scholarly journals Agronomic evaluation of perennial ryegrass wild populations from Ireland for use in French plant breeding programmes

Agronomie ◽  
1989 ◽  
Vol 9 (10) ◽  
pp. 985-991 ◽  
Author(s):  
G. Charmet ◽  
A. Bion ◽  
F. Balfourier
Keyword(s):  
Plant Breeding ◽  
Perennial Ryegrass ◽  
Wild Populations ◽  
Agronomic Evaluation ◽  
Breeding Programmes

Haploidy and plant breeding

1981 ◽  
Vol 292 (1062) ◽  
pp. 499-507 ◽  
Keyword(s):  
Plant Breeding ◽  
Doubled Haploids ◽  
Chromosome Complement ◽  
Basic Research ◽  
Breeding Value ◽  
Additive Variance ◽  
Ploidy Levels ◽  
Breeding Programmes ◽  
Dh Lines

A haploid is an organism that looks like a sporophyte, but has the chromosome complement of a reduced gamete. There are several ways in which haploids can occur or be induced in vivo : spontaneously, mostly associated with polyembryony, and through abnormal processes after crosses, like pseudogamy, semigamy, preferential elimination of the chromosomes of one parental species, and androgenesis. In the crops described, haploids are or are near to being used in basic research and plant breeding. The application of haploids in breeding self-pollinated crops is based on their potential for producing fully homozygous lines in one generation, which can be assessed directly in the field. Early generation testing of segregating populations is possible through haploids, because doubled haploids (DH) possess additive variance only. Haploids can also be applied in classical breeding programmes to make these more efficient through improved reliability of selection. The application of haploids in cross-pollinated crops is also based on a rapid production of DH-lines, which can be used as inbred lines for the production of hybrid varieties. By means of haploids all natural barriers to repeated selfing are bypassed. In autotetraploid crops there are two types of haploid. One cycle of haploidization leads to dihaploids; a second cycle produces monohaploids. The significance of dihaploids is in their greatly simplified genetics and breeding and in the possibility of estimation of the breeding value of tetraploid cultivars by assessing their dihaploids. The main drawback of dihaploids is their restriction to two alleles per locus. Also, after doubling, it is impossible to achieve tetra-allelism at many loci, the requirement for maximal performance of autotetraploid cultivars. Tetra-allelism can be obtained when improved dihaploids have a genetically controlled mechanism of forming highly heterozygous restitution gametes with the unreduced number of chromosomes. Monohaploids, after doubling or twice doubling, may lead to fully homozygous diploids and tetraploids. These are important for basic research, but not yet for practical application. Meiotic data of potato homozygotes at three ploidy levels are presented.

Wild populations as a source of germplasm for black poplar (Populus nigra L.) breeding programmes

2012 ◽  
Vol 8 (5) ◽  
pp. 1073-1084 ◽  
Author(s):  
Vojtěch Benetka ◽  
Kateřina Novotná ◽  
Petra Štochlová
Keyword(s):  
Populus Nigra ◽  
Wild Populations ◽  
Black Poplar ◽  
Breeding Programmes

scholarly journals Winter wheat in England and Wales, 1923–1995: what do indices of genetic diversity reveal?

2003 ◽  
Vol 1 (1) ◽  
pp. 43-57 ◽  
Author(s):  
C. S. Srinivasan ◽  
Colin Thirtle ◽  
Paolo Palladino
Keyword(s):  
Genetic Diversity ◽  
Winter Wheat ◽  
Plant Breeding ◽  
Genetic Resources ◽  
Wheat Crop ◽  
England And Wales ◽  
Genealogical Relationship ◽  
Breeding Programmes ◽  
Winter Wheat Crop ◽  
The Stability

AbstractGenealogical data have been used very widely to construct indices with which to examine the contribution of plant breeding programmes to the maintenance and enhancement of genetic resources. In this paper we use such indices to examine changes in the genetic diversity of the winter wheat crop in England and Wales between 1923 and 1995. We find that, except for one period characterized by the dominance of imported varieties, the genetic diversity of the winter wheat crop has been remarkably stable. This agrees with many studies of plant breeding programmes elsewhere. However, underlying the stability of the winter wheat crop is accelerating varietal turnover without any significant diversification of the genetic resources used. Moreover, the changes we observe are more directly attributable to changes in the varietal shares of the area under winter wheat than to the genealogical relationship between the varieties sown. We argue, therefore, that while genealogical indices reflect how well plant breeders have retained and exploited the resources with which they started, these indices suffer from a critical limitation. They do not reflect the proportion of the available range of genetic resources which has been effectively utilized in the breeding programme: complex crosses of a given set of varieties can yield high indices, and yet disguise the loss (or non-utilization) of a large proportion of the available genetic diversity.

Variability in hot pepper for phytochemicals offers promising tools in plant-breeding programmes

2010 ◽  
Vol 60 (3) ◽  
pp. 227-234
Author(s):  
Supradip Saha ◽  
N.K. Hedau ◽  
S. Kumar ◽  
V. Mahajan ◽  
H.S. Gupta
Keyword(s):  
Plant Breeding ◽  
Hot Pepper ◽  
Breeding Programmes

scholarly journals Growth under cold conditions in a wide perennial ryegrass panel is under tight physiological control

2018 ◽  
Author(s):  
Lena Förster ◽  
Jim Grant ◽  
Thibauld Michel ◽  
Carl Ng ◽  
Susanne Barth
Keyword(s):  
Low Temperature ◽  
Cold Stress ◽  
Perennial Ryegrass ◽  
Electrolyte Leakage ◽  
Growth Conditions ◽  
Plant Performance ◽  
Grass Species ◽  
Physiological Control ◽  
Breeding Programmes ◽  
The Impact

Background. Perennial ryegrass is a cool-season grass species from the family Poaceae and is widely cultivated in temperate regions because it exhibits rapid growth and establishment, and possesses high forage quality. The extension of the growing season in Ireland in spring and autumn is a breeding target to make farming more profitable since a rass-fed diet based on grazing is the cheapest way of nutrition for ruminants. Methods. Fifty-seven perennial ryegrass accessions were screened for their ability to grow under typical Irish spring conditions as taken from long term emperature records in controlled climate chambers. They were grown in low temperature (8°C/2°C day/night) and control conditions (15°C/8°C day/night) in three consecutive independent experiments. Fresh weight, height, clorophyll content and electrolyte leakage were measured, and these parameters were used to rank plant performance under low temperature growth conditions. Results. The results showed that height, yield and electrolyte leakage are xcellent measures for the impact of cold stress tolerance. Little variation in growth was seen undercold stress, but a wide variety of responses were observed under control conditions. Discussion. Our results suggest that cold stress is under tight physiological control. Interestingly, the various genotypes responded differentially to more amenable control conditions, indicating that a quick response to more amenable growth conditions is a better target for breeding programmes.

scholarly journals Plant responses to climate and relationships with pasture persistence

2011 ◽  
Vol 15 ◽  
pp. 99-107
Author(s):  
D.F. Chapman ◽  
G.R. Edwards ◽  
Z.N. Nie
Keyword(s):  
Plant Breeding ◽  
Perennial Ryegrass ◽  
White Clover ◽  
Climatic Factors ◽  
Insect Pest ◽  
Plant Responses ◽  
Negative Effects ◽  
Term Survival ◽  
Variable Environment ◽  
Resource Limitations

Relationships between climatic factors and persistence of grazed perennial ryegrass and white clover pastures in New Zealand are reviewed from an ecophysiological perspective. 'Persistence' is defined in terms of physical survival of plants of sown cultivars: the effects of climate on plant populations are considered. Substantial information is available on the population dynamics of perennial ryegrass and white clover in different climatic environments, particularly on the influence of drought on populations. Substantial, direct negative effects of drought on the density of perennial ryegrass tillers and white clover stolons have been recorded, though populations have generally recovered after release from drought conditions. Otherwise, the effects of climaterelated resource limitations on population size are more likely to be interactive, working in concert with other factors such as management, soil fertility and insect pest challenges to limit the capacity of homeostatic responses to restore the optimal (for long term survival) balance between above- and below-ground resources. The relative extent to which more recent cultivars of perennial ryegrass are able to tolerate multiple, simultaneous resource limitations compared to older cultivars (with different phenotype) is considered, but there is little direct evidence on this matter. Issues that should be considered in future pasture persistence research are identified and discussed. One of these concerns is the persistence of trait expression in cultivars bred for specific traits. More research on this topic is warranted, since molecular plant breeding techniques are strongly based on trait manipulation, and genotype x environment interactions can be expected in the spatially and temporally variable environment of grazed pastures. Keywords: drought, ecology, plant breeding, ryegrass, white clover

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