scholarly journals Effect of canopy management in the water status of cacao (Theobroma cacao) and the microclimate within the crop area

2019 ◽  
Vol 97 (4) ◽  
pp. 701-710
Author(s):  
Alfredo Jiménez-Pérez ◽  
Manuel J. Cach-Pérez ◽  
Mirna Valdez-Hernández ◽  
Edilia De la Rosa-Manzano
Keyword(s):  
Vapor Pressure ◽  
Water Potential ◽  
Sap Flow ◽  
Theobroma Cacao ◽  
Vapor Pressure Deficit ◽  
Soil Water Potential ◽  
Flow Density ◽  
Closed Canopy ◽  
Sap Flow Density ◽  
Crop Area

Background: Cacao is an umbrophile species and therefore the handling of shade by producers can cause a microclimatic modification that influences the physiology of the plant. Questions: Can canopy management influence the microclimate of the crop area and the water content of cacao? Species of study: Theobroma cacao L. (Malvaceae). Study site: Comalcalco, Tabasco, Mexico; dry and rainy season 2018. Methods: Three sites were selected with an open canopy (OC) and three with a closed canopy (CC), where we determined air temperature and humidity, soil temperature, vapor pressure deficit, photosynthetically active radiation, soil water potential and leaf water potential in 15 cacao trees and the sap flow density in 12 trees, by canopy condition and by season. Results: Higher values of solar radiation, air and soil temperature, vapor pressure deficit and lower relative humidity were recorded under OC compared to CC, in both seasons. Differences in soil water potential between 10 and 60 cm depth in CC were recorded during the dry season. There was a lower sap flow density and daily water use in OC. The leaf water potential was similar between canopy conditions, in both seasons. Conclusions: Changes in canopy coverage significantly modify the microclimate of the crop area, a less stressful environment being generated under closed canopy conditions, influencing the sap flow density of cacao trees.

A new perspective for transpiration estimation using an extended framework of isohydricity linking to drought-driven changes in VPD and leaf area

2020 ◽  
Author(s):  
Changming Li ◽  
Hanbo Yang
Keyword(s):  
Vapor Pressure ◽  
Leaf Area Index ◽  
Water Potential ◽  
Leaf Area ◽  
Vapor Pressure Deficit ◽  
Soil Water Potential ◽  
Area Index ◽  
Atmosphere Interaction ◽  
New Perspective ◽  
New Framework

<p>The framework of isohydry or anisohydry, which is usually defined as the sensitivity of leaf water potential (Ψ<sub>L</sub>) to soil water potential (Ψs), has been rapidly adopted to solve a range of eco-hydrologic problems. While its reliability to describe the impacts of land-atmosphere interaction and seasonal phenology on plants has been recently questioned. In this study, we propose an expansion of the modern isohydricity framework to coordinate the dynamics of Ψ<sub>L</sub> derived from vapor pressure deficit (VPD) and leaf area index (A<sub>L</sub>), respectively. The contributions of VPD and A<sub>L </sub>to the sensitivity of Ψ<sub>L</sub> to Ψs are calculated and further evaluated using the FLUXNET dataset, as to validate the applicability of the extended concept. Then, we suggested a new method to calculate transpiration based on the new framework to establish relationship between Ψ<sub>L</sub> and Ψs at ecosystem scale. Our results illustrate that the new framework is reasonable for describing the dynamics of Ψ<sub>L</sub> and provides a promising potential for transpiration estimation.</p>

Evaluation of sap flow density of Acacia melanoxylon R. Br. (blackwood) trees in overstocked stands in north-western Iberian Peninsula

2008 ◽  
Vol 129 (1) ◽  
pp. 61-72 ◽  
Author(s):  
E. Jiménez ◽  
J. A. Vega ◽  
P. Pérez-Gorostiaga ◽  
T. Fonturbel ◽  
C. Fernández
Keyword(s):  
Iberian Peninsula ◽  
Sap Flow ◽  
Flow Density ◽  
Acacia Melanoxylon ◽  
Sap Flow Density ◽  
North Western

scholarly journals Mist, Vapor Pressure Deficit, and Cutting Water Potential Influence Rooting of Stem Cuttings of Loblolly Pine

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 890D-890
Author(s):  
Anthony V. LeBude* ◽  
Barry Goldfarb ◽  
Frank A. Blazich
Keyword(s):  
Vapor Pressure ◽  
Water Potential ◽  
Pinus Taeda ◽  
Loblolly Pine ◽  
Large Scale ◽  
Vapor Pressure Deficit ◽  
Adventitious Root Formation ◽  
Silica Sand ◽  
Stem Cuttings ◽  
Range Of Values

Producing high quality rooted stem cuttings on a large scale requires precise management of the rooting environment. This study was conducted to investigate the effect of the rooting environment on adventitious root formation of stem cuttings of loblolly pine (Pinus taeda L.). Hardwood stem cuttings of loblolly pine were collected in Feb. 2002 from hedged stock plants and stored at 4 °C until setting in Apr. 2002. One hundred stem cuttings per plot in each of two replications received 45, 61, 73, 102, 147, or 310 mL·m-2 of mist delivered intermittently by a traveling gantry (boom) system. Mist frequency was similar for all treatments and was related inversely to relative humidity (RH) within the polyethylene covered greenhouse. Rooting tubs in each plot were filled with a substrate of fine silica sand, and substrate water potential was held constant using soil tensiometers that activated a subirrigation system. Cutting water potential was measured destructively on two cuttings per plot beginning at 0500 hr every 3 hh until 2300 hr (seven measurements) 7, 14, 21, or 28 days after setting. During rooting, leaf temperature and RH were recorded in each plot to calculate vapor pressure deficit (VPD). Cutting water potential and VPD were strongly related to mist application. Cutting water potential was also related to VPD. Rooting percentage had a linear and quadratic relationship with mean cutting water potential and VPD averaged between 1000 and 1800 HR. Eighty percent rooting occurred within a range of values for VPD. Data suggest that VPD can be used to manage the water deficit of stem cuttings of loblolly pine to increase rooting percentage. These results may be applicable to other species and to other rooting environments.

scholarly journals The relationship between sap flow density and environmental factors in the Yangtze River Delta region

2016 ◽  
Author(s):  
Xin Liu ◽  
Bo Zhang ◽  
Donald L DeAngelis ◽  
Jinchi Zhang ◽  
Jiayao Zhuang ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Sap Flow ◽  
Yangtze River ◽  
Meteorological Data ◽  
Growth Period ◽  
Yangtze River Delta ◽  
Flow Density ◽  
Yangtze River Delta Region ◽  
Sap Flow Density ◽  
The Yangtze River Delta

Transpiration is an important component of the water balance in forest ecosystems. Quercus acutissima and Cunninghamia lanceolata are two important, fast-growing and commercial tree species that have been extensively used for vegetation restoration, water conservation and building artificial forests in the Yangtze River Delta Region of China. The primary objective of this study was to characterize sap flow densities of the two species by comparing diurnal, nocturnal and seasonal sap flow patterns and their relationships with environmental factors. Sap flow densities (Sd) were measured between September 2012 and August 2013 using the commercially-available thermal dissipation probes. Hourly meteorological data were measured in an open field, located 200 m away from the study site. Standard meteorological data were logged hourly at this site, including photosynthetically active radiation (Par), air temperature (Ta), relative air humidity (Rh), vapor pressure deficit (Vpd) and precipitation (P). Soil water content (Swc) data were logged hourly in different layers at Q.acutissima and C.lanceolata forests. Results indicated that the mean Sd in summer was higher than that in spring and autumn, and was lowest in winter. The Sd of Q. acutissima showed distinct diurnal patterns during the growth period (between May and October), and C. lanceolata followed similar sap flow patterns in all months except February. Nocturnal sap flow densities (Sdn) were noticeable and both species followed similar patterns during the growth period, in which Q. acutissima followed a power function from April to November and C. lanceolata followed similar patterns in all months except February. Pearson correlation analysis suggested that the sap flow density responded to environmental factors differently among each of the growing stages. The diurnal sap flow density (Sdd) was more sensitive to environmental factors than Sdn. The Sd during the growth period was more sensitive to environmental factors than in the dormant period. Par, Vpd and Ta were significantly correlated with Sdd in the whole year. In the nighttime, the sap flow density was also effected by the Vpd, Ta and Rh. The results of this study can be used to estimate the transpiration of Q. acutissima and C. lanceolata.

Assessing reliability of HRM sap-flow sensors under large range of vapor pressure deficit

2020 ◽  
Author(s):  
Rémy Schoppach ◽  
Daniella Ekwalla Hangue ◽  
Julian Klaus
Keyword(s):  
Vapor Pressure ◽  
Sap Flow ◽  
Vapor Pressure Deficit ◽  
Heat Waves ◽  
Linear Trend ◽  
Water Flux ◽  
Gravimetric Method ◽  
Flow Sensors ◽  
Tree Transpiration ◽  
Sap Flow Sensors

<p>Evapotranspiration (ET) is a major water flux of ecosystems and represents globally 60-80% of the incoming precipitation lost by terrestrial environments. In forested lands, tree transpiration (TR) is the dominant component of ET, yet remains challenging to measure. Over the years, sap-flow sensors have become the standard tool for quantifying tree TR and different methods based on thermal approaches have been developed. Heat ratio methods (HRM) are considered as the most reliable and accurate method to quantify absolute flows. Leading commercial brands ensure an accurate measurement of positive flows up to 100 cm hr<sup>-1</sup> but different studies have highlighted a saturation effect at high flows with threshold for accuracy remaining elusive[RS1] . Due to climate change, the occurrence, the severity and the duration of extreme events like heat waves and dry periods are expected to increase in future, so the potential for high TR rate periods will also increase. Therefore, it is crucial to determine the species-specific environmental conditions allowing a reliable measurement of TR in order to improve or understanding of eco-hydrological and physiological processes during high potential TR periods that can be crucial for vegetation survival. In this study, we tested the accuracy of HRM sap-flow sensors for beech (Fagus sylvatica) and oak (Quercus robur) tree species under extreme vapor pressure deficit (VPD) conditions in order to determine threshold for reliable measurements. In greenhouse conditions, we collected a complete and dense series of TR response to VPD between 0.7 to 8.3 kPa for potted beech and oak trees using three different methods: infrared gas analyser, gravimetric method, and HRM sap-flow sensors. Responses shown a linear trend at the low-canopy leaf level (41.5 and 45.1 mg H<sub>2</sub>O m<sup>-2</sup> s<sup>-1</sup> kPa<sup>-1</sup> respectively for beech and oak) but a bi-linear conformation at the whole plant level (1<sup>st</sup> slope = 12.04 ± 0.7 mg H<sub>2</sub>O m<sup>-2</sup> s<sup>-1</sup> kPa<sup>-1</sup> and break-point at 3.9 ± 0.07 kPa for beech trees). Sap-flow sensors using the HRM method displayed a clear inability to reliably measure flows under high VPD conditions. Thresholds of 2.25 ± 0.04 and 2.87 ± 0.14 kPa were identified as the maximum limit of method reliability for beech and oak respectively. In highly demanding environments, we suggest a bi-linear extrapolation beyond VPD threshold for better quantifying tree TR. Further experiments aiming at characterizing TR responses to VPD for a broad range of species and in different water deficit conditions are certainly needed for better understanding tree transpiration at the whole stand level.</p>

Diurnal Patterns of Water Potential in Abiesconcolor and Pinusponderosa

1973 ◽  
Vol 3 (4) ◽  
pp. 556-564 ◽  
Author(s):  
John E. Barker
Keyword(s):  
Vapor Pressure ◽  
Water Potential ◽  
Environmental Conditions ◽  
Vapor Pressure Deficit ◽  
Square Root ◽  
Relative Lack ◽  
Independent Variables ◽  
Diurnal Patterns ◽  
Available Soil Moisture ◽  
Cohesion Theory

Diurnal patterns of water potential for Abiesconcolor and Pinusponderosa were studied in relation to concurrent environmental conditions. Up to 86% of variation in water potential was accounted for using irradiance, square root of vapor pressure deficit, height, and stomatal aperture as independent variables in A. concolor while up to 76% was accounted for in P. ponderosa using the same variables. Under comparable environmental conditions, A. concolor experienced lower water potentials than P. ponderosa due to its relative lack of stomatal control and its greater sensitivity to changes in vapor pressure deficit. Height effects were very nearly identical to those predicted by the cohesion theory. A procedure for estimating available soil moisture is suggested.

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