Agronomy

Editorial

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3 pages, 183 KiB

Open AccessEditorial

Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands

by Joseph G. Robins

Agronomy 2021, 11(4), 718; https://doi.org/10.3390/agronomy11040718 - 09 Apr 2021

Viewed by 1309

Abstract

Rangelands are the Earth’s largest land type and provide the feed source for the extensive grazing of beef and dairy cattle (Bos taurus), sheep (Ovis aries), goat (Capra aegagrus hircus), horse (Equus ferus caballus), camel (Camelus spp [...] Full article

(This article belongs to the Special Issue Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands)

Research

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17 pages, 2168 KiB

Open AccessArticle

Improving Seed Retention and Germination Characteristics of North American Basin Wildrye by Marker-Assisted Gene Introgression

by Steven R. Larson, Thomas A. Jones, Linnea M. Johnson and Blair L. Waldron

Agronomy 2020, 10(11), 1740; https://doi.org/10.3390/agronomy10111740 - 08 Nov 2020

Cited by 3 | Viewed by 1804

Abstract

Basin wildrye [Leymus cinereus (Scribn. and Merr.) Á. Löve] and creeping wildrye [Leymus triticoides (Buckley) Pilg.] are native perennial grasses cultivated for seed used for fire rehabilitation and revegetation in western North America. Although L. cinereus produces large spike inflorescences with [...] Read more.

Basin wildrye [Leymus cinereus (Scribn. and Merr.) Á. Löve] and creeping wildrye [Leymus triticoides (Buckley) Pilg.] are native perennial grasses cultivated for seed used for fire rehabilitation and revegetation in western North America. Although L. cinereus produces large spike inflorescences with many seeds, it is prone to seed shattering. Seed can be harvested before shattering, but often displays poor germination and seedling vigor. Conversely, L. triticoides has fewer seeds per spike, but relatively strong seed retention. Both species are allotetraploid (2n = 4x = 28) and form fertile hybrids used for breeding and genetic research. A dominant, major-effect seed-shattering gene (SH6) from L. cinereus was previously identified in an L. triticoides backcross population. In this study, a DNA marker was used to select the recessive L. triticoides seed-retention allele (sh6) in cycle six (C6) of a L. cinereus × L. triticoides breeding population and evaluate gene × harvest date effects on seed yield and germination characteristics in a full-sib family derived from homozygous (sh6/sh6) and heterozygous (SH6/sh6) C6 parents. Although seed yields of shattering genotypes were 19.4% greater than non-shattering genotypes on the first harvest dates, yields of non-shattering genotypes were 167% greater on the last harvest dates. Seed harvested on the last harvest date reached 50% germination 4.2 days (26.4%) earlier and displayed 20.5% higher upper percentage germination limits than seed harvested on the first harvest date. Results indicate that the sh6 seed-retention gene will improve basin wildrye seed retention and indirectly improve seed germination by enabling later harvest dates. Full article

(This article belongs to the Special Issue Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands)

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15 pages, 613 KiB

Open AccessArticle

Genotype × Environment Interaction Patterns in Rangeland Variety Trials of Cool-Season Grasses in the Western United States

by Joseph G. Robins, Craig W. Rigby and Kevin B. Jensen

Agronomy 2020, 10(5), 623; https://doi.org/10.3390/agronomy10050623 - 28 Apr 2020

Cited by 5 | Viewed by 2034

Abstract

Rangeland revegetation is necessary to stabilize disturbed sites and increase forage production, but frequently fails due to a variety of environmental and biotic factors. Plant breeding efforts in perennial cool-season grasses result in the development of potential cultivars that must be evaluated in [...] Read more.

Rangeland revegetation is necessary to stabilize disturbed sites and increase forage production, but frequently fails due to a variety of environmental and biotic factors. Plant breeding efforts in perennial cool-season grasses result in the development of potential cultivars that must be evaluated in multi-environment trials to determine their level of adaptation. This study evaluated 49 cultivars for stand frequency and dry matter yield over five years at five environments in the Intermountain and High Plains regions of the United States. The results were significant differences among the included cultivars for both traits across and within environments. Yet, there was also crossover genotype × environment interaction. Thus, highest performing cultivars were to some extent dependent on the environment. Hycrest II crested wheatgrass and Vavilov II Siberian wheatgrass possessed high stand frequency (>80 %) and dry matter yield (>800 kg·ha⁻¹) across environments and within environments except at the Eureka, UT environment where they possessed low stand frequency. These cultivars, and species, also possessed high productivity and stability for both traits. Thus, breeding efforts in the species resulted in widely adapted cultivars that may lack specific adaptation to some environments. Full article

(This article belongs to the Special Issue Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands)

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29 pages, 2014 KiB

Open AccessArticle

Forage Performance and Detection of Marker Trait Associations with Potential for Napier Grass (Cenchrus purpureus) Improvement

by Ermias Habte, Meki S. Muktar, Asebe Abdena, Jean Hanson, Alieu M. Sartie, Alemayehu T. Negawo, Juarez Campolina Machado, Francisco José da Silva Ledo and Chris S. Jones

Agronomy 2020, 10(4), 542; https://doi.org/10.3390/agronomy10040542 - 09 Apr 2020

Cited by 12 | Viewed by 4127

Abstract

The evaluation of forage crops for adaptability and performance across production systems and environments is one of the main strategies used to improve forage production. To enhance the genetic resource base and identify traits responsible for increased feed potential of Napier grass, forty-five [...] Read more.

The evaluation of forage crops for adaptability and performance across production systems and environments is one of the main strategies used to improve forage production. To enhance the genetic resource base and identify traits responsible for increased feed potential of Napier grass, forty-five genotypes from Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), Brazil, were evaluated for forage biomass yield and feed nutritional quality in a replicated trial under wet and dry season conditions in Ethiopia. The results revealed significant variation in forage yield and feed nutritional qualities among the genotypes and between the wet and dry seasons. Feed fiber components were lower in the dry season, while crude protein, in vitro organic matter digestibility, and metabolizable energy were higher. Based on the cumulative biomass and metabolizable energy yield, top performing genotypes were identified that are candidates for future forage improvement studies. Furthermore, the marker-trait association study identified diagnostic single nucleotide polymorphisms (SNP) and SilicoDArT markers and potential candidate genes that could differentiate high biomass yielding and high metabolizable energy genotypes in the collection. Full article

(This article belongs to the Special Issue Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands)

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11 pages, 263 KiB

Open AccessArticle

Genotype and Planting Date Influence on Establishment and Growth of Bassia prostrata (L) A.J. Scott in a Semiarid Subtropical Dry Winter Region

by Leonard Lauriault and Blair L. Waldron

Agronomy 2020, 10(2), 251; https://doi.org/10.3390/agronomy10020251 - 08 Feb 2020

Cited by 4 | Viewed by 1705

Abstract

Alfalfa (Medicago sativa L.) growers in semiarid subtropical regions seek forage crops having a lower irrigation requirement. Perennial forage kochia (Bassia prostrata (L) A.J. Scott (syn. Kochia prostrata)) can potentially fill this need. The New Mexico State University’s Agricultural Science [...] Read more.

Alfalfa (Medicago sativa L.) growers in semiarid subtropical regions seek forage crops having a lower irrigation requirement. Perennial forage kochia (Bassia prostrata (L) A.J. Scott (syn. Kochia prostrata)) can potentially fill this need. The New Mexico State University’s Agricultural Science Center at Tucumcari evaluated four genotypes of B. prostrata (subspecies virescens ”Immigrant” and “Pustinny-select” and subsp. grisea “Snowstorm” and “KZ-6X”) that were direct-seeded in March and May of 2014 under irrigation in semiarid continental precipitation conditions, in three randomized complete blocks. Canopy cover was rated in 2016 and 2018 and biomass production was measured in 2018. Snowstorm did not establish on either date. Canopy cover remained unchanged across years. Immigrant established the greatest canopy cover for the March seeding and Pustinny-select had greater canopy cover for the May seeding. The May seeding tended (p < 0.10) to have greater biomass production than the March seeding (12,357 and 8909 kg ha⁻¹, respectively, SEM = 2454). Irrigation or adequate precipitation to maintain soil moisture and weed control are critical to B. prostrata establishment by direct seeding, especially in dry winter regions. Further research is necessary to determine the potential of this species as an alternative to alfalfa in semiarid, subtropical, and continental precipitation regions. Full article

(This article belongs to the Special Issue Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands)

14 pages, 1490 KiB

Open AccessArticle

Evaluation of Different Fall Dormancy-Rating Alfalfa Cultivars for Forage Yield in a Semiarid Environment

by Koffi Djaman, Curtis Owen, Komlan Koudahe and Michael O’Neill

Agronomy 2020, 10(1), 146; https://doi.org/10.3390/agronomy10010146 - 19 Jan 2020

Cited by 22 | Viewed by 4618

Abstract

Alfalfa is one of the most important, nutritive, and high yielding forage legumes planted across the US. Fall dormancy in alfalfa influences forage yield characteristics and the plants persistence mostly under the cold and temperate climate. The objective of this study was to [...] Read more.

Alfalfa is one of the most important, nutritive, and high yielding forage legumes planted across the US. Fall dormancy in alfalfa influences forage yield characteristics and the plants persistence mostly under the cold and temperate climate. The objective of this study was to evaluate alfalfa cultivars with different fall dormancy-ratings for their forage yield at each cut and the annual forage yield. Two sets of 24 alfalfa cultivars were evaluated in a field experiment conducted at the Agricultural Science Center at Farmington, NM. The first set of 24 cultivars was planted late fall 2007 at seeding rate of 22.4 kg ha⁻¹ and managed for the 2007–2011 period and the second set was planted late fall 2009 and managed during the 2009–2013 period. Average forage yield varied with years from 7.6 to 2.9 Mg ha⁻¹, 6.8 to 4.3 Mg ha⁻¹, 9.2 to 4.2 Mg ha⁻¹, and 7.9 to 3.2 Mg ha⁻¹ during the 1st, 2nd, 3rd, and 4th alfalfa cut, respectively. The results showed no statistical differences between the moderately dormant, dormant, and the non-dormant alfalfa cultivars while they showed higher forage yield than the very dormant and semi-dormant alfalfa cultivars. There was a decreasing trend in forage yield from the first cut to the fourth cut in each growing season. However, the very dormant cultivars showed the lowest forage yield. Alfalfa forage yield decreased from the cut 1 to the cut 4 which represented on average 33, 29, 22, and 16% of the annual yield. The semi-dormant cultivars obtained the lowest forage yield at the first and second cutting while there was no difference between the cultivars for the third and fourth harvests. Average forage yields per harvest were 5.7, 5.9, 6.0, 5.5, and 5.9 Mg ha⁻¹ for the very dormant, dormant, moderately dormant, semi-dormant, and non-dormant alfalfa cultivars, respectively. Annual forage yield varied with alfalfa fall dormancy-ratings and ranged from 15.5 to 29.9 Mg ha⁻¹ with the highest forage yield achieved during the third years of the production. The moderately dormant and the non-dormant cultivars showed the highest yield during the first harvest year while the very dormant cultivars and dormant cultivars had the lowest forage yield. Alfalfa cultivars with a fall dormancy range 4–5 may be considered for alfalfa production in northwest New Mexico however, the good agricultural practices (conservation tillage, fertilizer management based on soil residual available nutrient and crop requirement, recommended planting rate, weed and pest management, irrigation scheduling to match crop evapotranspiration) should be the most important to maximize alfalfa forage yield in the southwest US. Full article

(This article belongs to the Special Issue Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands)

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25 pages, 11029 KiB

Open AccessArticle

Functional Analysis of Three miRNAs in Agropyron mongolicum Keng under Drought Stress

by Xuting Zhang, Bobo Fan, Zhuo Yu, Lizhen Nie, Yan Zhao, Xiaoxia Yu, Fengcheng Sun, Xuefeng Lei and Yanhong Ma

Agronomy 2019, 9(10), 661; https://doi.org/10.3390/agronomy9100661 - 20 Oct 2019

Cited by 10 | Viewed by 2718

Abstract

Agropyron mongolicum Keng, a perennial diploid grass with high drought tolerance, belongs to the genus Agropyron, tribe Triticeae. It has made tremendous contributions toward reseeding natural pasture and seeding artificial grassland in China, especially in the arid and semi-arid area of [...] Read more.

Agropyron mongolicum Keng, a perennial diploid grass with high drought tolerance, belongs to the genus Agropyron, tribe Triticeae. It has made tremendous contributions toward reseeding natural pasture and seeding artificial grassland in China, especially in the arid and semi-arid area of northern China. As a wild relative of wheat, A. mongolicum is also a valuable resource for the genetic improvement of wheat crops. MicroRNAs are small non-coding RNA molecules ubiquitous in plants, which have been involved in responses to a wide variety of stresses including drought, salinity, chilling temperature. To date, little research has been done on drought-responsive miRNAs in A. mongolicum. In this study, two miRNA libraries of A. mongolicum under drought and normal conditions were constructed, and drought-responsive miRNAs were screened via Solexa high throughput sequencing and bioinformatic analysis. A total of 114 new miRNAs were identified in A. mongolicum including 53 conservative and 61 unconservative miRNAs, and 1393 target genes of 98 miRNAs were predicted. Seventeen miRNAs were found to be differentially expressed under drought stress, seven (amo-miR21, amo-miR62, amo-miR82, amo-miR5, amo-miR77, amo-miR44 and amo-miR17) of which were predicted to target on genes involved in drought tolerance. QRT-PCR analysis confirmed the expression changes of the seven drought related miRNAs in A. mongolicum. We then transformed the seven miRNAs into Arabidopsis thaliana plants, and three of them (amo-miR21, amo-miR5 and amo-miR62) were genetically stable. The three miRNAs demonstrated the same expression pattern in A. thaliana as that in A. mongolicum under drought stress. Findings from this study will better our understanding of the molecular mechanism of miRNAs in drought tolerance and promote molecular breeding of forage grass with improved adaption to drought. Full article

(This article belongs to the Special Issue Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands)

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Review

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18 pages, 1364 KiB

Open AccessReview

Breeding Alfalfa for Semiarid Regions in the Northern Great Plains: History and Additional Genetic Evaluations of Novel Germplasm

by Arvid Boe, Kevin D. Kephart, John D. Berdahl, Michael D. Peel, E. Charles Brummer, Lan Xu and Yajun Wu

Agronomy 2020, 10(11), 1686; https://doi.org/10.3390/agronomy10111686 - 30 Oct 2020

Cited by 6 | Viewed by 2863

Abstract

Yellow-flowered alfalfa (Medicago sativa subsp. falcata) (also known as sickle medic) has been the cornerstone for breeding alfalfa for dual grazing and hay production in the semiarid regions of the northern Great Plains in the US and Canada. Most, if not [...] Read more.

Yellow-flowered alfalfa (Medicago sativa subsp. falcata) (also known as sickle medic) has been the cornerstone for breeding alfalfa for dual grazing and hay production in the semiarid regions of the northern Great Plains in the US and Canada. Most, if not all, of the cultivars developed for the northern Great Plains during the 20th century, had parentage tracing back to introductions by Niels Ebbesen Hansen that were obtained from expeditions to Russia, primarily the province of Siberia, on behalf of the United States Department of Agriculture during the early 1900s. The M. falcata genome contains alleles for high levels of drought-tolerance, winter hardiness, and tolerance to grazing, but is generally deficient for commercial seed production traits, such as non-shatter, compared with common alfalfa (M. sativa). A naturalized population, tracing to USDA plant introductions to Perkins County South Dakota by N.E. Hansen in early 1900, and subsequently, facilitated by the determined seed increase and interseeding of a population by a local rancher, Norman ‘Bud’ Smith, has shown highly desirable in situ characteristics for improving rangelands in the northern Great Plains. This includes adequate seed production to build a seed bank in the soil for natural seedling recruitment and population maintenance/expansion and support the production of a commercial seed source. This review documents the seminal events in the development of cultivars to date and describes novel germplasm with potential for new cultivars in the future. Full article

(This article belongs to the Special Issue Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands)

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12 pages, 300 KiB

Open AccessReview

Breeding of the Crested Wheatgrass Complex (Agropyron spp.) for North American Temperate Rangeland Agriculture and Conservation

by Joseph G. Robins and Kevin B. Jensen

Agronomy 2020, 10(8), 1134; https://doi.org/10.3390/agronomy10081134 - 04 Aug 2020

Cited by 6 | Viewed by 2877

Abstract

Species from the crested wheatgrass (Agropyron spp.) complex have been widely used for revegetation and grazing on North American rangelands for over 100 years. Focused crested wheatgrass breeding has been ongoing since the 1920s. These efforts resulted in the development of 18 [...] Read more.

Species from the crested wheatgrass (Agropyron spp.) complex have been widely used for revegetation and grazing on North American rangelands for over 100 years. Focused crested wheatgrass breeding has been ongoing since the 1920s. These efforts resulted in the development of 18 cultivars adapted to western USA and Canadian growing conditions. These cultivars establish rapidly, persist, and provide soil stabilization and a reliable feed source for domestic livestock and wildlife. To address ecological concerns and increase rangeland agriculture efficiency, crested wheatgrass breeding requires new emphases and techniques. This review covers the history of crested wheatgrass breeding and genetics in North America and discusses emerging methods and practices for improvement in the future. Full article

(This article belongs to the Special Issue Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands)

15 pages, 776 KiB

Open AccessReview

Morphological, Physiological, and Genetic Responses to Salt Stress in Alfalfa: A Review

by Surendra Bhattarai, Dilip Biswas, Yong-Bi Fu and Bill Biligetu

Agronomy 2020, 10(4), 577; https://doi.org/10.3390/agronomy10040577 - 17 Apr 2020

Cited by 55 | Viewed by 6732

Abstract

Alfalfa (Medicago sativa L.) is an important legume forage crop. However, its genetic improvement for salt tolerance is challenging, as alfalfa’s response to salt stress is genetically and physiologically complex. A review was made to update the knowledge of morphological, physiological, biochemical, [...] Read more.

Alfalfa (Medicago sativa L.) is an important legume forage crop. However, its genetic improvement for salt tolerance is challenging, as alfalfa’s response to salt stress is genetically and physiologically complex. A review was made to update the knowledge of morphological, physiological, biochemical, and genetic responses of alfalfa plants to salt stress, and to discuss the potential of applying modern plant technologies to enhance alfalfa salt-resistant breeding, including genomic selection, RNA-Seq analysis, and cutting-edge Synchrotron beamlines. It is clear that alfalfa salt tolerance can be better characterized, genes conditioning salt tolerance be identified, and new marker-based tools be developed to accelerate alfalfa breeding for salt tolerance. Full article

(This article belongs to the Special Issue Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands)

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