Genetic variability for leaf development in perennial ryegrass populations

1996 ◽  
Vol 76 (1) ◽  
pp. 113-118 ◽  
Author(s):  
L. Hazard ◽  
M. Ghesquière ◽  
C. Barraux
Keyword(s):  
Genetic Variability ◽  
Perennial Ryegrass ◽  
Natural Populations ◽  
Leaf Length ◽  
Divergent Selection ◽  
Leaf Elongation ◽  
Genetic Progress ◽  
Leaf Morphogenesis ◽  
Heritable Trait ◽  
Selection For

In perennial ryegrass (Lolium perenne, L.), leaf length is a highly heritable trait likely to respond to both natural and artificial selection. The genetic variability of components of leaf morphogenesis of perennial ryegrass was studied in 2 populations obtained from two cycles of divergent selection for lamina length, in 42 natural populations, and in forage and turf cultivars. The genetic progress in the two branches of the divergent selection was accompanied by a significant change in the leaf elongation rate, whereas the phyllochron and the leaf elongation duration remained relatively unchanged. The forage cultivars were not morphogenetically different from the natural populations, and hence progress for yield under infrequent cutting could be made by selection for long-leaf populations. Turf cultivars, however, were morphogenetically different from natural populations. Turf cultivars had small leaves with short sheaths and laminae. The population resulting from the selection for short leaf had laminae as long as those of turf cultivars but with longer sheaths.

Morphology and Rubisco turnover characteristics of perennial ryegrass breeding populations after two and four cycles of divergent selection for long or short leaf length

2013 ◽  
Vol 64 (7) ◽  
pp. 687 ◽  
Author(s):  
Edith N. Khaembah ◽  
François Gastal ◽  
Serge Carre ◽  
Louis J. Irving ◽  
Philippe Barre ◽  
...  
Keyword(s):  
Perennial Ryegrass ◽  
Morphological Traits ◽  
Dry Matter ◽  
Leaf Length ◽  
Elongation Rate ◽  
Leaf Elongation ◽  
Plant Yield ◽  
Leaf Elongation Rate ◽  
Selection For ◽  
Leaf Appearance

Perennial ryegrass populations previously subjected to two or four cycles of selection for short or long leaf length were studied to determine the response of morphological traits to selection and interaction to determine yield. Measured morphological traits were leaf length, leaf appearance interval, ligule appearance interval, leaf elongation duration, leaf elongation rate, tiller number, tiller dry weight, and herbage dry matter. Additionally, Rubisco concentration during leaf development was measured to determine the association of Rubisco turnover with morphological characteristics and yield. Rubisco was measured and modelled as a three-parameter (D, peak Rubisco concentration; G, time of D; and F, curve width measure), log-normal curve. Leaf length, leaf elongation rate, tiller weight, and plant dry matter diverged after two cycles of selection and further divergence occurred, with these traits being, respectively, 35, 28, 53, and 61% greater in the long- than the short-leaved plants after four cycles of selection. Opposite trends were displayed by Rubisco turnover, with selection for long leaves co-selecting for increased Rubisco turnover time and selection for short leaves resulting in increased leaf Rubisco concentration. There was indication of coupling of leaf appearance with Rubisco turnover. Across populations, multivariate analysis indicated that plant yield was associated with Rubisco concentration rather than Rubisco turnover. The association between higher yield and lower Rubisco concentration could be targeted in the breeding of high-yielding, nitrogen-efficient forage grasses. Plant yield was mainly associated with increased leaf area, indicating that yield could be improved by selecting for longer leaves and faster rates of leaf expansion.

The effect of reduced leaf shear strength on the nutritive value of perennial ryegrass

1988 ◽  
Vol 111 (3) ◽  
pp. 469-474 ◽  
Author(s):  
B. W. Mackinnon ◽  
H. S. Easton ◽  
T. N. Barry ◽  
J. R. Sedcole
Keyword(s):  
Shear Strength ◽  
Perennial Ryegrass ◽  
White Clover ◽  
Nutritive Value ◽  
Basal Diet ◽  
Leaf Length ◽  
Total N ◽  
Heritable Trait ◽  
Nutritional Characteristics ◽  
Ruminal Degradation

SummaryProgeny of perennial ryegrass (PRG) plants selected for low and high leaf shear strength were sown in a spaced-plant field experiment and were shown to differ in leaf strength in the same direction, confirming this to be a heritable trait. Selection for low leaf shear strength also reduced weight per leaf length, but had no effect on dry-matter (D.M.) percentage, growth score, rust score or tendency towards aftermath heading.Rates of D.M. consumption (g D.M./min) and ruminal degradation of D.M. using the polyester bag technique, were then determined with small quantities of the two PRG selection lines, and also white clover, using sheep fed a basal diet of fresh ryegrass/white clover pasture. Selecting PRG for low leaf shear strength slightly reduced concentrations of cellulose and hemicellulose, slightly increased total N concentration and increased rate of D.M. consumption by sheep (17%) but had no effect on rates of ruminal D.M. degradation. The selection thus moved the nutritional characteristics of PRG in the direction of white clover.The first nutritional response to the selection appears to be a faster rate of D.M. consumption, and it is considered that leaf shear strength has potential for selecting PRG with increased rates of voluntary intake by ruminants.

The relationship between productivity and some components of canopy structure in ryegrass (Lolium spp.)

1969 ◽  
Vol 73 (3) ◽  
pp. 315-319 ◽  
Author(s):  
Ian Rhodes
Keyword(s):  
Perennial Ryegrass ◽  
Natural Populations ◽  
Canopy Structure ◽  
Leaf Length ◽  
Population Differences ◽  
Base Population ◽  
Potential Production ◽  
Physiological Basis ◽  
Area Index ◽  
The Relationship

SummaryTwo experiments are described in which the potential production of genotypes selected from within S. 321 perennial ryegrass for differing leaf length was assessed (a) in micro-swards composed of populations of similar genotypes and (b) in micro-swards of individual genotypes. In Experiment 1 the long- and short-leaved populations were also compared with the base population of S. 321 and with several other natural populations and bred varieties.Under infrequent cutting the population of long-leaved genotypes was more productive than the short-leaved and base populations. Under frequent cutting, however, the population of short-leaved genotypes was most productive. Similarly, whilst Ba 6280 ryegrass was highly productive and the natural Ynyslas population unproductive under infrequent cutting the situation was reversed under frequent cutting. The population of long-leaved genotypes and Ba 6280 had a higher leaf area index (L) than other populations and varieties at complete light interception.Considerable differences in productivity existed between individual genotypes, and there was also an interaction between genotypes and cutting frequencies. The relationships between yield and both leaf length and chlorophyll content are presented and the physiological basis of inter-genotypic and inter-population differences in production are discussed.

Divergent Selection for In Vitro Dry Matter Digestibility in Smooth Bromegrass 1

Crop Science ◽  
1986 ◽  
Vol 26 (6) ◽  
pp. 1123-1126 ◽  
Author(s):  
N. J. Ehlke ◽  
M. D. Casler ◽  
P. N. Drolsom ◽  
J. S. Shenk
Keyword(s):  
Dry Matter ◽  
Divergent Selection ◽  
Smooth Bromegrass ◽  
Dry Matter Digestibility ◽  
Selection For

Effects of Divergent Selection for Growth on Carcass Traits in Japanese Quails

2014 ◽  
Vol 42 (2) ◽  
pp. 51-56
Author(s):  
Khairy M. El–Bayomi ◽  
Mahmoud S. El-Tarabany ◽  
Mohammed A.F. Nasr ◽  
El-Shimaa M. Roushdy
Keyword(s):  
Carcass Traits ◽  
Divergent Selection ◽  
Japanese Quails ◽  
Selection For

scholarly journals Polygenic and single gene responses to selection for resistance to diazinon in Lucilia cuprina.

Genetics ◽  
1992 ◽  
Vol 130 (3) ◽  
pp. 613-620 ◽  
Author(s):  
J A McKenzie ◽  
A G Parker ◽  
J L Yen
Keyword(s):  
Resistant Strain ◽  
Single Gene ◽  
Natural Populations ◽  
Susceptible Strain ◽  
Selection Line ◽  
Base Population ◽  
Gene Response ◽  
Biochemical Profiles ◽  
Resistant Strains ◽  
Selection For

Abstract Following mutagenesis with ethyl methanesulfonate, selection in a susceptible strain with a concentration of the insecticide diazinon (0.0004%, w/v) above that required to kill 100% of the susceptible strain, the LC100 of that strain, resulted in a single gene response. The resultant four mutant resistant strains have equivalent physiological, genetical and biochemical profiles to a diazinon-resistant strain derived from a natural population and homozygous for the Rop-1 allele. Modification of the microsomal esterase E3 is responsible for resistance in each case. The Rop-1 locus maps approximately 4.4 map units proximal to bu on chromosome IV. Selection within the susceptible distribution, at a concentration of diazinon [0.0001% (w/v)] less than the LC100, resulted in a similar phenotypic response irrespective of whether the base population had been mutagenized. The responses were polygenically based, unique to each selection line and independent of Rop-1. The relevance of the results to selection for insecticide resistance in laboratory and natural populations is discussed.

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