scholarly journals Ryegrass in pastures - breeding for resilience

2011 ◽  
Vol 15 ◽  
pp. 139-147 ◽  
Author(s):  
H.S. Easton ◽  
A.V. Stewart ◽  
G.A. Kerr
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Plant Breeding ◽  
Lolium Perenne ◽  
Final Evaluation ◽  
Knowledge Gaps ◽  
Critical Information ◽  
Breeding Objectives ◽  
Grass Sward ◽  
Industry Needs

The suggestion that modern pasture cultivars persist less well than their predecessors is not supported by facts. However in some regions there is a crisis in farmer experience of persistence of ryegrass pastures, and ryegrass breeding can contribute to a resolution. This paper considers the turnover of tillers in a pasture, the population structure of a grass sward and the involvement of endophyte and companion clover. Knowledge gaps in key processes of pasture persistence are discussed. The plant breeding process involves access to relevant genetic variation, its assessment, and creation of improved populations and eventually cultivars based on selected superior plants. All these scientific processes use ever-evolving techniques. Breeding objectives evolve with industry needs and the changing environment. The methods employed in the breeding phases, the breeding objectives and the final evaluation of cultivars require ongoing revision. Plant breeding will make a growing contribution to modern farming if its developing capabilities are interfaced with other research disciplines providing critical information on key pasture processes. Keywords: Lolium perenne, endophyte, persistence, tillering

Recovery and utilization of applied nitrogen by a diallel set of progenies of Lolium perenne L.

1970 ◽  
Vol 75 (1) ◽  
pp. 159-167 ◽  
Author(s):  
A. J. Thomson ◽  
H. H. Rogers
Keyword(s):  
Genetic Variation ◽  
Plant Breeding ◽  
Lolium Perenne ◽  
Measured Data ◽  
Lolium Perenne L ◽  
Linear Effect ◽  
Nitrogen Rates ◽  
Plant Breeding Programme ◽  
Plot Design ◽  
Applied Nitrogen

SUMMARYFive selected clones of Lolium perenne were selfed and the ten possible diallel crosses, without reciprocals, made. The progenies were grown in a split-plot design in which whole plots comprised the four nitrogen rates (0, 225, 450 and 675 kg/ha of N) and sub-plots the fifteen progenies, square planted at 0·25 m.The percentage of the applied nitrogen recovered, and the utilization of the nitrogen by the plant, were measured. Data were collected from four harvests in each of two consecutive years. The diallel was analysed by Griffing's (1956) Method II, Model II.There were significant effects for nitrogen rates, progenies and their interaction for both ‘recovery’ and ‘utilization’, but years were significantly different for ‘recovery’ only. The effect of applied nitrogen was mainly linear and it was the linear effect of applied nitrogen which interacted most with the progeny effects.Significant g.c.a. and s.c.a. effects were found but they varied between nitrogen rates and years. For ‘utilization’ the interaction nitrogen rates x g.c.a. was significant on two year means but there was no significance for the nitrogen interaction with s.c.a. The g.c.a. values obtained for both parameters did reveal some trends between the five parents.The presence of significant additive and non-additive genetic variation is discussed in relation to a plant breeding programme.

scholarly journals Lack of Population Structure in Coriander Populations Based on SDS (Seed Storage Protein) Page Analysis

2016 ◽  
Vol 4 (8) ◽  
pp. 656
Author(s):  
Gülsüm Yaldiz ◽  
Muhammad Sameeullah ◽  
Mahmut Çamlıca ◽  
Faheem Shehzad Baloch
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Plant Breeding ◽  
Storage Protein ◽  
Seed Storage Protein ◽  
Sampling Strategy ◽  
Seed Storage ◽  
Plant Introduction ◽  
Breeding Program ◽  
Plant Breeding Program

Genetic variation is prerequisite for plant breeding. Nothing information existed in the literature for available diversity of Coriander accession in Turkey. Plant breeding activities are negligible in Turkey. So in order to start effective plant breeding program in Turkey, information on the available genetic diversity is viable. Therefore we planned to study the genetic variation and population structure of 29 Coriander accessions by seed storage protein (SDS). SDS analysis elaborated the lack of population structure and genetic bottleneck in the Coriander accessions in Turkey. Based on the results of this study, it was clear that sampling strategy was not appropriate and plant introduction should be made from different sources and diverse genotypes should be used as parents to initialize the effective Turkish Coriander breeding program.

scholarly journals The effects of ploidy and seed mass on the emergence and early vigour of perennial ryegrass (Lolium perenne L.) cultivars

2003 ◽  
Vol 43 (5) ◽  
pp. 481 ◽  
Author(s):  
K. F. Smith ◽  
N. M. McFarlane ◽  
V. M. Croft ◽  
P. J. Trigg ◽  
G. A. Kearney
Keyword(s):  
Genetic Variation ◽  
Lolium Perenne ◽  
Perennial Ryegrass ◽  
Seed Mass ◽  
Leaf Length ◽  
Seedling Height ◽  
Seedling Vigour ◽  
Lolium Perenne L ◽  
Early Vigour ◽  
Shoot Mass

Genetic variation for seed mass and components of early vigour were measured on 120 seedlings of each of 18 diploid and 27 tetraploid perennial ryegrass (Lolium perenne L.) cultivars. Seeds of tetraploid cultivars were on average heavier (3.8 mg) than seed of diploid cultivars (2.4 mg). However, there was variation for mean seed mass both within and between ploidy classes and within cultivars. The components of early vigour measured on each of the seedlings were: date of emergence, leaf appearance rate, seedling height (10 days after germination), leaf length and width and dry matter at 33 days after emergence. Mean seed mass of a cultivar was significantly (P<0.05) positively correlated with seedling height, leaf length, leaf width, shoot length and shoot mass. Individual seed mass within a cultivar was significantly associated with all components of early vigour, except the date of emergence of the second true leaf. There was no difference in the rate of emergence of tetraploid and diploid cultivars, although tetraploid cultivars tended to have longer and wider leaves, greater seedling lengths and fewer leaves and tillers than diploid cultivars. There was also evidence of genetic variation for seedling vigour components in perennial ryegrass after seed mass and ploidy effects had been removed during analysis. These data suggest that seed mass has a large positive effect on early vigour of both diploid and tetraploid cultivars of perennial ryegrass and that, in the absence of any specific knowledge of the early vigour characteristics of a given cultivar, seed mass could be used as a surrogate when choosing between cultivars with similar adaptation and performance.

scholarly journals Determining Whether Geographic Origin and Potato Genotypes Shape the Population Structure of Phytophthora infestans in the Central Region of Colombia

2019 ◽  
Vol 109 (1) ◽  
pp. 145-154
Author(s):  
Sandra Catalina Chaves ◽  
María Camila Rodríguez ◽  
María Fernanda Mideros ◽  
Florencia Lucca ◽  
Carlos E. Ñústez ◽  
...  
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Phytophthora Infestans ◽  
Central Region ◽  
Geographic Origin ◽  
Geographic Area ◽  
Potato Cultivars ◽  
Clonal Lineage ◽  
Host Genotype ◽  
Genetic Population

Pathogen variation plays an important role in the dynamics of infectious diseases. In this study, the genetic variation of 279 Phytophthora infestans isolates was assessed using a combination of 12 microsatellite simple-sequence repeat markers. Isolates were collected from 11 different potato cultivars in 11 different geographic localities of the central region of Colombia. The objective of this study was to determine whether populations were differentiated by host genotype or geographic origin. Within a single clonal lineage, EC-1, 76 genotypes were detected. An analysis of molecular variance attributed most of the variation to differences within host genotypes rather than among the host genotypes, suggesting that host cultivars do not structure the populations of the pathogen. Furthermore, the lack of a genetic population structure according to the host cultivar was confirmed by all of the analyses, including the Bayesian clustering analysis and the minimum spanning network that used the Bruvo genetic distance, which suggested that there are no significant barriers to gene flow for P. infestans among potato cultivars. According to the geographic origin, the populations of P. infestans were also not structured, and most of the variation among the isolates was attributed to differences within localities. Only some but not all localities in the north and west of the central region of Colombia showed some genetic differentiation from the other regions. The absence of sexual reproduction of this pathogen in Colombia was also demonstrated. Important insights are discussed regarding the genetic population dynamics of the P. infestans populations of the central region of Colombia that were provided by the results. In Colombia, there is a high genetic variation within the EC-1 clonal lineage with closely related genotypes, none dominant, that coexist in a wide geographic area and on several potato cultivars.

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