Effects of nitrogen supply on xylem cytokinin delivery, transpiration and leaf expansion of pea genotypes differing in xylem-cytokinin concentration

2004 ◽  
Vol 31 (9) ◽  
pp. 903 ◽  
Author(s):  
Ian C. Dodd ◽  
Chuong Ngo ◽  
Colin G. N. Turnbull ◽  
Christine A. Beveridge
Keyword(s):  
Sap Flow ◽  
Leaf Growth ◽  
Xylem Sap ◽  
Leaf Expansion ◽  
Growth Responses ◽  
Flow Rates ◽  
Plant Transpiration ◽  
Discernible Effect ◽  
Whole Plant ◽  
N Treatment

The rms2 and rms4 pea (Pisum sativum L.) branching mutants have higher and lower xylem-cytokinin concentration, respectively, relative to wild type (WT) plants. These genotypes were grown at two levels of nitrogen (N) supply for 18–20 d to determine whether or not xylem-cytokinin concentration (X-CK) or delivery altered the transpiration and leaf growth responses to N deprivation. Xylem sap was collected by pressurising de-topped root systems. As sap-flow rate increased, X-CK declined in WT and rms2, but did not change in rms4. When grown at 5.0 mm N, X-CKs of rms2 and rms4 were 36% higher and 6-fold lower, respectively, than WT at sap-flow rates equivalent to whole-plant transpiration. Photoperiod cytokinin (CK) delivery rates (the product of transpiration and X-CK) decreased more than 6-fold in rms4. Growth of plants at 0.5 mm N had negligible (< 10%) effects on transpiration rates expressed on a leaf area basis in WT and rms4, but decreased transpiration rates of rms2. The low-N treatment decreased leaf expansion by 20–25% and expanding leaflet N concentration by 15%. These changes were similar in all genotypes. At sap-flow rates equivalent to whole-plant transpiration, the low N treatment decreased X-CK in rms2 but had no discernible effect in WT and rms4. Since the low N treatment decreased transpiration of all genotypes, photoperiod CK delivery rates also decreased in all genotypes. The similar leaf growth response of all genotypes to N deprivation despite differences in both absolute and relative X-CKs and deliveries suggests that shoot N status is more important in regulating leaf expansion than xylem-supplied cytokinins. The decreased X-CK and transpiration rate of rms2 following N deprivation suggests that changes in xylem-supplied CKs may modify water use.

scholarly journals SUPRAOPTIMAL ROOT-ZONE TEMPERATURE EFFECTS ON WATER USE OF THREE CERCIS SPP.

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 635c-635
Author(s):  
Beth Jez Lawrence ◽  
Jayne M. Zajicek
Keyword(s):  
Sap Flow ◽  
Root Zone ◽  
Time Intervals ◽  
Flow Measurements ◽  
Root Zone Temperature ◽  
Flow Rates ◽  
Plant Transpiration ◽  
Whole Plant ◽  
Environment Chamber ◽  
Sap Flow Measurements

Sap flow rates of three Cercis spp. exposed to supraoptimal root-zone temperatures were characterized in a controlled environment chamber using a water bath to control temperatures. Flow rates of sap in the xylem were measured every 15 sec. and averaged over 15 min. intervals. Sap flow measurements were correlated to root-zone temperatures recorded during the same time intervals. Whole plant transpiration was measured gravimetrically. Root-zone temperatures were maintained at 22C for three consecutive 24-hr cycles and then increased to 45C for an additional three 24-hr periods. All plants, regardless of species, had reduced sap flow patterns when exposed to high root-zone temperatures. Plants maintained at a constant temperature of 22C showed no extreme fluctuations in sap flow rate. Stomatal conductance rates and leaf water potentials showed similar trends to whole plant transpiration.

scholarly journals HIGH ROOT-ZONE TEMPERATURE EFFECTS ON DIURNAL WATER USE OF WOODY ORNAMENTAL

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1118a-1118
Author(s):  
B. Jez Lawrence ◽  
J.M. Zajicek
Keyword(s):  
Flow Rate ◽  
Sap Flow ◽  
Root Zone ◽  
Temperature Cycle ◽  
Root Zone Temperature ◽  
Flow Rates ◽  
Plant Transpiration ◽  
Whole Plant ◽  
Woody Ornamental ◽  
Zone Temperature

Root-zone temperature fluctuations and sap flow rates were characterized for several woody ornamental plants in a controlled environment using a water bath to control temperatures. Flow rates of sap in the xylem were measured every 15 seconds and averaged over 15 minute intervals. Sap flow measurements were correlated to root-zone temperatures recorded during the same time intervals. Whole plant transpiration was measured gravimetrically. Root-zone temperatures were raised from 22°C to 45°C (slightly below lethality between 9:00 am and 12:00 noon, held at that temperature until 4:00 pm, and then allowed to cool. There was a pronounced diurnal change in flow rate with peak flow during mid-morning declining in mid-afternoon. The decline in the rate of sap flow occurred at a faster rate than the decline in root-zone temperature. This diurnal flow rate was most pronounced during the first 24-hour elevated temperature cycle. Plants maintained at a constant temperature of 22°C showed no such extreme fluctuations in sap flow rate. Stomatal conductance measured with a porometer showed similar trends to whole plant transpiration.

Whole-Plant Responses to Salinity

1986 ◽  
Vol 13 (1) ◽  
pp. 143 ◽  
Author(s):  
R Munns ◽  
A Termaat
Keyword(s):  
Root Growth ◽  
Leaf Growth ◽  
Water Status ◽  
Leaf Expansion ◽  
Saline Soils ◽  
Plant Responses ◽  
Short Term ◽  
Whole Plant ◽  
Short Term Exposure

This paper discusses whole-plant responses to salinity in order to answer the question of what process limits growth of non-halophytes in saline soils. Leaf growth is more sensitive to salinity than root growth, so we focus on the process or processes that might limit leaf expansion. Effects of short-term exposure (days) are considered separately from long-term exposure (weeks to years). The answer in the short term is probably the water status of the root and we suggest that a message from the root is regulating leaf expansion. The answer to what limits growth in the long term may be the maximum salt concentration tolerated by the fully expanded leaves of the shoot; if the rate of leaf death approaches the rate of new leaf expansion, the photosynthetic area will eventually become too low to support continued growth.

Stem and leaf growth of alpine sun and prairie shade ecotypes of Stellaria longipes under different photoperiods: role of ethylene

2006 ◽  
Vol 84 (9) ◽  
pp. 1496-1502 ◽  
Author(s):  
Linda J. Walton ◽  
Leonid V. Kurepin ◽  
David M. Reid ◽  
C.C. Chinnappa
Keyword(s):  
Leaf Growth ◽  
Stem Elongation ◽  
Leaf Length ◽  
Leaf Expansion ◽  
Alpine Plants ◽  
Growth Responses ◽  
Stellaria Longipes ◽  
Length And Area ◽  
Radiation Conditions

Plant ecotypes of Stellaria longipes Goldie from competitive, shade-adapted prairie habitat and less competitive, nonshaded alpine habitat were subjected to shortened or extended photoperiod conditions. Increasing daylength was positively correlated to increased stem elongation in both ecotypes. Leaf length and area for shade (prairie) plants was significantly altered with increased photoperiods, whereas sun (alpine) plants exhibited minimal leaf expansion in response to increased photoperiod. Increased ethylene evolution in the alpine genotype during rapid stem elongation and extended photoperiods suggests that ethylene plays a growth regulatory role in this sun-adapted genotype. The prairie genotype evolved less ethylene during these same periods, indicating either a diminished requirement for elevated ethylene to effect elongation and leaf expansion responses or possibly increased ethylene sensitivity because of interactions with other hormones, such as gibberellin or auxin. The sun genotype consistently produced more ethylene than the shade genotype under all photoperiod treatments. We conclude that photoperiod alters stem elongation and leaf expansion responses; similar trends were observed for extended photoperiods as were observed for shaded conditions, specifically low light intensity (photosynthetically active radiation) conditions. Further, ethylene levels altered during these responses, especially in sun-adapted alpine plants, which suggests that ethylene is involved in these growth responses.

scholarly journals Impact of Laurel Wilt, Caused by Raffaelea lauricola, on Leaf Gas Exchange and Xylem Sap Flow in Avocado, Persea americana

2015 ◽  
Vol 105 (4) ◽  
pp. 433-440 ◽  
Author(s):  
Randy C. Ploetz ◽  
Bruce Schaffer ◽  
Ana I. Vargas ◽  
Joshua L. Konkol ◽  
Juanpablo Salvatierra ◽  
...  
Keyword(s):  
Sap Flow ◽  
Leaf Gas Exchange ◽  
Xylem Sap ◽  
Persea Americana ◽  
Laurel Wilt ◽  
Flow Rates ◽  
Raffaelea Lauricola ◽  
Close Relationship ◽  
Xylem Sap Flow ◽  
Individual Trees

Laurel wilt, caused by Raffaelea lauricola, is a destructive disease of avocado (Persea americana). The susceptibility of different cultivars and races was examined previously but more information is needed on how this host responds to the disease. In the present study, net CO2 assimilation (A), stomatal conductance of H2O (gs), transpiration (E), water use efficiency (WUE), and xylem sap flow rates were assessed in cultivars that differed in susceptibility. After artificial inoculation with R. lauricola, there was a close relationship between symptom development and reductions in A, gs, E, WUE, and mean daily sap flow in the most susceptible cultivar, ‘Russell’, and significantly greater disease and lower A, gs, E, WUE, and sap flow rates were usually detected after 15 days compared with the more tolerant ‘Brogdon’ and ‘Marcus Pumpkin’. Significant differences in preinoculation A, gs, E, and WUE were generally not detected among the cultivars but preinoculation sap flow rates were greater in Russell than in Brogdon and Marcus Pumpkin. Preinoculation sap flow rates and symptom severity for individual trees were correlated at the end of an experiment (r = 0.46), indicating that a plant’s susceptibility to laurel wilt was related to its ability to conduct water. The potential management of this disease with clonal rootstocks that reduce sap flow rates is discussed.

Concentrations of abscisic acid and other solutes in xylem sap from root systems of tomato and castor-oil plants are distorted by wounding and variable sap flow rates

1994 ◽  
Vol 45 (3) ◽  
pp. 317-323 ◽  
Author(s):  
M.A. Else ◽  
W.J. Davies ◽  
P.N. Whitford ◽  
K.C. Hall ◽  
M.B. Jackson
Keyword(s):  
Abscisic Acid ◽  
Sap Flow ◽  
Castor Oil ◽  
Xylem Sap ◽  
Root Systems ◽  
Flow Rates

scholarly journals Sap Flow Disruption in Grapevine Is the Early Signal Predicting the Structural, Functional, and Genetic Responses to Esca Disease

2021 ◽  
Vol 12 ◽  
Author(s):  
Loris Ouadi ◽  
Emilie Bruez ◽  
Sylvie Bastien ◽  
Amira Yacoub ◽  
Cindy Coppin ◽  
...  
Keyword(s):  
Sap Flow ◽  
Fungal Species ◽  
White Rot ◽  
Plant Responses ◽  
Plant Transpiration ◽  
Flow Disruption ◽  
Growing Seasons ◽  
Whole Plant ◽  
High Level ◽  
Leaf Symptoms

Fungal species involved in Esca cause the formation of grapevine wood necroses. It results in the deterioration of vascular network transport capacity and the disturbance of the physiological processes, leading to gradual or sudden grapevine death. Herein, for two consecutive growing seasons, a detailed analysis of the structural (wood necrosis and leaf discoloration) and physiological parameters related to the water use of healthy and esca-symptomatic grapevines was conducted. Measurements were carried out on 17-year-old grapevines that expressed, or not, Esca-leaf symptoms in a vineyard of the Bordeaux region (France). Whole-plant transpiration was recorded continuously from pre-veraison to harvest, using noninvasive sap flow sensors. Whole-plant transpiration was systematically about 40–50% lower in Esca-diseased grapevines compared with controls, and this difference can be observed around 2 weeks before the first Esca-foliar symptoms appeared in the vineyard. Unlike grapevine sap flow disruption, structural (e.g., leaf discolorations), functional (e.g., stomatal conductance, photosynthetic activity, phenolic compounds), and genetic (e.g., expression of leaf-targeted genes) plant responses were only significantly impacted by Esca at the onset and during leaf symptoms development. We conclude that sap flow dynamic, which was related to a high level of a white-rot necrosis, provides a useful tool to predict plant disorders due to Esca-grapevine disease.

scholarly journals Technical note on long-term probe misalignment and proposed quality control using the heat pulse method for transpiration estimations

2019 ◽  
Author(s):  
Elisabeth K. Larsen ◽  
Jose Luis Palau ◽  
Jose Antonio Valiente ◽  
Esteban Chirino ◽  
Juan Bellot
Keyword(s):  
Quality Control ◽  
Sap Flow ◽  
Hydrological Cycle ◽  
Individual Performance ◽  
Technical Note ◽  
Flow Measurements ◽  
Plant Transpiration ◽  
Whole Plant ◽  
Relative Standard

Abstract. Whole-plant transpiration is a crucial component in the hydrological cycle and a key parameter in many disciplines like agriculture, forestry and ecology. Sap flow measurements are one of the most widely used methods to estimate whole-plant transpiration in woody species due to its wide application range and its ready automation for continuous data readings. Several different methods have been developed and adjusted to different climatic conditions and wood properties. However, the scientific literature also identifies several sources of error in the method that needs to be accounted for; misalignment of the probes, wound to the xylem, thermal diffusivity and stem water content. This study aims to integrate probe misalignment as a function of time to improve readings during long-term measurements (> 3 months). We conclude that even when geometrical misalignments errors are small, the introduced corrections can imply an important shift in sap flow estimations. Additionally, we propose a new set of statistical information to be recorded during the measurement period to use as a quality control of the heat ratio readings obtained from the sensors. By using relative standard deviation and slope as quality indicators we concluded that no general time limit can be decided for all sensors but should rather be determined from individual performance over time.

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