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1
Burns, Edgar A. "Climate Sadness: The Fragile Beauty of Tonlé Sap." Qualitative Inquiry 28, no. 3-4 (December 30, 2021): 383–91. http://dx.doi.org/10.1177/10778004211065804.
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Tonlé Sap is the large fresh water lake-river near the geographic center of Cambodia. Visiting Tonlé Sap, following an academic conference in Phnom Penh, demanded a response at a personal and more visceral human level. Writing this poem attempted to express disquiet beyond academic examination of the biophysical dimensions of Tonlé Sap. The poem is sad for Tonlé Sap, for Cambodia, and implicitly for all of us on this planet. For thousands of years people have lived around Tonlé Sap, adapting to weather, the flow of water from mountain to sea, and the changing ebb and flow of civilizations. Anthropogenic sea level rise challenges all of this human history, unnecessarily.
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Angadi, S. V., H. W. Cutforth, and B. G. McConkey. "Determination of the water use and water use response of canola to solar radiation and temperature by using heat balance stem flow gauges." Canadian Journal of Plant Science 83, no. 1 (January 1, 2003): 31–38. http://dx.doi.org/10.4141/p02-022.
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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
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Terada, Yasuhiko, Yusuke Horikawa, Akiyoshi Nagata, Katsumi Kose, and Kenji Fukuda. "Dynamics of xylem and phloem sap flow in an outdoor zelkova tree visualized by magnetic resonance imaging." Tree Physiology 40, no. 3 (December 19, 2019): 290–304. http://dx.doi.org/10.1093/treephys/tpz120.
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Abstract Xylem and phloem sap flows in an intact, young Japanese zelkova tree (Zelkova serrata (Thunb.) Makino) growing outdoors were measured using magnetic resonance imaging (MRI). Two propagator-based sequences were developed for q-space imaging: pulse field gradient (PFG) with spin echo (PFG-SE) and stimulated echo (PFG-STE), which were used for xylem and phloem flow measurements, respectively. The data evaluation methods were improved to image fast xylem flow and slow phloem flow. Measurements were taken every 2–3 h for several consecutive days in August 2016, and diurnal changes in xylem and phloem sap flows in a cross-section of the trunk were quantified at a resolution of 1 mm2. During the day, apparent xylem flow volume exhibited a typical diurnal pattern following a vapor pressure deficit. The velocity mapping of xylem sap flow across the trunk cross section revealed that the greatest flow volume was found in current-year earlywood that had differentiated in April–May. The combined xylem flow in the 1- and 2-year-old annual rings also contributed to one-third of total sap flow. In the phloem, downward sap flow did not exhibit diurnal changes. This novel application of MRI in visualization of xylem and phloem sap flow by MRI is a promising tool for in vivo study of water transport in mature trees.
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T. WATHAM, N.R. PATEL, S.P.S. KUSHWAHA, and V. K. DADHWAL. "A study on sap flow rate of Mallotusphilippensis and its relationship with environmental factors." Journal of Agrometeorology 19, no. 2 (June 1, 2017): 104–9. http://dx.doi.org/10.54386/jam.v19i2.680.
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Understating of the water availability and its corresponding use by Mallotusphilippensis and its control by climatic factors can give an idea about the ecosystem interaction. The sap flow measurement taken in M. philippensis during 2014 in Barkot forest showed that,the sap flow rate varied with time of day and season and also with radial depth of the tree trunk. The average daily sap flow rate was found to be 11.5 ± 1.7 cm h-1. Month-wise daily sap flow rate ranged between 4.4 to 10.6 cm h-1in outer portion of the trunk and 12.7 to 17.7cm h-1 in the inner portion of the trunk. Night-time sap flow contributed about 44 per cent of the total annual sap flow. Relative humidity was found to have slightly higher effect on diurnal sap flow rate than air temperature. Monthly sap flow was found to be a function of air temperature. The sap flow rate obtained during this study will be used in augmenting carbon flux studies being carried out in Barkot Flux site (BFS) and can be used in development of canopy conductance and stand transpiration models and validations.
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Zhou, Qing Yun, Yang Ren Wang, and Shu Hong Sun. "Characteristic of Sap Flow of Poplar and Response to Meteorological Factors in Coastal Region." Advanced Materials Research 1010-1012 (August 2014): 1055–58. http://dx.doi.org/10.4028/www.scientific.net/amr.1010-1012.1055.
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Thermal dissipation sap flow rate probe was used to measure trunk sap flow dynamic of Poplar during the growing season from September 2011 to May 2012 in coastal region of China. The relationship of trunk sap flow rate and meteorological factors was analyzed. The results showed that the process of sap flow rate of Poplar presented an obvious day and night alternate phenomenon. The diurnal variation of sap flow was a single-peak curve in sunny day and a multi-peak curve in rainy day. According to Pearson correlation analysis, the diurnal sap flow rate of Poplar was positively correlated with solar radiation and atmospheric temperature, and negatively correlated with air relative humidity. The regression analysis showed that there was a significant correlation between multi-day sap flow rate and solar radiation, and the determination coefficient was 0.287 and 0.778 in summer and autumn, respectively. The linear regression model of multi-day sap flow with meteorological multi-factor was remarkable correlation, and the determination coefficient was 0.577 and 0.791 in summer and autumn, respectively. The regression model of multi-day sap flow with meteorological multi-factor was better than with single meteorological factor.
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Dugas, William A. "Sap flow in stems." Remote Sensing Reviews 5, no. 1 (January 1990): 225–35. http://dx.doi.org/10.1080/02757259009532131.
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Battey, N. H. "April-watching sap flow." Journal of Experimental Botany 54, no. 385 (April 4, 2003): 1121–24. http://dx.doi.org/10.1093/jxb/erg137.
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Gordon, R., D. M. Brown, A. Madani, and M. A. Dixon. "An assessment of potato sap flow as affected by soil water status, solar radiation and vapour pressure deficit." Canadian Journal of Soil Science 79, no. 2 (May 1, 1999): 245–53. http://dx.doi.org/10.4141/s97-079.
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Water-use of three field-grown potato cultivars (Atlantic, Monona and Norchip) was examined using a commercially available sap flow monitoring system over three consecutive growing seasons. The objectives of the investigation were to utilize the sap flow system to assess the water use of three field-grown potato cultivars. This included an assessment of the relationship between environmental conditions, water status and measured sap flow including the plant-to-plant variation in sap flow and an evaluation of relative transpiration in relation to the soil water status.Each cultivar maintained daily sap flow close to the atmospheric potential transpiration until approximately 70% of the available water was depleted. Under conditions where the soil was drier (>70% depleted), Monona potato plants exhibited a more rapid decline in transpiration than Norchip and Atlantic.Hourly sap flow rates were closely related to solar irradiance, especially under well-watered conditions, with no apparent light saturation point. Vapour pressure deficit effects on sap flow were less pronounced, although maximum vapour pressure deficits encountered were only 2 kPa. Key words: Water use, sap flow, transpiration, potato
9
Kim, Y. T., and R. H. Leech. "Effects of Climatic Conditions on Sap Flow in Sugar Maple." Forestry Chronicle 61, no. 4 (August 1, 1985): 303–7. http://dx.doi.org/10.5558/tfc61303-4.
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Temperature, sunlight and precipitation were studied to examine their influence on sugar maple (Acer saccharum Marsh) sap flow over a five-year period. Temperature was the most important climatic factor influencing the amount of sap flow. Sunlight also increased the sap flow, but rain one day before the sap collection reduced it.
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Yin, Li He, Guan Ccai Hou, Jin Ting Huang, Jia Qiu Dong, Jing Zhang, Hong Bo Li, and Ying Li. "Time Lag between Sap Flow and Climatic Factors in Arid Environments." Advanced Materials Research 518-523 (May 2012): 1647–51. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.1647.
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Sap flow of trees was controlled by climatic variables and a time lag presents between them. In this study, Time lag between sap flow and climatic factors was analyzed for willow in the Ordos Plateau. The result shows that sap flow velocity lags behind net radiation about 110 minutes and there is almost no time lag between net radiation and sap flow velocity.
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Fan, Bo, Ziqi Liu, Kangning Xiong, Yuan Li, Kaiping Li, and Xiao Yu. "Influence of Environmental Factors on the Sap Flow Activity of the Golden Pear in the Growth Period of Karst Area in Southern China." Water 14, no. 11 (May 26, 2022): 1707. http://dx.doi.org/10.3390/w14111707.
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Under extreme drought and climate change, golden pear trees have experienced problems such as yield reduction, dryness and death. This suggests that we know very little about the mechanisms regulating pear tree growth, assuming that meteorological factors positively influence plant sap flow. Based on this, we used the heat ratio method to monitor the sap flow of pear trees from June to December 2020, and recorded the changes in various environmental factors. The results showed that: (1) Sap flow velocity has obvious radial variability in tree sections; the sap flow velocity during the day was significantly higher than that at night (p < 0.05) and was higher in the growing season than in the non-growing season. (2) All environmental factors, except relative humidity and precipitation, were positively correlated with sap flow, vapor pressure deficit and photosynthetically active radiation, which are the key factors affecting daytime flow, and vapor pressure deficit and plant water potential are the key factors affecting nighttime flow. The linear regression results also showed that the daytime sap flow had a significant positive effect on the nighttime sap flow (p < 0.05). (3) The contribution of night flow to total daily flow varied from 17.3% to 50.7%, and most of the non-growing season values were above 40%. The results show that nighttime sap flow accounts for a significant portion of the pear tree’s water budget. Continuous irrigation during fruit enlargement and non-growing seasons will increase fruit yield and maintain plant sap flow activity to avoid death due to drought.
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Steppe, Kathy, Raoul Lemeur, and Diego Dierick. "Unravelling the relationship between stem temperature and air temperature to correct for errors in sap-flow calculations using stem heat balance sensors." Functional Plant Biology 32, no. 7 (2005): 599. http://dx.doi.org/10.1071/fp04242.
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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.
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Hara, Yuki, Naoki Hara, Hiroki Ishizuka, Kyohei Terao, Hidekuni Takao, and Fusao Shimokawa. "Microscale Xylem Sap Flow Sensor Facilitating the Simultaneous Measurement of Flow Velocity and Direction." Proceedings 2, no. 13 (January 31, 2019): 824. http://dx.doi.org/10.3390/proceedings2130824.
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In this study, we focused on direct and quantitative monitoring of sap dynamics in plant stems, and proposed the microscale xylem sap flow sensor. This sensor facilitates the simultaneous measurement of flow velocity and direction by combining the principles of a Granier sensor and a thermal flow sensor. We fabricated micro-sensor chips for functional verification by using MEMS technology, and assembled them on a resin film to facilitate mounting on the epidermis of plants. Furthermore, we measured the sap dynamics by using an experimental setup, and succeeded in measuring the flow velocity and direction at the same time.
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Uddin, Jasim, Rod Smith, Nigel Hancock, and Joseph Foley. "Evaluation of Sap Flow Sensors to Measure the Transpiration Rate of Plants during Canopy Wetting and Drying." Journal of Agricultural Studies 2, no. 2 (August 14, 2014): 105. http://dx.doi.org/10.5296/jas.v2i2.6134.
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Accurate measurement of transpiration is required to estimate the various components of evaporation losses during sprinkler irrigation. Among the methods, sap flow measurements have widely used for direct measurements of transpiration rate in plant. To evaluate the applicability of this method to field experiments involving canopy wetting (by sprinkler irrigation), stem flow measurements were compared with transpiration values estimated from successive mass measurements of small potted plants using pre-calibrated mini-lysimeters in a glasshouse at the University of Southern Queensland, during the period August–October 2010. From this study it was found that when the canopy was dry, the sap flow measurements mirrored the transpiration rate of plants with reasonable accuracy, overestimating the transpiration rate by about 11%. The measurements showed no evidence of time lag between sap flow and transpiration. Following wetting of the plant canopy the sap flow declined rapidly reflecting a decline in the transpiration rate transpiration and sap flow. Location of the sap flow gage on the stem was seen to be a factor with gages at different heights giving different sap flow rates again due to the buffering capacity of the stem.
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Forster, Michael A. "A Test of the Relationship between Sap Flow and Evapotranspiration, Normalized via Leaf Area, under Non-Limiting Soil Moisture." Forests 12, no. 7 (July 2, 2021): 875. http://dx.doi.org/10.3390/f12070875.
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Sap flow is the movement of fluid within plants, whereas reference evapotranspiration (ETo) occurs external to plants as the transfer of water vapor from a hypothetical grass crop. Yet, on daily time scales, and when soil moisture is non-limiting, sap flow has a positive linear relationship with ETo. Furthermore, the E2.88 model hypothesises that sap flow (Q) is equal to ETo when parameters are normalized by leaf area (AL) via the following relationship: Q/AL = ETo/2.88. The value of 2.88 is the supposed leaf area index of the hypothetical grass in the ETo model. Therefore, the E2.88 model potentially provides a null or expected value of sap flow based on independent ETo parameters and leaf area. A test of the E2.88 model was conducted via three sap flow methods (dual method approach [DMA], heat ratio [HRM], and Tmax method) on the measurement of three woody species: Pyrus communis L. (var. Beurre Bosc Pear), Syzygium floribundum F. Muell. (Weeping Lilly Pilly), and Syzygium paniculatum Gaertn. (Lilly Pilly). A data compilation of the literature expanded the sample size to include additional species. The measured trees and data compilation found a strong, positive correlation between sap flow and ETo normalized by leaf area. However, the interpretation of the results was dependent on the sap flow method. The DMA had an average accuracy of 1.6%, whereas the HRM and Tmax significantly underestimated and overestimated sap flow, respectively. This study suggested that sap flow can be reliably estimated from accurate leaf area and ETo measurements and when other variables, such as soil moisture, are non-limiting.
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Heilman, J. L., and J. M. Ham. "Measurement of Mass Flow Rate of Sap in Ligustrum japonicum." HortScience 25, no. 4 (April 1990): 465–67. http://dx.doi.org/10.21273/hortsci.25.4.465.
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The heat balance method of measuring mass flow of sap was tested on wax leaf ligustrum (Ligustrum japonicum Thunb.) to evaluate its usefulness for measuring water use in shrubs. Sap flow measurements were compared with gravimetric estimates of transpiration in growth chamber and field environments. Sap flow measurements in both environments were within 10% of transpiration, which compared favorably with results reported for herbaceous plants by other researchers. Sizable differences in sap flow, due mainly to differences in leaf area, were found among five plants tested in the field. When flow was expressed on a unit leaf-area basis, differences among plants were greatly reduced. Measurements under partly cloudy skies with fluctuating irradiance showed that changes in sap flow matched those occurring in irradiance.
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Pearsall, Kyle R., Larry E. Williams, Sean Castorani, Tim M. Bleby, and Andrew J. McElrone. "Evaluating the potential of a novel dual heat-pulse sensor to measure volumetric water use in grapevines under a range of flow conditions." Functional Plant Biology 41, no. 8 (2014): 874. http://dx.doi.org/10.1071/fp13156.
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The aim of this study was to validate a novel, dual sap-flow sensor that combines two heat-pulse techniques in a single set of sensor probes to measure volumetric water use over the full range of sap flows found in grapevines. The heat ratio method (HRM), which works well at measuring low and reverse flows, was combined with the compensation heat-pulse method (CHPM) that captures moderate to high flows. Sap-flow measurements were performed on Vitis vinifera L. (cvv. Thompson seedless, Chardonnay and Cabernet Sauvignon) grapevines growing in a greenhouse and in three different vineyards, one of which contained a field weighing lysimeter. The combined heat-pulse techniques closely tracked diurnal grapevine water use determined through lysimetry in two growing seasons, and this was true even at very high flow rates (>6 L vine–1 h–1 for Thompson seedless vines in the weighing lysimeter). Measurements made with the HRM technique under low flow conditions were highly correlated (R2 ~ 0.90) with those calculated using the compensated average gradient method that is used to resolve low flow with the CHPM method. Volumetric water use determined with the dual heat-pulse sensors was highly correlated with hourly lysimeter water use in both years (R2 = 0.92 and 0.94 in 2008 and 2009 respectively), but the nature of the relationship was inconsistent among replicate sensors. Similar results were obtained when comparing grapevine water use determined from sap-flow sensors to miniaturised weighing lysimetry of 2-year-old potted vines and to meteorological estimates for field-grown vines in two additional vineyards. The robust nature of all of the correlations demonstrates that the dual heat-pulse sensors can be used to effectively track relative changes in plant water use, but variability of flow around stems makes it difficult to accurately convert to sap-flow volumes.
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Bouamama-Gzara, Badra, Hassene Zemni, Noomene Sleimi, Abdelwahed Ghorbel, Lassaad Gzara, and Naima Mahfoudhi. "Diversification of Vascular Occlusions and Crystal Deposits in the Xylem Sap Flow of Five Tunisian Grapevines." Plants 11, no. 16 (August 22, 2022): 2177. http://dx.doi.org/10.3390/plants11162177.
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Xylem vessels are essential pivotal organs in bulk hydraulic flow through the whole woody plant. However, environmental constraints generate disagreements in xylem structures, which are characterized by air emboli and occlusions formations, compromising water conductivity in grapevines. The aim of this work was to explore xylem morphology dynamics through the xylem sap flow of five Tunisian grapevine cultivars during the natural bleeding sap periods of 2019, 2021, and 2022. In fact, Sakasly, Khamri, Hencha, Razegui1, and Razegui2 rain-fed grapevine cultivars revealed differential responses towards xylem sap movement. The results demonstrated that the xylem sap flow was significantly more abundant in 2019 than 2021 and 2022 bleeding sap campaigns. A variation was revealed between the cultivars regarding the xylem sap flow. In fact, Sakasly gave the best xylem flow during the three campaigns. Razegui1 and Razegui2 registered approximately similar xylem sap flow, while Hencha and Khamri present the lowest sap fluxes during the three campaigns. Moreover, several vascular occlusions forms were identified from stem cross sections using environmental scanning electron microscopy (ESEM), including tyloses, gels, starch, and gum deposits. The highest occlusion number was observed in Sakasly, Razegui1, and Razegui2 cultivars. Among different biogenic calcium shapes, several were observed for the first time in grapevine, including multi-faceted druse, cubic, crystalline sand, styloids, spherical, or drop-like structures. Considering their lower flow and totally blocked vessels, both Hencha and Khamri confirmed their susceptibility to environmental constraints. However, Sakasly, Razegui1, and Razegui2 cultivars presented higher tolerance according to their sap flow and xylem morphology.
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Lang, Alexander, and Richard K. Volz. "Spur Leaves Increase Calcium in Young Apples by Promoting Xylem Inflow and Outflow." Journal of the American Society for Horticultural Science 123, no. 6 (November 1998): 956–60. http://dx.doi.org/10.21273/jashs.123.6.956.
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The effects of spur leaf removal on xylem sap flows and calcium accumulation in fruit of apple (Malus ×domestica Borkh. `Royal Gala') were determined 56 to 61 days after full bloom. Fruit calcium concentrations were reduced but fruit size was not influenced by partial spur defoliation at bloom. Apples exchanged xylem sap with the tree in daily cycles of flow reversal. The presence of local spur leaves promoted this exchange by accentuating the xylem sap drawn out of the fruit during the day, requiring more to flow back into the fruit at night to replace it. Calcium concentrations were lower in the xylem sap leaving the fruit than in that entering it. The reduced calcium accumulation in the fruit borne on defoliated spurs can therefore be attributed to the reduced volume of xylem sap exchanged between tree and fruit.
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Hussein, Ismail A., and Marshall J. McFarland. "Rootstock-induced Differences in Sap Flow of `Granny Smith' Apple." HortScience 29, no. 10 (October 1994): 1120–23. http://dx.doi.org/10.21273/hortsci.29.10.1120.
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Two-year-old, greenhouse-grown, potted `Granny Smith' apple (Malus domestica Borkh.) trees grafted on seedling, M.7 EMLA, or Mark rootstock were subjected to water stress by withholding irrigation for three successive days. Sap flow rates were measured with steady-state, heat-balance stem gauges; daily water use was measured with an electronic balance; and instantaneous transpiration was measured with a diffusion porometer. Differences in the sap flow among the three rootstocks were observed by the third day of stress treatment. The cumulative sap flow over the 3-day stress period was higher for trees on seedling and M.7 EMLA rootstocks than for those on Mark. Cumulative sap flow was reduced on the second and third days of water stress compared to sap flow in the control. The diurnal peak of sap flow rate was flattened on the second and third days of stress compared to the pattern for the control and first day of stress treatment. In general, the trees on the standard rootstock (seedling) were least affected by the water stress; trees on the full dwarf rootstock (Mark) were the most affected. Good agreement between cumulative sap flow measurements and gravimetric measurements indicates that the steady-state, heat-balance method is practical and accurate.
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Tian, Yuan, Qiuliang Zhang, Xuan Liu, Meng Meng, and Bing Wang. "The Relationship between Stem Diameter Shrinkage and Tree Bole Moisture Loss Due to Transpiration." Forests 10, no. 3 (March 23, 2019): 290. http://dx.doi.org/10.3390/f10030290.
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The responsiveness of four types of stem diameter shrinkage indicators to sap flow changes was compared under four air temperature and cloudiness conditions: above 0 °C below 80% cloud cover days; above 0 °C large percentage cloud cover days; low temperature below 80% cloud cover days; and low temperature large percentage cloud cover days. In this study, we investigated the effects of indicative functions of relatively easy-to-access stem diameter shrinkage on variation characteristics of sap flow. High-resolution-based stem diameter shrinkage is related to changes in tree moisture content. Stem diameter shrinkage indicators are adopted to confirm sap flow changes resulting from transpiration pull, which may enhance the power of stem diameter shrinkage as an index for tree bole moisture loss. After measuring stem diameter variations, the following stem diameter shrinkage indicators were calculated: maximum daily shrinkage, daily stem diameter increment, daily stem diameter variation, and tree water deficit-induced stem shrinkage (TWD). Sap flow was measured synchronously, and stem diameter shrinkage indicators were analyzed to confirm their responses to sap flow. TWD was positively correlated (r ≥ 0.317) with daily variations in sap flow and reached extremely significant levels (p ≤ 0.001) under all conditions. TWD and maximum daily shrinkage were able to better reflect the correlation between changes in stem diameter and sap flow on a daily scale, except large percentage cloud cover days with low temperatures. Changes in stem diameter had no correlation with sap flow during low temperature and large percentage cloud cover days. Among all stem diameter shrinkage indicators, TWD showed the highest correlation (r ≥ 0.601 and p ≤ 0.001) with sap flow under all conditions, except during large percentage cloud cover days with low temperatures. The stem diameter shrinkage indicators did not reflect sap flow changes during large percentage cloud cover days with low temperatures. The indicator that best reflected moisture loss of trees was TWD.
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Hu, Meijun, Changming Ma, Jinsong Zhang, Yujie Ma, Chunyou Li, and Wei Xiong. "Calibration of Thermal Dissipation Probes for Xylem Sap Flow in the Wood of a Diffuse-Porous and a Conifer Species under Cyclic Heating." Forests 13, no. 11 (November 21, 2022): 1964. http://dx.doi.org/10.3390/f13111964.
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The most popular sap flow measurement technique uses thermal dissipation probes. Differences in wood characteristics and the natural temperature gradient between probes have affected the accuracy and applicability of the sap flow equation. In addition, the continued heat of the probe can also cause thermal damage to tree tissue. The objectives of this study were to use cyclic heating and calibrate the probes with two species: Pinus bungeana Zucc. And Salix matsudana Koidz., two typical diffuse-porous species. This experiment evaluated a thermal dissipation probe in three heating modes: continuous heating, 10 min heating and 50 min cooling (10/50), and 30 min heating and 30 min cooling (30/30). The heating modes were evaluated on two species. Temperature differences between the heating needle and the control needle under different heating modes and transpiration water consumption (whole-tree weighing method) were observed simultaneously. The sap flow estimation equation under cyclic heating mode was established by analyzing the relationship between the sap flow rate and the values obtained from whole-tree weighing. The results showed that the original equation underestimated sap flow rate of P. bungeana and S. matsudana by 67% and 60%. Under the cyclic heating modes, the modified equations were different from the original equation, and their accuracy was improved. After verification, the corrected equations [Fd = 0.0264K0.738 (P. bungeana, 30/30, R2 = 0.67), Fd = 0.0722K1.113(S. matsudana, 30/30, R2 = 0.60), Fd is the sap flow density, K is temperature coefficient] reduced the influence of the natural temperature gradient on the estimation of sap flow rate, thereby significantly improving the accuracy of sap flow rate estimation. The resulting equation may be more suitable for actual field observations of sap flow in the two tested species. The cyclic heating mode has the potential to measure plant transpiration for extended periods in the field.
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Schmid, J., and E. H. Rühl. "SAP FLOW MEASUREMENTS ON GRAPEVINES." Acta Horticulturae, no. 427 (December 1996): 27–28. http://dx.doi.org/10.17660/actahortic.1996.427.3.
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Schurer, K. "HEAT-PULSE SAP FLOW METER." Acta Horticulturae, no. 174 (December 1985): 541–46. http://dx.doi.org/10.17660/actahortic.1985.174.72.
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Lawrence, Beth Jez, and Jayne M. Zajicek. "SUPRAOPTIMAL ROOT-ZONE TEMPERATURE EFFECTS ON WATER USE OF THREE CERCIS SPP." HortScience 27, no. 6 (June 1992): 635c—635. http://dx.doi.org/10.21273/hortsci.27.6.635c.
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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.
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Engeda, A., and Y. Elkacimi. "A regenerative flow compressor as a secondary air pump for engine emission control." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 9 (September 1, 2008): 1707–15. http://dx.doi.org/10.1243/09544062jmes958.
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A secondary air pump (SAP) is an air compressor that supplies air to the exhaust system of an automotive engine for the emission control of the engine. The SAP system has been offered as an emission control device in later versions of cars, starting in the mid-1990s. Various types of rotary and positive displacement air pumps have been tested and used for SAP application. The regenerative flow compressor/pump (RFC or RFP) and the centrifugal compressor have been found to be best suited for SAP application. This paper discusses the performance of an RFC for SAP application and shows the RFC to be the best choice for satisfying the required specifications of the SAP. Computational fluid dynamics analysis of the RFC for an SAP application was carried out to study its performance in detail.
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Qiang, Yuquan, Xianying Xu, and Jinchun Zhang. "Study on the Dynamics of Stem Sap Flow in Minqin Wind and Sand Control Haloxylon ammodendron Forest, China." Sustainability 15, no. 1 (December 29, 2022): 609. http://dx.doi.org/10.3390/su15010609.
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In this study, we obtained real-time data on the stem fluid flow of Haloxylon ammodendron in the growing season in Minqin, China, based on thermal diffusion (TDP) monitoring technology, and analyzed the dynamic changes of stem fluid flow in it to provide important supporting evidence for understanding the water consumption of H. ammodendron during its growth. The results indicate that the fluid flow in the stem of the H. ammodendron increases with increasing growth age and also decreases as the H. ammodendron grows older and declines. The average daily sap flow rates of H. ammodendron stems were 0.956, 1.059, 1.460 and 0.570 cm3·(cm2·h)−1 at 5, 10, 15 and 20 years, respectively, and the cumulative sap flow masses during the growing season from May to October were 610.173, 423.386, 1041.186 and 430.212 kg, respectively. H. ammodendron stem sap flow increases with the thickening of H. ammodendron’s ground diameter. The average daily sap flow rate of H. ammodendron stems at different stem levels ranged from 0.276 to 2.132 cm3·(cm2·h)−1, and the cumulative sap flow mass during the growing season ranged from 121.656 to 1722.810 kg. The larger the diameter of the H. ammodendron at different forest ages, the earlier the sap flow initiation time and the higher the peak. The stem flow initiation time was 7:00–8:00, and the average daily maximum fluid flow rate was 2.493–5.536 cm3·(cm2·h)−1, with the peak occurrence time advancing with age. The sap flow variation of H. ammodendron at different stand ages reflects the water-consuming process of H. ammodendron growth and its response to a drought environment, while the sap flow variation of H. ammodendron at different diameter classes shows that the individual growth differences of H. ammodendron also yield obvious competitive advantages. The results of the analysis can provide theoretical support for the estimation of ecological water use in desert H. ammodendron sand-fixing forests.
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Jian, Shengqi, Zening Wu, Caihong Hu, and Xueli Zhang. "Sap flow in response to rainfall pulses for two shrub species in the semiarid Chinese Loess Plateau." Journal of Hydrology and Hydromechanics 64, no. 2 (June 1, 2016): 121–32. http://dx.doi.org/10.1515/johh-2016-0023.
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Abstract Rainfall pulses can significantly drive the evolution of the structure and function of semiarid ecosystems, and understanding the mechanisms that underlie the response of semiarid plants to rainfall is the key to understanding the responses of semi–arid ecosystems to global climatic change. We measured sap flow in the branches and stems of shrubs (Caragana korshinskii Kom. and Hippophae rhamnoides Linn.) using sap flow gauges, and studied the response of sap flow density to rainfall pulses using the “threshold–delay” model in the Chinese Loess Plateau. The results showed that the sap flow began about 1 h earlier, and increased twofold after rainfall, compared to its pre-rainfall value. The sap flow increased significantly with increasing rainfall classes, then gradually decreased. The response of sap flow was different among rainfall, species, position (branch and stem) during the pulse period, and the interactive effects also differed significantly (P < 0.0001). The response pattern followed the threshold–delay model, with lower rainfall thresholds of 5.2, 5.5 mm and 0.7, 0.8 mm of stem and branch for C. korshinskii and H. rhamnoides, demonstrating the importance of small rainfall events for plant growth and survival in semi–arid regions.
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Solum, James, and Bwalya Malama. "Estimating Canopy-Scale Evapotranspiration from Localized Sap Flow Measurements." Water 14, no. 11 (June 4, 2022): 1812. http://dx.doi.org/10.3390/w14111812.
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The results reported in this work are based in part on measurements of sap flow in a few select trees on a representative riparian forest plot coupled with a forest-wide randomized sampling of tree sapwood area in a watershed located along the Pacific coast in Santa Cruz County, California. These measurements were upscaled to estimate evapotranspiration (ET) across the forest and to quantify groundwater usage by dominant phreatophyte vegetation. Canopy cover in the study area is dominated by red alder (Alnus rubra) and arroyo willow (Salix lasiolepis), deciduous phreatophyte trees from which a small sample was selected for instrumentation with sap flow sensors on a single forest plot. These localized sap flow measurements were then upscaled to the entire riparian forest to estimate forest ET using data from a survey of sapwood area on six plots scattered randomly across the entire forest. The estimated canopy-scale ET was compared to reference ET and NDVI based estimates. The results show positive correlation between sap flow based estimates and those of the other two methods, though over the winter months, sap flow-based ET values were found to significantly underestimate ET as predicted by the other two methods. The results illustrate the importance of ground-based measurements of sap flow for calibrating satellite based methods and for providing site-specific estimates and to better characterize the ET forcing in groundwater flow models.
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Dirnagl, Ulrich, and William Pulsinelli. "Autoregulation of Cerebral Blood Flow in Experimental Focal Brain Ischemia." Journal of Cerebral Blood Flow & Metabolism 10, no. 3 (May 1990): 327–36. http://dx.doi.org/10.1038/jcbfm.1990.61.
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The relationship between systemic arterial pressure (SAP) and neocortical microcirculatory blood-flow (CBF) in areas of focal cerebral ischemia was studied in 15 spontaneously hypertensive rats (SHRs) anesthetized with halothane (0.5%). Ischemia was induced by ipsilateral middle cerebral artery/common carotid artery occlusion and CBF was monitored continuously in the ischemic territory using laser-Doppler flowmetry during manipulation of SAP with I-norepinephrine (hypertension) or nitroprusside (hypotension). In eight SHRs not subjected to focal ischemia, we demonstrated that 0.5% halothane and the surgical manipulations did not impair autoregulation. Autoregulation was partly preserved in ischemic brain tissue with a CBF of >30% of preocclusion values. In areas where ischemic CBF was <30% of preocclusion values, autoregulation was completely lost. Changes in SAP had a greater influence on CBF in tissue areas where CBF ranged from 15 to 30% of baseline (9% change in CBF with each 10% change in SAP) than in areas where CBF was <15% of baseline (6% change in CBF with each 10% change in SAP). These findings demonstrate that the relationship between CBF and SAP in areas of focal ischemia is highly dependent on the severity of ischemia. Autoregulation is lost in a gradual manner until CBF falls below 30% of normal. In areas without autoregulation, the slope of the CBF/SAP relationship is inversely related to the degree of ischemia.
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Vandegehuchte, Maurits W., and Kathy Steppe. "Sap-flux density measurement methods: working principles and applicability." Functional Plant Biology 40, no. 3 (2013): 213. http://dx.doi.org/10.1071/fp12233.
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Sap-flow measurements have become increasingly important in plant science. Since the early experiments with dyes, many methods have been developed. Most of these are based on the application of heat in the sapwood which is transported by the moving sap. By measuring changes in the temperature field around the heater, sap flow can be derived. Although these methods all have the same basis, their working principles vary widely. A first distinction can be made between those measuring the sap-flow rate (g h–1) such as the stem heat balance and trunk sector heat balance method and those measuring sap-flux density (cm3 cm–2 h–1). Within the latter, the thermal dissipation and heat field deformation methods are based on continuous heating, whereas the compensation heat pulse velocity, Tmax, heat ratio, calibrated average gradient and Sapflow+ methods are based on the application of heat pulses. Each of these methods has its advantages and limitations. Although the sap-flow rate methods have been adequately described in previous reviews, recent developments in sap-flux density methods prompted a synthesis of the existing but scattered literature. This paper reviews sap-flux density methods to enable users to make a well founded choice, whether for practical applications or fundamental research questions, and to encourage further improvement in sap-flux density measurement techniques.
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Vandegehuchte, Maurits W., and Kathy Steppe. "Corrigendum to: Sap-flux density measurement methods: working principles and applicability." Functional Plant Biology 40, no. 10 (2013): 1088. http://dx.doi.org/10.1071/fp12233_co.
Full textAbstract:
Sap-flow measurements have become increasingly important in plant science. Since the early experiments with dyes, many methods have been developed. Most of these are based on the application of heat in the sapwood which is transported by the moving sap. By measuring changes in the temperature field around the heater, sap flow can be derived. Although these methods all have the same basis, their working principles vary widely. A first distinction can be made between those measuring the sap-flow rate (g h–1) such as the stem heat balance and trunk sector heat balance method and those measuring sap-flux density (cm3 cm–2 h–1). Within the latter, the thermal dissipation and heat field deformation methods are based on continuous heating, whereas the compensation heat pulse velocity, Tmax, heat ratio, calibrated average gradient and Sapflow+ methods are based on the application of heat pulses. Each of these methods has its advantages and limitations. Although the sap-flow rate methods have been adequately described in previous reviews, recent developments in sap-flux density methods prompted a synthesis of the existing but scattered literature. This paper reviews sap-flux density methods to enable users to make a well founded choice, whether for practical applications or fundamental research questions, and to encourage further improvement in sap-flux density measurement techniques.
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Eliades, Marinos, Adriana Bruggeman, Hakan Djuma, and Maciek Lubczynski. "Tree Water Dynamics in a Semi-Arid, Pinus brutia Forest." Water 10, no. 8 (August 6, 2018): 1039. http://dx.doi.org/10.3390/w10081039.
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This study aims to examine interactions between tree characteristics, sap flow, and environmental variables in an open Pinus brutia (Ten.) forest with shallow soil. We examined radial and azimuthal variations of sap flux density (Jp), and also investigated the occurrence of hydraulic redistribution mechanisms, quantified nocturnal tree transpiration, and analyzed the total water use of P. brutia trees during a three-year period. Sap flow and soil moisture sensors were installed onto and around eight trees, situated in the foothills of the Troodos Mountains, Cyprus. Radial observations showed a linear decrease of sap flux densities with increasing sapwood depth. Azimuthal differences were found to be statistically insignificant. Reverse sap flow was observed during low vapor pressure deficit (VPD) and negative air temperatures. Nocturnal sap flow was about 18% of the total sap flow. Rainfall was 507 mm in 2015, 359 mm in 2016, and 220 mm in 2017. Transpiration was 53%, 30%, and 75%, respectively, of the rainfall in those years, and was affected by the distribution of the rainfall. The trees showed an immediate response to rainfall events, but also exploited the fractured bedrock. The transpiration and soil moisture levels over the three hydrologically contrasting years showed that P. brutia is well-adapted to semi-arid Mediterranean conditions.
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Bleby, Timothy M., Stephen S. O. Burgess, and Mark A. Adams. "A validation, comparison and error analysis of two heat-pulse methods for measuring sap flow in Eucalyptus marginata saplings." Functional Plant Biology 31, no. 6 (2004): 645. http://dx.doi.org/10.1071/fp04013.
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We validated and compared two heat-pulse methods for measuring sap flow in potted Eucalyptus marginata Donn ex. Smith (jarrah) saplings. During daylight hours and under well-watered conditions, rates of sap flow (0.1–0.5 kg h–1) measured by the established compensation heat-pulse method (CHPM) and the newly developed heat-ratio method (HRM) were similar to rates measured with a weighing lysimeter, and most of the time there was no significant difference (P<0.001) between methods. The HRM accurately described sap flow at night when rates of flow were low (< 0.1 kg h–1) or near zero, but the CHPM was unable to measure low rates of sap flow due to its inability to distinguish heat-pulse velocities below a threshold velocity of 0.1 kg h–1 (3–4 cm h–1). The greatest potential for error in the calculation of daily sap flow was associated with the misalignment of temperature sensors, the estimation of sapwood area and the method used to acquire total sap flow from point measurements of sap velocity. A direct comparison of the two heat-pulse methods (applied synchronously) revealed that the HRM had a more convincing mechanism for correcting spacing errors and was more resistant to random fluctuation in measurements than the CHPM. While we view the HRM more favourably than the CHPM in some key areas, both methods are valid and useful, within their constraints, for measuring transpiration in jarrah and other woody species.
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Rose, Mark A. "The Use of Sap Flow Gauges for Estimating Transpiration." HortScience 30, no. 4 (July 1995): 905C—905. http://dx.doi.org/10.21273/hortsci.30.4.905c.
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New electronic biosensors that directly monitor plant physiological and morphological processes are now being developed for use in research and commercial applications. Although methods for measuring sap flow by applying heat to stems have been used for more than 20 years, they have usually been intrusive, required empirical calibrations and conversions, and been too fragile for rugged commercial environments. A more-promising method for monitoring sap flow is balancing the thermal fluxes into and out of a stem segment using heat sources wrapped around a stem. Constant heat-balance sap-flow gauges have been used for the direct, accurate, non-invasive, and continuous measurement of sap flow rate in many herbaceous and woody plants, including forest and fruit trees, vines, landscaping shrubs, and numerous agronomic plants. The performance of sap-flow gauges has steadily improved as they have been used in a wider range of basic and applied research. Research is now being conducted to use these gauges as on-line sensors to schedule irrigations, monitor plant stress, and even control the greenhouse environment.
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Korakaki, Evangelia, and Mariangela N. Fotelli. "Sap Flow in Aleppo Pine in Greece in Relation to Sapwood Radial Gradient, Temporal and Climatic Variability." Forests 12, no. 1 (December 22, 2020): 2. http://dx.doi.org/10.3390/f12010002.
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Research Highlights: The radial gradient of sap flux density (Js) and the effects of climatic factors on sap flow of Aleppo pine were assessed at different time scales in an eastern Mediterranean ecosystem to improve our understanding of the species water balance. Background and Objectives: Aleppo pine’s sap flow radial profile and responses to environmental parameters in the eastern Mediterranean were, to our best knowledge, originating to date from more arid planted forests. Information from natural forests in this region was lacking. Our objectives were to (a) determine the species’ radial variability in Js on a diurnal and seasonal basis and under different climatic conditions, (b) scale up to tree sap flow taking into account the radial profile of Js and (c) determine the responses of Aleppo pine’s sap flow over the year to climatic variability. Materials and Methods: Js was monitored in Aleppo pine in a natural forest in northern Greece with Granier’s method using sensors at three sapwood depths (21, 51, and 81 mm) during two periods differing in climatic conditions, particularly in soil water availability. Results: Js was the highest at 21 mm sapwood depth, and it declined with increasing depth. A steeper gradient of Js in deep sapwood was observed under drier conditions. The same patterns of radial variability in Js were maintained throughout the year, but the contribution of inner sapwood to sap flow was the highest in autumn when the lower seasonal Js was recorded in both study periods. Not taking into account the radial gradient of Js in the studied Aleppo pine would result in a c. 20.2–27.7 % overestimation of total sap flow on a sapwood basis (Qs), irrespective of climatic conditions. On a diurnal and seasonal basis, VPD was the strongest determinant of sap flux density, while at a larger temporal scale, the effect of soil water content was evident. At SWC > 20% sap flow responded positively to increasing solar radiation and VPD, indicating the decisive role of water availability in the studied region. Moreover, in drier days with VPD > 0.7 KPa, SWC controlled the variation of sap flow. Conclusions: There is a considerable radial variability in Js of the studied Aleppo pine and a considerable fluctuation of sap flow with environmental dynamics that should be taken into account when addressing the species water balance.
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Qiu, Rangjian, Taisheng Du, Shaozhong Kang, Renqiang Chen, and Laosheng Wu. "Influence of Water and Nitrogen Stress on Stem Sap Flow of Tomato Grown in a Solar Greenhouse." Journal of the American Society for Horticultural Science 140, no. 2 (March 2015): 111–19. http://dx.doi.org/10.21273/jashs.140.2.111.
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Accurate measurement of crop water use under different water and nitrogen (N) conditions is of great importance for irrigation scheduling and N management. This research investigated the effect of water and N status on stem sap flow of tomato (Solanum lycopersicum) grown in an unheated solar greenhouse in northwest China. A water experiment included sufficient water supply (T1) based on in situ water content measurement, two-thirds T1 (T2) and half T1 (T3) under a typical N application rate (N1); i.e., 57.4 g·m−2 N. The N experiment included N1, two-thirds N1 (N2), and half N1 (N3) under T2 irrigation. Results showed that deficit water supply reduced the stem sap flow by 22.1% and 42.8% in T2 and T3, respectively, compared with T1. The average daily stem sap flow between N1 and N2 was similar, and both were higher than that of N3. Significant differences between N1 or N2 and N3 were only observed on four dates (totally 34 days). Nighttime stem sap flow accounted for 6.0% to 6.9% of the daily value for the water treatments and 5.7% to 8.5% of the daily value for the N treatments. No significant differences for nighttime stem sap flow were found among water and N treatments. The daily stem sap flow was significantly and positively correlated with solar radiation, air temperature, vapor pressure deficit, and reference evapotranspiration under the water and N experiments. The slopes of the regression equations between the daily stem sap flow and these parameters were lower when soil water availability was limited, whereas the slopes of the regressions had no significant differences among N treatments. A parabolic relationship between the ratio of the daily stem sap flow of water deficit treatments to that of T1 and soil relative extractable water content was observed.
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Bayona-Rodríguez, Cristihian Jarri, and Hernán Mauricio Romero. "Estimation of transpiration in oil palm (Elaeis guineensis Jacq.) with the heat ratio method." Agronomía Colombiana 34, no. 2 (May 1, 2016): 172–78. http://dx.doi.org/10.15446/agron.colomb.v34n2.55649.
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Sap flow sensors were installed on the leaf petioles of 5-year-old oil palms (Elaeis guineensis Jacq.) to measure the xylem water flow for 12 days based on the heat ratio method (HRM). It was found that young leaves have higher sap flow rates, reaching values of over 250 cm3 h-1, and that sap flow fluctuations are directly related to weather conditions, particularly the vapor pressure deficit (VPD) component. It was observed that the sap flow rates remained constant and very close to 0 cm3 h-1 between 18:00 and 6:00 h and that the upward and downward movement of sap was faster during the day, with peak levels between 9:00 and 16:00 h. Under the evaluation conditions, the oil palm crop transpiration was estimated to be 1.15 mm H2O/ha-day. The HRM is a highly repeatable method and an useful tool to quantify the total oil palm transpiration. It could potentially be applied to irrigation.
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Lawrence, B. Jez, and J. M. Zajicek. "HIGH ROOT-ZONE TEMPERATURE EFFECTS ON DIURNAL WATER USE OF WOODY ORNAMENTAL." HortScience 25, no. 9 (September 1990): 1118a—1118. http://dx.doi.org/10.21273/hortsci.25.9.1118a.
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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.
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RANASINGHE, C. S., and U. P. DE S. WAIDYANATHA. "ETHREL STIMULATION OF INFLORESCENCE SAP FLOW IN TAPPED COCONUT (COCOS NUCIFERA) PALMS." Experimental Agriculture 39, no. 2 (April 2003): 161–66. http://dx.doi.org/10.1017/s0014479702001217.
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The effect of Ethrel on the yield and sugar content of coconut (Cocos nucifera) inflorescence sap and sustainability of productivity was investigated on forty-year-old tall coconut palms (var. typica) at Bandirippuwa Estate, Lunuwila, Sri Lanka. Ethrel was applied at a concentration of 2.5% and the volume and sugar content of the sap were measured. Application of Ethrel consistently increased the yield per day, yield per spadix, yield per palm per annum and sugar content in the sap for a period of four years. The removal of carbon, nitrogen, phosphorus, potassium and magnesium with the sap was greater from Ethrel-treated than from untreated palms, and this was attributed mainly to the enhanced sap yields and sugar concentrations.
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Sun, Xi, Jie Li, Donald Cameron, and Gregory Moore. "On the Use of Sap Flow Measurements to Assess the Water Requirements of Three Australian Native Tree Species." Agronomy 12, no. 1 (December 27, 2021): 52. http://dx.doi.org/10.3390/agronomy12010052.
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The measurement of sap movement in xylem sapwood tissue using heat pulse velocity sap flow instruments has been commonly used to estimate plant transpiration. In this study, sap flow sensors (SFM1) based on the heat ratio method (HRM) were used to assess the sap flow performance of three different tree species located in the eastern suburbs of Melbourne, Australia over a 12-month period. A soil moisture budget profile featuring potential evapotranspiration and precipitation was developed to indicate soil moisture balance while the soil-plant-atmosphere continuum was examined at the study site using data obtained from different monitoring instruments. The comparison of sap flow volume for the three species clearly showed that the water demand of Corymbia maculata was the highest when compared to Melaleuca styphelioides and Lophostemon confertus and the daily sap flow volume on the north side of the tree on average was 63% greater than that of the south side. By analysing the optimal temperature and vapour pressure deficit (VPD) for transpiration for all sampled trees, it was concluded that the Melaleuca styphelioides could better cope with hotter and drier weather conditions.
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Wei, Xinguang, Shining Fu, Dianyu Chen, Siyu Zheng, Tieliang Wang, and Yikui Bai. "Grapevine Sap Flow in Response to Physio-Environmental Factors under Solar Greenhouse Conditions." Water 12, no. 11 (November 3, 2020): 3081. http://dx.doi.org/10.3390/w12113081.
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Understanding transpiration responses to physiological and environmental factors is essential for efficient water management practices in greenhouse grapevine farms. To determine the driving factors of grapevine sap flow under solar greenhouse conditions in a typical cold climate, the sap flow, greenhouse micro-environmental conditions, and canopy details were measured and analyzed for the 2017–2018 growing season in Northeast China. The results showed that leaf area index controlled the upper boundary of sap flow rate (SFR). Correlations between SFR and meteorological factors obviously varied with time scales. Besides, the correlations at the hourly scale varied across the seasons. Photo-synthetically active radiation (PAR) was the primary control factor of sap flow, irrespective of time scale or season. The start and stop times of sap flow did not change with weather conditions, but SFR had broader peaks with higher peak values during sunny days. The diurnal variation of SFR lagged behind that of PAR, but remained ahead of those of VPD and temperature. Weather condition changed the sizes of the hysteresis loops, but not the rotation direction. The hydrological and physiological processes involved in sap flow are useful for refining transpiration models and improving water use efficiency in the greenhouse environment.
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Ploetz, Randy C., Bruce Schaffer, Ana I. Vargas, Joshua L. Konkol, Juanpablo Salvatierra, and Ronney Wideman. "Impact of Laurel Wilt, Caused by Raffaelea lauricola, on Leaf Gas Exchange and Xylem Sap Flow in Avocado, Persea americana." Phytopathology® 105, no. 4 (April 2015): 433–40. http://dx.doi.org/10.1094/phyto-07-14-0196-r.
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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.
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Peng, Xuelian, Xiaotao Hu, Dianyu Chen, Zhenjiang Zhou, Yinyin Guo, Xin Deng, Xingguo Zhang, and Tinggao Yu. "Prediction of Grape Sap Flow in a Greenhouse Based on Random Forest and Partial Least Squares Models." Water 13, no. 21 (November 2, 2021): 3078. http://dx.doi.org/10.3390/w13213078.
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Understanding variations in sap flow rates and the environmental factors that influence sap flow is important for exploring grape water consumption patterns and developing reasonable greenhouse irrigation schedules. Three irrigation levels were established in this study: adequate irrigation (W1), moderate deficit irrigation (W2) and deficit irrigation (W3). Grape sap flow estimation models were constructed using partial least squares (PLS) and random forest (RF) algorithms, and the simulation accuracy and stability of these models were evaluated. The results showed that the daily mean sap flow rates in the W2 and W3 treatments were 14.65 and 46.94% lower, respectively, than those in the W1 treatment, indicating that the average daily sap flow rate increased gradually with an increase in the irrigation amount within a certain range. Based on model error and uncertainty analyses, the RF model had better simulation results in the different grape growth stages than the PLS model did. The coefficient of determination and Willmott’s index of agreement for RF model exceeded 0.78 and 0.90, respectively, and this model had smaller root mean square error and d-factor (evaluation index of model uncertainty) values than the PLS model did, indicating that the RF model had higher prediction accuracy and was more stable. The relative importance of the model predictors was determined. Moreover, the RF model more comprehensively reflected the influence of meteorological factors and the moisture content in different soil layers on the sap flow rate than the PLS model did. In summary, the RF model accurately simulated sap flow rates, which is important for greenhouse grape irrigation.
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Zeppel, Melanie, Catriona Macinnis-Ng, Anthony Palmer, Daniel Taylor, Rhys Whitley, Sigfredo Fuentes, Isa Yunusa, Mathew Williams, and Derek Eamus. "An analysis of the sensitivity of sap flux to soil and plant variables assessed for an Australian woodland using a soil - plant - atmosphere model." Functional Plant Biology 35, no. 6 (2008): 509. http://dx.doi.org/10.1071/fp08114.
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Daily and seasonal patterns of tree water use were measured for the two dominant tree species, Angophora bakeri E.C.Hall (narrow-leaved apple) and Eucalyptus sclerophylla (Blakely) L.A.S. Johnson & Blaxell (scribbly gum), in a temperate, open, evergreen woodland using sap flow sensors, along with information about soil, leaf, tree and micro-climatological variables. The aims of this work were to: (a) validate a soil–plant–atmosphere (SPA) model for the specific site; (b) determine the total depth from which water uptake must occur to achieve the observed rates of tree sap flow; (c) examine whether the water content of the upper soil profile was a significant determinant of daily rates of sap flow; and (d) examine the sensitivity of sap flow to several biotic factors. It was found that: (a) the SPA model was able to accurately replicate the hourly, daily and seasonal patterns of sap flow; (b) water uptake must have occurred from depths of up to 3 m; (c) sap flow was independent of the water content of the top 80 cm of the soil profile; and (d) sap flow was very sensitive to the leaf area of the stand, whole tree hydraulic conductance and the critical water potential of the leaves, but insensitive to stem capacitance and increases in root biomass. These results are important to future studies of the regulation of vegetation water use, landscape-scale behaviour of vegetation, and to water resource managers, because they allow testing of large-scale management options without the need for large-scale manipulations of vegetation cover.
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Alizadeh, Azadeh, Arash Toudeshki, Reza Ehsani, and Kati Migliaccio. "Potential Sources of Errors in Estimating Plant Sap Flow Using Commercial Thermal Dissipation Probes." Applied Engineering in Agriculture 34, no. 6 (2018): 899–906. http://dx.doi.org/10.13031/aea.12854.
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Thermal dissipation systems are a conventional technique to estimate sap velocity by determining the temperature difference between sap flow probes. The Thermal Dissipation Probe (TDP) method is commercially available and has been used by many researchers and professionals to estimate sap flow in plants. However, some errors and practical issues cause inaccuracy when evaluating plant sap velocity with this technique. Specifically, the sources of these errors are from the effect of the ambient thermal gradient (i.e., error caused by the cold junction location), the underestimation of nighttime sap flow, and the deficient thermal contact between the probe and tree body. This article focuses on errors associated with the traditional TDP, which effect on the thermal difference between the reference and heated probes. These errors vary as a nonlinear function of the transmitter length and the numbers of cold junctions which are affected by changes in the ambient temperature. Keywords: Ambient thermal gradient, Sap velocity, Thermal dissipation probe (TDP), Thermocouple cold junction.
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M. Siqueira, Jucilene, Teresa A. Paço, José Machado da Silva, and José C. Silvestre. "Biot-Granier Sensor: A Novel Strategy to Measuring Sap Flow in Trees." Sensors 20, no. 12 (June 22, 2020): 3538. http://dx.doi.org/10.3390/s20123538.
Full textAbstract:
The Biot-Granier (Gbt) is a new thermal dissipation-based sap flow measurement methodology, comprising sensors, data management and automatic data processing. It relies on the conventional Granier (Gcv) methodology upgraded with a modified Granier sensor set, as well as on an algorithm to measure the absolute temperatures in the two observation points and perform the Biot number approach. The work described herein addresses the construction details of the Gbt sensors and the characterization of the overall performance of the Gbt method after comparison with a commercial sap flow sensor and independent data (i.e., volumetric water content, vapor pressure deficit and eddy covariance technique). Its performance was evaluated in three trials: potted olive trees in a greenhouse and two vineyards. The trial with olive trees in a greenhouse showed that the transpiration measures provided by the Gbt sensors showed better agreement with the gravimetric approach, compared to those provided by the Gcv sensors. These tended to overestimate sap flow rates as much as 4 times, while Gbt sensors overestimated gravimetric values 1.5 times. The adjustments based on the Biot equations obtained with Gbt sensors contribute to reduce the overestimates yielded by the conventional approach. On the other hand, the heating capacity of the Gbt sensor provided a minimum of around 7 °C and maximum about 9 °C, contrasting with a minimum around 6 °C and a maximum of 12 °C given by the Gcv sensors. The positioning of the temperature sensor on the tip of the sap flow needle proposed in the Gbt sensors, closer to the sap measurement spot, allow to capture sap induced temperature variations more accurately. This explains the higher resolution and sensitivity of the Gbt sensor. Overall, the alternative Biot approach showed a significant improvement in sap flow estimations, contributing to adjust the Granier sap flow index, a vulnerability of that methodology.
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Jones, A. R. C., and I. Alli. "Sap yields, sugar content, and soluble carbohydrates of saps and syrups of some Canadian birch and maple species." Canadian Journal of Forest Research 17, no. 3 (March 1, 1987): 263–66. http://dx.doi.org/10.1139/x87-044.
Full textAbstract:
During the spring of 1984 and 1985, white birch (Betulapapyrifera Marsh), sweet birch (B. lenta L), and yellow birch (B. alleghaniensis Britt.) were tapped to determine sap yields and syrup characteristics. These properties were compared with sap yields and syrup produced from sugar maple (Acersaccharum Marsh) and red maple (A. rubrum L). The sap flow seasons were as follows: white birch, 23 days (April 7–29, 1984) and 29 days (April 5 – May 3, 1985); sweet birch, 26 days (1984); yellow birch, 25 days (1985). The sap flow season for the maple species was much earlier than the birch species. Maple sap flow seasons were as follows: sugar maple, 16 days (March 28 – April 12, 1984) and 45 days (March 10 – April 23, 1985); red maple, 44 days (March 11 – April 23, 1985). Sap yields were as follows: white birch, 80.5 L in 1984 (1.0% sap) 51.0 L in 1985 (1.0% sap); sweet birch, 48.0 L in 1984 (0.5% sap); yellow birch, 28.4 L in 1985 (0.5% sap); red maple, 30.6 L in 1985 (2.3% sap); sugar maple, 53.5 L in 1985 (4.5% sap). Sap analyses showed the average total carbohydrate content of all birch saps and all maple saps was 9.2 and 24.5 g/L, respectively. The average sugar contents of the syrups from the birch saps and the maple saps were 302 and 711 g/L, respectively. The average pH of birch and maple saps were similar but the average pH of the syrups obtained from the birch saps was substantially lower than that of the syrups obtained from the maple saps.
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Cohen, Y., F. M. Kelliher, and T. A. Black. "Determination of sap flow in Douglas-fir trees using the heat pulse technique." Canadian Journal of Forest Research 15, no. 2 (April 1, 1985): 422–28. http://dx.doi.org/10.1139/x85-068.
Full textAbstract:
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.
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Quintana, J. M., H. C. Harrison, J. P. Palta, J. Nienhuis, K. Kmiecik, and E. Miglioranza. "Xylem Flow Rate Differences Are Associated with Genetic Variation in Snap Bean Pod Calcium Concentration." Journal of the American Society for Horticultural Science 124, no. 5 (September 1999): 488–91. http://dx.doi.org/10.21273/jashs.124.5.488.
Full textAbstract:
Two commercial snap bean (Phaseolus vulgaris L.) cultivars (Hystyle and Labrador) that differ in pod Ca concentration were grown aeroponically to assess physiological factors associated with these differences. Xylem flow rate, Ca absorbed, and Ca concentration in sieve sap and pods (all and commercial size no. 4) were measured. Flow rate, Ca absorption and pod Ca concentration, but not sap Ca concentration, differed between cultivars, and this suggests that genetic variability in pod Ca concentration is caused mainly by differences in flow rate, rather than differences in sap Ca concentration. `Hystyle' showed 1.6 times greater flow rate, 1.5 times greater pod Ca concentration, and 1.7 times greater Ca absorbed than `Labrador'. Flow rate correlated positively with Ca absorbed (R = 0.90), Ca concentration in pods of size no. 4 (R = 0.55), and total pods (R = 0.65). Plant maturity influenced sap Ca concentration and Ca translocated increased as plant matured. These results provide evidence that flow rate differences may cause variability for pod Ca concentration in snap beans.