scholarly journals ABA, Hydraulics, and Gas Exchange of Split-rooted Apple Trees

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1097C-1097
Author(s):  
Todd C. Einhorn ◽  
Horst W. Caspari ◽  
Steve Green
Keyword(s):  
Gas Exchange ◽  
Time Domain ◽  
Sap Flow ◽  
Leaf Gas Exchange ◽  
Heat Pulse ◽  
Time Domain Reflectometry ◽  
Apple Trees ◽  
Pulse Technique ◽  
Predawn Leaf Water Potential ◽  
Single Leaf

Approach-grafted 1-year-old `Gala'/M7 apple trees were grown with both tops for the remainder of the 2003 season in a greenhouse. Trees were supplied with >100% (control, PRD100) or 50% (PRD50, DI50) of daily ETc either applied to one root compartment only (PRD100, PRD50) or divided evenly across both root compartments (control and DI50). ETc was estimated from gravimetric measurements, and irrigation was switched between wet and dry root compartments several times throughout the experiment. Soil moisture was measured both gravimetrically (tripod) and volumetrically (time-domain reflectometry). Predawn leaf water potential (υpd) and single leaf gas exchange (photosynthesis, stomatal conductance, and transpiration) were recorded daily, and sap flow in stems and roots was monitored continuously using the heat-pulse technique. Leaves were collected for abscisic acid (ABA) determination following gas exchange measurements. Regardless of irrigation placement (i.e., PRD or DI), both 50% ETc treatments experienced similar declines in υpd and single leaf gas exchange relative to control levels. In addition, ABA concentrations were similar for PRD50 and DI50, and were significantly higher than the control and PRD100 treatments. PRD100 trees had similar υpd as control trees; however, gas exchange was reduced >25% compared to the control. Bulk leaf ABA concentration did not differ significantly from control levels and does not by itself explain the down regulation of stomata with PRD100.

Gas Exchange Characteristics of Apple at Various Light Intensities under Two Levels of European Red Mite Damage

HortScience ◽  
1998 ◽  
Vol 33 (4) ◽  
pp. 601b-601
Author(s):  
Krista L. Kugler-Quinn ◽  
Curt R. Rom ◽  
Donn T. Johnson
Keyword(s):  
Gas Exchange ◽  
Light Intensity ◽  
Leaf Gas Exchange ◽  
Mite Population ◽  
Mite Infestation ◽  
Apple Trees ◽  
Single Leaf ◽  
European Red Mite ◽  
Light Intensities ◽  
Gas Exchange Characteristics

Single leaf gas exchange measurements were taken at a range of light intensities from 20 to 1500 μmol·m-2·s-1 PAR under greenhouse conditions on `Washington Spur'/EMLA seven potted apple trees subjected to either 1500 cumulative mite days (CMD) European Red mite (ERM) damage or no mite damage. 1500 CMD ERM damage significantly reduced assimilation (A) over all light intensities for leaves present during mite damage at 6 days after the mite population had reached the 1500 CMD level and the mites were killed. Mite damage did not significantly affect A of either leaves present during mite damage or leaves produced after the mites were killed on any other sampling date. However, a trend of reduced A of leaves present during mite infestation on the mite-damaged trees was apparent on all sampling dates after the mites were killed. Evapotranspiration (E) was not affected by mite damage. The mite damage by light intensity interaction did not have a significant effect on A or E on any sampling date.

scholarly journals CALIBRATING THE COMPENSATION HEAT-PULSE TECHNIQUE FOR MEASURING SAP FLOW IN OLIVE

1999 ◽  
pp. 455-460 ◽  
Author(s):  
J.E. Fernández ◽  
M.J. Palomo ◽  
A. Díaz-Espejo ◽  
I.F. Girón
Keyword(s):  
Sap Flow ◽  
Heat Pulse ◽  
Pulse Technique

Measuring peat moisture content using the dual-probe heat pulse technique

Soil Research ◽  
2002 ◽  
Vol 40 (1) ◽  
pp. 177 ◽  
Author(s):  
David I. Campbell ◽  
Claire E. Laybourne ◽  
Ian J. Blair
Keyword(s):  
Moisture Content ◽  
Gravimetric Method ◽  
Heat Pulse ◽  
Time Domain Reflectometry ◽  
Peat Soils ◽  
Pulse Technique ◽  
Mineral Soils ◽  
Reference Measurements ◽  
High Level ◽  
Dual Probe

The dual-probe heat pulse (DPHP) technique for measuring soil volumetric moisture content (Θv) is evaluated for use in peat soils with very high organic matter contents. The method has a greater sensitivity in peat soils compared with mineral soils and excellent resolution is possible, even at moisture contents as high as 90% by volume. Advantages of the DPHP technique are that sensors are simple to construct from inexpensive parts and calibration is not required since the method is based on a physical model of radial heat flow in soil. A multiplexer method was developed to allow multiple probes to be deployed in the field. DPHP measurements of Θv for small peat samples compared closely to reference measurements made using the gravimetric method, and in the field were similar to results obtained using a time domain reflectometry (TDR) method. Peat soils display a high level of spatial variation in Θv at the scales of both DPHP and TDR probes, so that multiple probes of each type are required for adequate spatial sampling of Θv. Rapid changes in peat moisture content were recorded following rainfall infiltration events yet moisture storage did not remain elevated following rainfall, even for peat that was very dry. wetlands, hydrology, soil moisture.

Determination of sap flow in Douglas-fir trees using the heat pulse technique

1985 ◽  
Vol 15 (2) ◽  
pp. 422-428 ◽  
Author(s):  
Y. Cohen ◽  
F. M. Kelliher ◽  
T. A. Black
Keyword(s):  
Flow Rate ◽  
Sap Flow ◽  
Water Flow Rate ◽  
Vapour Pressure Deficit ◽  
Heat Pulse ◽  
Douglas Fir ◽  
Temperature Sensing ◽  
Sap Flux ◽  
Pulse Technique ◽  
Laboratory Calibration

A modified heat pulse technique was used to determine volumetric sap flow in 15–17 m tall Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) trees. Laboratory calibration of the heat pulse technique, accomplished by passing water through 200 mm long by 77 mm diameter stem sections with a gas pressure apparatus, showed an underestimation of the actual water flow rate by 47%. Using a six-thermistor temperature sensing probe inserted radially to a depth of 60 mm, field measurements of sap flux density were found to change with depth into the sap wood. Simultaneous measurements using the temperature sensing probes inserted in three azimuthal directions (0, 120, and 240°) showed good agreement during the daytime in three trees, while in another tree the ratio of the three sap flux densities gradually changed during the daytime. Hourly values of sap flow rate in two different trees, obtained using the laboratory calibration factor were 29 and 53% larger than corresponding foliar transpiration rates estimated using measurements of stomatal conductance, tree leaf area and vapour pressure deficit. Using a microprocessor-based data acquisition system, the technique was successfully used to monitor the course of sap flow rate over a 4-month period.

scholarly journals Red and Blue Netting Alters Leaf Morphological and Physiological Characteristics in Apple Trees

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 127
Author(s):  
Richard M. Bastías ◽  
Pasquale Losciale ◽  
Camilla Chieco ◽  
Luca Corelli-Grappadelli
Keyword(s):  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Red Light ◽  
Net Photosynthesis ◽  
Fruit Trees ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Apple Trees ◽  
Intrinsic Water Use Efficiency

There is little information about the role of red and blue light on leaf morphology and physiology in fruit trees, and more studies have been developed in herbaceous plants grown under controlled light conditions. The objective of this research was to evaluate the effect of red and blue screens on morpho-anatomy and gas exchange in apple leaves grown under ambient sunlight conditions. Apple trees cv. Fuji were covered by 40% red and blue nets, leaving trees with 20% white net as control. Light relations (photosynthetic photon flux density, PPFD; red to far-red light ratio, R/FR and blue to red light ratio, B/R), morpho-anatomical features of the leaf (palisade to spongy mesophyll ratio, P/S, and stomata density, SD) and leaf gas exchange (net photosynthesis rate, An; stomatal conductance, gs; transpiration rate, E; and intrinsic water use efficiency, IWUE) were evaluated. Red and blue nets reduced 27% PPFD, reducing by 20% SD and 25% P/S compared to control, but without negative effects on An and gs. Blue net increased gs 21%, leading to the highest E and lowest IWUE by increment of B/R light proportion. These findings demonstrate the potential use of red and blue nets for differential modulation of apple leaf gas exchange through sunlight management under field conditions.

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