Water Relations of Root-Pruned Jarrah (Eucalyptus marginata Donn ex Smith) Saplings

1987 ◽  
Vol 35 (6) ◽  
pp. 653 ◽  
Author(s):  
DS Crombie ◽  
JT Tippett ◽  
DJ Gorddard
Keyword(s):  
Water Relations ◽  
Phytophthora Cinnamomi ◽  
Leaf Water ◽  
Lateritic Soil ◽  
Root Pruning ◽  
Deep Roots ◽  
Eucalyptus Marginata ◽  
Water Potentials ◽  
Severe Water Stress ◽  
Leaf Shedding

Roots were pruned from jarrah (Eucalyptus marginata Donn ex Smith) saplings to simulate the effects of root loss induced by Phytophthora cinnamomi Rands. Stomatal conductance was more sensitive to root loss than was leaf water potential. Stomatal conductances of trees on moist soils declined when more than 50% of roots were removed but were more variable and were affected more severely by root pruning when soils were dry. Predawn leaf water potentials were unaffected by removal of up to 80% of roots irrespective of whether surface soils were dry or moist. The effects of root pruning on midday water potentials were variable especially when soils were dry. Leaf shedding and efficient stornatal closure prevented severe water stress developing in leaves until nearly 90% of the roots had been removed. It is suggested that destruction of the deep 'sinker' roots by P. cinnamomi has greater effects on jarrah's water relations during summer than does loss of shallow roots. The deep roots are especially important as jarrah grows on highly developed lateritic soil profiles.

Infection by Phytophthora cinnamomi Rands of Roots of Eucalyptus calophylla R.Br. and Eucalyptus marginata Donn. ex Sm

1977 ◽  
Vol 25 (5) ◽  
pp. 483 ◽  
Author(s):  
N Malajczuk ◽  
AJ Mccomb ◽  
CA Parker
Keyword(s):  
Phytophthora Cinnamomi ◽  
Light And Electron Microscopy ◽  
Inhibitory Effect ◽  
Lateritic Soil ◽  
Root Damage ◽  
Mature Trees ◽  
Cortical Cells ◽  
Eucalyptus Marginata ◽  
Seedling Roots ◽  
Loam Soil

On lateritic podzolic soils in Western Australia Eucalyptus calophylla is resistant to Phytophthora cinnamomi whereas Eucalyptus marginata is susceptible and eventually killed by the pathogen. On loam soils both eucalypts are resistant. Possible mechanisms for resistance of E. calophylla in lateritic soil and the inhibitory action of loam soils were investigated. Aseptically raised eucalypt seedlings succumbed to infection in liquid culture tubes. The mechanism of infection was compared by light and electron microscopy which showed similar fungal invasion and penetration into roots of both eucalypt species. Vegetative hyphae initially penetrated intercellularly and proliferated rapidly within cortical and stelar tissue. Intracellular invasion of these tissues occurred 48hr after initial infection through dissolution of the host cell wall. Chlamydospores were formed within a number of cortical cells. Unsuberized roots of mature trees produced aseptically showed reactions to invasion similar to those of the eucalypt seedling roots. Suberized roots were not invaded. The addition of small quantities of lateritic soil to sterile sand so as to introduce soil micro-organisms without altering the chemical and physical status of the sand, and subsequent inoculation of the sand with P.cinnamomi, resulted in a reduction of root damage on both eucalypts when compared with seedlings raised in sterile sand. Roots of E.calophylla were less severely damaged than those of E.marginata. The addition of small quantities of loam soil significantly reduced root damage in seedlings of both species. These results parallel both pot experiments and field observations, and suggest that microorganisms of the rhizosphere may be an important factor in the resistance of E.calophylla to infection, and in the inhibitory effect of loam soil on P.cinnamomi.

Water relations characteristics of Alnusrubra and Populustrichocarpa: responses to field drought

1988 ◽  
Vol 18 (9) ◽  
pp. 1159-1166 ◽  
Author(s):  
S. R. Pezeshki ◽  
T. M. Hinckley
Keyword(s):  
Water Relations ◽  
Root Development ◽  
Osmotic Potential ◽  
Stomatal Closure ◽  
Leaf Age ◽  
Leaf Water ◽  
Black Cottonwood ◽  
Red Alder ◽  
Mature Leaves ◽  
Water Potentials

Water relations of red alder (AlnusrubraBong.) and black cottonwood (populustrichocarpa Torr. & Gray) were studied in the field during the 1980, 1981, and 1982 growing seasons. Stomatal closure in response to drought was noted in both species; however, the following major differences were noted between the 1980 observations and those of 1981 and 1982; (i) stomatal conductance was greater in black cottonwood than in red alder, whereas the reverse was noted in 1980, and (ii) even though 1981 and 1982 were warmer and drier than 1980, corresponding changes in predawn and minimum leaf water potentials were not observed. These differences were attributed to greater root development, particularly in black cottonwood, in the second (1981) and third (1982) years following establishment (1980) of these species. Leaf age and drought exposure were observed to influence osmotic potentials in both species. Values of the osmotic potential at saturation varied from −0.80 to −1.03 MPa in newly mature leaves of red alder and from −1.00 to −1.26 MPa in similarly aged leaves of black cottonwood. Values in mature leaves ranged from −0.84 to −1.27 MPa in red alder and from −1.37 to −1.75 MPa in black cottonwood. There appeared to be a continued decrease in osmotic potential in both species throughout the growing season, a response associated with leaf development and drought exposure. Throughout the study, significantly lower values of osmotic potential at saturation and at the turgor loss point were found in black cottonwood than in red alder. Consequently, black cottonwood had a potential adaptive advantage in comparison with red alder. Leaf shedding in response to drought was noted mainly in red alder. Generally, both of these riparian species exhibited slight to moderate capabilities of surviving exposure to low leaf water potentials and moderate to excellent capabilities of stomatal closure under conditions potentially leading to low water potentials. The role played by root development in the differences observed among the years and between black cottonwood and red alder is discussed.

Water Relations of Rural Eucalypt Dieback.

1988 ◽  
Vol 36 (2) ◽  
pp. 233 ◽  
Author(s):  
DS Crombie ◽  
JA Milburn
Keyword(s):  
Disease Severity ◽  
Water Relations ◽  
New South ◽  
New South Wales ◽  
Leaf Water ◽  
Eucalyptus Species ◽  
Water Potentials ◽  
South Wales ◽  
Individual Trees

The water relations of healthy and dieback-affected individuals of three Eucalyptus species typical of the northern tablelands of New South Wales were compared. Dawn water potentials of healthy and dieback-affected trees were all very similar. Midday water potentials of trees with the most severe dieback symptoms were often lower than those of nearby healthy trees by up to 0.6 MPa. Leaf con- ductances of the most severely dieback-affected trees were usually greater than those of healthy trees. Differences decreased with time and when more trees with less severe symptoms were measured late in the study no significant differences in water relations were found. It seems therefore that the effects of dieback on the water relations of trees are too small for measurements of leaf water potentials or leaf conductances to be useful indicators of disease severity in individual trees.

Effects of preconditioning on subsequent water relations, stomatal sensitivity, and photosynthesis in osmotically stressed black spruce

1989 ◽  
Vol 67 (8) ◽  
pp. 2240-2244 ◽  
Author(s):  
Janusz J. Zwiazek ◽  
Terence J. Blake
Keyword(s):  
Water Stress ◽  
Water Relations ◽  
Black Spruce ◽  
Water Potentials ◽  
Conditioning Treatment ◽  
Severe Water Stress ◽  
Use Efficiency ◽  
Stomatal Sensitivity ◽  
Stress Conditioning ◽  
Osmotic Potentials

The effects of stress conditioning with polyethylene glycol on water relations and photosynthesis in preconditioned ramets were compared with those of unconditioned black spruce (Picea mariana Mill. BSP). Preconditioned plants maintained lower osmotic and water potentials and higher turgor potentials (measured as a difference between osmotic and water potentials), but photosynthetic rates were similar in both groups of plants. The conditioning treatment increased stomatal sensitivity to water stress, and stomatal conductance was lower in preconditioned plants soon after water stress was imposed. Preconditioned plants maintained significantly lower osmotic potentials during a severe water stress and were able to maintain turgor at the time when unconditioned plants wilted. Water-use efficiency was not affected by stress-conditioning treatment.

scholarly journals Comparison of Branch Water Relations in Two Riparian Species: Populus euphratica and Tamarix ramosissima

2019 ◽  
Vol 11 (19) ◽  
pp. 5461
Author(s):  
Duan Li ◽  
Jianhua Si ◽  
Xiaoyou Zhang ◽  
Yayu Gao ◽  
Huan Luo ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Water Supply ◽  
Water Relations ◽  
Water Status ◽  
Populus Euphratica ◽  
Hydraulic Conductance ◽  
Leaf Water ◽  
Tamarix Ramosissima ◽  
Water Potentials ◽  
Branch Dieback

Water relations in plants maintain healthy tree branches and drought conditions during plant growth may affect water relations, but the mechanisms are poorly known. In our study, we determined the stomatal conductance, hydraulic conductance, water potential and ion concentration of xylem sap to increase the understanding of changes in water relations in branches of Populus euphratica (P. euphratica) and Tamarix ramosissima (T. ramosissima), which are the dominant plant species in the lower reaches of the Heihe River Basin in China. The results showed that both species responded to vapor pressure deficit (VPD) during the growing season by adjusting stomatal conductance to achieve homeostasis in leaf water potentials. The leaf-specific hydraulic conductance (LSC) of the branch was determined using water status in the branch, and the LSC of the leaf was determined using water status in the leaf. Because of homeostasis in leaf water potentials, hydraulic conductance in leaves remained stable. As a result, branch dieback, which might be induced by deficits in water supply, could rarely be seen in T. ramosissima owing to the homeostasis in branch and leaf water status. The ion sensitivity of xylem hydraulic conductance in P. euphratica induced an increase in hydraulic conductance caused by the deficits in the water supply which might lead to branch dieback. The evaluation of water relations provides a further understanding of the internal mechanisms of drought acclimation for riparian plants.

Leaf water potentials of pasture plants in a semi-arid subtropical environment

1975 ◽  
Vol 15 (76) ◽  
pp. 645 ◽  
Author(s):  
DCI Peake ◽  
GD Stirk ◽  
EF Henzell
Keyword(s):  
Water Stress ◽  
Leaf Water ◽  
Panicum Maximum ◽  
Research Station ◽  
Buffel Grass ◽  
Heteropogon Contortus ◽  
Drought Avoidance ◽  
Water Potentials ◽  
Severe Water Stress ◽  
Pasture Plants

Leaf water potentials (�1) were measured on pasture plants at the Narayen Research Station in southern Queensland. The main findings were: 1. There were marked differences between species in the value of �1, measured during drought. Lucerne (Medicago sativa cv. Hunter River) and buffel grass (Cenchrus ciliaris cv. Biloela) usually showed a lower (i.e. more negative) �1 than Siratro (Macroptilium atropurpureum cv. Siratro), when they were grown together in a mixed pasture. Siratro seemed to possess a useful degree of drought avoidance. High drought resistance was observed in buffel grass; this was attributed to its tolerance of water stress. Green panic (Panicum maximum var. trichoglume cv. Petrie) was found to have as low a �1 as lucerne during drought when the two species were grown with Siratro in a mixed pasture. 2. The plants were under severe water stress before all the available water was removed from the deeper soil horizons. 3. �1 was lower in nitrogen-fertilized buffel grass or spear grass (Heteropogon contortus), than in the corresponding unfertilized controls. 4. The vapour-exchange and dye-marker densiometric methods gave different values for �1 in buffel grass, green panic and Siratro; the vapour exchange technique recorded lower, i.e, more negative figures than the other method when the plants were under severe water stress. The two methods gave similar values for lucerne. The relation between the values obtained for buffel grass by the two methods was affected by nitrogen fertilization. The reaction of sown pasture plants to drought at Narayen is discussed.

scholarly journals THE EFFECTS OF VARIOUS HOST PLANTS ON GROWTH, WATER RELATIONS, AND CARBON BALANCE OF THE HEMIPARASITE CASTILLEJA INDIVISA

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 631e-631
Author(s):  
Michael R. Sweatt ◽  
Jayne M. Zajicek
Keyword(s):  
Soil Moisture ◽  
Water Relations ◽  
Carbon Balance ◽  
Host Plants ◽  
Leaf Water ◽  
Carbon Exchange ◽  
Water Potentials ◽  
Carbon Transfer ◽  
Nutritional Factor

Castilleja indivisa grows hemiparasitically attached to the roots of various nearby plants. Studies were done using several host plants to determine the effects of the parasitic relationship on the growth of C. indivisa and the host plants. Transpiration rates, and leaf water potentials of C. indivisa, and various hosts, were also measured at various soil moisture levels. Carbon transfer between C. indivisa and each host was examined using a 14CO2 tracing technique. The various hosts used in this experiment enhanced the growth of C. indivisa by 200-700% compared to non-parasitic controls. Transpiration rates of non-parasitic controls remained relatively low at all soil moisture levels while transpiration rates of parasitic C. indivisa increased rapidly as soil moisture increased, and generally exceeded that of its host at low to medium soil moisture levels. Leaf water potentials of non-parasitic controls were generally more negative than other treatments. Carbon exchange between C. indivisa and its hosts was insignificant and appears not to be a major nutritional factor.

The Microflora of Unsuberized Roots of Eucalyptus calophylla R.Br. And Eucalyptus marginata Donn ex Sm. Seedlings Grown in Soil Suppressive and Conducive to Phytophthora cinnamomi Rands. I. Rhizosphere Bacteria, Actinomycetes and Fungi

1979 ◽  
Vol 27 (3) ◽  
pp. 235 ◽  
Author(s):  
N Malajczuk ◽  
AJ Mccomb
Keyword(s):  
Unit Area ◽  
Phytophthora Cinnamomi ◽  
Natural Infection ◽  
Differential Susceptibility ◽  
Root Surface ◽  
Lateritic Soil ◽  
Eucalyptus Marginata ◽  
Rhizosphere Microflora ◽  
Rhizosphere Population ◽  
Loam Soil

An investigation was made of the microflora associated with unsuberized roots of Eucalyptus marginata and Eucalyptus calophylla raised in different soils. The studies were made for 'conducive' lateritic soil (in which E. marginata is susceptible to infection by Phytophthora cinnamomi but E. Calophylla is resistant); and in 'suppressive' loam soil in which both eucalypt species are unaffected by the pathogen. Lateritic soil in some cases contained natural infection of P. cinnamomi. Rhizospheres of both species contained larger microflora populations (expressed as numbers per g of root) than in the soils. In general, the population of rhizosphere microflora was greater for E. Marginata than E. calophylla seedlings in the uninfected lateritic soil. Qualitative differences were also recorded in populations of bacteria, actinomycetes and fungi, and in particular, fluorescent pseudomonads were more numerous in the rhizosphere of E. marginata seedlings. Eucalypt seedlings raised in loam soil harboured greater microbial populations than in lateritic soil. This could in part be attributed to the higher nutrient and organic matter status of the loam. E. marginata had a greater total rhizosphere population, but actinomycetes were more numerous in the rhizosphere of E. calophylla. Qualitative differences in populations of bacteria, actinomycetes and fungi were also noted. In naturally infected lateritic soil the microflora populations were invariably lower than for the other soils. When the counts of bacteria and actinomycetes were expressed as numbers per mm2 of root surface, E. calophylla had a significantly higher number of propagules per unit area than E. marginata. The loam soil was an exception; there E. marginata had three times as many bacteria per unit area of the root surface as E. calophylla. It is suggested that the microflora population differences recorded for the two eucalypts in lateritic soil may contribute to the differential susceptibility of species to infection by P. cinnamomi; and that the higher populations of microflora in the loam soil contribute to the suppression of P. Cinnamomi in that soil.

Effect of root pruning and irrigation regimes on leaf water relations and xylem ABA and ionic concentrations in pear trees

2014 ◽  
Vol 135 ◽  
pp. 84-89 ◽  
Author(s):  
Yufei Wang ◽  
Marianne G. Bertelsen ◽  
Karen K. Petersen ◽  
Mathias N. Andersen ◽  
Fulai Liu
Keyword(s):  
Water Relations ◽  
Leaf Water ◽  
Root Pruning ◽  
Leaf Water Relations ◽  
Ionic Concentrations ◽  
Irrigation Regimes ◽  
Pear Trees

scholarly journals POST-TRANSPLANT WATER RELATIONS AND GROWTH RESPONSES OF `RED SUNSET' RED MAPLE TREES TO ROOT PRUNING AND Cu (OH)2-TREATED CONTAINER PRODUCTION

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 569d-569
Author(s):  
Michael A. Arnold. ◽  
G. Kim Stearman ◽  
Reed W. Cripps
Keyword(s):  
Soil Water ◽  
Water Relations ◽  
Root Pruning ◽  
Red Maple ◽  
Growth Responses ◽  
Field Plot ◽  
Latex Paint ◽  
Rooted Cuttings ◽  
Post Transplant ◽  
Water Potentials

Rooted cuttings of Acer rubrum `Red Sunset' grown in containers treated on interior surfaces with 100 g Cu(OH)2/liter white interior latex paint, or left untreated, were root pruned or not root pruned and planted in a field plot. A pseudo-bareroot treatment, trees from untreated containers shaken free of media, was included. Height (115 vs. 108 cm) and caliper (12.0 vs. 10.7 mm) at transplant was slightly greater for copper treated trees than for untreated trees. Leaf water potentials (LWP) at transplant were similar for all treatments. Mid-day LWP of trees transplanted from untreated containers tended to be lower than that of trees grown in copper treated containers at days 3, 14, 28, and 53 after transplant. Pseudo-bareroot trees had the most negative mid-day and pre-dawn LWP through day 92. Soil water potentials were from -0.01 to -0.03MPa.

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