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Koehler T, Wankmüller FJP, Sadok W, Carminati A. Transpiration response to soil drying versus increasing vapor pressure deficit in crops: physical and physiological mechanisms and key plant traits. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:4789-4807. [PMID: 37354081 PMCID: PMC10474596 DOI: 10.1093/jxb/erad221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 06/07/2023] [Indexed: 06/26/2023]
Abstract
The water deficit experienced by crops is a function of atmospheric water demand (vapor pressure deficit) and soil water supply over the whole crop cycle. We summarize typical transpiration response patterns to soil and atmospheric drying and the sensitivity to plant hydraulic traits. We explain the transpiration response patterns using a soil-plant hydraulic framework. In both cases of drying, stomatal closure is triggered by limitations in soil-plant hydraulic conductance. However, traits impacting the transpiration response differ between the two drying processes and act at different time scales. A low plant hydraulic conductance triggers an earlier restriction in transpiration during increasing vapor pressure deficit. During soil drying, the impact of the plant hydraulic conductance is less obvious. It is rather a decrease in the belowground hydraulic conductance (related to soil hydraulic properties and root length density) that is involved in transpiration down-regulation. The transpiration response to increasing vapor pressure deficit has a daily time scale. In the case of soil drying, it acts on a seasonal scale. Varieties that are conservative in water use on a daily scale may not be conservative over longer time scales (e.g. during soil drying). This potential independence of strategies needs to be considered in environment-specific breeding for yield-based drought tolerance.
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Affiliation(s)
- Tina Koehler
- Physics of Soils and Terrestrial Ecosystems, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
- Soil Physics, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
| | - Fabian J P Wankmüller
- Physics of Soils and Terrestrial Ecosystems, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
| | - Walid Sadok
- Agronomy and Plant Genetics, College of Food, Agricultural and Natural Resource Sciences, University of Minnesota, Twin Cities, MN, USA
| | - Andrea Carminati
- Physics of Soils and Terrestrial Ecosystems, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
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2
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Vadez V, Pilloni R, Grondin A, Hajjarpoor A, Belhouchette H, Brouziyne Y, Chehbouni G, Kharrou MH, Zitouna-Chebbi R, Mekki I, Molénat J, Jacob F, Bossuet J. Water use efficiency across scales: from genes to landscapes. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:4770-4788. [PMID: 36779607 PMCID: PMC10474597 DOI: 10.1093/jxb/erad052] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 02/10/2023] [Indexed: 06/18/2023]
Abstract
Water scarcity is already set to be one of the main issues of the 21st century, because of competing needs between civil, industrial, and agricultural use. Agriculture is currently the largest user of water, but its share is bound to decrease as societies develop and clearly it needs to become more water efficient. Improving water use efficiency (WUE) at the plant level is important, but translating this at the farm/landscape level presents considerable challenges. As we move up from the scale of cells, organs, and plants to more integrated scales such as plots, fields, farm systems, and landscapes, other factors such as trade-offs need to be considered to try to improve WUE. These include choices of crop variety/species, farm management practices, landscape design, infrastructure development, and ecosystem functions, where human decisions matter. This review is a cross-disciplinary attempt to analyse approaches to addressing WUE at these different scales, including definitions of the metrics of analysis and consideration of trade-offs. The equations we present in this perspectives paper use similar metrics across scales to make them easier to connect and are developed to highlight which levers, at different scales, can improve WUE. We also refer to models operating at these different scales to assess WUE. While our entry point is plants and crops, we scale up the analysis of WUE to farm systems and landscapes.
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Affiliation(s)
- Vincent Vadez
- French National Research Institute for Sustainable Development (IRD), UMR DIADE, University of Montpellier, 911 Av. Agropolis BP65401, 34394, Montpellier, France
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, 502 324, Telangana, India
- LMI LAPSE, CERAAS-ISRA, Thiès, Senegal
| | - Raphael Pilloni
- French National Research Institute for Sustainable Development (IRD), UMR DIADE, University of Montpellier, 911 Av. Agropolis BP65401, 34394, Montpellier, France
| | - Alexandre Grondin
- French National Research Institute for Sustainable Development (IRD), UMR DIADE, University of Montpellier, 911 Av. Agropolis BP65401, 34394, Montpellier, France
| | - Amir Hajjarpoor
- French National Research Institute for Sustainable Development (IRD), UMR DIADE, University of Montpellier, 911 Av. Agropolis BP65401, 34394, Montpellier, France
| | - Hatem Belhouchette
- ABSys, Université de Montpellier, CIHEAM-IAMM, CIRAD, INRAE, Institut Agro, Montpellier, France
| | - Youssef Brouziyne
- International Water Management Institute (IWMI), MENA Office, Giza 12661, Egypt
| | - Ghani Chehbouni
- International Water Research Institute (IWRI), Mohammed VI Polytechnic University (UM6P) UMR CESBIO, Benguerir 43150, Morocco
| | - Mohamed Hakim Kharrou
- International Water Research Institute (IWRI), Mohammed VI Polytechnic University (UM6P) UMR CESBIO, Benguerir 43150, Morocco
| | | | - Insaf Mekki
- INRGREF, Carthage University, B.P. 10, 2080 Ariana, Tunisia
| | - Jérôme Molénat
- UMR LISAH, Université de Montpellier, INRAE, IRD, Institut Agro Montpellier, AgroParisTech, Montpellier, France
| | - Frédéric Jacob
- UMR LISAH, Université de Montpellier, INRAE, IRD, Institut Agro Montpellier, AgroParisTech, Montpellier, France
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Lu Y, Jeffers R, Raju A, Kenny T, Ratchanniyasamu E, Fricke W. Does night-time transpiration provide any benefit to wheat (Triticum aestivum L.) plants which are exposed to salt stress? PHYSIOLOGIA PLANTARUM 2023; 175:e13839. [PMID: 36511643 PMCID: PMC10107941 DOI: 10.1111/ppl.13839] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 12/09/2022] [Indexed: 05/27/2023]
Abstract
The study aimed to test whether night-time transpiration provides any potential benefit to wheat plants which are subjected to salt stress. Hydroponically grown wheat plants were grown at four levels of salt stress (50, 100, 150, and 200 mM NaCl) for 5-8 days prior to harvest (day 14-18). Salt stress caused large decreases in transpiration and leaf elongation rates during day and night. The quantitative relation between the diurnal use of water for transpiration and leaf growth was comparatively little affected by salt. Night-time transpirational water loss occurred predominantly through stomata in support of respiration. Diurnal gas exchange and leaf growth were functionally linked to each other through the provision of resources (carbon, energy) and an increase in leaf surface area. Diurnal rates of water use associated with leaf cell expansive growth were highly correlated with the water potential of the xylem, which was dominated by the tension component. The tissue-specific expression level of nine candidate aquaporin genes in elongating and mature leaf tissue was little affected by salt stress or day/night changes. Growing plants under conditions of reduced night-time transpirational water loss by increasing the relative humidity (RH) during the night to 95% had little effect on the growth response to salt stress, nor was the accumulation of Na+ and Cl- in shoot tissue altered. We conclude that night-time gas exchange supports the growth in leaf area over a 24 h day/night period. Night-time transpirational water loss neither decreases nor increases the tolerance to salt stress in wheat.
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Affiliation(s)
- Yingying Lu
- School of Biology and Environmental SciencesUniversity College DublinDublinRepublic of Ireland
| | - Ruth Jeffers
- School of Biology and Environmental SciencesUniversity College DublinDublinRepublic of Ireland
| | - Anakha Raju
- School of Biology and Environmental SciencesUniversity College DublinDublinRepublic of Ireland
| | - Tamara Kenny
- School of Biology and Environmental SciencesUniversity College DublinDublinRepublic of Ireland
| | | | - Wieland Fricke
- School of Biology and Environmental SciencesUniversity College DublinDublinRepublic of Ireland
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Tamang BG, Monnens D, Anderson JA, Steffenson BJ, Sadok W. The genetic basis of transpiration sensitivity to vapor pressure deficit in wheat. PHYSIOLOGIA PLANTARUM 2022; 174:e13752. [PMID: 36281842 PMCID: PMC9543498 DOI: 10.1111/ppl.13752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 07/12/2022] [Accepted: 07/26/2022] [Indexed: 05/10/2023]
Abstract
Genetic manipulation of whole-plant transpiration rate (TR) response to increasing atmospheric vapor pressure deficit (VPD) is a promising approach for crop adaptation to various drought regimes under current and future climates. Genotypes with a non-linear TR response to VPD are expected to achieve yield gains under terminal drought, thanks to a water conservation strategy, while those with a linear response exhibit a consumptive strategy that is more adequate for well-watered or transient-drought environments. In wheat, previous efforts indicated that TR has a genetic basis under naturally fluctuating conditions, but because TR is responsive to variation in temperature, photosynthetically active radiation, and evaporative demand, the genetic basis of its response VPD per se has never been isolated. To address this, we developed a controlled-environment gravimetric phenotyping approach where we imposed VPD regimes independent from other confounding environmental variables. We screened three nested association mapping populations totaling 150 lines, three times over a 3-year period. The resulting dataset, based on phenotyping nearly 1400 plants, enabled constructing 63-point response curves for each genotype, which were subjected to a genome-wide association study. The analysis revealed a hotspot for TR response to VPD on chromosome 5A, with SNPs explaining up to 17% of the phenotypic variance. The key SNPs were found in haploblocks that are enriched in membrane-associated genes, consistent with the hypothesized physiological determinants of the trait. These results indicate a promising potential for identifying new alleles and designing next-gen wheat cultivars that are better adapted to current and future drought regimes.
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Affiliation(s)
- Bishal G. Tamang
- Department of Agronomy and Plant GeneticsUniversity of MinnesotaSt. PaulMinnesotaUSA
| | - Daniel Monnens
- Department of Agronomy and Plant GeneticsUniversity of MinnesotaSt. PaulMinnesotaUSA
| | - James A. Anderson
- Department of Agronomy and Plant GeneticsUniversity of MinnesotaSt. PaulMinnesotaUSA
| | | | - Walid Sadok
- Department of Agronomy and Plant GeneticsUniversity of MinnesotaSt. PaulMinnesotaUSA
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Itam MO, Wahbi A, Fujimaki H, Tsujimoto H. Transpiration response of two bread wheat lines differing in drought resilience and their backcross parent under dry-down conditions. BREEDING SCIENCE 2021; 71:575-583. [PMID: 35087321 PMCID: PMC8784354 DOI: 10.1270/jsbbs.20154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 09/08/2021] [Indexed: 06/14/2023]
Abstract
Improving wheat productivity in drylands largely depends on how plants manage limited water resources. Using fraction of transpirable soil water threshold (FTSWTh) and drought stress response function, we characterized the water conservation traits of two wheat multiple synthetic derivative lines (MSD53 and MSD345) which both contain introgressed segments from Aegilops tauschii but differ in drought resilience. The lines and their backcross parent, 'Norin 61', were subjected to dry-down conditions. MSD53 had a higher FTSWTh for transpiration decrease than 'Norin 61' and MSD345. In terms of drought stress response function, MSD53 had the lowest threshold suction, suggesting a lower drought resilience capacity compared with MSD345. However, MSD53 exhibited an effective-water-use trait whereas MSD345 exhibited a water-saving trait under dry-down conditions. These results are consistent with the reported higher yield of MSD53 in comparison with MSD345 under drought stress in Sudan, and demonstrate that high FTSWTh supports effective water use for improved agricultural productivity in drylands. The differences in water conservation traits between the two MSD lines may be attributed to variation in introgressed segments, which can be further explored for drought resilience breeding.
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Affiliation(s)
- Michael O. Itam
- Arid Land Research Center, Tottori University, Tottori 680-0001, Japan
| | - Ammar Wahbi
- Arid Land Research Center, Tottori University, Tottori 680-0001, Japan
| | - Haruyuki Fujimaki
- Arid Land Research Center, Tottori University, Tottori 680-0001, Japan
| | - Hisashi Tsujimoto
- Arid Land Research Center, Tottori University, Tottori 680-0001, Japan
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Ranawana SRWMCJK, Siddique KHM, Palta JA, Stefanova K, Bramley H. Stomata coordinate with plant hydraulics to regulate transpiration response to vapour pressure deficit in wheat. FUNCTIONAL PLANT BIOLOGY : FPB 2021; 48:839-850. [PMID: 33934747 DOI: 10.1071/fp20392] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/18/2021] [Indexed: 06/12/2023]
Abstract
Genotypic variation in transpiration (Tr) response to vapour pressure deficit (VPD) has been studied in many crop species. There is debate over whether shoots or roots drive these responses. We investigated how stomata coordinate with plant hydraulics to mediate Tr response to VPD and influence leaf water status in wheat (Triticum aestivum L.). We measured Tr and stomatal conductance (gs) responses to VPD in well-watered, water-stressed and de-rooted shoots of eight wheat genotypes. Tr response to VPD was related to stomatal sensitivity to VPD and proportional to gs at low VPD, except in the water-stressed treatment, which induced strong stomatal closure at all VPD levels. Moreover, gs response to VPD was driven by adaxial stomata. A simple linear Tr response to VPD was associated with unresponsive gs to VPD. In contrast, segmented linear Tr to VPD response was mostly a function of gs with the breakpoint depending on the capacity to meet transpirational demand and set by the shoots. However, the magnitude of Tr response to VPD was influenced by roots, soil water content and stomatal sensitivity to VPD. These findings, along with a theoretical model suggest that stomata coordinate with plant hydraulics to regulate Tr response to VPD in wheat.
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Affiliation(s)
- S R W M C J K Ranawana
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6001, Australia; and Department of Export Agriculture, Faculty of Animal Science and Export Agriculture, Uva Wellassa University, Badulla 90000, Sri Lanka; and Corresponding author.
| | - K H M Siddique
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6001, Australia
| | - J A Palta
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6001, Australia; and CSIRO Agriculture, Private Bag No. 5, Wembley, WA 6913, Australia
| | - K Stefanova
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6001, Australia
| | - H Bramley
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6001, Australia; and Plant Breeding Institute, School of Life and Environmental Sciences, The University of Sydney, Narrabri, NSW 2390, Australia
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7
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Sadok W, Lopez JR, Smith KP. Transpiration increases under high-temperature stress: Potential mechanisms, trade-offs and prospects for crop resilience in a warming world. PLANT, CELL & ENVIRONMENT 2021; 44:2102-2116. [PMID: 33278035 DOI: 10.1111/pce.13970] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 11/19/2020] [Accepted: 11/20/2020] [Indexed: 05/24/2023]
Abstract
The frequency and intensity of high-temperature stress events are expected to increase as climate change intensifies. Concomitantly, an increase in evaporative demand, driven in part by global warming, is also taking place worldwide. Despite this, studies examining high-temperature stress impacts on plant productivity seldom consider this interaction to identify traits enhancing yield resilience towards climate change. Further, new evidence documents substantial increases in plant transpiration rate in response to high-temperature stress even under arid environments, which raise a trade-off between the need for latent cooling dictated by excessive temperatures and the need for water conservation dictated by increasing evaporative demand. However, the mechanisms behind those responses, and the potential to design the next generation of crops successfully navigating this trade-off, remain poorly investigated. Here, we review potential mechanisms underlying reported increases in transpiration rate under high-temperature stress, within the broader context of their impact on water conservation needed for crop drought tolerance. We outline three main contributors to this phenomenon, namely stomatal, cuticular and water viscosity-based mechanisms, and we outline research directions aiming at designing new varieties optimized for specific temperature and evaporative demand regimes to enhance crop productivity under a warmer and dryer climate.
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Affiliation(s)
- Walid Sadok
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota, USA
| | - Jose R Lopez
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota, USA
| | - Kevin P Smith
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota, USA
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López JR, Schoppach R, Sadok W. Harnessing nighttime transpiration dynamics for drought tolerance in grasses. PLANT SIGNALING & BEHAVIOR 2021; 16:1875646. [PMID: 33465000 PMCID: PMC7971256 DOI: 10.1080/15592324.2021.1875646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/08/2021] [Accepted: 01/09/2021] [Indexed: 06/12/2023]
Abstract
Non-negligible nighttime transpiration rates (TRN) have been identified in grasses such as wheat and barley. Evidence from the last 30 years indicate that in drought-prone environments with high evaporative demand, TRN could amount to 8-55% of daytime TR, leading several investigators to hypothesize that reducing TRN might represent a viable water-saving strategy that minimizes seemingly 'wasteful' water loss that is not traded for CO2 fixation. More recently however, evidence suggests that actual increases in TRN during pre-dawn hours, which are presumably controlled by the circadian clock, mediate drought tolerance - not through water conservation - but by enabling maximized gas exchange early in the morning before midday depression sets in. Finally, new findings point to a previously undocumented role for leaf sheaths as substantial contributors (up to 45%) of canopy TRN, although the extent of their involvement in these two strategies remains unknown. In this paper, we synthesize and reconcile key results from experimental and simulation-based modeling efforts conducted at scales ranging from the leaf tissue to the field plot on wheat and barley to show that both strategies could in fact concomitantly enable yield gains under limited water supply. We propose a simple framework highlighting the role played by TRN dynamics in drought tolerance and provide a synthesis of potential research directions, with an emphasis on the need for further examining the role played by the circadian clock and leaf sheath gas exchange.
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Affiliation(s)
- Jose R. López
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN, USA
| | - Rémy Schoppach
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN, USA
| | - Walid Sadok
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN, USA
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9
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Chieppa J, Brown T, Giresi P, Juenger TE, Resco de Dios V, Tissue DT, Aspinwall MJ. Climate and stomatal traits drive covariation in nighttime stomatal conductance and daytime gas exchange rates in a widespread C 4 grass. THE NEW PHYTOLOGIST 2021; 229:2020-2034. [PMID: 33037633 DOI: 10.1111/nph.16987] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 09/25/2020] [Indexed: 06/11/2023]
Abstract
Nighttime stomatal conductance (gsn ) varies among plant functional types and species, but factors shaping the evolution of gsn remain unclear. Examinations of intraspecific variation in gsn as a function of climate and co-varying leaf traits may provide new insight into the evolution of gsn and its adaptive significance. We grew 11 genotypes of Panicum virgatum (switchgrass) representing differing home-climates in a common garden experiment and measured nighttime and daytime leaf gas exchange, as well as stomatal density (SD) and size during early-, mid-, and late-summer. We used piecewise structural equation modelling to determine direct and indirect relationships between home-climate, gas exchange, and stomatal traits. We found no direct relationship between home-climate and gsn . However, genotypes from hotter climates possessed higher SD, which resulted in higher gsn . Across genotypes, higher gsn was associated with higher daytime stomatal conductance and net photosynthesis. Our results indicate that higher gsn may arise in genotypes from hotter climates via increased SD. High SD may provide benefits to genotypes from hotter climates through enhanced daytime transpirational cooling or by permitting maximal gas exchange when conditions are suitable. These results highlight the role of climate and trait coordination in shaping genetic differentiation in gsn .
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Affiliation(s)
- Jeff Chieppa
- Department of Biology, University of North Florida, Jacksonville, FL, 32224, USA
- School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Tia Brown
- Department of Biology, Haverford College, Haverford, PA, 19041, USA
| | - Presley Giresi
- Department of Biology, University of North Florida, Jacksonville, FL, 32224, USA
| | - Thomas E Juenger
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78717, USA
| | - Víctor Resco de Dios
- School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, 621010, China
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
| | - Michael J Aspinwall
- Department of Biology, University of North Florida, Jacksonville, FL, 32224, USA
- School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL, 36849, USA
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10
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Deery DM, Jones HG. Field Phenomics: Will It Enable Crop Improvement? PLANT PHENOMICS (WASHINGTON, D.C.) 2021; 2021:9871989. [PMID: 34549194 PMCID: PMC8433881 DOI: 10.34133/2021/9871989] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 08/14/2021] [Indexed: 05/19/2023]
Abstract
Field phenomics has been identified as a promising enabling technology to assist plant breeders with the development of improved cultivars for farmers. Yet, despite much investment, there are few examples demonstrating the application of phenomics within a plant breeding program. We review recent progress in field phenomics and highlight the importance of targeting breeders' needs, rather than perceived technology needs, through developing and enhancing partnerships between phenomics researchers and plant breeders.
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Affiliation(s)
| | - Hamlyn G. Jones
- CSIRO Agriculture and Food, Canberra, ACT, Australia
- Division of Plant Sciences, University of Dundee, UK
- School of Agriculture and Environment, University of Western Australia, Australia
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11
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Schoppach R, Sinclair TR, Sadok W. Sleep tight and wake-up early: nocturnal transpiration traits to increase wheat drought tolerance in a Mediterranean environment. FUNCTIONAL PLANT BIOLOGY : FPB 2020; 47:1117-1127. [PMID: 32684244 DOI: 10.1071/fp20044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 06/20/2020] [Indexed: 06/11/2023]
Abstract
In wheat, night-time transpiration rate (TRN) could amount to 14-55% of daytime transpiration rate (TR), depending on the cultivar and environment. Recent evidence suggests that TRN is much less responsive to soil drying than daytime TR, and that such 'wasteful' water losses would increase the impact of drought on yields. In contrast, other evidence indicates that pre-dawn, circadian increases in TRN may enable enhanced radiation use efficiency, resulting in increased productivity under water deficit. Until now, there have been no attempts to evaluate these seemingly conflicting hypotheses in terms of their impact on yields in any crop. Here, using the Mediterranean environment of Tunisia as a case study, we undertook a simulation modelling approach using SSM-Wheat to evaluate yield outcomes resulting from these TRN trait modifications. TRN represented 15% of daytime TR-generated yield penalties of up to 20%, and these worsened when TRN was not sensitive to soil drying TR. For the same TRN level (15%), simulating a predawn increase in TRN alleviated yield penalties, leading to yield gains of up to 25%. Overall, this work suggests that decreasing TRN but increasing pre-dawn circadian control would be a viable breeding target to increase drought tolerance in a Mediterranean environment.
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Affiliation(s)
- Rémy Schoppach
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108-6026, USA
| | - Thomas R Sinclair
- Crop Science Department, North Carolina State University, Raleigh, NC 27695-7620, USA
| | - Walid Sadok
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN 55108-6026, USA; and Corresponding author.
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12
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Sadok W, Lopez JR, Zhang Y, Tamang BG, Muehlbauer GJ. Sheathing the blade: Significant contribution of sheaths to daytime and nighttime gas exchange in a grass crop. PLANT, CELL & ENVIRONMENT 2020; 43:1844-1861. [PMID: 32459028 DOI: 10.1111/pce.13808] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 03/31/2020] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
Despite representing a sizeable fraction of the canopy, very little is known about leaf sheath gas exchange in grasses. Specifically, estimates of sheath stomatal conductance, transpiration and photosynthesis along with their responses to light, CO2 and vapour pressure deficit (VPD) are unknown. Furthermore, the anatomical basis of these responses is poorly documented. Here, using barley as a model system, and combining leaf-level gas exchange, whole-plant gravimetric measurements, transpiration inhibitors, anatomical observations, and biophysical modelling, we found that sheath and blade stomatal conductance and transpiration were similar, especially at low light, in addition to being genotypically variable. Thanks to high abaxial stomata densities and surface areas nearly half those of the blades, sheaths accounted for up to 17% of the daily whole-plant water use, which -surprisingly- increased to 45% during the nighttime. Sheath photosynthesis was on average 17-25% that of the blade and was associated with lower water use efficiency. Finally, sheaths responded differently to the environment, exhibiting a lack of response to CO2 but a strong sensitivity to VPD. Overall, these results suggest a key involvement of sheaths in feedback loops between canopy architecture and gas exchange with potentially significant implications on adaptation to current and future climates in grasses.
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Affiliation(s)
- Walid Sadok
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota, USA
| | - Jose R Lopez
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota, USA
| | - Yangyang Zhang
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota, USA
- Department of Grassland Science, China Agricultural University, Beijing, China
| | - Bishal G Tamang
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota, USA
| | - Gary J Muehlbauer
- Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota, USA
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13
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Sadok W, Jagadish SVK. The Hidden Costs of Nighttime Warming on Yields. TRENDS IN PLANT SCIENCE 2020; 25:644-651. [PMID: 32526169 DOI: 10.1016/j.tplants.2020.02.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 02/05/2020] [Accepted: 02/06/2020] [Indexed: 05/18/2023]
Abstract
Nighttime warming poses a threat to global food security as it is driving yield declines worldwide, but our understanding of the physiological basis of this phenomenon remains very limited. Furthermore, it is often assumed that such declines are driven solely by increases in nighttime temperature (TNight). Here we argue that, in addition to temperature, increases in nighttime evaporative demand may 'conspire' to penalize yields and end-use quality traits. We propose an ecophysiological framework outlining the possible mechanistic basis of such declines in yield and quality. We suggest ways to use the proposed framework as a guide to future efforts aimed at alleviating productivity losses by integrating crop ecophysiology with modeling, breeding, and management.
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Affiliation(s)
- Walid Sadok
- Department of Agronomy and Plant Genetics, University of Minnesota Twin Cities, MN, USA.
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