Genetic improvement of early vigour in wheat

1999 ◽  
Vol 50 (3) ◽  
pp. 291 ◽  
Author(s):  
G. J. Rebetzke ◽  
R. A. Richards
Keyword(s):  
Genetic Variation ◽  
Leaf Area ◽  
Plant Biomass ◽  
Genetic Correlations ◽  
Yield Potential ◽  
Environment Interaction ◽  
Narrow Sense Heritability ◽  
Wheat Varieties ◽  
Early Vigour ◽  
Selection For

Grain yield potential of Australian wheat crops is often limited because of inadequate water for crop growth and grain filling. Greater early vigour, defined here as the amount of leaf area produced early in the season, should improve the water-use efficiency and yield of wheat crops grown in Mediterranean-type climates such as occurs in southern Australia. In order to maximise selection efficiency for early vigour in breeding programs, the magnitude and form of genetic variation for early vigour and its components was investigated for 2 contrasting wheat populations. The first population comprised 28 Australian and overseas wheat varieties evaluated in a serial sowing study in Canberra. The second population contained 50 random F 2:4 and F 2:6 families derived from a convergent cross of elite CIMMYT wheat lines evaluated in Canberra, and in the field at Condobolin, New South Wales. For the first population, environmental effects on leaf breadth and length, and to a lesser extent, phyllochron interval, produced significant (P < 0.05) changes in leaf area. Large and significant (P < 0.05) differences were observed among Australian and overseas wheats for early vigour and its components. Australian varieties were among the least vigorous of the lines tested, with a number of overseas varieties producing about 75% greater leaf area than representative Australian wheats. Increased leaf area was genetically correlated with increases in leaf breadth and length, and a longer phyllochron interval. Significant (P < 0.05) genotype ´ environment interaction reduced broad-sense heritability (%) for early vigour (H ± s.e., 87 ± 26) compared with leaf breadth (96 ± 25) and length (97 ± 27). Narrow-sense heritability (%) in the second population was small for leaf area (h2 ± s.e., 30 ± 6) and plant biomass (35 ± 7), but high for leaf breadth (76 ± 14) and length (67 ± 16). Genetic correlations were strong and positive for leaf area with plant biomass, leaf breadth and length, specific leaf area and coleoptile tiller frequency, whereas faster leaf and primary tiller production were negatively correlated with leaf area. The high heritability for leaf breadth coupled with its strong genetic correlation with leaf area (rg = 0.56-0.57) indicated that selection for leaf breadth should produce genetic gain in leaf area similar to selection for leaf area per se. However, the ease with which leaf breadth can be measured indicates that selection for this character either by itself, or in combination with coleoptile tiller production, should provide a rapid and non-destructive screening for early vigour in segregating wheat populations. The availability of genetic variation for early vigour and correlated traits should enable direct or indirect selection for greater leaf area in segregating wheat populations.

The genetic variation in the timing of heteroblastic transition in Eucalyptus globulus is stable across environments

2011 ◽  
Vol 59 (2) ◽  
pp. 170 ◽  
Author(s):  
M. G. Hamilton ◽  
P. A. Tilyard ◽  
D. R. Williams ◽  
R. E. Vaillancourt ◽  
T. J. Wardlaw ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Phase Change ◽  
Eucalyptus Globulus ◽  
Developmental Change ◽  
Genetic Correlations ◽  
Genotype By Environment Interaction ◽  
Environment Interaction ◽  
Narrow Sense Heritability ◽  
Genotype By Environment ◽  
Analyse Data

Eucalyptus globulus is one of the best known examples of a heteroblastic plant. It exhibits a dramatic phase change from distinctive juvenile to adult leaves, but the timing of this transition varies markedly. We examined the genetic variation in the timing of heteroblastic transition using five large open-pollinated progeny trials established in north-western Tasmania. We used univariate and multi-variate mixed models to analyse data on the presence/absence of adult or intermediate foliage at age 2 years from a total of 14 860 trees across five trials, as well as height to heteroblastic phase change from one trial. Up to 566 families and 15 geographic subraces of E. globulus were represented in the trials. The timing of the heteroblastic transition was genetically variable and under strong genetic control at the subrace and within-subrace level, with single-trial narrow-sense heritability estimates for the binary trait averaging 0.50 (range 0.44–0.65). The degree of quantitative trait differentiation in the timing of heteroblastic transition among subraces, as measured by QST, exceeded the published level of neutral molecular marker (FST) differentiation in all cases, arguing that diversifying selection has contributed to shaping broad-scale patterns of genetic differentiation. Most inter-trial genetic correlations were close to one at the subrace and additive genetic levels, indicating that the genetic variation in this important developmental change is expressed in a stable manner and that genotype-by-environment interaction is minimal across the environments studied.

Response to divergent selection for early vigour in sunflower (Helianthus annuus L.)

1998 ◽  
Vol 49 (5) ◽  
pp. 749 ◽  
Author(s):  
F. Agüera ◽  
F. J. Villalobos ◽  
F. Orgaz ◽  
J. M. Fernandez-Martinez
Keyword(s):  
Field Experiments ◽  
Plant Biomass ◽  
Selection Response ◽  
Divergent Selection ◽  
Stem Volume ◽  
Initial Population ◽  
Environment Interaction ◽  
Positive Trait ◽  
Early Vigour ◽  
Selection For

Early vigour (EV), biomass at the first development stages, may be a positive trait to improve sunflower yield in water-limited environments. Field experiments were carried out from 1992 to 1995 to define an index to quantify EV in sunflower plants, evaluate the response to divergent selection for this trait, study EV ×environment interaction, estimate the heritability of EV, and study the association of EV with other traits. A sunflower population with a broad genetic base and 10 sunflower lines derived from it were used. Stem volume calculated from stem diameter and height measured approximately 425 degree-days after emergence was correlated with above-ground plant biomass at the same date. In 1992, divergent selection for high and low stem volume was carried out on this population and plants from every group were recombined independently, obtaining 2 new populations. Selection response, using these and the initial population, was studied in 1993. Ten S2 lines, 5 with high-EV derived from the high-EV population and 5 with low-EV derived from the low EV population, were sown in 1995 to study the EV ×environment interaction. Differences among lines with different EV were significant in all the environments studied. In 1993, a random sample from the initial population was selfed and broad sense heritability and heritability by parent-offspring regression were estimated. Heritability based on variance component estimates of S1 progeny means was 0·61. Realised heritability (± s.e.) from a divergent selection for high and low stem volume were 0·40±0·10 and 0·52±0·15, respectively. Heritability by parent-offspring regression was 0· 40± 0·10. These values and the high variability of stem volume observed in the new populations indicate that additional gain from selection should be possible.

Genetic variation in fatty acid composition of subcutaneous fat in cattle

2013 ◽  
Vol 53 (2) ◽  
pp. 129 ◽  
Author(s):  
M. J. Kelly ◽  
R. K. Tume ◽  
S. Newman ◽  
J. M. Thompson
Keyword(s):  
Fatty Acids ◽  
Genetic Variation ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Saturated Fatty Acids ◽  
Genetic Correlations ◽  
Subcutaneous Fat ◽  
Monounsaturated Fatty Acids ◽  
Selection For

Genetic parameters were estimated for fatty acid composition of subcutaneous beef fat of 1573 animals which were the progeny of 157 sires across seven breeds grown out on pasture and then finished on either grain or grass in northern New South Wales or in central Queensland. There was genetic variation in individual fatty acids with estimates of heritability for the proportions of C14 : 0, C14 : 1c9, C16 : 0, C16 : 1c9, C18 : 0 and C18 : 1c9 fatty acids in subcutaneous beef fat of the order of 0.4 or above. Also substantial correlations between some fatty acids were observed. Genetic correlations between fatty acids and fat depth at the P8 site suggested that much of the genetic variation in fatty acid composition was related to changes in fatness. Selection for decreased fatness resulted in decreased proportions of C18 : 1c9 with concomitant increases in C18 : 0, C14 : 0 and C16 : 0. This suggested that selection for decreased fatness at a given weight will result in a decrease in the proportions of monounsaturated fatty acids in the subcutaneous fat in the carcass with a corresponding increase in the proportions of saturated fatty acids.

Response to selection in Australian Merino sheep. VIII.* Further results on selection for high clean wool weight with attention to quality

1978 ◽  
Vol 29 (3) ◽  
pp. 615 ◽  
Author(s):  
HN Turner ◽  
N Jackson
Keyword(s):  
Genetic Correlations ◽  
Fibre Diameter ◽  
Control Group ◽  
Environment Interaction ◽  
Genetic Progress ◽  
Weight One ◽  
The Mean ◽  
Selection For ◽  
Made In ◽  
Australian Merino

Results of selection for high clean wool weight per head with control of quality are reported for two selection groups over the period 1966–74. Results for the same experiment for the periods 1950–1959 and 1961–64 were reported earlier. Both groups were selected for high clean wool weight, one (S) with a ceiling on fibre diameter and degree of skin wrinkle, and the other (MS) with a lower limit on staple crimp frequency and a ceiling on skin wrinkle. Genetic progress in clean wool weight was greater in S than in MS over the 1966–74 period (0.12–0.15 lb/annum, compared with 0.06–0.09). This was to be expected from genetic correlations of clean wool weight with fibre diameter (low positive) and staple crimp frequency (high negative). The result supports the previous recommendation that staple crimp frequency is an inefficient way of controlling wool quality while attempting to improve quantity by selection, because its use severely restricts the likely progress in quantity. The actual rate of progress in the S group was similar to that in the period 1950–59, which was followed by a fall in superiority of the selected over the control group animals born during 1961–64. The recovery of response in the 1966–74 period negates the suggestion that the loss of response during the 1961-64 period was due to a 'plateau'. The most likely explanation is that a genotype x environment interaction occurred, such that the genetic gain made in the 1950-59 period could not be expressed in the poorer environments of 1960–65, but reappeared gradually under the improving environment of the 1966–74 period. Attempts to remove this interaction by regression of response on the mean clean wool weight of the unselected control group (as an index of the level of the environment) for each year, were not successful. The interaction is, therefore, not simply a case of all selection groups being equal when the environment is poor. ________________ *Part VII, Aust. J. Agric. Res., 26: 937 (1975).

Variation for kernel number and related traits in triticale (x Triticosecale Wittmack)

2011 ◽  
Vol 62 (10) ◽  
pp. 823 ◽  
Author(s):  
Rosella Motzo ◽  
Simona Bassu ◽  
Francesco Giunta
Keyword(s):  
Genetic Variation ◽  
Genetic Correlations ◽  
Genotype By Environment Interaction ◽  
Unit Weight ◽  
Environment Interaction ◽  
Kernel Number ◽  
Breeding Lines ◽  
High Level ◽  
Genetic Coefficient ◽  
Triticosecale Wittmack

Assessing the existence and extent of genetic variation in kernel number per m2 (KNO) and in KNO-related traits is necessary both for overcoming sink limitations through breeding and in order to correctly model triticale grain yield. A set of 112 advanced breeding lines derived from various crosses between winter and spring hexaploid triticales was grown for 2 years in a field experiment to evaluate genetic variation and heritability for KNO, chaff weight per m2 at maturity (CHAFFW) and number of kernels per unit weight of chaff (K/CHAFF). Genetic correlations were also calculated between these traits and grain weight and yield. K/CHAFF (but not CHAFFW) exhibited a high level of genetic variation and a low contribution of the genotype by environment interaction component to the overall variance and was highly heritable. There was no detectable genetic correlation between K/CHAFF and CHAFFW; however, K/CHAFF was correlated with KNO (r = 0.66, P < 0.001). K/CHAFF fulfils the major requirements of an indirect screening trait for KNO and of a genetic coefficient in modelling.

Genetic variation in tree structure and its relation to size in Douglas-fir. I. Biomass partitioning, foliage efficiency, stem form, and wood density

1994 ◽  
Vol 24 (6) ◽  
pp. 1226-1235 ◽  
Author(s):  
J. B. St.Clair
Keyword(s):  
Genetic Variation ◽  
Leaf Area ◽  
Wood Density ◽  
Harvest Index ◽  
Genetic Correlations ◽  
Douglas Fir ◽  
Biomass Partitioning ◽  
Alternative Measure ◽  
Sapwood Area ◽  
Stem Size

Genetic variation and covariation among traits of tree size and structure were assessed in an 18-year-old Douglas-fir (Pseudotsugamenziesii var. menziesii (Mirb.) Franco) genetic test in the Coast Range of Oregon. Considerable genetic variation was found in size, biomass partitioning, and wood density, and genetic gains may be expected from selection and breeding of desirable genotypes. Estimates of heritability for partitioning traits, including harvest index, were particularly high. Foliage efficiency (stem increment per unit leaf area) was strongly correlated with harvest index and may represent an alternative measure of partitioning to the stem. Estimates of foliage efficiency where leaf area was estimated based on stem diameter or sapwood area were unrelated to foliage efficiency where leaf area was measured directly. Strong negative genetic correlations were found between harvest index and stem size, and between wood density and stem size. Achieving simultaneous genetic gain in stem size and either harvest index or wood density would be difficult.

Genetic improvement of resistance to cyclaneusma needle cast in Pinus radiata

2019 ◽  
Vol 49 (2) ◽  
pp. 128-133 ◽  
Author(s):  
Mari Suontama ◽  
Yongjun Li ◽  
Charlie B. Low ◽  
Heidi S. Dungey
Keyword(s):  
New Zealand ◽  
Pinus Radiata ◽  
Genetic Improvement ◽  
Genetic Correlations ◽  
Tree Height ◽  
Progeny Testing ◽  
Environment Interaction ◽  
Needle Cast ◽  
Genotype Environment Interaction ◽  
Selection For

Progeny testing of resistance to needle loss caused by Cyclaneusma minus (cyclaneusma needle cast) has been included in the needle disease resistance strategy of Pinus radiata D. Don in New Zealand since the late 1970s. Data on progeny trials, two in the North Island of New Zealand and one in Tasmania, Australia, were available to estimate heritability between trait genetic correlations and genotype × environment interaction. Resistance to cyclaneusma needle cast had moderate estimates of heritability (0.25 to 0.46) at all sites. Genetic correlations between the assessed traits indicated that selection for faster early growth, i.e., tree height at age 4 years and diameter at breast height at age 6 years, favours trees that are prone to Cyclaneusma infection, while a favourable genetic association between resistance to cyclaneusma needle cast and productivity was evident at a later assessment at age 9 years. No significant genotype × environment interaction was found for resistance to cyclaneusma needle cast; however, stability of genotypes across a wider range of environments and with a high genetic connectedness requires more research. Considerable genetic improvement can be achieved for resistance to cyclaneusma needle cast and indirect selection for the trait should be pursued by selecting for productivity and culling susceptible genotypes from breeding.

scholarly journals Genetic Variability of Fruit Set, Fruit Weight, and Yield in a Tomato Population Grown in Two High-temperature Environments

1992 ◽  
Vol 117 (5) ◽  
pp. 867-870 ◽  
Author(s):  
Linda Wessel-Beaver ◽  
J.W. Scott
Keyword(s):  
Puerto Rico ◽  
Genetic Variance ◽  
Fruit Set ◽  
Genetic Correlations ◽  
Fruit Weight ◽  
Environment Interaction ◽  
Significant Component ◽  
Genotype Environment Interaction ◽  
Single Location ◽  
Selection For

Heritabilities (h2) and genetic correlations between percent fruit set, yield, and fruit weight were estimated from one summer planting each in Florida and Puerto Rico of 100 S, tomato (Lycopersicon esculentum Mill.) families from a synthetic population. Single-location h2 was high for all traits. Across-locations h2 was low for yield, intermediate for fruit set, and high for fruit weight. Genotype × environment interaction (G × E) was 1) the only significant component of variance for yield, 2) somewhat important for fruit set, and 3) not an important variance component for fruit weight. The greater importance of genetic variance compared to G × E variance explains why across-location heritabilities for fruit weight and fruit set were high. Genetic correlations between fruit set and weight were strongly negative, while those between yield and set were large and positive. Yields under high temperatures may increase with selection for fruit set, but a reduction in fruit weight would be expected in this population and those with similar genetic correlations.

scholarly journals Genetic Analysis of Advanced Populations in Antirrhinum majus L. with Special Reference to Cut Flower Postharvest Longevity

2005 ◽  
Vol 130 (3) ◽  
pp. 434-441 ◽  
Author(s):  
William J. Martin ◽  
Dennis P. Stimart
Keyword(s):  
Special Reference ◽  
Genetic Correlations ◽  
Antirrhinum Majus ◽  
Quality Traits ◽  
Cut Flower ◽  
Narrow Sense ◽  
Narrow Sense Heritability ◽  
Breeding Programs ◽  
Postharvest Longevity ◽  
Selection For

Narrow-sense heritabilities and genetic correlations of ornamental quality traits of Antirrhinum majus (snapdragon) were evaluated with special reference to cut flower postharvest longevity (PHL). Inbreds P1 (16 days PHL) and P2 (3 days PHL) were hybridized to produce an F1 (P1 × P2) that was self-pollinated to produce an F2 population. The F2 were self-pollinated to produce F3 families and advanced through single-seed descent by self-pollination to the F5 generation. P1, P2, F1, F3, F4, and F5 were evaluated for ornamental quality traits. Quality traits were found to be quantitative and normally distributed. Narrow-sense heritability (h2) estimates were high and consistent across generations examined; PHL h2 ranged from 0.79 to 0.81 ± 0.06. Phenotypic and genotypic correlations revealed underlying physiological and pleiotropic interactions relevant to breeding programs aimed at simultaneous improvement of ornamental quality traits. PHL is inversely related to cut flower strength and days to flower, -0.44 ± 0.04 and -0.43 ± 0.44. Buds at discard is positively correlated to cut flower and plant diameter, cut flower weight and days to flower, 0.77 ± 0.05, 0.58 ± 0.06, 0.71 ± 0.06, and 0.77 ± 0.07, respectively. Gain from selection for quality traits of interest can be rapid.

Heat stress effects on farrowing rate in sows: Genetic parameter estimation using within-line and crossbred models1

2012 ◽  
Vol 90 (7) ◽  
pp. 2109-2119 ◽  
Author(s):  
S. Bloemhof ◽  
A. Kause ◽  
E. F. Knol ◽  
J.A.M. Van Arendonk ◽  
I. Misztal
Keyword(s):  
Genetic Variation ◽  
Genetic Correlation ◽  
Heat Tolerance ◽  
Genetic Parameter ◽  
Genetic Correlations ◽  
Random Regression ◽  
Production Traits ◽  
Selection For ◽  
Heritability Estimates ◽  
Farrowing Rate

Abstract The pork supply chain values steady and undisturbed piglet production. Fertilization and maintaining gestation in warm and hot climates is a challenge that can be potentially improved by selection. The objective of this study was to estimate 1) genetic variation for farrowing rate of sows in 2 dam lines and their reciprocal cross; 2) genetic variation for farrowing rate heat tolerance, which can be defined as the random regression slope of farrowing rate against increasing temperature at day of insemination, and the genetic correlation between farrowing rate and heat tolerance; 3) genetic correlation between farrowing rate in purebreds and crossbreds; and 4) genetic correlation between heat tolerance in purebreds and crossbreds. The estimates were based on 93,969 first insemination records per cycle from 24,456 sows inseminated between January 2003 and July 2008. These sows originated from a Dutch purebred Yorkshire dam line (D), an International purebred Large White dam line (ILW), and from their reciprocal crosses (RC) raised in Spain and Portugal. Within-line and crossbred models were used for variance component estimation. Heritability estimates for farrowing rate were 0.06, 0.07, and 0.02 using within-line models for D, ILW, and RC, respectively, and 0.07, 0.07, and 0.10 using the crossbred model, respectively. For farrowing rate, purebred-crossbred genetic correlations were 0.57 between D and RC and 0.50 between ILW and RC. When including heat tolerance in the within-line model, heritability estimates for farrowing rate were 0.05, 0.08, and 0.03 for D, ILW, and RC, respectively. Heritability for heat tolerance at 29.3°C was 0.04, 0.02, and 0.05 for D, ILW, and RC, respectively. Genetic correlations between farrowing rate and heat tolerance tended to be negative in crossbreds and ILW-line sows, implying selection for increased levels of production traits, such as growth and reproductive output, is likely to increase environmental sensitivity. This study shows that genetic selection for farrowing rate and heat tolerance is possible. However, when this selection is based solely on purebred information, the expected genetic progress on farrowing rate and heat tolerance in crossbreds (commercial animals) would be inconsequential.

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