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Saeidnia F, Majidi MM, Mirlohi A, Ahmadi B. Association analysis revealed loci linked to post-drought recovery and traits related to persistence of smooth bromegrass (Bromus inermis). PLoS One 2022; 17:e0278687. [PMID: 36477736 PMCID: PMC9728867 DOI: 10.1371/journal.pone.0278687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 11/22/2022] [Indexed: 12/12/2022] Open
Abstract
Association analysis has been proven as a powerful tool for the genetic dissection of complex traits. This study was conducted to identify association of recovery, persistence, and summer dormancy with sequence related amplified polymorphism (SRAP) markers in 36 smooth bromegrass genotypes under two moisture conditions and find stable associations. In this study, a diverse panel of polycross-derived progenies of smooth bromegrass was phenotyped under normal and water deficit regimes for three consecutive years. Under water deficit, dry matter yield of cut 1 was approximately reduced by 36, 39, and 37% during 2013, 2014, and 2015, respectively, compared with the normal regime. For dry matter yield of cut 2, these reductions were approximately 38, 60, and 56% in the same three consecutive years relative to normal regime. Moreover, water deficit decreased the RY and PER of the genotypes by 35 and 28%, respectively. Thirty primer combinations were screened by polymerase chain reaction (PCR). From these, 541 polymorphic bands were developed and subjected to association analysis using the mixed linear model (MLM). Population structure analysis identified five main subpopulations possessing significant genetic differences. Association analysis identified 69 and 46 marker-trait associations under normal and water deficit regimes, respectively. Some of these markers were associated with more than one trait; which can be attributed to pleiotropic effects or tightly linked genes affecting several traits. In normal and water-deficit regimes, these markers could potentially be incorporated into marker-assisted selection and targeted trait introgression for the improvement of drought tolerance of smooth bromegrass.
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Affiliation(s)
- Fatemeh Saeidnia
- Assistant Professor of Agricultural and Horticultural Science Research Department, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization, Mashhad, Iran
- * E-mail:
| | - Mohammad Mahdi Majidi
- Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan, Iran
| | - Aghafakhr Mirlohi
- Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan, Iran
| | - Benyamin Ahmadi
- Department of Horticulture, College of Agriculture, Isfahan University of Technology, Isfahan, Iran
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Pirnajmedin F, Majidi MM, Taleb MH, Rostami D. Genetic parameters and selection in full-sib families of tall fescue using best linear unbiased prediction (BLUP) analysis. BMC PLANT BIOLOGY 2022; 22:293. [PMID: 35701757 PMCID: PMC9199132 DOI: 10.1186/s12870-022-03675-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 06/01/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Better understanding of genetic structure of economic traits is crucial for identification and selection of superior genotypes in specific breeding programs. Best linear unbiased prediction (BLUP) is the most efficient method in this regard, which is poorly used in forage plant breeding. The present study aimed to assess genetic variation, estimate genetic parameters, and predict breeding values of five essential traits in full sib families (recognized by EST-SSR markers) of tall fescue using REML/BLUP procedure. METHOD Forty-two full-sib families of tall fescue (included of 120 individual genotypes), recognized by EST-SSR markers along with twenty-one their corresponding parental genotypes were assessed for biomass production and agro-morphological traits at three harvests (spring, summer, and autumn) in the field during 4 years (2017-2020). RESULTS Considerable genotypic variability was observed for all traits. Low narrow-sense heritability (h2n) for dry forage yield (DFY) at three harvest indicates that non-additive gene actions may play an important role in the inheritance of this trait. Higher h2n of yield related traits and flowering time and also significant genetic correlation of these traits with forage yield, suggests that selection based on these traits may lead to indirect genetic improvement of DFY. CONCLUSION Our results showed the adequacy of REML/BLUP procedure for identification and selection of preferable parental genotypes and progenies with higher breeding values for future breeding programs such as variety development in tall fescue. Parental genotypes 21 M, 1 M, and 20 L were identified as superior and stable genotypes and could also produce the best hybrid combinations when they were mostly used as maternal parent.
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Affiliation(s)
- Fatemeh Pirnajmedin
- Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan, 84156-83111 Iran
| | - Mohammad Mahdi Majidi
- Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan, 84156-83111 Iran
| | - Mohammad Hadi Taleb
- Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan, 84156-83111 Iran
| | - Davoud Rostami
- Department of Animal Science, College of Agriculture, Isfahan University of Technology, Isfahan, 84156-83111 Iran
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Zhouri L, Kallida R, Shaimi N, Barre P, Volaire F, Gaboun F, Fakiri M. Evaluation of cocksfoot ( Dactylis glomerata L.) population for drought survival and behavior. Saudi J Biol Sci 2019; 26:49-56. [PMID: 30622406 PMCID: PMC6319197 DOI: 10.1016/j.sjbs.2016.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 10/27/2016] [Accepted: 12/01/2016] [Indexed: 11/22/2022] Open
Abstract
Climate change models predict frequent and intense droughts in the world. Development of drought-tolerant species and cultivars is necessary to cope with such changes. Forage grass species are affected, especially in the Mediterranean region. The aim of the present study was to investigate the diversity for drought survival, summer dormancy, and productivity within a cocksfoot population. The study was conducted in Morocco, under field conditions from 2011 to 2013. 283 genotypes of cocksfoot and parents were tested, characterized for dry matter yield, heading date, plant height, senescence, summer dormancy, and drought survival. Results exhibited a large variability between traits. 79% of the population had survived after severe drought summer while 57% yielded more than both parents. Also, 63% of the progeny had an intermediate score of summer dormancy estimated by senescence score. Large variability was also noticed for heading date and plant height. Several accessions combined a high yield and persistence under severe summer drought. Which explain the significant correlation (r = 0.18, P < 0.005) founded between total dry matter accumulated in 2013 and plant survival. Accordingly, our results showed that we can rise persistent and resilient genotypes among population with a good level of biomass.
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Key Words
- ADM, autumn recovery dry matter
- ANOVA, one-way analysis of variance procedure
- Cocksfoot
- DS, drought survival
- Drought resistance
- HD, heading date
- Hybrids
- PCA, Principal Component Analyses
- PH, plant height
- Plants survival
- S/Sp, Norton index
- SD, summer dormancy
- SDI, summer dormancy index
- Senesc, senescence
- SpB, spring biomass
- Summer dormancy
- TDM, total dry matter
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Affiliation(s)
- Latifa Zhouri
- Laboratory of Agri-Food and Health, Faculty of Sciences and Techniques, Hassan 1st University, BP 577, 26000 Settat, Morocco
- Research Unit Animal Production and Forage, INRA, RCAR-Rabat, P.O. Box 6570, Rabat Institutes, 10101 Rabat, Morocco
| | - Rajae Kallida
- Research Unit Animal Production and Forage, INRA, RCAR-Rabat, P.O. Box 6570, Rabat Institutes, 10101 Rabat, Morocco
| | - Naima Shaimi
- Research Unit Plant Breeding, Conservation and Valorization of Plant Genetic Resources, INRA, RCAR-Rabat, P.O. Box 6570, Rabat Institutes, 10101 Rabat, Morocco
| | - Philippe Barre
- UR4 Multidisciplinary Research Unit Prairies and Forage Plants, National Institute for Agricultural Research, Lusignan, France
| | - Florence Volaire
- USC1338, Center of Functional and Evolutionary Ecology, UMR5175, National Institute for Agricultural Research, Montpellier, France
| | - Fatima Gaboun
- Research Unit Biotechnology, INRA, RCAR-Rabat, P.O. Box 6356, Rabat Institutes, 10101 Rabat, Morocco
| | - Malika Fakiri
- Laboratory of Agri-Food and Health, Faculty of Sciences and Techniques, Hassan 1st University, BP 577, 26000 Settat, Morocco
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Bristiel P, Gillespie L, Østrem L, Balachowski J, Violle C, Volaire F. Experimental evaluation of the robustness of the growth–stress tolerance trade‐off within the perennial grass
Dactylis glomerata. Funct Ecol 2018. [DOI: 10.1111/1365-2435.13112] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Pauline Bristiel
- INRA CEFE UMR 5175 CNRS Université Paul‐Valéry Montpellier EPHE Université de Montpellier Montpellier, Cedex 5 France
| | - Lauren Gillespie
- CEFE UMR 5175 CNRS Université Paul‐Valéry Montpellier EPHE Université de Montpellier Montpellier, Cedex 5 France
| | - Liv Østrem
- NIBIO Norwegian Institute of Bioeconomy Research Fureneset, Fjaler Norway
| | - Jennifer Balachowski
- USDA Agricultural Research Service California Climate Hub John Muir Institute of the Environment University of California, Davis Davis California
| | - Cyrille Violle
- CEFE UMR 5175 CNRS Université Paul‐Valéry Montpellier EPHE Université de Montpellier Montpellier, Cedex 5 France
| | - Florence Volaire
- INRA CEFE UMR 5175 CNRS Université Paul‐Valéry Montpellier EPHE Université de Montpellier Montpellier, Cedex 5 France
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Missaoui AM, Malinowski DP, Pinchak WE, Kigel J. Insights into the Drought and Heat Avoidance Mechanism in Summer-Dormant Mediterranean Tall Fescue. FRONTIERS IN PLANT SCIENCE 2017; 8:1971. [PMID: 29204152 PMCID: PMC5698279 DOI: 10.3389/fpls.2017.01971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 11/01/2017] [Indexed: 05/11/2023]
Abstract
Summer dormancy is an evolutionary response that some perennial cool-season grasses adopted as an avoidance strategy to escape summer drought and heat. It is correlated with superior survival after severe summer droughts in many perennial grass species originating from Mediterranean environments. Understanding the genetic mechanism and environmental determinants of summer dormancy is important for interpreting the evolutionary history of seasonal dormancy and for the development of genomic tools to improve the efficiency of genetic selection for this important trait. The objectives of this research are to assess morphological and biochemical attributes that seem to be specific for the characterization of summer dormancy in tall fescue, and to validate the hypothesis that genes underlying stem determinacy might be involved in the mechanism of summer dormancy. Our results suggest that vernalization is an important requirement in the onset of summer dormancy in tall fescue. Non-vernalized tall fescue plants do not exhibit summer dormancy as vernalized plants do and behave more like summer-active types. This is manifested by continuation of shoot growth and high root activity in water uptake during summer months. Therefore, summer dormancy in tall fescue should be tested only in plants that underwent vernalization and are not subjected to water deficit during summer months. Total phenolic concentration in tiller bases (antioxidants) does not seem to be related to vernalization. It is most likely an environmental response to protect meristems from oxidative stress. Sequence analysis of the TFL1 homolog CEN gene from tall fescue genotypes belonging to summer-dormant and summer-active tall fescue types showed a unique deletion of three nucleotides specific to the dormant genotypes. Higher tiller bud numbers in dormant plants that were not allowed to flower and complete the reproductive cycle, confirmed that stem determinacy is a major component in the mechanism of summer dormancy. The number of variables identified in these studies as potential players in summer dormancy in tall fescue including vernalization, TFL1/CEN, water status, and protection from oxidative stress are a further confirmation that summer dormancy is a quantitative trait controlled by several genes with varying effects and prone to genotype by environment interactions.
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Affiliation(s)
- Ali M. Missaoui
- Institute of Plant Breeding Genetics and Genomics, The University of Georgia, Athens, GA, United States
| | | | | | - Jaime Kigel
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Hebrew University of Jerusalem, Rehovot, Israel
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Balachowski JA, Volaire FA. Implications of plant functional traits and drought survival strategies for ecological restoration. J Appl Ecol 2017. [DOI: 10.1111/1365-2664.12979] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Balachowski JA, Bristiel PM, Volaire FA. Summer dormancy, drought survival and functional resource acquisition strategies in California perennial grasses. ANNALS OF BOTANY 2016; 118:357-68. [PMID: 27325898 PMCID: PMC4970370 DOI: 10.1093/aob/mcw109] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 04/27/2016] [Indexed: 05/13/2023]
Abstract
BACKGROUND AND AIMS Evidence suggests drought severity is increasing due to climate change, but strategies promoting severe drought survival in perennial grasses have been seldom explored. This is particularly true of summer dormancy, an adaptation common in summer-dry Mediterranean-type climates. In addition, though theory predicts superior drought survival results in lower potential productivity, studies rarely measure both drought survival and growth under optimal conditions. METHODS Physiological and functional ecological approaches were integrated to quantify interspecific variation in foliar and root traits in a suite of eight California perennial grass species. In a glasshouse experiment, summer dormancy, foliar functional trait variation, and seasonal growth and phenology under non-limiting water conditions and dehydration tolerance under progressive drought were quantified. In a second glasshouse study, root functional traits were quantified under non-limiting water conditions in rhizotrons. KEY RESULTS Summer dormancy was associated with higher dehydration tolerance, and negatively associated with traits conferring dehydration avoidance. Species with greater summer dormancy were characterized by greater springtime productivity, earlier reproduction, and a shallow and fine root system, which are indicative of dehydration escape. Summer dormancy was associated with an acquisitive, competitive functional strategy in spring, and a conservative strategy in summer. CONCLUSIONS Both the escape and acquisitive springtime strategies observed in summer dormant perennial taxa are typically associated with annual grasses. California grasslands were once dominated by perennial species, but have been overtaken by non-native Mediterranean annual grasses, which are expected to be further favoured by climate change. Owing to functional similarity with these exotic annuals, it is suggested that native summer dormant taxa may play an important ecological role in the future of both natural and restored California grasslands.
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Affiliation(s)
| | - Pauline M Bristiel
- INRA USC 1338, CEFE UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, 1919 Route de Mende, 34293 Montpellier cedex, France
| | - Florence A Volaire
- INRA USC 1338, CEFE UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, 1919 Route de Mende, 34293 Montpellier cedex, France
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Kallida R, Zhouri L, Volaire F, Guerin A, Julier B, Shaimi N, Fakiri M, Barre P. Combining Drought Survival via Summer Dormancy and Annual Biomass Productivity in Dactylis glomerata L. FRONTIERS IN PLANT SCIENCE 2016; 7:82. [PMID: 26904054 PMCID: PMC4746912 DOI: 10.3389/fpls.2016.00082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 01/17/2016] [Indexed: 06/05/2023]
Abstract
Under Mediterranean climates, the best strategy to produce rain-fed fodder crops is to develop perennial drought resistant varieties. Summer dormancy present in native germplasm has been shown to confer a high level of survival under severe drought. Nevertheless it has also been shown to be negatively correlated with annual biomass productivity. The aim of this study was to analyze the correlations between summer dormancy and annual biomass productivity related traits and to identify quantitative trait loci (QTL) for these traits in a progeny of a summer dormant cocksfoot parent (Kasbah) and a summer active parent (Medly). A total of 283 offspring and the parents were phenotyped for summer dormancy, plant growth rate (PGR) and heading date in Morocco and for maximum leaf elongation rate (LERm) in France. The individuals were genotyped with a total of 325 markers including 59 AFLP, 64 SSR, and 202 DArT markers. The offspring exhibited a large quantitative variation for all measured traits. Summer dormancy showed a negative correlation with both PGR (-0.34 p < 0.005) and LERm (-0.27 p < 0.005). However, genotypes with both a high level of summer dormancy and a high level of PGR were detected in the progeny. One genetic map per parent was built with a total length of 377 and 423 cM for Kasbah and Medly, respectively. Both different and co-localized QTL for summer dormancy and PGR were identified. These results demonstrate that it should be possible to create summer dormant cocksfoot varieties with a high annual biomass productivity.
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Affiliation(s)
- Rajae Kallida
- Unité de Recherche de Production Animales et Fourrage, INRA Maroc, Centre Régional de la Recherche Agronomique de RabatRabat, Morocco
| | - Latifa Zhouri
- Unité de Recherche de Production Animales et Fourrage, INRA Maroc, Centre Régional de la Recherche Agronomique de RabatRabat, Morocco
- Laboratoire d’agroalimentaire et santé, Faculté des Sciences Techniques de Settat, Université Hassan 1erSettat, Morocco
| | - Florence Volaire
- USC 1338, Centre d’Ecologie Fonctionnelle et Evolutive, UMR 5175, Institut National de la Recherche AgronomiqueMontpellier, France
| | - Adrien Guerin
- UR4 Unité de Recherche Pluridisciplinaire Prairies et Plantes Fourragères, Institut National de la Recherche AgronomiqueLusignan, France
| | - Bernadette Julier
- UR4 Unité de Recherche Pluridisciplinaire Prairies et Plantes Fourragères, Institut National de la Recherche AgronomiqueLusignan, France
| | - Naima Shaimi
- Unité de Recherche d’Amélioration des Plantes Valorisation et Conservation des Ressources Phytogénétiques, INRA Maroc, Centre Régional de la Recherche Agronomique de RabatRabat, Morocco
| | - Malika Fakiri
- Laboratoire d’agroalimentaire et santé, Faculté des Sciences Techniques de Settat, Université Hassan 1erSettat, Morocco
| | - Philippe Barre
- UR4 Unité de Recherche Pluridisciplinaire Prairies et Plantes Fourragères, Institut National de la Recherche AgronomiqueLusignan, France
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Chapman DF, Dassanayake K, Hill JO, Cullen BR, Lane N. Forage-based dairying in a water-limited future: use of models to investigate farming system adaptation in southern Australia. J Dairy Sci 2012; 95:4153-75. [PMID: 22720972 DOI: 10.3168/jds.2011-5110] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 02/27/2012] [Indexed: 11/19/2022]
Abstract
The irrigated dairy industry in southern Australia has experienced significant restrictions in irrigation water allocations since 2005, consistent with climate change impact predictions for the region. Simulation models of pasture growth (DairyMod), crop yield (Agricultural Production Systems Simulator, APSIM), and dairy system management and production (UDDER) were used in combination to investigate a range of forage options that may be capable of sustaining dairy business profitability under restricted water-allocation scenarios in northern Victoria, Australia. A total of 23 scenarios were simulated and compared with a base farm system (100% of historical water allocations, grazed perennial ryegrass pasture with supplements; estimated operating surplus $A2,615/ha at a milk price of $A4.14/kg of milk solids). Nine simulations explored the response of the base farm to changes in stocking rate or the implementation of a double cropping rotation on 30% of farm area, or both. Five simulations explored the extreme scenario of dairying without any irrigation water. Two general responses to water restrictions were investigated in a further 9 simulations. Annual ryegrass grazed pasture, complemented by a double cropping rotation (maize grown in summer for silage, followed by either brassica forage crop and annual ryegrass for silage in winter and spring) on 30% of farm area, led to an estimated operating surplus of $A1746/ha at the same stocking rate as the base farm when calving was moved to autumn (instead of late winter, as in the base system). Estimated total irrigation water use was 2.7ML/ha compared with 5.4ML/ha for the base system. Summer-dormant perennial grass plus double cropping (30% of farm area) lifted operating surplus by a further $A100/ha if associated with autumn calving (estimated total irrigation water use 3.1ML/ha). Large shifts in the forage base of dairy farms could sustain profitability in the face of lower, and fluctuating, water allocations. However, changes in other strategic management policies, notably calving date and stocking rate, would be required, and these systems would be more complex to manage. The adaptation scenarios that resulted in the highest estimated operating surplus were those where at least 10 t of pasture or crop DM was grazed directly by cows per hectare per year, resulting in grazed pasture intake of at least 2 t of DM/cow, and at least 60% of all homegrown feed that was consumed was grazed directly.
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Affiliation(s)
- D F Chapman
- Melbourne School of Land and Environment, University of Melbourne, Parkville, Victoria 3010, Australia.
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Soussana JF, Graux AI, Tubiello FN. Improving the use of modelling for projections of climate change impacts on crops and pastures. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:2217-2228. [PMID: 20410317 DOI: 10.1093/jxb/erq100] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Projections of climate change impacts on global food supply are largely based on crop and pasture modelling. The consistency of these models with experimental data and their ability to simulate the effects of elevated CO(2) and of increased climate variability has been debated. The effects of high temperatures, of increased climate variability and of several limiting factors which interact with elevated CO(2) such as soil nutrients, pests and weeds are neither fully understood nor well implemented in leading models. Targeted model developments will be required based on experimental data concerning: (i) the role of extreme climatic events, (ii) the interactions between abiotic factors and elevated CO(2), (iii) the genetic variability in plant CO(2) and temperature responses, (iv) the interactions with biotic factors, and (v) the effects on harvest quality. To help make better use of the available knowledge, it is envisioned that future crop and pasture modelling studies will need to use a risk assessment approach by combining an ensemble of greenhouse gas emission (or stabilization) scenarios, of regional climate models and of crop and pasture models, as well as an ensemble of adaptation options concerning both management practices and species/varieties.
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Affiliation(s)
- Jean-François Soussana
- INRA, Grassland Ecosystem Research, 234, avenue du Brézet, F-63100 Clermont-Ferrand, France.
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Volaire F, Seddaiu G, Ledda L, Lelievre F. Water deficit and induction of summer dormancy in perennial Mediterranean grasses. ANNALS OF BOTANY 2009; 103:1337-46. [PMID: 19369219 PMCID: PMC2685321 DOI: 10.1093/aob/mcp080] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 02/05/2009] [Accepted: 03/04/2009] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND AIMS Summer dormancy is a trait conferring superior drought survival in Mediterranean perennial grasses. As the respective roles of environmental factors and water deficit on induction of summer dormancy are unclear, the effect of intense drought were tested under contrasting day lengths in a range of forage and native grasses. METHODS Plants of Poa bulbosa, Dactylis glomerata 'Kasbah' and Lolium arundinaceum 'Flecha' were grown in pots (a) from winter to summer in a glasshouse and subjected to either an early or a late-spring drought period followed by a summer water deficit and (b) in controlled conditions, with long days (LD, 16 h) or short days (SD, 9 h) and either full irrigation or water deficit followed by rehydration. Leaf elongation, senescence of aerial tissues and dehydration of basal tissues were measured to assess dormancy. Endogenous abscisic acid (ABA) in basal tissues was determined by monoclonal immunoassay analysis. KEY RESULTS Even under irrigation, cessation of leaf elongation, senescence of lamina and relative dehydration of basal tissues were triggered only by a day length longer than 13 h 30 min (late spring and LD) in plants of Poa bulbosa and Dactylis glomerata 'Kasbah' which exhibit complete dormancy. Plants of Lolium arundinaceum 'Flecha' maintained leaf growth under irrigation irrespective of the day length since its dormancy is incomplete. ABA concentrations were not higher during late-spring drought than early, and could not be associated with spring dormancy induction. In summer, ABA concentration in bulbs of the desiccation-tolerant Poa were greater than in basal tissues of other species. CONCLUSIONS The results of both experiments tend to invalidate the hypothesis that water deficit has a role in early summer-dormancy induction in the range of tested grasses. However, a late-spring drought tends to increase plant senescence and ABA accumulation in basal tissues of forage grasses which could enhance summer drought survival.
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Affiliation(s)
- Florence Volaire
- Institut National de Recherche Agronomique, INRA, UMR SYSTEM, 2 place Viala, 34060 Montpellier, France.
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