Genetic diversity of alfalfa (<i>Medicago sativa</i>) in response to temperature during germination

Ahmed, Lina Qadir; Durand, J. L.; Escobar‐Gutiérrez, Abraham J.

doi:10.15258/sst.2019.47.3.10

Cited by 12 publications

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“…In our study, germinability was very low, on average 12% only, at 40°C. In contrast, germinability at 40°C ranged from 60 to 80% in a preliminary study on a subset of seven accessions among the ones studied here ( Ahmed et al, 2019 ). We suppose that the high germinability in the latter study originates both from the temperature during counting (counting in the laboratory at 20°C) and/or from the natural light received by the seeds during counting (L. Ahmed, personal observation).…”

Section: Discussionmentioning

confidence: 69%

“…Information on genetic variation for germination capacity is useful in breeding programmes especially if wild accessions are used to adapt varieties to new climatic conditions or practices related to ecosystem services, or for the preservation of genetic diversity in genetic resources centres. Studies at the intra-specific level are not frequent in pasture species ( Moot et al, 2000 ; Mcgraw et al, 2003 ; Monks et al, 2009 ; Ahmed, 2015 ; Ahmed et al, 2019 ). In the model legume species Medicago truncatula , a significant diversity for germination was evidenced among accessions ( Brunel et al, 2009 ) and within a mapping population ( Dias et al, 2011 ).…”

Section: Introductionmentioning

confidence: 99%

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The History of Domestication and Selection of Lucerne: A New Perspective From the Genetic Diversity for Seed Germination in Response to Temperature and Scarification

et al. 2021

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Lucerne (Medicago sativa), a major perennial pasture legume, belongs to a species complex that includes several subspecies with wild and cultivated populations. Stand establishment may be compromised by poor germination. Seed scarification, deterioration and temperature have an impact on germination. The objective of this study was to analyse the genetic diversity of lucerne germination in response to three factors: (1) temperature, with seven constant temperatures ranging from 5 to 40°C, was tested on 38 accessions, (2) seed scarification was tested on the same accessions at 5 and 22°C, (3) seed deterioration was tested on two accessions and two seed lots at the seven temperatures. The germination dynamics of seed lots over time was modelled and three parameters were analysed: germinability (germination capacity), maximum germination rate (maximum% of seeds germinating per time unit), and lag time before the first seed germinates. Seed scarification enhanced germinability at both temperatures and its effect was much higher on falcata and wild sativa accessions. Incomplete loss of the hardseededness trait during domestication and selection is hypothesised, indicating that the introduction of wild material in breeding programmes should be followed by the selection for germinability without scarification. Seed lots with altered germinability had low germination at extreme temperatures, both cold and hot, suggesting that mild temperatures are required to promote germination of damaged seed lots. A large genetic diversity was revealed for germination (both capacity and rate) in response to temperature. All accessions had an optimal germination at 15 or 22°C and a poor germination at 40°C. The sativa varieties and landraces had a high germination from 5 to 34°C while the germination of falcata and the wild sativa accessions were weakened at 5 or 34°C, respectively. These differences are interpreted in terms of adaptation to the climate of their geographical origin regions in order to escape frost or heat/drought risks. These new findings give insights on adaptation and domestication of lucerne in its wide geographic area. They suggest further improvement of germination is needed, especially when introducing wild material in breeding pools to remove scarification requirements and to limit differences in response to temperature.

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Section: Discussionmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

The History of Domestication and Selection of Lucerne: A New Perspective From the Genetic Diversity for Seed Germination in Response to Temperature and Scarification

et al. 2021

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“…However, before any breeding effort in such a direction, an account of the intraspecific variability of responses to temperature is essential (Ghaleb et al, 2021(Ghaleb et al, , 2022. Seed germination (Ahmed et al, 2019;Ghaleb et al, 2021) and early heterotrophic growth (Escobar-Gutiérrez et al, 1998a,b;Ahmed, 2015) in response to temperature can be used as an early marker for selecting promising material.…”

Section: Introductionmentioning

confidence: 99%

Unexpected Intraspecific Variability of Perennial Ryegrass (Lolium perenne L.) in Response to Constant Temperature During Germination and Initial Heterotrophic Growth

Ahmed

Escobar‐Gutiérrez

2022

Front. Plant Sci.

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Lolium perenne (L.) is one of the most important species in temperate grasslands. Temperature is a major factor controlling plant development. Breeding L. perenne cultivars adapted to new ranges of temperature could be necessary under most climate change scenarios. However, before any breeding effort in such direction, knowing the intraspecific variability of responses to temperature is essential. Our objective was to analyze a sample of accessions of L. perenne for their response to constant temperature during germination and initial heterotrophic growth. Eight accessions were taken out from a genebank containing 160 accessions. Six accessions were wild populations collected in different places in France and the other two were populations from a selection program. For germination, four replicates of 100 seeds per accession were tested in Petri dishes in the dark at eight constant temperatures, from 5 to 40°C with increases of 5°C. Germination countings were carried out at variable time intervals and durations that depended on treatments. For initial heterotrophic growth analysis, seeds were germinated at 25°C. Sets of 30 seedlings per accession were placed in polypropylene boxes on blotter blue paper and transferred to each one of the eight treatments in the dark. They were pictured at variable time intervals for root and shoot growth measurement by image analysis. Neither seed germination nor heterotrophic growth was observed at 40°C, for any accession. Temperature and time course response surfaces were markedly different between accessions. Equally, maximum germinability and the shape of the response curves to temperature were significantly different between accessions. This means that limited similarities between responses were observed. Furthermore, germination rates followed the non-linear beta function with significant differences between some accessions. These also showed significant differences in their root and shoot growth rate in response to temperature. In general, the relative growth rates of roots and shoots were slow at 5°C, peaked between 25 and 30°C, and showed a sharp reduction afterward. These results reveal, for the first time, high genetic variability within L. perenne germplasm for the response to temperature in the initial life phases. This discovered variability should serve breeders to create perennial ryegrass varieties for the future.

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“…The available literature determines alfalfa growing season using very loose and arbitrary definitions, such as (i) a fixed day of the year ( Raun et al, 1999 ), (ii) the occurrence of at least five days when the mean temperature is above 5°C ( Sanderson et al, 1994 ), (iii) a flexible growing season definition based on a combination of the approaches above ( Sulc et al, 1999 ), or (iv) the occurrence of Tmin below −2.8°C, a temperature threshold below which substantial damage to vegetative tissue occur in alfalfa ( Sprague, 1955 ; Nath and Fisher, 1971 ; McKenzie and McLean, 1982 ). Despite the discrepancies above, there is a consensus that the base temperature for alfalfa is 5°C ( Wolf and Blaser, 1972 ; Onstad and Fick, 1983 ; Fick et al, 1988 ; Sharratt et al, 1989 ; Confalonieri and Bechini, 2004 ), as seed germination and seedling growth are restricted below this threshold ( Vough and Marten, 1971 ; Townsend and McGinnies, 1972 ; Andrews, 1987 ; Leep et al, 2001 ; Ahmed et al, 2019 ). Because determination of the length of the growing period is important to estimate crop potential yield ( Purcell et al, 2003 ; Lobell et al, 2009 ; Torres et al, 2013 ), there is a need to objectively determine the growing season for alfalfa using daily weather data.…”

Section: Introductionmentioning

confidence: 99%

Yield gap analysis of rainfed alfalfa in the United States

Baral

Lollato²,

Bhandari³

et al. 2022

Front. Plant Sci.

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The United States (US) is the largest alfalfa (Medicago sativa L.) producer in the world. More than 44% of the US alfalfa is produced under rainfed conditions, although it requires a relatively high amount of water compared to major field crops. Considering that yield and production of rainfed alfalfa have been relatively stagnant in the country for decades, there is a need to better understand the magnitude of yield loss due to water limitation and how far from yield potential current yields are. In this context, the main objective of this study was to estimate the current yield gap of rainfed alfalfa in the US. We collected 10 year (2009–2018) county-level government-reported yield and weather data from 393 counties within 12 major US rainfed alfalfa producing states and delineated alfalfa growing season using probabilistic approaches based on temperature thresholds for crop development. We then calculated county-level growing season rainfall (GSR), which was plotted against county-level yield to determine attainable yield (Ya) using frontier function analysis, and water-limited potential yield (Yw) using boundary function analysis. Average and potential water use efficiencies (WUE) were estimated, and associated yield gap referring to attainable (YGa) or water-limited yields (YGw) were calculated. Finally, we used conditional inference trees (CIT) to identify major weather-related yield-limiting factors to alfalfa forage yield. The frontier model predicted a mean Ya of 9.6 ± 1.5 Mg ha−1 and an associated optimum GSR of 670 mm, resulting in a mean YGa of 34%. The boundary function suggested a mean Yw of 15.3 ± 3 Mg ha−1 at the mean GSR of 672 ± 153 mm, resulting in a mean yield gap of 58%. The potential alfalfa WUE was 30 kg ha−1 mm−1 with associated minimum water losses of 24% of mean GSR, which was three times greater than the mean WUE of 10 kg ha−1 mm−1. The CIT suggested that GSR and minimum temperature in the season were the main yield-limiting weather variables in rainfed alfalfa production in the US. Our study also revealed that alfalfa was only limited by water availability in 21% of the environments. Thus, future research on management practices to narrow yield gaps at current levels of water supply is necessary.

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Genetic diversity of alfalfa (Medicago sativa) in response to temperature during germination

Cited by 12 publications

References 0 publications

The History of Domestication and Selection of Lucerne: A New Perspective From the Genetic Diversity for Seed Germination in Response to Temperature and Scarification

The History of Domestication and Selection of Lucerne: A New Perspective From the Genetic Diversity for Seed Germination in Response to Temperature and Scarification

Unexpected Intraspecific Variability of Perennial Ryegrass (Lolium perenne L.) in Response to Constant Temperature During Germination and Initial Heterotrophic Growth

Yield gap analysis of rainfed alfalfa in the United States

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