scholarly journals Growth, Gas Exchange, Water Uptake, and Drought Response of Seedling- and Cutting-propagated Peach and Citrus Rootstocks

1992 ◽  
Vol 117 (5) ◽  
pp. 834-840 ◽  
Author(s):  
Mark Rieger
Keyword(s):  
Hydraulic Conductivity ◽  
Gas Exchange ◽  
Prunus Persica ◽  
Poncirus Trifoliata ◽  
Drought Response ◽  
Sour Orange ◽  
Short Term ◽  
Root Hydraulic Conductivity ◽  
Fibrous Roots

Growth, gas exchange, root hydraulic conductivity, and drought response of seedling and rooted cuttings of Lovell and Nemaguard peach [Prunus persica (L.) Batsch], and Carrizo (Poncirus trifoliata × Citrus sinensis) and sour orange (C. aurantium L.) citrus rootstocks were compared to determine the influence of propagation method on these characteristics. Rooted peach cuttings had a higher proportion of root biomass in fibrous roots (≤ mm in diameter) and lower root: shoot ratios than seedlings, although this did not occur in citrus. Net CO2 assimilation (A) was higher for peach seedlings than for cuttings, but similar for `Redhaven' (RH) scions on either seedling- or cutting-propagated rootstocks, suggesting that leaf-associated factors were responsible for differences. As in peach, A was higher for Carrizo seedlings than for cuttings, but A was not affected by propagation method in sour orange. Peach seedlings maintained higher A than cuttings as water potentials declined during short-term soil drying, although in citrus this occurred only for Carrizo. RH scions on either root type exhibited similar declines in A as soil dried, indicating the lack of a rootstock effect. Root hydraulic conductivity (Lp) was similar between seedlings and cuttings of all cultivars when expressed on a length basis. Leaf conductance and osmotic adjustment were similar for RH scions on seedling- or cutting-propogated rootstocks during 45 days of drought stress, indicating the lack of a rootstock effect on long-term stress response.

scholarly journals 082 OFFSETTING EFFECTS OF REDUCED ROOT HYDRAULIC CONDUCTIVITY AND OSMOTIC ADJUSTMENTIN DROUGHT-STRESSED PEACH, OLIVE, CITRUS, AND PISTACHIO

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 439g-440
Author(s):  
M. Rieger
Keyword(s):  
Hydraulic Conductivity ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Prunus Persica ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Poncirus Trifoliata ◽  
Potential Range ◽  
Root Hydraulic Conductivity ◽  
Turgor Maintenance

Root hydraulic conductivity (Lp) and osmotic potential (π) were measured in young, drought-stressed and non-stressed peach (Prunus persica), Olive (Olea europea), Citrumelo (Citrus paradisi x Poncirus trifoliata) and Pistachio (Pistachia integerrima) plants. Drought stress reduced Lp 2.5 to 4.2-fold, depending on species, but π was reduced only in expanded citrumelo leaves and unexpanded olive leaves by 0.34 and 1.4 MPa, respectively. A simulation model of plant water uptake and leaf water relations was constructed to quantify the offsetting effects of reduced Lp and osmotic adjustment (OA) on turgor maintenance. For olive data, a 2.5-fold reduction of Lp caused a linear decrease in turgor pressure difference between stressed and non-stressed plants, such that the effect of OA was totally offset at a leaf water potential (stressed) of ≈ -3.0 MPa. For citrumelo, because the degree of OA was lower, the water potential at which the effects of OA and reduced Lp were offsetting with respect to turgor maintenance was ≈ -0.6 MPa. The analysis suggests that some level of stomatal closure would be necessary to extend the water potential range over which stressed plants maintain higher turgor than non-stressed plants for citrumelo. Conversely, no degree of stomatal closure would be required of stressed olive plants to maintain higher turgor than non-stressed counterparts over a physiologically meaningful range of leaf water potential.

scholarly journals Estimation of Root Hydraulic Conductivity on Intact Peach and Citrus Rootstock

HortScience ◽  
1990 ◽  
Vol 25 (12) ◽  
pp. 1631-1634 ◽  
Author(s):  
Mark Rieger ◽  
Antonio Motisi
Keyword(s):  
Hydraulic Conductivity ◽  
Prunus Persica ◽  
Sour Orange ◽  
Xylem Water Potential ◽  
Root Hydraulic Conductivity ◽  
Lp Estimates ◽  
Ohm’S Law ◽  
Citrus Rootstock ◽  
Ohm's Law ◽  
Approach Zero

Estimates of root hydraulic conductivity (Lp) were obtained on intact peach (Prunus persica × P. davidiana `Nemaguard') and sour orange (Citrus aurantium L.) rootstock over a broad range of transpiration rates. Within a species, Lp was lower when estimated using the Ohm's law analog than the reciprocal of the slope of the linear regression between transpiration (E) and stem xylem water potential (Ψ). Nonzero y-intercepts in linear regressions of Ψ vs. E resulted in the lack of agreement between Lp estimates. Removal of the root system caused xylem Ψ to rapidly approach zero in both species when E ≈ 0, suggesting that factors responsible for nonzero y intercepts resided within roots. Lp was 2.2 and 3.5 times lower for sour orange than peach when calculated by the Ohm's law and regression methods, respectively.

Response to oxygen deficiency in primary maize roots. II. Development of oxygen deficiency in the stele has limited short-term impact on radial hydraulic conductivity

1998 ◽  
Vol 25 (6) ◽  
pp. 759 ◽  
Author(s):  
J. Gibbs ◽  
D. W. Turner ◽  
W. Armstrong ◽  
K. Sivasithamparam ◽  
H. Greenway
Keyword(s):  
Hydraulic Conductivity ◽  
Driving Forces ◽  
Oxygen Deficiency ◽  
Pressure Probe ◽  
Similar Response ◽  
Short Term ◽  
Root Hydraulic Conductivity ◽  
Maize Roots ◽  
Dissolved O2

The short-term impact of oxygen deficiency on root hydraulic conductivity (Lpr), was evaluated in excised maize roots using hydrostatic and osmotic driving forces, after exposing the roots to a flowing medium containing 0.05 mol m-3 dissolved O2. Hypoxia reduced hydrostatically-determined Lpr of roots in a pressure probe, but this reduction was transient, usually recovering to values for aerated roots after 4–6 h of exposure to 0.05 mol m-3 O2. The Lpr of exuding maize roots, calculated using the rate of exudation and osmotic pressure of exuding sap, was depressed after 24 h exposure to 0.05 mol m-3 dissolved O2, but only marginally so. The data suggested that a reduction in Lpr is not a principal effect of exposure of these roots to hypoxia, and that long term changes in water fluxes in O2 deficient roots, reported in the literature, may be an indirect, rather than direct effect of O2 deficiency on roots. Despite a similar response to O2 deficiency, Lpr calculated for exuding roots was 1/30th of that for roots attached to the pressure probe. The reduction in hydrostatically determined Lpr in response to O2 deficiency, although transient, suggests that under a hydrostatic driving force, there is a substantial flow of water via the protoplastic pathway, in addition to the generally accepted apoplastic component.

scholarly journals Histological Comparison of Fibrous Root Infection of Disease-Tolerant and Susceptible Citrus Hosts by Phytophthora nicotianae and P. palmivora

1998 ◽  
Vol 88 (5) ◽  
pp. 389-395 ◽  
Author(s):  
T. L. Widmer ◽  
J. H. Graham ◽  
D. J. Mitchell
Keyword(s):  
Light And Electron Microscopy ◽  
Cellular Responses ◽  
Poncirus Trifoliata ◽  
Phytophthora Nicotianae ◽  
Sour Orange ◽  
Trifoliate Orange ◽  
Fibrous Root ◽  
Cortical Cells ◽  
Phytophthora Spp ◽  
Fibrous Roots

Phytophthora nicotianae and P. palmivora infect and cause rot of fibrous roots of susceptible and tolerant citrus rootstocks in Florida orchards. The infection and colonization by the two Phytophthora spp. of a susceptible citrus host, sour orange (Citrus aurantium), and a tolerant host, trifoliate orange (Poncirus trifoliata), were compared using light and electron microscopy. Penetration by both Phytophthora spp. occurred within 1 h after inoculation, regardless of the host species. No differences were observed in mode of penetration of the hypodermis or the hosts' response to infection. After 24 h, P. palmivora had a significantly higher colonization of cortical cells in susceptible sour orange than in tolerant trifoliate orange. Intracellular hyphae of both Phytophthora spp. were observed in the cortex of sour orange, and cortical cells adjacent to intercellular hyphae of P. palmivora were disrupted. In contrast, the cortical cells of sour orange and trifoliate orange adjacent to P. nicotianae hyphae and the cortical cells of trifoliate orange adjacent to P. palmivora were still intact. After 48 h, the cortical cells of both hosts adjacent to either Phytophthora spp. were disrupted. After 48 and 72 h, P. palmivora hyphae colonized the cortex of sour orange more extensively than the cortex of trifoliate orange; P. palmivora also colonized both hosts more extensively than P. nicotianae. A higher rate of electrolyte leakage among host-pathogen combinations reflected the combined effects of greater cell disruption by P. palmivora than by P. nicotianae, and the higher concentration of electrolytes in healthy roots of trifoliate orange than of sour orange. Although cellular responses unique to the tolerant host were not observed, reduced hyphal colonization by both pathogens in the cortex of trifoliate orange compared with sour orange is evidence for a putative resistance factor(s) in the trifoliate orange roots that inhibits the growth of Phytophthora spp.

scholarly journals Limitations on Growth and Net Gas Exchange of Diploid and Tetraploid Citrus Rootstock Cultivars Grown at Elevated CO2

2000 ◽  
Vol 125 (2) ◽  
pp. 228-234 ◽  
Author(s):  
J.P. Syvertsen ◽  
L.S. Lee ◽  
J.W Grosser
Keyword(s):  
Gas Exchange ◽  
Plant Growth ◽  
Leaf Area ◽  
Dry Weight ◽  
Poncirus Trifoliata ◽  
Plant Transpiration ◽  
Whole Plant ◽  
Volkamer Lemon ◽  
Citrus Rootstock ◽  
Fibrous Roots

Diploid (2x) and autotetraploid (4x) Citrus L. rootstock cultivars were grown at elevated CO2 to obtain insights into limitations on growth and net gas exchange that have been associated with tetraploidy. Well-nourished 2x and 4x seedlings of `Volkamer' lemon (Volk, C. volkameriana Ten & Pasq.), `Troyer' citrange [Troy, C. sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf.] and `Cleopatra' mandarin (Cleo, C. reticulata Blanco.), were grown in greenhouses at either ambient or twice ambient CO2 for 4 months. Plant growth, water relations, mineral nutrition, and net gas exchange characteristics of leaves were measured. Most 4x plants were smaller and had lower rates of whole plant transpiration but shorter fibrous roots than 2x plants. Fibrous roots of 4x were thicker than 2x roots as indicated by a lower specific root length (SRL) in 4x than in 2x roots. Root hydraulic conductivity was correlated to total plant growth but there were no effects of CO2 or ploidy on root conductivity. Tetraploid leaves had lower N concentrations than 2x leaves when expressed on a dry weight basis but these differences disappeared when N concentration was expressed on an leaf area basis because 4x leaves had more leaf dry weight per area (LDW/a) than 2x leaves. Plant growth was greater and SRL was lower at elevated CO2 than at ambient CO2. LDW concentrations of N, P, and K were lower at elevated CO2 than at ambient apparently due to a growth dilution effect. LDW/a, net CO2 assimilation (ACO2), and leaf water use efficiency were greater at elevated CO2 than at ambient. Overall, there was no effect of ploidy on ACO2 but 4x Volk and Troy had lower rates of ACO2 than their 2x at elevated CO2. Net gas exchange of tetraploid leaves was less responsive to elevated CO2 than 2x leaves. The low SRL of tetraploids was correlated with low whole plant transpiration rates and low leaf area-based N concentrations, which may be operative in determining the growth characteristics associated with tetraploidy.

scholarly journals Ozone Amplifies Water Loss from Mature Trees in the Short Term But Decreases It in the Long Term

Forests ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 46
Author(s):  
Elena Paoletti ◽  
Nancy E. Grulke ◽  
Rainer Matyssek
Keyword(s):  
Steady State ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Loss ◽  
Vapour Pressure Deficit ◽  
Environmental Parameters ◽  
Mechanistic Explanation ◽  
Short Term ◽  
Mature Trees

We measured whole-tree transpiration of mature Fagus sylvatica and Picea abies trees exposed to ambient and twice-ambient O3 regimes (1xO3 and 2xO3 free-air fumigation). After eight years, mean daily total transpiration did not vary with the O3 regime over the 31 days of our study, even though individual daily values increased with increasing daily O3 peaks in both species. Although the environmental parameters were similar at 1xO3 and 2xO3, the main factors affecting daily transpiration were vapour pressure deficit in 2xO3 spruce and O3 peaks in beech. For a mechanistic explanation, we measured O3-induced sluggish stomatal responses to variable light (sunflecks) by means of leaf-level gas exchange measurements only in the species where O3 was a significant factor for transpiration, i.e., beech. Stomata were always slower in closing than in opening. The 2xO3 stomata were slower in opening and mostly in closing than 1xO3 stomata, so that O3 uptake and water loss were amplified before a steady state was reached. Such delay in the stomatal reaction suggests caution when assessing stomatal conductance under O3 pollution, because recording gas exchange at the time photosynthesis reached an equilibrium resulted in a significant overestimation of stomatal conductance when stomata were closing (ab. 90% at 1xO3 and 250% at 2xO3). Sun and shade leaves showed similar sluggish responses, thus suggesting that sluggishness may occur within the entire crown. The fact that total transpiration was similar at 1xO3 and 2xO3, however, suggests that the higher water loss due to stomatal sluggishness was offset by lower steady-state stomatal conductance at 2xO3. In conclusion, O3 exposure amplified short-term water loss from mature beech trees by slowing stomatal dynamics, while decreased long-term water loss because of lower steady-state stomatal conductance. Over the short term of this experiment, the two responses offset each other and no effect on total transpiration was observed.

scholarly journals Gas exchange, root hydraulic conductivity, water use efficiency and the growth of Toona ciliata clones and seedlings

2019 ◽  
Vol 29 (2) ◽  
pp. 715 ◽  
Author(s):  
Taiane Pires de Freitas de Oliveira ◽  
Deborah Guerra Barroso ◽  
Fábio Afonso Mazzei Moura de Assis Figueiredo ◽  
Thais Chagas Barros ◽  
Gregory Gambetta ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Use ◽  
Root Hydraulic Conductivity ◽  
Toona Ciliata ◽  
Conductivity Water ◽  
Use Efficiency

As plantações florestais estabelecidas com mudas apresentam heterogeneidade e dificuldades de manejo. Assim, uma alternativa a estes obstáculos é o uso de clones com alta produtividade. Além disso, as plantas clonais diferem das plantas seminíferas na estrutura do sistema radicular, o que pode influenciar a eficiência na absorção de água e de nutrientes minerais e, portanto, a produtividade.Nesta pesquisa, avaliaram-se as trocas gasosas foliares, a condutividade hidráulica da raiz, a eficiência no uso da água e o crescimento de plântulas de estacas clonais e de plantas propagadas por semente da espécie Toona ciliata. O estudo foi realizado em delineamento inteiramente casualizado com quatro tratamentos: a) clone TC3; b) clone TC9; c) clone TC15 e d) mudas seminíferas, com cinco repetições e dez plantas por parcela. Aos 120 dias, a taxa fotossintética líquida, a transpiração e a condutância estomática foram avaliadas entre as 12h00 e as 13h00 horas, e a partir desses valores foram calculados as eficiências instantânea (A/E) e intrínseca (A/gs) do uso da água. A condutividade hidráulica da raiz (Kroot) foi obtida pela aplicação de pressões crescentes (0,1, 0,2, 0,3 e 0,4 MPa) neste órgão por meio de uma câmara de pressão. A altura, o diâmetro do caule, a área foliar, a massa seca da parte aérea e raiz, o comprimento, o diâmetro, a área superficial e o volume radicular foram determinados. Os dados foram submetidos à correlação de Pearson e à análise de variância, comparando-se pelo teste de Tukey (5%). Os materiais genéticos estudados tiveram igual capacidade de absorção e transporte de água através das raízes, apesar de terem diferenças anatômicas visuais do sistema radicular. Os clones tiveram taxas de transpiração e taxa fotossintética líquida reduzidas, e estes foram mais eficientes no uso da água. Os clones TC3 e TC9 foram mais eficientes na conversão do carbono assimilado em biomassa.

Short-Term Changes in Cambial Growth and Endogenous IAA Concentrations in Relation to Phloem Girdling of Peach, Prunus persica (L.) Batsch

1985 ◽  
Vol 12 (4) ◽  
pp. 395 ◽  
Author(s):  
IR Dann ◽  
PH Jerie ◽  
DJ Chalmers
Keyword(s):  
Growth Rate ◽  
Prunus Persica ◽  
Term Effect ◽  
Control Mechanisms ◽  
Subsequent Growth ◽  
Short Term ◽  
Cambial Growth ◽  
Long Term Effect ◽  
Ylacetic Acid

For 2-3 days after all except one of the secondary limbs of a peach tree were girdled, all limbs (including the non-girdled limb) shrank. Shrinkage and subsequent growth was greatest in the zone immediately above the girdle whereas growth was least immediately below. After initial shrinkage the growth rate of the cambium, at specific positions in relation to the girdle, was more-or-less constant and consistent with the long-term effect of the girdle at each position. The concentration of indole-3-ylacetic acid (IAA) extracted from the bark immediately above the girdle first increased sharply but then decreased to the level in the non-girdled limb. On the other hand, beneath the girdle the IAA concentration decreased by 75% and remained low. Thus, immediately above the girdle IAA concentration in the bark increased while the limb shrank, and declined before the cambial growth rate increased. Beneath the girdle, however, the concentration of IAA was severely depleted while growth of the limb was inhibited. The possible implications of these observations in relation to control mechanisms of cambial growth are discussed.

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