Determination of the water use and water use response of canola to solar radiation and temperature by using heat balance stem flow gauges

2003 ◽  
Vol 83 (1) ◽  
pp. 31-38 ◽  
Author(s):  
S. V. Angadi ◽  
H. W. Cutforth ◽  
B. G. McConkey
Keyword(s):  
Solar Radiation ◽  
Real Time ◽  
Heat Loss ◽  
Water Use ◽  
Heat Balance ◽  
Heat Input ◽  
Sap Flow ◽  
Flow System ◽  
Major Portion ◽  
Flow Rates

Sap flow gauges using a heat balance have been reliable for measuring real-time transpiration in a number of crops. However, information on the accuracy of sap flow gauges in canola is lacking. Therefore, a study was conducted to validate the sap flow system in canola and to observe sap flow response to variations in temperature and solar radiation. There were strong relationships between sap flow measured with sap flow gauges and actual transpiration measured by the gravimetric method over short periods of 1 h (r2 = 0.93 and RMSE = 2.34 g h-1), and over longer periods of 1 d (r2 = 0.83 and RMSE = 48 g d-1), although sap flow slightly overestimated transpiration. In both cases the slope was not significantly different from 1. Water use in canola, estimated with sap flow gauges or from actual transpiration measurement, was dependent upon temperature (r2 = 0.94 to 0.96). Water use increased until daytime temperatures reached 36°C, after which water use decreased. Sap flow followed solar radiation trends in the field. Heat is lost or dissipated from the gauges convectively as the sap flows through the stem, conductively through the solid stem material, and radially into the surrounding air. As the convective proportion of the heat loss from the gauge increased, the accuracy of the water use estimation using the sap flow gauges increased. For sunny days, convective heat loss through sap flow accounted for a major portion of the total heat input to the gauges, while on cloudy days radial heat loss from the gauges accounted for a major portion of the heat input. Thus, at low sap flow rates during cloudy days, the possibility of error in the sap flow system was high. Overall, sap flow in canola was strongly related to daily solar radiation (r2 = 0.92). The sensitive response to weather variations and the possibility of improving the accuracy at high flow rates in the field makes the use of sap flow gauges a viable option for measuring real-time transpiration in canola. Key words: Brassica napus, canola, heat balance, sap flow, transpiration, temperature, solar radiation

Determination of the water use of two pairs of soybean isolines differing in stomatal frequency using a heat balance stem flow gauge

1995 ◽  
Vol 75 (1) ◽  
pp. 99-103 ◽  
Author(s):  
C. S. Tan ◽  
B. R. Buttery
Keyword(s):  
Soil Moisture ◽  
Water Use ◽  
Heat Balance ◽  
Sap Flow ◽  
Stomatal Frequency ◽  
Flow Rates ◽  
High Soil Moisture ◽  
Stem Flow ◽  
Glycine Max L

Using heat-balance stem flow gauges, we were able to measure directly and continuously the sap flow rates in two pairs of soybean [Glycine max (L.) Merr.] isolines differing in stomatal frequency. Plants with high stomatal frequency transpired significantly more water than the low stomatal frequency plants at high soil moisture levels. Under low soil moisture levels, the water use rate decreased greatly for the high stomatal frequency plants. Plants with low stomatal frequency were able to maintain greater sap flow rates than those with high stomatal frequency. Higher leaf temperatures associated with the low stomatal frequency plants were likely due to lower transpiration rates which reduced evaporative cooling especially under well-watered conditions. Key words:Glycine max (L.) Merr., transpiration, water deficits

scholarly journals Drought Superimposes the Positive Effect of Silver Fir on Water Relations of European Beech in Mature Forest Stands

Forests ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 897 ◽  
Author(s):  
Magh ◽  
Bonn ◽  
Grote ◽  
Burzlaff ◽  
Pfautsch ◽  
...  
Keyword(s):  
Water Use ◽  
Water Relations ◽  
Sap Flow ◽  
Mixed Stand ◽  
Ratio Method ◽  
Silver Fir ◽  
Pure Stand ◽  
Mixed Stands ◽  
Flow Rates ◽  
Beech Stand

Research Highlights: Investigations of evapotranspiration in a mature mixed beech-fir forest stand do not indicate higher resilience towards intensified drying-wetting cycles as compared with pure beech stands. Background and Objectives: Forest management seeks to implement adaptive measures, for example, the introduction of more drought resistant species into prevailing monospecific stands to minimize forest mortality and monetary losses. In Central Europe this includes the introduction of native silver fir (Abies alba) into monospecific beech (Fagus sylvatica) stands. In order to determine, if the introduction of fir would improve the resilience against drier conditions, this study investigates water relations of a mature pure beech and a mature mixed beech-fir stand under natural as well as reduced water availability. Materials and Methods: Sap flow rates and densities were measured in two consecutive years using the heat ratio method and scaled using stand inventory data and modeling. Results: Transpiration rates estimated from sap flow were significantly higher for beech trees as compared with silver fir which was attributed to the more anisohydric water-use strategy of the beech trees. We estimate that stand evapotranspiration was slightly higher for mixed stands due to higher interception losses from the mixed stand during times of above average water supply. When precipitation was restricted, beech was not able to support its transpiration demands, and therefore there was reduced sap flow rates in the mixed, as well as in the pure stand, whereas transpiration of fir was largely unaffected, likely due to its more isohydric behavior toward water use and access to moister soil layers. Thus, we found the rates of evapotranspiration in the mixed beech-fir stand to be smaller during times with no precipitation as compared with the pure beech stand, which was accountable to the severely reduced transpiration of beech in the mixed stand. Conclusions: We conclude that smaller evapotranspiration rates in the mixed beech-fir stand might not be the result of increased water use efficiency but rather caused by restricted hydraulic conductivity of the root system of beech, making mixed beech-fir stands at this site less resilient towards drought.

scholarly journals TRANSPIRATION OF A POTTED ROSE PLANT USING A HEAT BALANCE STEM FLOW GAUGE

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1073a-1073
Author(s):  
Mark A. Rose ◽  
John W. White ◽  
Joel L. Cuello
Keyword(s):  
Heat Balance ◽  
Sap Flow ◽  
Continuous Measurement ◽  
Future Research ◽  
Total Leaf Area ◽  
Flow Rates ◽  
Non Invasive ◽  
Significant Linear Correlation ◽  
Stem Flow ◽  
Plant Sap

Recently developed stem flow gauges that allow for direct, accurate, non-invasive, and continuous measurement of plant sap flow rates have not been used to monitor transpiration of floricultural plants grown in greenhouses.A Dynamax SGA10 heat-balance sap-flow sensor was mounted on a potted rose plant's main stem containing a total leaf area of 0.52 m in order to monitor transpiration. The sensor was connected to a CR21X Micrologger for data calculation and temporary storage. The results showed average midday sap-flow rates range from 20-30 g·hr-1 to 50-70 g·hr-1 at low and high levels of PPF, respectively. Nighttime levels of 4-7 g·hr-1 persisted throughout early winter trials. Monitoring transpiration of the same rose stem using a lysimeter revealed a significant linear correlation (r2 = 0.999) between the lysimeter and the stem flow gauge values.In the future, research will be conducted with the gauge to investigate relationships between microclimatic variables, photosynthesis, and transpiration.

scholarly journals Heat Balance When Climbing Mount Everest

2021 ◽  
Vol 12 ◽  
Author(s):  
Robert K. Szymczak ◽  
Krzysztof Błażejczyk
Keyword(s):  
Solar Radiation ◽  
High Altitude ◽  
Heat Loss ◽  
Heat Balance ◽  
Meteorological Data ◽  
Air Pressure ◽  
Main Element ◽  
Activity Levels ◽  
Clothing Insulation ◽  
Factors Affecting

Background: Mountaineers must control and regulate their thermal comfort and heat balance to survive the rigors of high altitude environment. High altitudes feature low air pressure and temperatures, strong winds and intense solar radiation, key factors affecting an expedition’s success. All these climatic elements stress human heat balance and survival. We assess components of human heat balance while climbing Mt. Everest.Materials and Methods: We calculated climbers’ heat balance using the Man-ENvironment heat EXchange model (MENEX-2005) and derived meteorological data from the National Geographic Expedition’s in situ dataset. Three weather stations sited between 3810 and 7945 m a.s.l. provided data with hourly resolution. We used data for summer (1 May–15 August 2019) and winter (16 October 2019–6 January 2020) seasons to analyze heat balance elements of convection, evaporation, respiration and radiation (solar and thermal).Results: Meteorological and other factors affecting physiology—such as clothing insulation of 3.5–5.5 clo and activity levels of 3–5 MET—regulate human heat balance. Elevation above sea level is the main element affecting heat balance. In summer two to three times more solar radiation can be absorbed at the summit of the mountain than at the foot. Low air pressure reduces air density, which reduces convective heat loss at high altitude by up to half of the loss at lower locations with the same wind speed and air temperature.Conclusion: 1. Alpinists face little risk of overheating or overcooling while actively climbing Mt. Everest, despite the potential risk of overcooling at extreme altitudes on Mt. Everest in winter. 2. Convection and evaporation are responsible for most of the heat lost at altitude. 3. Levels of physical activity and clothing insulation play the greatest role in counteracting heat loss at high altitude.

Unravelling the relationship between stem temperature and air temperature to correct for errors in sap-flow calculations using stem heat balance sensors

2005 ◽  
Vol 32 (7) ◽  
pp. 599 ◽  
Author(s):  
Kathy Steppe ◽  
Raoul Lemeur ◽  
Diego Dierick
Keyword(s):  
Air Temperature ◽  
Flow Rate ◽  
Heat Balance ◽  
Sap Flow ◽  
Heat Storage ◽  
Flow Rates ◽  
Storage Effects ◽  
Stem Temperature ◽  
Oak Tree ◽  
Set Up

Results from measurement of sap flow by heat balance sensors on the stem of a young oak tree (Quercus robur L.) revealed that thermal disequilibrium (i.e. heat storage) within the heated stem segment can introduce considerable errors in the measured sap-flow rates. The magnitude, sign and significance of these errors depend on the sap-flow rate and on the relationship between stem temperature and air temperature. Sap-flow rates were found to be more prone to errors caused by heat storage effects under low flow conditions than at higher rates of sap flow. Furthermore, daytime fluctuations of air temperature and stem temperature inside the heat balance sensor were either in phase when a low, or in opposite phase when a high sap-flow rate was passing through the stem of the young tree. To investigate this relationship, we developed an experimental set-up with cut stem segments through which tap water could be pressed. This set-up allowed the effects of air temperature and sap-flow rates on stem temperatures within heat balance sensors to be clearly separated. Good mathematical relationships were obtained and were successfully used to assess the relative importance of air temperature and sap-flow rate with respect to the fluctuations in stem temperature of the young oak tree. Based on the established relationships, a novel approach was put forward to correct for errors introduced into sap-flow calculations caused by heat storage effects if no measured data on stem temperature are available.

scholarly journals 583 Scaling-up Heat-balance Sap Flow Sensors for the High Flow Rates of Mature Grape Vines

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 497A-497
Author(s):  
J.M. Tarara ◽  
J.C. Ferguson
Keyword(s):  
Water Use ◽  
Water Loss ◽  
Heat Balance ◽  
Sap Flow ◽  
Management Strategies ◽  
Absolute Error ◽  
Stem Segment ◽  
Maximum Absolute Error ◽  
The Heat Balance ◽  
Zero Flow

Management strategies like “deficit irrigation” in wine grapes require accurate, reliable information on vine water use, making direct measurements of vine transpiration highly desirable. The heat-balance sap flow method has the advantages of being non-invasive and requiring no other calibration beyond a zero-flow set. Potential violations of the method's assumptions were dealt with and the heat balance method successfully applied to mature grape vines under conditions of extremely high sap flow. Greenhouse studies suggested that vines transpire at night, up to 9.5% of the total 24-h water loss, thus violating the zero-flow assumption for setting the gauge constant. Using a predetermined gauge constant caused smaller errors than using daily, pre-dawn constants set in situ. The steady-state assumption was violated only in early and late hours of the day, and the inclusion of a term to account for the change in heat stored by the stem only marginally improved daily estimates of water use. The assumption of radially uniform temperature across the heated stem segment is violated at very high flows (e.g., >700 g·h–1), but can be corrected for by using wider heaters and adjusting the placement of thermocouples. For a mature, potted vine in the greenhouse, the maximum absolute error in cumulative daytime water use between a sap gauge and a precision load cell was about –10%, with the gauge almost exclusively underestimating water loss. A custom-built, 20-gauge system was run continuously in the field for 90 days. Vine-to-vine variability in water use was not accounted for by normalizing sap flow by leaf area, suggesting that it is critical to include in any field study the largest number of gauges that are technically feasible.

scholarly journals Transpiration by Crape Myrtle Cultivars Surrounded by Mulch, Soil, and Turfgrass Surfaces

HortScience ◽  
1991 ◽  
Vol 26 (9) ◽  
pp. 1207-1210 ◽  
Author(s):  
Jayne M. Zajicek ◽  
J.L. Heilman
Keyword(s):  
Vapor Pressure ◽  
Water Use ◽  
Heat Balance ◽  
Sap Flow ◽  
Longwave Radiation ◽  
Soil Surface ◽  
Bare Soil ◽  
The Other ◽  
Stem Flow ◽  
Daily Water

A study was conducted to explore how surface materials, including pine bark mulch, bare soil, and turfgrass, affect water use of diverse cultivars (dwarf weeping, dwarf upright, standard weeping, and standard upright) of crape myrtle (Lagerstroemia indica L.). Daily water use was measured gravimetrically, and instantaneous rates of sap flow were measured using heat balance stem flow gauges. Plants of all cultivars surrounded by the mulched surface lost 0.63 to 1.25 kg·m-2·day-1 more water than plants on the soil surface and 0.83 to 1.09 kg·m-2·day-1 more than plants surrounded by turf. The surface temperature of the mulch was higher than that of the other surfaces, resulting in greater fluxes of longwave radiation from the surface. Because of the greater energy load, plants on the mulched surface had higher leaf temperatures and higher leaf-air vapor pressure deficits (VPD) throughout the day. Plants on the mulched area also had higher stomata1 conductances during most of the day compared with those on bare soil and turfgrass surfaces.

Effects of Different Irrigation Amounts on Water Use of Precocious Walnuts

2014 ◽  
Vol 651-653 ◽  
pp. 1423-1431
Author(s):  
Hua Bing Ma ◽  
Mei Mei Li ◽  
Jun Jie Ren ◽  
Bao Guo Li ◽  
Guo Hui Qi
Keyword(s):  
Diurnal Variation ◽  
Water Use Efficiency ◽  
Water Potential ◽  
Soil Water ◽  
Water Use ◽  
Leaf Water Potential ◽  
Sap Flow ◽  
Leaf Water ◽  
Flow Rates ◽  
Use Efficiency

Objective : To provide scientific guidance for water management of precocious walnuts. Method: With 8 years old ‘Lvling’ walnut trees as samples, 5 irrigation quantity treatments were designed, including 0, 15, 30, 45 and 60 kg of water per plant for each time, respectively and the routine irrigation amount (CK) was 600 kg of water per plant for each time. During the draught stage in growing season, 3 times of irrigation were carried out, and the effects of different treatments on sap flow, water use efficiency, yield and fruit quality were compared. Results: The daily instantaneous maximum average sap flow rates were found with 60 kg of water and control; the daily highest average water use efficiency was 1.54 mmol/mol with the treatment of 30 kg water; the daily highest average leaf water potential was-1.23 MPa with control; the highest yield per plant (1.48 kg) was found with the control, and the yield of 45 kg and 60 kg water per plant one time accounted for 98.65% and 99.32% of that of control, respectively. with T1 the yield was the lowest, only accounting for 70.65% of the control. Conclusion: As the soil water contents increased, the diurnal variation curve of sap flow rates changed from unimodal to bimodal patterns in sunny days, the main peak was narrowed; the curve of diurnal variation of leaf water potential changed from "V" to "W" type; the leaf water use efficiency increased initially and then decreased later; and the nut quality was improved and the yield increased. The optimal soil water content (SWC) of 'Lvling' precocious walnuts ranged from 20.01% ~ 21.96%.

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