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Sargent D, Amthor JS, Stinziano JR, Evans JR, Whitney SM, Bange MP, Tissue DT, Conaty WC, Sharwood RE. The importance of species-specific and temperature-sensitive parameterisation of A/C i models: A case study using cotton (Gossypium hirsutum L.) and the automated 'OptiFitACi' R-package. Plant Cell Environ 2024; 47:1701-1715. [PMID: 38294051 DOI: 10.1111/pce.14800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/10/2023] [Accepted: 12/15/2023] [Indexed: 02/01/2024]
Abstract
Leaf gas exchange measurements are an important tool for inferring a plant's photosynthetic biochemistry. In most cases, the responses of photosynthetic CO2 assimilation to variable intercellular CO2 concentrations (A/Ci response curves) are used to model the maximum (potential) rate of carboxylation by ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, Vcmax) and the rate of photosynthetic electron transport at a given incident photosynthetically active radiation flux density (PAR; JPAR). The standard Farquhar-von Caemmerer-Berry model is often used with default parameters of Rubisco kinetic values and mesophyll conductance to CO2 (gm) derived from tobacco that may be inapplicable across species. To study the significance of using such parameters for other species, here we measured the temperature responses of key in vitro Rubisco catalytic properties and gm in cotton (Gossypium hirsutum cv. Sicot 71) and derived Vcmax and J2000 (JPAR at 2000 µmol m-2 s-1 PAR) from cotton A/Ci curves incrementally measured at 15°C-40°C using cotton and other species-specific sets of input parameters with our new automated fitting R package 'OptiFitACi'. Notably, parameterisation by a set of tobacco parameters produced unrealistic J2000:Vcmax ratio of <1 at 25°C, two- to three-fold higher estimates of Vcmax above 15°C, up to 2.3-fold higher estimates of J2000 and more variable estimates of Vcmax and J2000, for our cotton data compared to model parameterisation with cotton-derived values. We determined that errors arise when using a gm,25 of 2.3 mol m-2 s-1 MPa-1 or less and Rubisco CO2-affinities in 21% O2 (KC 21%O2) at 25°C outside the range of 46-63 Pa to model A/Ci responses in cotton. We show how the A/Ci modelling capabilities of 'OptiFitACi' serves as a robust, user-friendly, and flexible extension of 'plantecophys' by providing simplified temperature-sensitivity and species-specificity parameterisation capabilities to reduce variability when modelling Vcmax and J2000.
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Affiliation(s)
- Demi Sargent
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
- CSIRO Agriculture and Food, Narrabri, New South Wales, Australia
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Jeffrey S Amthor
- Department of Biological Sciences, Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | | | - John R Evans
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Spencer M Whitney
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Michael P Bange
- Cotton Seed Distributors Ltd, Wee Waa, New South Wales, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
- Global Centre for Land-Based Innovation, Hawkesbury Campus, Western Sydney University, Richmond, New South Wales, Australia
| | - Warren C Conaty
- CSIRO Agriculture and Food, Narrabri, New South Wales, Australia
| | - Robert E Sharwood
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, New South Wales, Australia
- Global Centre for Land-Based Innovation, Hawkesbury Campus, Western Sydney University, Richmond, New South Wales, Australia
- School of Science, Western Sydney University, Richmond, New South Wales, Australia
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2
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Farazi M, Conaty WC, Egan L, Thompson SPJ, Wilson IW, Liu S, Stiller WN, Petersson L, Rolland V. HairNet2: deep learning to quantify cotton leaf hairiness, a complex genetic and environmental trait. Plant Methods 2024; 20:46. [PMID: 38504327 PMCID: PMC10949638 DOI: 10.1186/s13007-024-01149-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 01/24/2024] [Indexed: 03/21/2024]
Abstract
BACKGROUND Cotton accounts for 80% of the global natural fibre production. Its leaf hairiness affects insect resistance, fibre yield, and economic value. However, this phenotype is still qualitatively assessed by visually attributing a Genotype Hairiness Score (GHS) to a leaf/plant, or by using the HairNet deep-learning model which also outputs a GHS. Here, we introduce HairNet2, a quantitative deep-learning model which detects leaf hairs (trichomes) from images and outputs a segmentation mask and a Leaf Trichome Score (LTS). RESULTS Trichomes of 1250 images were annotated (AnnCoT) and a combination of six Feature Extractor modules and five Segmentation modules were tested alongside a range of loss functions and data augmentation techniques. HairNet2 was further validated on the dataset used to build HairNet (CotLeaf-1), a similar dataset collected in two subsequent seasons (CotLeaf-2), and a dataset collected on two genetically diverse populations (CotLeaf-X). The main findings of this study are that (1) leaf number, environment and image position did not significantly affect results, (2) although GHS and LTS mostly correlated for individual GHS classes, results at the genotype level revealed a strong LTS heterogeneity within a given GHS class, (3) LTS correlated strongly with expert scoring of individual images. CONCLUSIONS HairNet2 is the first quantitative and scalable deep-learning model able to measure leaf hairiness. Results obtained with HairNet2 concur with the qualitative values used by breeders at both extremes of the scale (GHS 1-2, and 5-5+), but interestingly suggest a reordering of genotypes with intermediate values (GHS 3-4+). Finely ranking mild phenotypes is a difficult task for humans. In addition to providing assistance with this task, HairNet2 opens the door to selecting plants with specific leaf hairiness characteristics which may be associated with other beneficial traits to deliver better varieties.
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Affiliation(s)
- Moshiur Farazi
- Data61, Commonwealth Scientific and Industrial Research Organisation, Clunies Ross street, Canberra, 2601, Australian Capital Territory, Australia
| | - Warren C Conaty
- Australian Cotton Research Institute, 21888 Kamilaroi Hwy, Narrabi, 2390, New South Wales, Australia
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Clunnies Ross St, Canberra, 2601, Australian Capital Territory, Australia
| | - Lucy Egan
- Australian Cotton Research Institute, 21888 Kamilaroi Hwy, Narrabi, 2390, New South Wales, Australia
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Clunnies Ross St, Canberra, 2601, Australian Capital Territory, Australia
| | - Susan P J Thompson
- Australian Cotton Research Institute, 21888 Kamilaroi Hwy, Narrabi, 2390, New South Wales, Australia
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Clunnies Ross St, Canberra, 2601, Australian Capital Territory, Australia
| | - Iain W Wilson
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Clunnies Ross St, Canberra, 2601, Australian Capital Territory, Australia
| | - Shiming Liu
- Australian Cotton Research Institute, 21888 Kamilaroi Hwy, Narrabi, 2390, New South Wales, Australia
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Clunnies Ross St, Canberra, 2601, Australian Capital Territory, Australia
| | - Warwick N Stiller
- Australian Cotton Research Institute, 21888 Kamilaroi Hwy, Narrabi, 2390, New South Wales, Australia
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Clunnies Ross St, Canberra, 2601, Australian Capital Territory, Australia
| | - Lars Petersson
- Data61, Commonwealth Scientific and Industrial Research Organisation, Clunies Ross street, Canberra, 2601, Australian Capital Territory, Australia
| | - Vivien Rolland
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Clunnies Ross St, Canberra, 2601, Australian Capital Territory, Australia.
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3
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Qiu Z, Verma JP, Liu H, Wang J, Batista BD, Kaur S, de Araujo Pereira AP, Macdonald CA, Trivedi P, Weaver T, Conaty WC, Tissue DT, Singh BK. Response of the plant core microbiome to Fusarium oxysporum infection and identification of the pathobiome. Environ Microbiol 2022; 24:4652-4669. [PMID: 36059126 DOI: 10.1111/1462-2920.16194] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 09/01/2022] [Indexed: 11/29/2022]
Abstract
Plant core microbiomes consist of persistent key members that provide critical host functions, but their assemblages can be interrupted by biotic and abiotic stresses. The pathobiome is comprised of dynamic microbial interactions in response to disease status of the host. Hence, identifying variation in the core microbiome and pathobiome can significantly advance our understanding of microbial-microbial interactions and consequences for disease progression and host functions. In this study, we combined glasshouse and field studies to analyse the soil and plant rhizosphere microbiome of cotton plants (Gossypium hirsutum) in the presence of a cotton-specific fungal pathogen, Fusarium oxysporum f. sp. vasinfectum (FOV). We found that FOV directly and consistently altered the rhizosphere microbiome, but the biocontrol agents enabled microbial assemblages to resist pathogenic stress. Using co-occurrence network analysis of the core microbiome, we identified the pathobiome comprised of the pathogen and key associate phylotypes in the cotton microbiome. Isolation and application of some negatively correlated pathobiome members provided protection against plant infection. Importantly, our field survey from multiple cotton fields validated the pattern and responses of core microbiomes under FOV infection. This study advances key understanding of core microbiome responses and existence of plant pathobiomes, which provides a novel framework to better manage plant diseases in agriculture and natural settings. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Zhiguang Qiu
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Jay Prakash Verma
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia.,Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Hongwei Liu
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Juntao Wang
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia.,Global Centre for Land-Based Innovation, Western Sydney University, Penrith, NSW, Australia
| | - Bruna D Batista
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Simranjit Kaur
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | | | - Catriona A Macdonald
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Pankaj Trivedi
- Microbiome Network and Department of Agricultural Biology, Colorado State University, Fort Collins, CO, USA
| | - Tim Weaver
- CSIRO Agriculture & Food, Locked Bag 59, Narrabri, NSW, Australia
| | - Warren C Conaty
- CSIRO Agriculture & Food, Locked Bag 59, Narrabri, NSW, Australia
| | - David T Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia.,Global Centre for Land-Based Innovation, Western Sydney University, Penrith, NSW, Australia
| | - Brajesh K Singh
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia.,Global Centre for Land-Based Innovation, Western Sydney University, Penrith, NSW, Australia
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Conaty WC, Broughton KJ, Egan LM, Li X, Li Z, Liu S, Llewellyn DJ, MacMillan CP, Moncuquet P, Rolland V, Ross B, Sargent D, Zhu QH, Pettolino FA, Stiller WN. Cotton Breeding in Australia: Meeting the Challenges of the 21st Century. Front Plant Sci 2022; 13:904131. [PMID: 35646011 PMCID: PMC9136452 DOI: 10.3389/fpls.2022.904131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/08/2022] [Indexed: 06/15/2023]
Abstract
The Commonwealth Scientific and Industrial Research Organisation (CSIRO) cotton breeding program is the sole breeding effort for cotton in Australia, developing high performing cultivars for the local industry which is worth∼AU$3 billion per annum. The program is supported by Cotton Breeding Australia, a Joint Venture between CSIRO and the program's commercial partner, Cotton Seed Distributors Ltd. (CSD). While the Australian industry is the focus, CSIRO cultivars have global impact in North America, South America, and Europe. The program is unique compared with many other public and commercial breeding programs because it focuses on diverse and integrated research with commercial outcomes. It represents the full research pipeline, supporting extensive long-term fundamental molecular research; native and genetically modified (GM) trait development; germplasm enhancement focused on yield and fiber quality improvements; integration of third-party GM traits; all culminating in the release of new commercial cultivars. This review presents evidence of past breeding successes and outlines current breeding efforts, in the areas of yield and fiber quality improvement, as well as the development of germplasm that is resistant to pests, diseases and abiotic stressors. The success of the program is based on the development of superior germplasm largely through field phenotyping, together with strong commercial partnerships with CSD and Bayer CropScience. These relationships assist in having a shared focus and ensuring commercial impact is maintained, while also providing access to markets, traits, and technology. The historical successes, current foci and future requirements of the CSIRO cotton breeding program have been used to develop a framework designed to augment our breeding system for the future. This will focus on utilizing emerging technologies from the genome to phenome, as well as a panomics approach with data management and integration to develop, test and incorporate new technologies into a breeding program. In addition to streamlining the breeding pipeline for increased genetic gain, this technology will increase the speed of trait and marker identification for use in genome editing, genomic selection and molecular assisted breeding, ultimately producing novel germplasm that will meet the coming challenges of the 21st Century.
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Affiliation(s)
| | | | - Lucy M. Egan
- CSIRO Agriculture and Food, Narrabri, NSW, Australia
| | - Xiaoqing Li
- CSIRO Agriculture and Food, Canberra, ACT, Australia
| | - Zitong Li
- CSIRO Agriculture and Food, Canberra, ACT, Australia
| | - Shiming Liu
- CSIRO Agriculture and Food, Narrabri, NSW, Australia
| | | | | | | | | | - Brett Ross
- Cotton Seed Distributors Ltd., Wee Waa, NSW, Australia
| | - Demi Sargent
- CSIRO Agriculture and Food, Narrabri, NSW, Australia
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Qian-Hao Zhu
- CSIRO Agriculture and Food, Canberra, ACT, Australia
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5
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Broughton KJ, Conaty WC. Understanding and Exploiting Transpiration Response to Vapor Pressure Deficit for Water Limited Environments. Front Plant Sci 2022; 13:893994. [PMID: 35620701 PMCID: PMC9127727 DOI: 10.3389/fpls.2022.893994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 04/19/2022] [Indexed: 06/15/2023]
Abstract
More frequent droughts and an increased pressure on water resources, combined with social licence to operate, will inevitably decrease water resources available for fully irrigated cotton production. Therefore, the long-term future of the cotton industry will require more drought tolerant varieties that can perform well when grown in rainfed cropping regions often exposed to intermittent drought. A trait that limits transpiration (TRLim) under an increased vapour pressure deficit (VPD) may increase crop yield in drier atmospheric conditions and potentially conserve soil water to support crop growth later in the growing season. However, this trait has not been tested or identified in cotton production systems. This study tested the hypotheses that (1) genetic variability to the TRLim VPD trait exists amongst 10 genotypes in the Australian cotton breeding programme; (2) genotypes with a TRLim VPD trait use less water in high VPD environments and (3) variation in yield responses of cotton genotypes is linked with the VPD environment and water availability during the peak flowering period. This study combined glasshouse and field experiments to assess plant transpiration and crop yield responses of predominantly locally bred cotton genotypes to a range of atmospheric VPD under Australian climatic conditions. Results indicated that genetic variation to the limiting transpiration VPD trait exists within cotton genotypes in the Australian breeding programme, with five genotypes identified as expressing the TRLim VPD trait. A modelling study suggests that this trait may not necessarily result in overall reduced plant water use due to greater transpiration rates at lower VPD environments negating the water conservation in high VPD environments. However, our study showed that the yield response of cotton genotypes is linked with both VPD environment and water availability during the peak flowering period. Yield performance of the TRLim genotype was improved at some high VPD environments but is unlikely to out-perform a genotype with a lower yield potential. Improved understanding of integrated plant- and crop-level genotypic responses to the VPD environments will enhance germplasm development to benefit cotton production in both rainfed and semi-irrigated cotton systems, thereby meeting the agricultural challenges of the twenty-first Century.
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6
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Rolland V, Farazi MR, Conaty WC, Cameron D, Liu S, Petersson L, Stiller WN. HairNet: a deep learning model to score leaf hairiness, a key phenotype for cotton fibre yield, value and insect resistance. Plant Methods 2022; 18:8. [PMID: 35042523 PMCID: PMC8767704 DOI: 10.1186/s13007-021-00820-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 11/12/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND Leaf hairiness (pubescence) is an important plant phenotype which regulates leaf transpiration, affects sunlight penetration, and provides increased resistance or susceptibility against certain insects. Cotton accounts for 80% of global natural fibre production, and in this crop leaf hairiness also affects fibre yield and value. Currently, this key phenotype is measured visually which is slow, laborious and operator-biased. Here, we propose a simple, high-throughput and low-cost imaging method combined with a deep-learning model, HairNet, to classify leaf images with great accuracy. RESULTS A dataset of [Formula: see text] 13,600 leaf images from 27 genotypes of Cotton was generated. Images were collected from leaves at two different positions in the canopy (leaf 3 & leaf 4), from genotypes grown in two consecutive years and in two growth environments (glasshouse & field). This dataset was used to build a 4-part deep learning model called HairNet. On the whole dataset, HairNet achieved accuracies of 89% per image and 95% per leaf. The impact of leaf selection, year and environment on HairNet accuracy was then investigated using subsets of the whole dataset. It was found that as long as examples of the year and environment tested were present in the training population, HairNet achieved very high accuracy per image (86-96%) and per leaf (90-99%). Leaf selection had no effect on HairNet accuracy, making it a robust model. CONCLUSIONS HairNet classifies images of cotton leaves according to their hairiness with very high accuracy. The simple imaging methodology presented in this study and the high accuracy on a single image per leaf achieved by HairNet demonstrates that it is implementable at scale. We propose that HairNet replaces the current visual scoring of this trait. The HairNet code and dataset can be used as a baseline to measure this trait in other species or to score other microscopic but important phenotypes.
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Affiliation(s)
- Vivien Rolland
- CSIRO Agriculture and Food, Clunies Ross St, Canberra, ACT 2601 Australia
| | | | - Warren C. Conaty
- CSIRO Agriculture and Food, Locked Bag 59, Narrabri, NSW 2390 Australia
| | - Deon Cameron
- CSIRO Agriculture and Food, Locked Bag 59, Narrabri, NSW 2390 Australia
| | - Shiming Liu
- CSIRO Agriculture and Food, Locked Bag 59, Narrabri, NSW 2390 Australia
| | - Lars Petersson
- CSIRO Data61, Clunies Ross St, Canberra, ACT 2601 Australia
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7
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Jaconis SY, Thompson AJE, Smith SL, Trimarchi C, Cottee NS, Bange MP, Conaty WC. A standardised approach for determining heat tolerance in cotton using triphenyl tetrazolium chloride. Sci Rep 2021; 11:5419. [PMID: 33686101 PMCID: PMC7940608 DOI: 10.1038/s41598-021-84798-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 02/22/2021] [Indexed: 11/09/2022] Open
Abstract
Improving the heat tolerance of cotton is a major concern for breeding programs. To address this need, a fast and effect way of quantifying thermotolerant phenotypes is required. Triphenyl tetrazolium chloride (TTC) based enzyme viability testing following high-temperature stress can be used as a vegetative heat tolerance phenotype. This is because when live cells encounter a TTC solution, TTC undergoes a chemical reduction producing a visible, insoluble red product called triphenyl formazan, that can be quantified spectrophotometrically. However, existing TTC based cell viability assays cannot easily be deployed at the scale required in a crop improvement program. In this study, a heat stress assay (HSA) based on the use of TTC enzyme viability testing has been refined and improved for efficiency, reliability, and ease of use through four experiments. Sampling factors that may influence assay results, such as leaf age, plant water status, and short-term cold storage, were also investigated. Experiments conducted in this study have successfully downscaled the assay and identified an optimal sampling regime, enabling measurement of large segregating populations for application in breeding programs. The improved HSA methodology is important as it is proposed that long-term improvements in cotton thermotolerance can be achieved through the concurrent selection of superior phenotypes based on the HSA and yield performance in hot environments. Additionally, a new way of interpreting both heat tolerance and heat resistance was developed, differentiating genotypes that perform well at the time of a heat stress event and those that maintain a similar performance level to a non-stressed control.
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Affiliation(s)
- Susan Y Jaconis
- CSIRO Agriculture and Food, Locked Bag 59, Narrabri, NSW, 2390, Australia.,USA Dry Pea and Lentil Council, 2780 West Pullman Road, Moscow, ID, 83843-4024, USA
| | - Alan J E Thompson
- CSIRO Agriculture and Food, Locked Bag 59, Narrabri, NSW, 2390, Australia
| | - Shanna L Smith
- CSIRO Agriculture and Food, Locked Bag 59, Narrabri, NSW, 2390, Australia
| | - Chiara Trimarchi
- CSIRO Agriculture and Food, Locked Bag 59, Narrabri, NSW, 2390, Australia
| | - Nicola S Cottee
- CSIRO Agriculture and Food, Locked Bag 59, Narrabri, NSW, 2390, Australia.,NSW Environment Protection Authority, 4 Parramatta Square, 12 Darcy Street, Parramatta, NSW, 2124, Australia
| | - Michael P Bange
- CSIRO Agriculture and Food, Locked Bag 59, Narrabri, NSW, 2390, Australia.,GRDC (North), 214 Herries St, Toowoomba, QLD, 4350, Australia
| | - Warren C Conaty
- CSIRO Agriculture and Food, Locked Bag 59, Narrabri, NSW, 2390, Australia.
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8
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Conaty WC, Mahan JR, Neilsen JE, Constable GA. Vapour pressure deficit aids the interpretation of cotton canopy temperature response to water deficit. Funct Plant Biol 2014; 41:535-546. [PMID: 32481011 DOI: 10.1071/fp13223] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 12/10/2013] [Indexed: 06/11/2023]
Abstract
Crop canopy temperature (Tc) is coupled with transpiration, which is a function of soil and atmospheric conditions and plant water status. Thus, Tc has been identified as a real-time, plant-based tool for crop water stress detection. Such plant-based methods theoretically integrate the water status of both the plant and its environment. However, previous studies have highlighted the limitations and difficulty of interpreting the Tc response to plant and soil water stress. This study investigates the links between cotton Tc, established measures of plant water relations and atmospheric vapour pressure deficit (VPDa). Concurrent measures of carbon assimilation (A), stomatal conductance (gs), leaf water potential (Ψl), soil water (fraction of transpirable soil water (FTSW)) and Tc were conducted in surface drip irrigated cotton over two growing seasons. Associations between A, gs, Ψl, FTSW and Tc are presented, which are significantly improved with the inclusion of VPDa. It was concluded that utilising the strong associations between Ψl, VPDa and Tc, an adjustment of 1.8°C for each unit of VPDa should be made to the critical Tc for irrigation. This will improve the precision of irrigation in Tc based irrigation scheduling protocols. Improved accuracy in water stress detection with Tc, and an understanding of the interaction the environment plays in this response, can potentially improve the efficiency of irrigation.
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Affiliation(s)
- Warren C Conaty
- CSIRO Plant Industry, Locked Bag 59, Narrabri, NSW 2390, Australia
| | - James R Mahan
- USDA/ARS Plant Stress and Water Conservation Laboratory, 3810 4th St, Lubbock, TX, USA
| | - James E Neilsen
- CSIRO Plant Industry, Locked Bag 59, Narrabri, NSW 2390, Australia
| | - Greg A Constable
- CSIRO Plant Industry, Locked Bag 59, Narrabri, NSW 2390, Australia
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