgren, Roger. "Growth and Water Relations of Kentucky Coffee Tree in Protective Shelters during Establishment." HortScience 29, no. 7 (1994): 777–80. http://dx.doi.org/10.21273/hortsci.29.7.777.
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Growth and water relations of Kentucky coffee tree [Gymnocladus dioica (L.) K. Koch] whips in translucent tubelike shelters were investigated. In a container study, 1.2-m-high shelters were placed over whips following transplanting, then diurnal microclimate, water relations, and water use were measured. Shelter air temperature and vapor pressure were substantially higher, and solar radiation was 70% lower, than ambient conditions. Sheltered trees responded with nearly three-times higher stomatrd conductance than nonsheltered trees. However, due to substantially lower boundary layer conductance created by the shelter, normalized water use was 40910 lower. In a second experiment, same-sized shelters were placed on whips following spring transplanting in the field. Predawn and midday leaf water potentials and midday stomatal conductance (g,) were monitored periodically through the season, and growth was measured in late summer. Midday gs was also much higher in field-grown trees with shelters than in those without. Sheltered trees in the field had four times greater terminal shoot elongation but 40% less stem diameter growth. Attenuated radiation in the shelters and lower specific leaf area of sheltered trees indicated shade acclimation. Shelters can improve height and reduce water loss during establishment in a field nursery, but they do not allow for sufficient trunk growth.
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Kjelgren, Roger, and Larry Rupp. "WATER USE OF GREEN ASH AND NORWAY MAPLE IN TREE SHELTERS DURING ESTABLISHMENT." HortScience 28, no. 5 (1993): 561b—561. http://dx.doi.org/10.21273/hortsci.28.5.561b.
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We investigated how tree shelters affected seedling water use as a fractional coefficient of potential evapotranspiration (ETo) and ability to delay water stress in a nursery setting. A field study investigated water relations of newly planted whips with-and-without shelters irrigated at 100% of ETo or unirrigated. Trees in shelters were shade acclimated based on higher specific leaf area, but in diurnal studies had consistently higher stomatal conductances (gs) than non-sheltered trees. Non-irrigated trees with shelters had higher gs than treatments without shelters. There were no consistent overall differences in water potential (ψ) between irrigation treatments. Predawn ψ of trees in shelters was more negative, but midday ψ was similar to non-sheltered trees regardless of irrigation treatment. A separate study placed shelters over foliage of container-grown whips of green ash and Norway maple and enclosed the roots in plastic to eliminate evaporation. Daily gravimetric water use and ETo was followed for six weeks in 1992. Trees in shelters used substantially less water than control trees. Gravimetric water use normalized to depth units varied from 5-10% as a fraction of ETo. This was less than half that of control trees without shelters. Tree shelters reduced water loss while maintaining high gas exchange, but whether shelters helped tree seedlings to delay water stress during establishment was inconclusive from these data.
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Proebsting, L., P. H. Jerie, and J. Irvine. "Water Deficits and Rooting Volume Modify Peach Tree Growth and Water Relations." Journal of the American Society for Horticultural Science 114, no. 3 (1989): 368–72. http://dx.doi.org/10.21273/jashs.114.3.368.
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Abstract To compare the effects of water deficits and restricted root volume, 1- and 2-year-old peach trees (Prunus persica L.) with roots divided among four 2.5-Iiter pots were irrigated daily with 30% (deficit irrigation) or 100% (non-deficit) replacement of water used the day before. The water was applied to one, two, or all four pots during the period of rapid terminal growth. After 7 weeks, all trees received 100% replacement of water used the previous day. After terminal growth ended, the root : shoot ratio of the 2-year-old trees was adjusted by 1) tripling available soil volume, 2) removing two-thirds of lateral branches, 3) both 1 and 2, 4) treatment 3 defoliated, or 5) left unchanged. Deficit irrigation reduced midday leaf water potential, leaf conductance, and terminal growth equally, regardless of irrigated soil volume, whereas in non-deficit irrigated trees these factors were proportional to the irrigated soil volume. After deficit irrigation ended, terminal growth resumed at rates above those of the trees with non-deficit irrigation applied to all four pots and proportional to the severity of growth reduction during deficit irrigation. Pruning and defoliation increased leaf conductance within 3 days. Increased soil volume increased leaf conductance after 4 weeks. Deficit irrigation nearly eliminated flowering for the following year. Tripling the soil volume overcame the effect of deficit irrigation on flowering, but pruning did not. Defoliation inhibited flowering. The effect of restricted irrigated soil volume was similar to that of deficit irrigation. Increasing root : shoot ratios by adjusting the soil volume or by pruning the shoot always increased leaf conductance.
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Iwasaki, Naoto, Asaki Tamura, and Kyoka Hori. "Altered Carbohydrate Allocation Due to Soil Water Deficit Affects Summertime Flowering in Meiwa Kumquat Trees." Horticulturae 6, no. 3 (2020): 49. http://dx.doi.org/10.3390/horticulturae6030049.
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The summertime flowers of the ever-flowering Meiwa kumquat (Fortunella crassifolia Swingle) are the most useful for fruit production in Japan; however, summertime flowers bloom in three or four successive waves at approximately 10 day intervals, resulting in fruit of different maturity occurring on the same tree. Soil water deficit (SWD) treatment has been shown to reduce the flowering frequency and improve harvest efficiency; therefore, in this study, the effects of SWD treatment on the accumulation of soluble sugars in each tree organ above-ground were examined and it was discussed how SWD affects the whole-tree water relations and sugar accumulation by osmoregulation. The number of first-flush summertime flowers was higher in SWD-treated trees than non-treated control (CONT) trees (177.0 and 58.0 flowers, respectively), whereas the second- and third-flush flowers were only observed in CONT trees. The soluble sugar content was higher in SWD treated trees than CONT trees for all organs and tended to be higher in current-year organs than previous-year organs; however, when the sugar content of the current-year spring stems exceeded approximately 100 mg g−1 dry weight, the current-year leaf water potential decreased sharply and the rate of increase in the number of first-flush flowers also tended to decrease. SWD treatment significantly increased the total sugar content of the xylem tissue of the scaffold branches to three times the value in CONT trees (p = 0.001); however, the increase was observed even in sucrose, a disaccharide, similar to that in monosaccharides such as glucose and fructose. These results suggest that the increased sugar levels in the xylem tissue resulted from not only osmoregulation but also other factors as well; therefore, these sugars may affect whole-tree water relations as well as the development of flower buds.
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Kjelgren, Roger, and Larry A. Rupp. "Establishment in Treeshelters I: Shelters Reduce Growth, Water Use, and Hardiness, but not Drought Avoidance." HortScience 32, no. 7 (1997): 1281–83. http://dx.doi.org/10.21273/hortsci.32.7.1281.
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We investigated water use and potential drought avoidance of Norway maple (Acer platanoides L.) and green ash (Fraxinus pennsylvanica Marsh) seedlings grown in protective plastic shelters. Gravimetric tree water use and reference evapotranspiration for fescue turf (ETo) were monitored for 1 to 3 days during the growing season. Water use of trees was 8% to 14% of ETo in shelters vs. 29% to 40% for trees not in shelters. Trunk diameter was affected more than whole-tree water relations by lack of irrigation, suggesting that the nonirrigated trees were subjected to only mild water stress. Shelters did not improve drought avoidance, as water potentials were generally more negative and trunk diameter increment was lower for nonirrigated trees in shelters. Maples in shelters were affected more adversely by lack of water than were ash. Higher temperatures in shelters also may have reduced trunk growth. Air temperatures were 13 °C warmer than ambient in nonirrigated shelters, but only 5 °C warmer in irrigated shelters. Tree shelters can reduce transpiration rates by over half, but benefits from reduced water loss may be offset by negative effects of higher air temperatures. Shelters reduced cold hardiness of both species, but maple was affected more than ash.
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Hamido, Said A., Robert C. Ebel, and Kelly T. Morgan. "Interaction of Huanglongbing and Foliar Applications of Copper on Water Relations of Citrus sinensis cv. Valencia." Plants 8, no. 9 (2019): 298. http://dx.doi.org/10.3390/plants8090298.
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The following study was conducted to determine the impact of frequent foliar Cu applications on water relations of Huanglongbing (HLB)-affected Citrus sinensis cv. ‘Valencia’. HLB in Florida is putatively caused by Candidatus Liberibacter asiaticus that is vectored by the Asian citrus psyllid. The experiment was conducted in a psyllid-free greenhouse with trees grown in Immokalee fine sand soil with the trees well-maintained to promote health. Cu was applied to the foliage at 0×, 0.5×, 1×, and 2× the commercially recommended rates, which were 0, 46, 92, and 184 mM, respectively, with applications made 3× in both 2016 and 2017. Previous studies indicate that HLB causes roots to decline before the canopy develops symptoms, which increases the ratio between the evaporative surface area of the canopy to the uptake surface area of roots and increases the hydraulic strain within the tree. In the current study, overall growth was suppressed substantially by HLB and Cu treatments but the ratio between evaporative surface area (leaf surface area) and the uptake surface area of roots (feeder root surface area) was not affected by either treatment. Stem water potential (Ψxylem), which was used as a measure of plant water deficits and the hydraulic strain within the tree, was significantly 13% lower for HLB-affected trees than the non-HLB controls but were not affected by Cu treatments. All Ψxylem measurements were in a range typical of well-watered trees conditions. Stomatal conductance (ks) and root and soil resistances (Rr+s) were not affected by HLB and Cu. The results of this experiment suggest that tree leaf area and feeder roots are reduced when the trees are affected by HLB or are treated with foliar Cu applications such that plant water deficits are not significantly different over that of the controls.
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Egea, Gregorio, Ian C. Dodd, María M. González-Real, Rafael Domingo, and Alain Baille. "Partial rootzone drying improves almond tree leaf-level water use efficiency and afternoon water status compared with regulated deficit irrigation." Functional Plant Biology 38, no. 5 (2011): 372. http://dx.doi.org/10.1071/fp10247.
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To determine whether partial rootzone drying (PRD) optimised leaf gas exchange and soil–plant water relations in almond (Prunus dulcis (Mill.) D.A. Webb) compared with regulated deficit irrigation (RDI), a 2 year trial was conducted on field-grown trees in a semiarid climate. Five irrigation treatments were established: full irrigation (FI) where the trees were irrigated at 100% of the standard crop evapotranspiration (ETc); three PRD treatments (PRD70, PRD50 and PRD30) that applied 70, 50 and 30% ETc, respectively; and a commercially practiced RDI treatment that applied 50% ETc during the kernel-filling stage and 100% ETc during the remainder of the growth season. Measurements of volumetric soil moisture content in the soil profile (0–100 cm), predawn leaf water potential (Ψpd), midday stem water potential (Ψms), midday leaf gas exchange and trunk diameter fluctuations (TDF) were made during two growing seasons. The diurnal patterns of leaf gas exchange and stem water potential (Ψs) were appraised during the kernel-filling stage in all irrigation regimes. When tree water relations were assessed at solar noon, PRD did not show differences in either leaf gas exchange or tree water status compared with RDI. At similar average soil moisture status (adjudged by similar Ψpd), PRD50 trees had higher water status than RDI trees in the afternoon, as confirmed by Ψs and TDF. Although irrigation placement showed no effects on diurnal stomatal regulation, diurnal leaf net photosynthesis (Al) was substantially less limited in PRD50 than in RDI trees, indicating that PRD improved leaf-level water use efficiency.
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David, Teresa Soares, Clara Assunção Pinto, Nadezhda Nadezhdina, and Jorge Soares David. "Water and forests in the Mediterranean hot climate zone: a review based on a hydraulic interpretation of tree functioning." Forest Systems 25, no. 2 (2016): eR02. http://dx.doi.org/10.5424/fs/2016252-08899.
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Aim of the study: Water scarcity is the main limitation to forest growth and tree survival in the Mediterranean hot climate zone. This paper reviews literature on the relations between water and forests in the region, and their implications on forest and water resources management. The analysis is based on a hydraulic interpretation of tree functioning.Area of the study: The review covers research carried out in the Mediterranean hot climate zone, put into perspective of wider/global research on the subject. The scales of analysis range from the tree to catchment levels.Material and Methods: For literature review we used Scopus, Web of Science and Google Scholar as bibliographic databases. Data from two Quercus suber sites in Portugal were used for illustrative purposes.Main results: We identify knowledge gaps and discuss options to better adapt forest management to climate change under a tree water use/availability perspective. Forest management is also discussed within the wider context of catchment water balance: water is a constraint for biomass production, but also for other human activities such as urban supply, industry and irrigated agriculture.Research highlights: Given the scarce and variable (in space and in time) water availability in the region, further research is needed on: mapping the spatial heterogeneity of water availability to trees; adjustment of tree density to local conditions; silvicultural practices that do not damage soil properties or roots; irrigation of forest plantations in some specific areas; tree breeding. Also, a closer cooperation between forest and water managers is needed.Keywords: tree hydraulics; tree mortality; climate change; forest management; water resources.
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Barry, Graham H., William S. Castle, and Frederick S. Davies. "Rootstocks and Plant Water Relations Affect Sugar Accumulation of Citrus Fruit Via Osmotic Adjustment." Journal of the American Society for Horticultural Science 129, no. 6 (2004): 881–89. http://dx.doi.org/10.21273/jashs.129.6.0881.
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Citrus rootstocks have well-known effects on tree size, crop load, fruit size, and various fruit quality factors. Fruit from trees budded on invigorating rootstocks are generally larger with lower soluble solids concentration (SSC) and titratable acidity compared to fruit from trees budded on less invigorating rootstocks. Although it is unclear how rootstocks exert their influence on juice quality of Citrus L. species, plant water relations are thought to play a central role. In addition, the larger fruit size associated with invigorating rootstocks and the inverse relationship between SSC and fruit size implies that fruit borne on trees on invigorating rootstocks have lower SSC due to dilution effects in larger fruit. To determine how rootstock type affects sugar accumulation in fruit of Citrus species, controlled water-deficit stress was applied to mature `Valencia' sweet orange [C. sinensis (L.) Osb.] trees on Carrizo citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] or rough lemon (C. jambhiri Lush.) rootstocks. Withholding water from the root zone of citrus trees during stage II of fruit development decreased midday stem water potential and increased the concentrations of primary osmotica, fructose and glucose. Sucrose concentration was not affected, suggesting that sucrose hydrolysis took place. Increased concentrations of sugars and SSC in fruit from moderately water-stressed trees occurred independently of fruit size and juice content. Thus, passive dehydration of juice sacs, and concentration of soluble solids, was not the primary cause of differences in sugar accumulation. Controlled water-deficit stress caused active osmotic adjustment in fruit of `Valencia' sweet orange. However, when water-deficit stress was applied later in fruit development (e.g., stage III) there was no increase in sugars or SSC. The evidence presented supports the hypothesis that differential sugar accumulation of citrus fruit from trees on rootstocks of contrasting vigor and, hence, plant water relations, is caused by differences in tree water status and the enhancement of sucrose hydrolysis into component hexose sugars resulting in osmotic adjustment. Therefore, inherent rootstock differences affecting plant water relations are proposed as a primary cause of differences in sugar accumulation and SSC among citrus rootstocks.
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Barry, Graham H., William S. Castle, and Frederick S. Davies. "Rootstocks and Plant Water Relations Affect Sugar Accumulation of Citrus Fruit Via Osmotic Adjustment." Journal of the American Society for Horticultural Science 129, no. 6 (2004): 881–89. https://doi.org/10.21273/jashs.129.6.881.
Full textAbstract:
Citrus rootstocks have well-known effects on tree size, crop load, fruit size, and various fruit quality factors. Fruit from trees budded on invigorating rootstocks are generally larger with lower soluble solids concentration (SSC) and titratable acidity compared to fruit from trees budded on less invigorating rootstocks. Although it is unclear how rootstocks exert their influence on juice quality of Citrus L. species, plant water relations are thought to play a central role. In addition, the larger fruit size associated with invigorating rootstocks and the inverse relationship between SSC and fruit size implies that fruit borne on trees on invigorating rootstocks have lower SSC due to dilution effects in larger fruit. To determine how rootstock type affects sugar accumulation in fruit of Citrus species, controlled water-deficit stress was applied to mature `Valencia' sweet orange [C. sinensis (L.) Osb.] trees on Carrizo citrange [C. sinensis × Poncirus trifoliata (L.) Raf.] or rough lemon (C. jambhiri Lush.) rootstocks. Withholding water from the root zone of citrus trees during stage II of fruit development decreased midday stem water potential and increased the concentrations of primary osmotica, fructose and glucose. Sucrose concentration was not affected, suggesting that sucrose hydrolysis took place. Increased concentrations of sugars and SSC in fruit from moderately water-stressed trees occurred independently of fruit size and juice content. Thus, passive dehydration of juice sacs, and concentration of soluble solids, was not the primary cause of differences in sugar accumulation. Controlled water-deficit stress caused active osmotic adjustment in fruit of `Valencia' sweet orange. However, when water-deficit stress was applied later in fruit development (e.g., stage III) there was no increase in sugars or SSC. The evidence presented supports the hypothesis that differential sugar accumulation of citrus fruit from trees on rootstocks of contrasting vigor and, hence, plant water relations, is caused by differences in tree water status and the enhancement of sucrose hydrolysis into component hexose sugars resulting in osmotic adjustment. Therefore, inherent rootstock differences affecting plant water relations are proposed as a primary cause of differences in sugar accumulation and SSC among citrus rootstocks.
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Firth, D. J., G. G. Johns, and R. D. B. Whalley. "Glasshouse and field studies on the effects of groundcovers on banana and macadamia growth and water relations." Australian Journal of Experimental Agriculture 43, no. 10 (2003): 1245. http://dx.doi.org/10.1071/ea02002.
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Groundcovers can be useful for controlling erosion in macadamia orchards but they can have adverse effects on tree growth and crop yield. The effects of groundcovers versus bare soil on banana and macadamia were compared in a glasshouse study and on macadamia in the field. A glasshouse trial compared the effect of 3 water regimes with unmown or mown Arachis pintoi cv. Amarillo groundcover versus bare soil, on stomatal conductance and growth of banana and macadamia. Mean stomatal conductance was higher overall for macadamia (178 mmol/m2.s) compared with banana (90 mmol/m2.s) when data were pooled across groundcover and water treatments. Medium and dry substrate moisture treatments significantly reduced the growth and vigour of banana compared with the wet treatments, as indicated by reduced total dry matter, leaf area, number of live leaves at harvest, and total root length, but had no significant effect on macadamia. Groundcover had a more adverse effect on the growth of banana than macadamia compared with bare soil and, likewise, unmown cover had a greater effect on growth of banana than mown cover, while there was no mowing effect on macadamia.In an unirrigated field trial, mown and unmown groundcover and bare soil treatments were compared for their effect on early morning leaf xylem water potential of young and older macadamia trees at 3 sites where groundcover was established at different tree ages. Water potential was generally <0.2 MPa more negative in the groundcover treatment than bare soil in spring and summer under dry seasonal conditions over 2 years, although there was no apparent effect on tree health. The difference in water potential between groundcover and bare soil was highest in young trees planted in established groundcover. The more adverse effect of groundcover on water status of young trees in established cover correlates with a greater reduction in growth compared with older trees reported separately (Firth et al. 2003 Aust. J. Exp. Agric. 43, 419–423).Soil bulk density under groundcover was slightly reduced (0.028 g/cm3) at 0–10 cm depth, and penetrometer resistance also slightly reduced (<0.3 MPa) at 0–12 cm depth, compared with bare soil. Higher penetrometer readings in the traffic zone (often >4 MPa at 30–40 cm in the initial survey) compared with the tree line indicate the potential long-term benefits to be derived from groundcovers.
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Beeson, R. C. "Water Relations of Field-grown Quercus virginiana Mill. from Preharvest through Containerization and 1 Year into a Landscape." Journal of the American Society for Horticultural Science 119, no. 2 (1994): 169–74. http://dx.doi.org/10.21273/jashs.119.2.169.
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Large (≈5 m high) Quercus virginiana Mill. (live oak) trees produced in 0.64-m-diameter in-ground fabric containers were root pruned or not root pruned inside containers before harvest. Harvested trees were grown in two sizes of polyethylene containers for 10 months, then transplanted into a landscape. Water potential (ψT) of small branches (<4 mm in diameter) was measured diurnally during containerization and for 1 year in the landscape. Root pruning had no influence on postharvest survival. Neither root pruning nor container size affected tree water status during containerization or in the landscape. All surviving trees recovered from transplant shock following harvest after 16 weeks in a container, independent of treatment. In the landscape, 35 weeks of daily irrigation were required before dusk ψT declined to within 0.1 MPa of predawn values, a result indicating alleviation of transplant shock. Trunk growth rate during containerization was highest in larger containers. However, in the landscape, root pruning and small containers were associated with higher trunk growth rate. Tree water status during containerization and in the landscape is discussed.
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Olien, W. C., and A. N. Lakso. "Effect of rootstock on apple (Malus domestica) tree water relations." Physiologia Plantarum 67, no. 3 (1986): 421–30. http://dx.doi.org/10.1111/j.1399-3054.1986.tb05757.x.
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Zweifel, R., H. Item, and R. Hasler. "Link between diurnal stem radius changes and tree water relations." Tree Physiology 21, no. 12-13 (2001): 869–77. http://dx.doi.org/10.1093/treephys/21.12-13.869.
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Arend, Matthias, Roman M. Link, Rachel Patthey, Günter Hoch, Bernhard Schuldt, and Ansgar Kahmen. "Rapid hydraulic collapse as cause of drought-induced mortality in conifers." Proceedings of the National Academy of Sciences 118, no. 16 (2021): e2025251118. http://dx.doi.org/10.1073/pnas.2025251118.
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Understanding the vulnerability of trees to drought-induced mortality is key to predicting the fate of forests in a future climate with more frequent and intense droughts, although the underlying mechanisms are difficult to study in adult trees. Here, we explored the dynamic changes of water relations and limits of hydraulic function in dying adults of Norway spruce (Picea abies L.) during the progression of the record-breaking 2018 Central European drought. In trees on the trajectory to drought-induced mortality, we observed rapid, nonlinear declines of xylem pressure that commenced at the early onset of xylem cavitation and caused a complete loss of xylem hydraulic conductance within a very short time. We also observed severe depletions of nonstructural carbohydrates, though carbon starvation could be ruled out as the cause of the observed tree death, as both dying and surviving trees showed these metabolic limitations. Our observations provide striking field-based evidence for fast dehydration and hydraulic collapse as the cause of drought-induced mortality in adult Norway spruce. The nonlinear decline of tree water relations suggests that considering the temporal dynamics of dehydration is critical for predicting tree death. The collapse of the hydraulic system within a short time demonstrates that trees can rapidly be pushed out of the zone of hydraulic safety during the progression of a severe drought. In summary, our findings point toward a higher mortality risk for Norway spruce than previously assumed, which is in line with current reports of unprecedented levels of drought-induced mortality in this major European tree species.
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Gonzalez-Benecke, Carlos A., Timothy A. Martin, and Wendell P. Cropper,. "Whole-tree water relations of co-occurring mature Pinus palustris and Pinus elliottii var. elliottii." Canadian Journal of Forest Research 41, no. 3 (2011): 509–23. http://dx.doi.org/10.1139/x10-230.
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The natural range of longleaf pine ( Pinus palustris P. Mill.) and slash pine ( Pinus elliottii var. elliottii Engelm.) includes most of the southeastern US Coastal Plain, and there is now considerable interest in using these species for ecological forestry, restoration, and carbon sequestration. It is therefore surprising that little information is currently available concerning differences in their ecological water relations in natural stands. In this study, we compared water use, stomatal conductance at the crown scale (Gcrown), and whole-tree hydraulic conductance of mature pine trees growing in a naturally regenerated mixed stand on a flatwoods site in north-central Florida. We found remarkable similarities between longleaf and slash pine in stored water use, nocturnal transpiration, and whole-tree hydraulic conductance. Mean daily transpiration rate was higher for slash than for longleaf pine, averaging 39 and 26 L·tree–1, respectively. This difference was determined by variations in tree leaf area. Slash pine had 60% more leaf area per unit basal sapwood area than longleaf pine, but the larger plasticity of longleaf pine stomatal regulation partially compensated for leaf area differences: longleaf pine had higher Gcrown on days with high volumetric water content (θv) but this was reduced to similar or even lower values than for slash pine on days with low θv. There was no species difference in the sensitivity of Gcrown to increasing vapor pressure deficit.
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Kwakye, Samuel, and Davie M. Kadyampakeni. "Impact of Deficit Irrigation on Growth and Water Relations of HLB-Affected Citrus Trees under Greenhouse Conditions." Water 15, no. 11 (2023): 2085. http://dx.doi.org/10.3390/w15112085.
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Huanglongbing (HLB) is a citrus disease that affects the growth of the fibrous roots of citrus trees. This means that HLB-affected trees may have reduced root volume and may impact water uptake. A greenhouse study was conducted from October 2019 to July 2021 at the Citrus Research and Education Center (CREC) in Lake Alfred, FL, to evaluate the growth and development of HLB-affected citrus trees under a deficit irrigation system. The objective was to assess the impact of deficit irrigation on tree growth, water availability, stem water potential (SWP), sap flow, and root growth of HLB-affected “cv. Valencia” (Citrus sinensis (L.)) orange trees on ‘Kuharske citrange’ rootstock (Citrus sinensis (L.) × Poncirus trifoliata) using an evapotranspiration (ET)-based irrigation schedule. The study hypothesized that HLB-affected citrus trees require less irrigation water to complete their biological functions than healthy citrus trees because of severe fibrous root loss. A total of 20 potted trees were either HLB-positive or non-HLB-affected, and one-half of the trees were subjected to deficit irrigation (80% ET) and the other half to full irrigation (100% ET). There was no significant difference in tree height in both years between HLB-affected trees irrigated at 80% ET and 100% ET. In general, there was no difference in SWP between the HLB-affected trees subjected to deficit irrigation and full irrigation. At 80% and 100% ET, non-HLB trees had greater sap flow than HLB-affected trees. Sap flow for the periods of March–April and June–July 2021 was comparable between HLB-affected trees at all irrigation rates. Maximum sap flow occurred between 11 and 16 h for HLB-affected trees during the three measurement periods. HLB-affected trees had an average water use of 1.6 mm day−1 compared to 2.1 mm day−1 for non-HLB trees. Healthy trees (non-HLB) used about 20% more water than HLB-affected trees, equivalent to 0.5 mm day−1. Thus, irrigating at 80% ET may be appropriate for achieving water savings in controlled environments for HLB-affected trees without causing water stress. However, since these results were conducted under greenhouse conditions in pots, a follow-up study is needed to validate these results under on-farm field conditions.
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Boland, A. M., P. H. Jerie, P. D. Mitchell, I. Goodwin, and D. J. Connor. "Long-term Effects of Restricted Root Volume and Regulated Deficit Irrigation on Peach: II. Productivity and Water Use." Journal of the American Society for Horticultural Science 125, no. 1 (2000): 143–48. http://dx.doi.org/10.21273/jashs.125.1.143.
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Individual and interactive effects of restricted root volume (RRV) and regulated deficit irrigation (RDI) on productivity and water use of peach trees [Prunus persica (L.) Batsch `Golden Queen'] were studied over 3 years (1992-95). Trees were grown in lysimeters of five different soil volumes (0.025, 0.06, 0.15, 0.4, and 1.0 m3) with either full or deficit (RDI) irrigation. In Years 3 and 4, fruit size was reduced by up to 30% on trees in the two smallest volumes. Tree water use was positively related to increasing soil volume (linear, P < 0.001; quadratic, P < 0.011) in all years ranging from 1.8 to 4.4 L·mm-1 Epan in the post-RDI period of Year 2. Water use of deficit-irrigated trees was less than fully irrigated trees and there was an interaction between soil volume and irrigation treatment during RDI. Water relations did not limit growth or productivity. Tree water use was reduced under root restriction as a consequence of canopy demand rather than leaf function. Results suggest that a combination of restricted root volume and development of water stress achieve the RDI response in the Goulburn Valley, Australia.
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Preisler, Yakir, Teemu Hölttä, José M. Grünzweig, et al. "The importance of tree internal water storage under drought conditions." Tree Physiology 42, no. 4 (2021): 771–83. http://dx.doi.org/10.1093/treephys/tpab144.
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Abstract Global warming and drying trends, as well as the increase in frequency and intensity of droughts, may have unprecedented impacts on various forest ecosystems. We assessed the role of internal water storage (WS) in drought resistance of mature pine trees in the semi-arid Yatir Forest. Transpiration (T), soil moisture and sap flow (SF) were measured continuously, accompanied by periodical measurements of leaf and branch water potential (Ψleaf) and water content (WC). The data were used to parameterize a tree hydraulics model to examine the impact of WS capacitance on the tree water relations. The results of the continuous measurements showed a 5-h time lag between T and SF in the dry season, which peaked in the early morning and early afternoon, respectively. A good fit between model results and observations was only obtained when the empirically estimated WS capacitance was included in the model. Without WS during the dry season, Ψleaf would drop below a threshold known to cause hydraulic failure and cessation of gas exchange in the studied tree species. Our results indicate that tree WS capacitance is a key drought resistance trait that could enhance tree survival in a drying climate, contributing up to 45% of the total daily transpiration during the dry season.
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Vanhatalo, A., T. Chan, J. Aalto, et al. "Tree water relations trigger monoterpene emissions from Scots pine stem during spring recovery." Biogeosciences Discussions 12, no. 10 (2015): 7783–814. http://dx.doi.org/10.5194/bgd-12-7783-2015.
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Abstract. Tree canopies are known to emit large amounts of VOCs (volatile organic compounds) such as monoterpenes to the surrounding air. The main source for these is considered to be the green biomass, i.e. foliage, but emissions from the woody compartments have not been quantified. A VOC emission anomaly has been observed during transition from winter to summer activity. We analyzed if non-foliar components could partially explain the anomaly. We measured the VOC emissions from Scots pine (Pinus sylvestris L.) stems and shoots during the dehardening phase of trees in field conditions in two consecutive springs. We observed a large, transient monoterpene burst from stems, while the shoot monoterpene emissions and transpiration remained low. The burst lasted about 12 h. Simultaneously, an unusual night-time sap flow and an anomalous diurnal pattern of tree diameter were detected. Hence, we suggest that the monoterpene burst was a consequence of the recovery of the stem from winter-time. This indicates that the dominant processes and environmental drivers triggering the monoterpene emissions are different between stems and foliage.
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Kjelgren, R., and L. A. Rupp. "Shelters Improve Tree Establishment under Herbaceous Competition." HortScience 30, no. 4 (1995): 895A—895. http://dx.doi.org/10.21273/hortsci.30.4.895a.
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We investigated how shelters and competing herbaceous vegetation affected tree growth and water relations during establishment. A bunch-type forage grass was concurrently seeded around 1-year-old bigtooth maple (Acer grandidentatum) and gambel oak (Quercus gambelii) planted in a silt loam field soil. During the second year following planting, irrigation was withheld, and midday water potential was measured twice to determine differences in water stress. At the end of the season, we measured total survival, elongative growth, and leaf area, as well as root growth of trees without competition. In the presence of competing vegetation, trees in shelters were less water stressed by –1.0 MPa than those without shelters. All maples without shelters and with competition died, and oak survival was 28%. Survival of both species in shelters was 86%. All trees without competing vegetation survived, but shelters affected maples differently than oaks. Maples without shelters had multiple stems that resulted in less shoot elongation and coarse roots but higher leaf area than those in shelters, and there were no differences in midday water potential. By contrast leaf area, elongation, and root growth of oaks in shelters were not different from those without shelters, but water potential was less negative. Tree shelters mitigated the effects of competition during establishment, but overall growth in shelters varied with species as oaks did not grow as well as maples.
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Guittonny-Larchevêque, Marie, Bruno Bussière, and Carl Pednault. "Tree-Substrate Water Relations and Root Development in Tree Plantations Used for Mine Tailings Reclamation." Journal of Environmental Quality 45, no. 3 (2016): 1036–45. http://dx.doi.org/10.2134/jeq2015.09.0477.
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Blaikie, S. J., E. K. Chacko, P. Lu, and W. J. Müller. "Productivity and water relations of field-grown cashew: a comparison of sprinkler and drip irrigation." Australian Journal of Experimental Agriculture 41, no. 5 (2001): 663. http://dx.doi.org/10.1071/ea00158.
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Cashew is an emerging crop in the seasonally ‘wet–dry’ tropical regions of northern Australia. In North Queensland flowering and fruiting of cashew coincides with the dry season (May–November). During this period growers sprinkler irrigate at 500 L/tree.week. A 3-year (1996–98) experiment compared this strategy with alternatives, including no irrigation or drip irrigation in which 115 or 230 L/tree.week was applied by drippers placed near the tree trunk and near the canopy drip line throughout the dry season. Measurements of soil water to 1.3 m, leaf gas exchange, chlorophyll fluorescence, tree sap flow and yield were made. Data collected in the first 2 years showed that the water requirement of the trees increased progressively as the crop load and evaporative demand increased during the dry season. During the final year of the study, additional sprinkler and drip treatments, in which water applications were progressively increased during the dry season, were introduced. The productivity of cashew in this experiment was strongly influenced by irrigation treatments, ranging (over all years) from 42 to 160 g nut/m 2 canopy surface area. Depletion of plant-available water in the root zone was associated with a reduction in photosynthesis mediated by partial stomatal closure. These effects of soil drying were evident in all irrigated treatments during the mid and late stages of the dry season but were more severe in treatments receiving the least water. When irrigation was withheld until the mid-stage of the dry season the trees had similar yields to those that were irrigated throughout, emphasising the importance of providing adequate irrigation between nut set and harvest. When rainfall from January to September in each year of the study was taken into account, there was a strong linear relationship between nut yield and water applied (rainfall + irrigation), with each extra kilolitre of water applied resulting in about 6 extra g nut/m 2 canopy surface area. This linear relationship was based on water application in the range 25–50 kL per season. It is possible that if the seasonal water application had exceeded 50 kL the marginal response to extra water may have diminished. Using drippers was slightly more efficient than sprinklers, with drip-irrigated trees requiring about 5% less water applied to achieve a given nut yield. In years when rainfall is average, and subject to other economic factors, growers in North Queensland should aim to irrigate about 500 L/tree.week. In years of low rainfall between January and September it is likely that yield will be improved by applying more irrigation water; high rainfall during these months of the year may reduce the irrigation requirement. In all cases growers should be careful to accurately monitor water applications, particularly when the total (from rainfall &plus; irrigation) exceeds 40 kL/tree for the season.
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CARR, M. K. V. "THE WATER RELATIONS OF RUBBER (HEVEA BRASILIENSIS): A REVIEW." Experimental Agriculture 48, no. 2 (2011): 176–93. http://dx.doi.org/10.1017/s0014479711000901.
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SUMMARYThe results of research done on water relations of rubber are collated and summarised in an attempt to link fundamental studies on crop physiology to crop management practices. Background information is given on the centres of origin (Amazon Basin) and production of rubber (humid tropics; south-east Asia), but the crop is now being grown in drier regions. The effects of water stress on the development processes of the crop are summarised, followed by reviews of its water relations, water requirements and water productivity. The majority of the recent research published in the international literature has been conducted in south-east Asia. The rubber tree has a single straight trunk, the growth of which is restricted by ‘tapping’ for latex. Increase in stem height is discontinuous, a period of elongation being followed by a ‘rest’ period during which emergence of leaves takes place. Leaves are produced in tiers separated by lengths of bare stem. Trees older than three to four years shed senescent leaves (a process known as ‘wintering’). ‘Wintering’ is induced by dry, or less wet, weather; trees may remain (nearly) leafless for up to four weeks. The more pronounced the dry season the shorter the period of defoliation. Re-foliation begins before the rains start. The supply of latex is dependent on the pressure potential in the latex vessels, whereas the rate of flow is negatively correlated with the saturation deficit of the air. Radial growth of the stem declines in tapped trees relative to untapped trees within two weeks of the start of tapping. Roots can extend in depth to more than 4 m and laterally more than 9 m from the trunk. The majority of roots are found within 0.3 m of the soil surface. Root elongation is depressed during leaf growth, while root branching is enhanced. Stomata are only found on the lower surface of the leaf, at densities from 280 to 700 mm−2. The xylem vessels of rubber trees under drought stress are vulnerable to cavitation, particularly in the leaf petiole. By closing, the stomata play an essential role in limiting cavitation. Clones differ in their susceptibility to cavitation, which occurs at xylem water potentials in the range of −1.8 to −2.0 MPa. Clone RRII 105 is capable of maintaining higher leaf water potentials than other clones because of stomatal closure, supporting its reputation for drought tolerance. Clones differ in their photosynthetic rates. Light inhibition of photosynthesis can occur, particularly in young plants, when shade can be beneficial. Girth measurements have been used to identify drought-tolerant clones. Very little research on the water requirements of rubber has been reported, and it is difficult to judge the validity of the assumptions made in some of the methodologies described. The actual evapotranspiration rates reported are generally lower than might be expected for a tree crop growing in the tropics (<3 mm d−1). Virtually no research on the yield responses to water has been reported and, with the crop now being grown in drier regions, this is surprising. In these areas, irrigation can reduce the immaturity period from more than 10 years to six years. The important role that rubber plays in the livelihoods of smallholders, and in the integrated farming systems practised in south-east Asia, is summarized.
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Hamido, Said A., and Kelly T. Morgan. "The Effect of Irrigation Rate on the Water Relations of Young Citrus Trees in High-Density Planting." Sustainability 13, no. 4 (2021): 1759. http://dx.doi.org/10.3390/su13041759.
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The availability and proper irrigation scheduling of water are some of the most significant limitations on citrus production in Florida. The proper volume of citrus water demand is vital in evaluating sustainable irrigation approaches. The current study aims to determine the amount of irrigation required to grow citrus trees at higher planting densities without detrimental impacts on trees’ water relation parameters. The study was conducted between November 2017 and September 2020 on young sweet orange (Citrus sinensis) trees budded on the ‘US-897’ (Cleopatra mandarin x Flying Dragon trifoliate orange) citrus rootstock transplanted in sandy soil at the Southwest Florida Research and Education Center (SWFREC) demonstration grove, near Immokalee, Florida. The experiment contained six planting densities, including 447, 598, and 745 trees per ha replicated four times, and 512, 717, and 897 trees per ha replicated six times. Each density treatment was irrigated at 62% or 100% during the first 15 months between 2017 and 2019 or one of the four irrigation rates (26.5, 40.5, 53, or 81%) based on the calculated crop water supplied (ETc) during the last 17 months of 2019–2020. Tree water relations, including soil moisture, stem water potential, and water supplied, were collected periodically. In addition, soil salinity was determined. During the first year (2018), a higher irrigation rate (100% ETc) represented higher soil water contents; however, the soil water content for the lower irrigation rate (62% ETc) did not represent biological stress. One emitter per tree regardless of planting density supported stem water potential (Ψstem) values between −0.80 and −0.79 MPa for lower and full irrigation rates, respectively. However, when treatments were adjusted from April 2019 through September 2020, the results substantially changed. The higher irrigation rate (81% ETc) represented higher soil water contents during the remainder of the study, the lower irrigation rate (26.5% ETc) represents biological stress as a result of stem water potential (Ψstem) values between −1.05 and −0.91 MPa for lower and higher irrigation rates, respectively. Besides this, increasing the irrigation rate from 26.5% to 81%ETc decreased the soil salinity by 33%. Although increasing the planting density from 717 to 897 trees per hectare reduced the water supplied on average by 37% when one irrigation emitter was used to irrigate two trees instead of one, applying an 81% ETc irrigation rate in citrus is more efficient and could be managed in commercial groves.
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CARR, M. K. V., and C. M. MENZEL. "THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF LYCHEE (LITCHI CHINENSIS SONN.): A REVIEW." Experimental Agriculture 50, no. 4 (2013): 481–97. http://dx.doi.org/10.1017/s0014479713000653.
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SUMMARYThe results of research into the water relations and irrigation requirements of lychee are collated and reviewed. The stages of plant development are summarised, with an emphasis on factors influencing the flowering process. This is followed by reviews of plant water relations, water requirements, water productivity and, finally, irrigation systems. The lychee tree is native to the rainforests of southern China and northern Vietnam, and the main centres of production remain close to this area. In contrast, much of the research on the water relations of this crop has been conducted in South Africa, Australia and Israel where the tree is relatively new. Vegetative growth occurs in a series of flushes. Terminal inflorescences are borne on current shoot growth under cool (<15 °C), dry conditions. Trees generally do not produce fruit in the tropics at altitudes below 300 m. Poor and erratic flowering results in low and irregular fruit yields. Drought can enhance flowering in locations with dry winters. Roots can extract water from depths greater than 2 m. Diurnal trends in stomatal conductance closely match those of leaf water status. Both variables mirror changes in the saturation deficit of the air. Very little research on crop water requirements has been reported. Crop responses to irrigation are complex. In areas with low rainfall after harvest, a moderate water deficit before floral initiation can increase flowering and yield. In contrast, fruit set and yield can be reduced by a severe water deficit after flowering, and the risk of fruit splitting increased. Water productivity has not been quantified. Supplementary irrigation in South-east Asia is limited by topography and competition for water from the summer rice crop, but irrigation is practised in Israel, South Africa, Australia and some other places. Research is needed to determine the benefits of irrigation in different growing areas.
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Fernandes-Silva, Anabela A., António Esteves, Manuela Correia, and Francisco Lúcio Santos. "Partial Rootzone Drying Irrigation Modulates Transpiration of Olive Trees." Biology and Life Sciences Forum 4, no. 1 (2020): 78. http://dx.doi.org/10.3390/iecps2020-08844.
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Water scarcity and the increasing demand for irrigation in olive orchards lead to the adoption of deficit irrigation approaches to save water. A partial rootzone drying (PRD) irrigation technique has been proposed for woody crops as an agronomic practice to improve water productivity. This study was conducted to evaluate the effects of this irrigation strategy on water relations and transpiration of olive trees (cv. Cobrançosa) under climate conditions in the northeast of Portugal during the summer season of 2014. Two irrigation treatments were used: control (FI), irrigated with 100% of the estimated crop evapotranspiration (ET) and PRD50, irrigated with 50% of the control (FI) on one side and switching every two weeks. Whole tree transpiration (T) was quantified by sap flow, which was monitored within the trunks of both the control (FI) and deficit irrigated (PRD50) trees using the compensation heath-pulse technique. Foliage gas exchange and water potentials were determined throughout the experimental period. During the summer, daily transpiration reached roughly 27 and 43 L d−1 for PRD50 and FI olive trees, respectively, with a clear reduction of 37% in PRD50 olive trees. PRD50 showed statistically comparable values of water potentials to the control, which appeared to prevent an excessive drop in tree water status by modulating stomatal closure.
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O'Connell, Mark G., and Ian Goodwin. "Responses of 'Pink Lady ' apple to deficit irrigation and partial rootzone drying: physiology, growth, yield, and fruit quality." Australian Journal of Agricultural Research 58, no. 11 (2007): 1068. http://dx.doi.org/10.1071/ar07033.
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Partial rootzone drying (PRD) is a new irrigation strategy whereby water is withheld from part of the rootzone while another part is well watered. A successful PRD strategy should reduce tree water use through stomatal control of transpiration and reduce vegetative growth while maintaining fruit size and yield. A field experiment examined crop water relations and production performance of PRD in a commercial apple orchard on loam soil in the Goulburn Valley, Australia. The orchard consisted of high-density (1420 trees/ha) 8-year-old ‘Pink Lady’ apple trees trained as central leader and irrigated by microjets. The effects of PRD on leaf/stem water potential, vegetative growth, yield components and fruit quality were investigated during two seasons (2001–02, Year 1 and 2002–03, Year 2). The 2-year average growing season reference crop evapotranspiration and rainfall was 954 and 168 mm, respectively. Three irrigation treatments were established: (1) deficit irrigation (DI, supplied 50% of water to a fixed side of tree); (2) PRD supplied 50% of water to alternating sides of tree; (3) and conventional irrigation (CI, supplied 100% water to both sides of tree). Irrigation inputs under the CI treatment were 334 and 529 mm for Year 1 and Year 2, respectively. In Year 1, the volume of irrigation applied to CI treatment inputs equated to the replacement of predicted crop evapotranspiration (ETc) based on a mid-season FAO-56 crop coefficient with adjustment for tree size. Vegetative growth, fruit production and water status showed both PRD and DI treatments led to a classical ‘deficit irrigation’ water stress response. Leaf water potential, leaf conductance, fruit size, shoot growth and yield were reduced on PRD and DI trees compared to the fully watered (CI) trees. In Year 2, CI inputs exceeded estimated ETc by 2-fold. Consequently, minimal or no differences between irrigation regimes were measured in stem water potential, vegetative growth, yield components and fruit quality. Fruit disorders (sunburn, russet, misshape, markings, frost damage) were not affected by irrigation regime in either season. We contend that further effort is required to determine under what circumstances or environments there is a PRD response that saves water and maintains yield and quality for apple.
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Tyree, Melvin T., David A. Snyderman, Timothy R. Wilmot, and Jose-Luis Machado. "Water Relations and Hydraulic Architecture of a Tropical Tree (Schefflera morototoni)." Plant Physiology 96, no. 4 (1991): 1105–13. http://dx.doi.org/10.1104/pp.96.4.1105.
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OLADI, Reza, and Kambiz POURTAHMASI. "Intra-annual Secondary Growth Rate-Climate Relations of Fagus orientalis Lipsky in the Center of Hyrcanian Forests." Notulae Scientia Biologicae 4, no. 2 (2012): 136–40. http://dx.doi.org/10.15835/nsb427557.
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Weekly rate of Beech tree ring increment were related to the changes of climatic factors in weekly intervals. In order to do so, small samples were extracted from 5 Oriental beech trees located in Nowshahr educational forest in the central part of the Hyrcanian forests of Iran during 2008 growing season. Microscopic sections were prepared and average increases in tree ring width were measured, standardized and modeled using Gompertz equation. The results showed that the minimum air temperature and water evaporation had the strongest and positive effect on the secondary growth rate while the role of precipitation was minor and negative. Air temperature and evaporation variations during growing season were assumed to remain in their optimum level; increasing xylem formation by accelerating carbohydrate production and carbon uptake of trees, respectively. Since the studied site had warm and humid climate receiving sufficient amount of rainfall before and during growing season, water availability was not a limiting factor of radial growth and its minor negative relation was interpreted according to its small hampering effect on the air temperature and sunlight absorption of trees. It was concluded that meteorological factors affecting secondary growth rate of trees should be interpreted as a package rather than analyzed disconnectedly.
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Barton, Amy J., and Christopher S. Walsh. "Effect of Transplanting on Water Relations and Canopy Development in Acer." Journal of Environmental Horticulture 18, no. 4 (2000): 202–6. http://dx.doi.org/10.24266/0738-2898-18.4.202.
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Abstract Transplanting large-caliper trees frequently leads to poor tree growth and survival. A longitudinal study of the changes in water relations and canopy development was conducted to study this effect. Pruning and watering were used to test the recovery of maple trees following transplanting. Water potential (ψ), transpiration rate (tr), and leaf area index (LAI) were the measured dependent variables. In the summer after transplanting, date and treatment significantly affected LAI, tr and mid-day ψ in Acer truncatum. In this species, trees receiving a post-transplant pruning treatment in combination with watering did not significantly differ in tr and mid-day ψ from nontransplanted controls, although LAI did differ between these treatments. In both A. truncatum and A. tataricum ginnala, treatment and day interacted significantly on pre-dawn ψ. While the seasonal patterns differed between species, the most negative pre-dawn ψ measurements were made four months after transplanting. In the spring following transplanting, significant differences due to prior-year treatment were again measurable in mid-day ψ in leaves of A.tataricum ginnala. In that species, mid-day ψ of the transplanted control trees differed from non-transplanted controls. Transplanting led to a measurable, long-term water stress. Pruning and watering in combination partially relieved that stress. Leaf area index was markedly affected by transplanting. It is suggested that this readily-measurable variable could be useful in assessing recovery from transplant stress.