Foliar temperature as a tool for quantifying whole-plant transpiration in tree seedlings under laboratory and greenhouse conditions

Plant Ecology ◽  
2020 ◽  
Vol 221 (4) ◽  
pp. 283-293
Author(s):  
Ricardo M. Holdo ◽  
William McHargue
Keyword(s):  
Tree Seedlings ◽  
Plant Transpiration ◽  
Whole Plant

Genotypic variation in whole-plant transpiration efficiency in sorghum only partly aligns with variation in stomatal conductance

2019 ◽  
Vol 46 (12) ◽  
pp. 1072 ◽  
Author(s):  
Geetika Geetika ◽  
Erik J. van Oosterom ◽  
Barbara George-Jaeggli ◽  
Miranda Y. Mortlock ◽  
Kurt S. Deifel ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Photosynthetic Capacity ◽  
Genotypic Variation ◽  
Vapour Pressure Deficit ◽  
Genotypic Differences ◽  
Transpiration Efficiency ◽  
Plant Transpiration ◽  
Leaf Chlorophyll ◽  
Residual Variation ◽  
Whole Plant

Water scarcity can limit sorghum (Sorghum bicolor (L.) Moench) production in dryland agriculture, but increased whole-plant transpiration efficiency (TEwp, biomass production per unit of water transpired) can enhance grain yield in such conditions. The objectives of this study were to quantify variation in TEwp for 27 sorghum genotypes and explore the linkages of this variation to responses of the underpinning leaf-level processes to environmental conditions. Individual plants were grown in large lysimeters in two well-watered experiments. Whole-plant transpiration per unit of green leaf area (TGLA) was monitored continuously and stomatal conductance and maximum photosynthetic capacity were measured during sunny conditions on recently expanded leaves. Leaf chlorophyll measurements of the upper five leaves of the main shoot were conducted during early grain filling. TEwp was determined at harvest. The results showed that diurnal patterns in TGLA were determined by vapour pressure deficit (VPD) and by the response of whole-plant conductance to radiation and VPD. Significant genotypic variation in the response of TGLA to VPD occurred and was related to genotypic differences in stomatal conductance. However, variation in TGLA explained only part of the variation in TEwp, with some of the residual variation explained by leaf chlorophyll readings, which were a reflection of photosynthetic capacity. Genotypes with different genetic background often differed in TEwp, TGLA and leaf chlorophyll, indicating potential differences in photosynthetic capacity among these groups. Observed differences in TEwp and its component traits can affect adaptation to drought stress.

scholarly journals Predicting Tree Sap Flux and Stomatal Conductance from Drone-Recorded Surface Temperatures in a Mixed Agroforestry System—A Machine Learning Approach

2020 ◽  
Vol 12 (24) ◽  
pp. 4070
Author(s):  
Florian Ellsäßer ◽  
Alexander Röll ◽  
Joyson Ahongshangbam ◽  
Pierre-André Waite ◽  
Hendrayanto ◽  
...  
Keyword(s):  
Machine Learning ◽  
Stomatal Conductance ◽  
Prediction Models ◽  
Hydrological Cycle ◽  
Machine Learning Algorithms ◽  
Sap Flux ◽  
Plant Transpiration ◽  
Surface Temperatures ◽  
Whole Plant ◽  
Wide Range

Plant transpiration is a key element in the hydrological cycle. Widely used methods for its assessment comprise sap flux techniques for whole-plant transpiration and porometry for leaf stomatal conductance. Recently emerging approaches based on surface temperatures and a wide range of machine learning techniques offer new possibilities to quantify transpiration. The focus of this study was to predict sap flux and leaf stomatal conductance based on drone-recorded and meteorological data and compare these predictions with in-situ measured transpiration. To build the prediction models, we applied classical statistical approaches and machine learning algorithms. The field work was conducted in an oil palm agroforest in lowland Sumatra. Random forest predictions yielded the highest congruence with measured sap flux (r2 = 0.87 for trees and r2 = 0.58 for palms) and confidence intervals for intercept and slope of a Passing-Bablok regression suggest interchangeability of the methods. Differences in model performance are indicated when predicting different tree species. Predictions for stomatal conductance were less congruent for all prediction methods, likely due to spatial and temporal offsets of the measurements. Overall, the applied drone and modelling scheme predicts whole-plant transpiration with high accuracy. We conclude that there is large potential in machine learning approaches for ecological applications such as predicting transpiration.

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

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

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

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

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

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

scholarly journals Cold Storage Method Affects Root and Shoot Water Potential of Bare-root Hawthorn and Maple Trees

1994 ◽  
Vol 12 (4) ◽  
pp. 219-222
Author(s):  
Rick M. Bates ◽  
Alexander X. Niemiera ◽  
John R. Seiler
Keyword(s):  
Cold Storage ◽  
Water Loss ◽  
Poor Quality ◽  
Tree Seedlings ◽  
Water Potentials ◽  
Whole Plant ◽  
Norway Maple ◽  
Root Stock ◽  
Bare Root ◽  
Root Tree

Abstract Desiccation of bare-root tree seedlings during storage can result in reduced growth and poor quality after transplanting. For 12 weeks, shoot and root water potentials of bare-root Norway maple (Acer platanoides L.) and Washington hawthorn (Crataegus phaenopyrum Medic.) seedlings were measured in response to four cold storage treatments: whole plant exposed, roots exposed, shoots exposed, whole plant covered. In another experiment, water loss was measured from stem sections of both species during four weeks of cold storage. Shoot and root water potentials decreased during storage regardless of treatment or species. For maple, shoot and root water potentials of the exposed shoot treatment were the same as the whole plant covered treatment. In contrast, hawthorn shoot and root water potentials of the exposed shoot treatment were lower (more negative) than for the whole plant covered treatment. Most of the water stress experienced by roots and shoots of both species accumulated during the first six weeks of storage. Water loss was greater for hawthorn stem sections than for maple during the first two weeks of storage. Results indicated that while protection of roots of all bare-root stock reduces water loss, sensitive species such as Washington hawthorn require both root and shoot protection to minimize water loss.

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