Efficiency Of Early Selection Research Articles

Age trends of genetic variation and early selection for growth traits in Cunninghamia lanceolata open-pollinated families

Abstract The present study measured the growth traits of 98 open-pollinated half-sibling families from the second-generation clonal seed orchard of Chinese fir for 6 consecutive years from age 2 to 7, the change patterns of genetic variation in growth traits and genetic parameters were analyzed, and best linear unbiased prediction (BLUP) was used for early selection to determine the excellent families. The growth traits of Chinese fir revealed highly significant differences between families, indicating that there was significant genetic variation at the family level, which serves as the foundation for exceptional family selection. The heritabilities of family and individual for H (height) ranged from 0.61 to 0.65 and 0.41 to 0.46, respectively; for DGH (the diameter at ground height)/DBH (the diameter at breast height), they were 0.55 to 0.66 and 0.35 to 0.46, respectively; and for V (tree volume), they were 0.66 to 0.70 and 0.48 to 0.49, respectively. The growth traits of genetic control were at a greater level at age 5. The findings of the coefficient of variation analysis demonstrated that the phenotypic variation coefficient were larger than the genetic variation coefficient for three growth traits at various ages. The juvenile-mature genetic and phenotypic correlations revealed an increasing tendency with age, and mainly controlled by genetic factors. Compared to other age groups for growth traits, age 5 had greater phenotypic and genetic association coefficients, as well as greater efficiency of early selection. Based on the selection method of breeding value, nine families were selected with a 9.2 % selection rate.

Early selection efficiency for fiber dimensions and their relationships with growth and wood quality for Pinus elliottii Engelm. in southern China

Early selection efficiency for fiber dimensions and their relationships with growth and wood quality for Pinus elliottii Engelm. in southern China

Efficiency of early selection for growth and wood quality traits of slash pine in three progeny trials in southern China

Abstract A firm understanding of the early selection efficiency of ring width and wood quality traits is a prerequisite for breeding of higher growth rates and wood quality of slash pine (Pinus elliottii Engelm.). To accomplish effective early selection for the studied traits, wood core samples were collected from 360 trees of 20 open-pollinated families from three slash pine rotation-aged (harvest age) genetic trials. Wood cores were measured by SilviScan, and the annual patterning, heritability, age-age genetic correlation and efficiency of early selection for ring width, modulus of elasticity (MOE), microfibril angle (MFA) and wood density for early to reference age (age 27) were investigated. The greatest annual ring width was observed at age 4, and this trait decreased gradually toward the bark. Different radial trends were found for MOE and MFA. Wood density was lowest near the pith and then increased steadily with age. Overall, heritability was moderate to high for all area-weighted wood quality traits. Very high age-age genetic correlation values were observed for all traits researched. Estimates of efficiency for early selection indicated that the optimal age of early selection for ring width was 9–12 years, while that for area-weighted MOE, MFA and wood density was 7–8 years.

Age–age correlations and efficiency of early selection for growth traits and inner shell color parameters in a golden strain of Hyriopsis cumingii

Hyriopsis cumingii is the most important freshwater mussel for pearl production in China, however, early selection for growth traits and inner shell color in this species is poorly characterized. To explore the optimal selection age, the growth traits (SW, SH, SL, and BW) and inner shell color parameters (L*, a*, b* and dE*) of 22 half-sib families were measured at the ages of 5, 12, and 17 months in a progeny test population established at the Weimin Aquaculture Company breeding base, Zhejiang Province, China. The phenotypic data for growth traits and inner shell color parameters were divided into breeding (50% growth traits × 50% shell color traits)and control groups and were analyzed. Age–age genetic and phenotypic correlations, and heritability were also examined. The results showed significant differences in growth traits between the two groups as age increased (P < 0.05). The b* values in the breeding group were considerably higher than those in the control group and the difference between the two groups was highly significant at all the tested ages (P < 0.01). The growth traits and inner shell color parameters had a moderate to high heritability (h2 ≥ 0.15) at all ages and b* values reached 0.44 at 5 months of age. The age–age genetic and phenotypic correlations of growth traits were always positive, ranging from 0.224 to 0.933 and 0.087 to 0.615, respectively. The age–age genetic and phenotypic correlations of the inner shell color parameters were also always positive, ranging from 0.224 to 0.954 and 0.097 to 0.816, respectively. The results of this study can be used to assist in the early selection practices for the selective breeding of H. cumingii's golden strain. For the early selection of growth traits and inner shell color, SH and b* are preferable, respectively, as target traits.

Breeders' Sensory Test: A new tool for early selection in breeding for tomato (Solanum lycopersicum) flavour

AbstractFor several decades, improved flavour has not been a main focus in tomato breeding because it is difficult and expensive to evaluate. Sensory panels are designed to assess flavour, but they are not able to evaluate large sample numbers typical for early breeding generations. Selection in the first segregating generation could enhance breeding for flavour by preventing the loss of favourable alleles. The efficiency of early selection is unknown due to the polygenetic inheritance of flavour. To address these issues, F2 plants from 32 crosses and their parents (910 individuals) were evaluated for aroma, sweetness and sourness with the Breeders' Sensory Test (small team and large number of small samples from individuals), as well as for physicochemical traits (total soluble solids, titratable acidity and dry matter), and volatile compounds in low‐input organic and hydroponic cultivation. Corresponding physicochemical and sensory traits were significantly correlated. For most of the studied traits, it was possible to select between single plants in the F2 generation. Thus, the Breeders' Sensory Test can be used as a new tool in breeding for flavour.

Estimation of optimal timing of early selection based on time trends of genetic parameters in Abies sachalinensis

Abstract Early selection is an imperative in ongoing forest tree breeding. This study estimated the optimal timing of early selection in Abies sachalinensis (F. Schmidt) Mast. based on time trends of genetic parameters obtained from two test sites. Tree height (Ht ) at 5, 10 (11), 15, 20, 30, and 40 years of age and diameter at breast height (DBH) at 20, 30, and 40 years of age were analyzed. The efficiency of early selection per year (E) for performing early indirect selection relative to performing direct selection at the earliest rotation age (40 years of age) was estimated based on narrow-sense heritability (h 2) and age–age genetic correlation (r). The h 2 of Ht peaked at 10 or 15 years of age (0.52–0.71), and that of DBH was the highest at 20 years of age (0.19 or 0.22). The age–age genetic correlation between tree heights or between tree height and DBH at different ages decreased with increasing differences between ages (regression coefficients were −0.011 and −0.007, respectively). The E values were highest at 10 or 15 years of age (0.84-1.74 and 1.42-2.24 for Ht and Ht -DBH, respectively), indicating the optimum selection timing. In Japapnese forestry, the initial growth rate is considered important for reducing weeding costs. Selection at 10 or 15 years of age had more than in &gt;65 % indirect genetic gain relative to the direct genetic gain at 5 years of age; thus, selection at 10-15 years of age is appropriate considering the initial and mature phases of tree growth.

Multi-Level Genetic Variation and Selection Strategy of Neolamarckia cadamba in Successive Years

Neolamarckia cadamba (Roxb.) Bosser is a tropical evergreen broadleaf tree species that could play an important role in meeting the increasing demand for wood products. However, multi-level genetic variation and selection efficiency for growth traits in N. cadamba is poorly characterized. We therefore investigated the efficiency of early selection in N. cadamba by monitoring the height (HT), diameter at breast height (DBH), and tree volume (V) in 39 half-sib families from 11 provenances at ages 2, 3, 4, 5, and 6 years in a progeny test. Age-related trends in growth rate, genetic parameters in multi-level, efficiency of early selection, and realized gain in multi-level for growth traits were analyzed. The result showed that genetic variation among families within provenances was higher than that among provenances. The estimated individual heritability values for the growth traits ranged from 0.05 to 0.26, indicating that the variation of growth traits in N. cadamba was subject to weak or intermediate genetic control. The age–age genetic correlations for growth traits were always positive and high (0.51–0.99), and the relationships between the genetic/phenotypic correlations and the logarithm of the age ratio (LAR) were described well by linear models (R2 &gt; 0.85, except the fitting coefficient of genetic correlation and LAR for HT was 0.35). On the basis of an early selection efficiency analysis, we found that it is the best time to perform early selection for N. cadamba at age 5 before half-rotation, and the selection efficiencies were 157.28%, 151.56%, and 127.08% for V, DBH, and HT, respectively. Higher realized gain can be obtained by selecting superior trees from superior families. These results can be expected to provide theoretical guidance and materials for breeding programs in N. cadamba and can even be a reference for breeding strategies of other fast-growing tree species.

Early selection efficiency for recommendation of Eucalyptus sp.

This paper aims to estimate genetic and phenotypical parameters to assess the viability of early selection in progeny tests of Eucalyptus sp. We analyzed data from experiments conducted in the state of Minas Gerais, Brazil. The evaluated traits were diameter at breast height and plant height in 482 progenies of full sibs under randomized block design, into nine experiments: four of which were assessed at progenies mean level, and five assessed at individuals mean level. It were evaluated the predicted gains with combined selection index under 5, 10 and 20% of selection; the coincidence among selected families in juvenile and adult ages, and the efficiency of early selection. Results indicated that the procedures were efficient in most of the scenarios, and the gains comparable to the direct selection on tree harvest age.

Age–age correlations and early selection for growth traits in 40 half-sib families of Larix principis-rupprechtii

Larix principis-rupprechtii Mayr is a dominant species in coniferous forests of North China. However, early selection of L. principis-rupprechtii for growth traits is poorly characterised. To explore the optimal selection age for this species, heights (HT) and diameters at breast (DBH) of 40 half-sib families were measured at ages 3, 12, 22, and 28 years in a progeny test population established in the town of Kangjiahui, Shanxi Province. Age trends in heritability, age–age genetic correlations, and early selection efficiency for height and DBH were analysed. The individual heritability of these growth traits varied over time, and maximized at different ages (0.55 at age 12 for HT and 0.48 at age 28 for DBH). The age–age genetic correlations were always positive, and the majority were high (0.790–0.953) between the juvenile and mature ages for HT and DBH. For the same pairs of measurements, HT demonstrated higher age–age genetic correlations than DBH, and both age–age genetic correlation data sets were described well by the linear relationship with the logarithm of the age ratio (r2 > 0.90). The regression slope for DBH was lower than that for HT. Based on the early selection efficiency estimates, the optimal selection age could be as early as age 6 for DBH and 8–9 years for HT. The results of this study provide information that can be used to assist early selection practices in L. principis-rupprechtii improvement programs in Shanxi Province.

Efficiency of early selection in Calycophyllum spruceanum and Guazuma crinita, two fast-growing timber species of the Peruvian Amazon

Bolaina (Guazuma crinita Mart., Malvaceae) and capirona (Calycophyllum spruceanum (Benth.) Hook. f. ex K. Schum., Rubiaceae) are fast-growing Amazonian timber trees. In Peru, they are increasingly being used in agroforestry systems and plantations, and interest in developing improved germplasm is growing. However, tree improvement incurs both direct costs and interest costs on investments; because of this, early selection is of interest. We examine the efficiency of early selection 13 or 17 months after field trial establishment. These are compared with selection after 49 or 53 months using two efficiency metrics: one based on discounted response to selection per unit of present value of cost, and the second on net discounted revenues, using discount rates of 5%, 10%, and 15%. Our metrics differed from those used in previous studies by taking into account direct costs, as well as costs of capital. We found that in most scenarios, early selection was attractive, partly due to direct cost savings. We conclu...

Genetic analysis of lodgepole pine (Pinus contorta) solid-wood quality traits

Potential improvement of lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) solid-wood properties was examined by estimating age trends of inheritance, age–age genetic correlations, and the efficiency of early selection using 823 increment cores sampled from 207 half-sib families at two independent progeny trials, aged 34–35 years, located in northern Sweden. High-resolution radial variation of annual ring width, wood density, microfibril angle (MFA), and modulus of elasticity (clearwood stiffness; MOES) was measured using SilviScan. The dynamic stiffness (MOEtof) of standing trees was also obtained using Hitman ST300. Heritabilities ranged from 0.10 to 0.64 for growth and earlywood, transition-wood, and latewood proportions, from 0.29 to 0.77 for density traits, and from 0.13 to 0.33 for MFA and stiffness traits. Genetic correlations between early age and the reference age (26 years) suggested that early selection is efficient at age 4 years for MFA and between ages 5 to 8 years for density and MOES. Unfavorable diameter–stiffness genetic correlations and correlated responses indicate that breeding for a 1% increase in diameter would confer 5.5% and 2.3% decreases in lodgepole pine MOES and MOEtof, respectively. Index selection with appropriate economical weights for growth and wood stiffness is highly recommended for selective breeding.

Age-related trends in genetic parameters for wood properties in Larix kaempferi clones and implications for early selection

Wood properties are important traits that determine quality of structural wood. With the aim of performing efficient early selection for wood properties, we investigated genetic variation in 20 <i>Larix kaempferi</i> clones aged from 4 to 15 years for four quality traits: wood density, wall thickness to lumen area, microfibrillar angle (MFA) and modulus of elasticity (MOE). We observed that age-related trends in overall means varied for different traits: MFA decreased with the age, while the others generally increased with the age. Phenotypic variance always showed significant differences from the age of 8 years onward, with CVG ranging from 4% to 25%. Also, clonal repeatability increased steadily until 9 years old and then kept medium or higher intensity (0.4–0.8). After the age of 6, genetic correlations were generally higher than phenotypic correlations. Estimates of early selection efficiency suggested that the optimal selection age for wood density was at age 5–6 years, while it was 9–10 years for the other traits. In combination with previous results, we proposed a comprehensive early selection strategy for larch clonal breeding that involved selection based on nursery rooting ability, phenology, growth traits, and wood properties.

Genetic analysis of fiber dimensions and their correlation with stem diameter and solid-wood properties in Norway spruce

Adverse genetic correlations between growth traits and solid-wood, as well as fiber traits are a concern in conifer breeding programs. To evaluate the impact of selection for growth and solid-wood properties on fiber dimensions, we investigated the inheritance and efficiency of early selection for different wood-fiber traits and their correlations with stem diameter, wood density, modulus of elasticity (MOE), and microfibril angle (MFA) in Norway spruce (Picea abies L). The study was based on two large open-pollinated progeny trials established in southern Sweden in 1990 with material from 524 families comprising 5618 trees. Two increment cores were sampled from each tree. Radial variations from pith to bark were determined for rings 3–15 with SilviScan for fiber widths in the radial (RFW) and tangential (TFW) direction, fiber wall thickness (FWT), and fiber coarseness (FC). Fiber length (FL) was determined for rings 8–11. Heritabilities based on rings 8–11 using joint-site data were moderate to high (0.24–0.51) for all fiber-dimension traits. Heritabilities based on stem cross-sectional averages varied from 0.34 to 0.48 and reached a plateau at rings 6–9. The “age-age” genetic correlations for RFW, TFW, FWT, and FC cross-sectional averages at a particular age with cross-sectional averages at ring 15 reached 0.9 at rings 4–7. Our results indicated a moderate to high positive genetic correlation for density and MOE with FC and FWT, moderate and negative with RFW, and low with TFW and FL. Comparison of several selection scenarios indicated that the highest profitability is reached when diameter and MOE are considered jointly, in which case, the effect on any fiber dimension is negligible. Early selection was highly efficient from ring 5 for RFW and from rings 8–10 for TFW, FWT, and FC.

Efficiency of Early Selection in Improving Biomass and Predicted Ethanol Yield in Switchgrass

Switchgrass (Panicum virgatum L.) takes 3 yr to reach maximum biomass yields, delaying selection and cultivar improvement. This study evaluated the efficiency of early selection in improving third‐year biomass and ethanol yields in lowland switchgrass. Fifty‐six full‐sib families were planted in Knoxville and Crossville, TN, with 1‐m spacing in a randomized complete block design. In 2012 to 2014, plants were evaluated for biomass yield, ethanol yield, and morphological traits at 8 wk after emergence and in years one through three. Trait means, efficiency of indirect selection, and genetic gain were calculated. Biomass yield differed significantly by year (92 g in yr 1, 1069 g in yr 2, and 1425 g in yr 3) while ethanol yield did not . Juvenile selection was ineffective. Biomass selection was most efficient using first‐year fall height with genetic gains per year 2.4 times those of direct selection on third‐year biomass. First‐year biomass and second‐year biomass, fall height, spring height, and tiller diameter also exhibited high efficiency (1.3 to 1.9). For ethanol yield, negative efficiency indicated selection for low first‐year height and low second‐year spring height, and tiller diameter would result in 1 to 1.3 times the genetic gain expected from direct selection on third‐year ethanol yield. Results indicate that early selection and indirect selection using morphological traits may speed yield improvement due to greater selection efficiency and higher genetic gains.

JUVENILE-MATURE GENETIC CORRELATIONS IN Pinus taeda CLONES PROPAGATED VIA SOMATIC EMBRYOGENESIS

ABSTRACT This study aimed to estimate the genetic correlation among selection ages (juvenile - adult) and efficiency of early selection for the height, diameter, and volume traits of individuals from Pinus taeda families propagated via somatic embryogenesis. This study was carried out by genetic-statistical analysis, estimation procedure of variance (Reml), and prediction components of breeding values (Blup), using the Selegen-Reml/Blup software. Genetic correlations among juvenile ages and rotation age were performed by applying the linear model developed by Lambeth (1980). In accordance with results of the established model, the early selection can be performed in clones of Pinus taeda with high selection efficiency. Ages from 4 to 6 years old are enough to select Pinus taeda clones propagated via somatic embryogenesis for harvesting at 8 and 12 years old; and 6 to 10 years old are enough to select them for harvesting at 20 years old. On the basis of the genetic correlations estimates from the environments, the clones' selection of Pinus taeda propagated via somatic embryogenesis should be developed specifically for each environment. The clones' selection can be performed considering the diameter due to the high correlation between volume and diameter.

Rubber tree ortet-ramet genetic correlation and early selection efficiency to reduce rubber tree breeding cycle

The present study aimed to correlate the performance of rubber tree [Hevea brasiliensis (Willd. ex. Adr. de Juss.) Muell-Arg] ortets selected in progenies tests and the performance of their respective ramets in the clonal test. In the progenies tests three early measurements were carried out for the traits early rubber yield (ERP), number of vassel latex rings (NVR) and bark thickness (BKT). Using the HMMm (Hamaker Morris-Mann modified) test the best ortets were selected based on rubber yield and cloned to set the clonal test. In the clonal test the same traits were studied, but the dry rubber production (DRP) was assessed in the normal tapping (from the seventh year of age). Statistical analyses were carried out using the REML/BLUP (restricted maximum likelihood/best linear unbiased prediction) method. After studying the progenies and clonal tests, the correlation between the performance of ortets and ramets was estimated and the performance of the ortets in the second and third early tests (ERP2 and ERP3) has proven to be reliable, since the observed estimate of the correlation coefficient with its ramets was significant. The study showed that if taken into account the second and/or third early test, there is reliability that the most productive ortets selected in nursery stage will originate more productive clones. It is efficient to select rubber tree based on the early rubber production, thus reducing the long rubber tree breeding cycle.

Age trend of heritability, genetic correlation, and efficiency of early selection for wood quality traits in Scots pine

To examine the efficiency of early selection for wood quality traits in the Scots pine (Pinus sylvestris L.) breeding program in Sweden, a total of 778 wood increment cores were sampled from 179 full-sib families in a single progeny trial at 40 years of age. Age trend of inheritance, age–age genetic correlation, and early selection efficiency for eight wood traits including annual ring width, wood density, microfibril angle (MFA), modulus of elasticity (i.e., wood stiffness; MOE), and fibre dimensions were studied. Heritabilities for the eight wood traits reached a plateau between age 5 years and age 15 years, with the highest heritability for radial fibre width and fibre coarseness (∼0.6) and the lowest heritability for ring width (∼0.2). Heritability reached about 0.4 for both wood density and MFA but only reached about 0.3 for MOE. Genetic correlation from early to reference age 30 years reached a very high level (&gt;0.8) for all eight wood traits at age 5 years. Early selection was effective for wood quality traits in Scots pine, and selection at age 8 years is recommended for MOE in Scots pine.

Estimation of genetic parameters and verification of early selection efficiency in baru (Dipteryx alata)

This study aimed at verifying the efficiency of early selection, and estimating the genetic parameters in Dipteryx alata. The 66 half-sib families were obtained from three seed provenances at the Brazilian Savannah of the state of Minas Gerais. The experiment was carried out in a randomized block design with 3 replications and 5 plants per plot. Data diameters at breast height (DBH) and total height (TH) were taken at the ages of 64, 125 and 138 months. REML/BLUP methodology was applied in the D. alata different provenances and progenies. Analysis indicated significant genetic variability (P &lt; 0.01) between and within provenances. Both traits, DBH and TH, presented high narrow sense heritability for the ages analyzed. High genetic correlation occurred between DBH and TH traits, and between ages (age-age); thus, it allowed indirect selection, as well as early selection with high genetics gains.

Age-related trends in genetic parameters for Larix kaempferi and their implications for early selection.

BackgroundJapanese larch (Larix kaempferi) has been introduced in China at the end of the 19th century, and as one successful exotic species, is becoming the preferred coniferous in northern China and sub-tropical alpine region. The rotation age is about 25-28 years for L. kaempferi as pulpwood in Henan province. Waiting for even one-half rotation age for final evaluation will be inefficient due to accumulated testing costs and delayed return on investment, which suggests that selection at an early age is highly desirable for L. kaempferi improvement programs in Henan province. In this study, we determined age trends of genetic parameters and evaluated early selection efficiency for L. kaempferi in Henan province to find out the appropriate trait for early selection and its selection age.ResultsGrowth traits of 78 clones were measured periodically from age 2 to age 15 in a clonal trial of Larix kaempferi establishted at Son town, Henan Province. The genetic variation among clones, age-age correlations, and age trends in genetic parameters for growth traits were analyzed. Variant analysis revealed that tree height (HGT) and diameter at breast (DBH) were significant (1% level) among clones at every ages. The clonal repeatability of growth traits varied year-by-year, reaching the highest levels at different ages for different traits (0.77 at age 2 for HGT, 0.70 at age 5 for DBH and 0.66 from age 8 to age 10 for volume, respectively). The age-age genetic correlations ranged from 0.904 to 1.000 for HGT, and from 0943 to 1.000 for DBH. DBH at different ages was more genetically correlated to volume-15 than HGT. At the phenotypic level, HGT was always less correlated to volume-15 than DBH. With the estimates of efficiencies of early selection, the recommendation from present study was that the optimum age of early selection was age 2 for HGT and age 5 for DBH.ConclusionsOur study showed that there were significant (1% level) on growth traits among clones at every ages. The genetic parameters for growth traits varied from age to age. We found dual trait selection was more efficient than single trait selection for early selection.

Early selection in open-pollinated Eucalyptus families based on competition covariates

The objetive of this work was to evaluate the influence of intergenotypic competition in open-pollinated families of Eucalyptus and its effects on early selection efficiency. Two experiments were carried out, in which the timber volume was evaluated at three ages, in a randomized complete block design. Data from the three years of evaluation (experiment 1, at 2, 4, and 7 years; and experiment 2, at 2, 5, and 7 years) were analyzed using mixed models. The following were estimated: variance components, genetic parameters, selection gains, effective number, early selection efficiency, selection gain per unit time, and coincidence of selection with and without the use of competition covariates. Competition effect was nonsignificant for ages under three years, and adjustment using competition covariates was unnecessary. Early selection for families is effective; families that have a late growth spurt are more vulnerable to competition, which markedly impairs ranking at the end of the cycle. Early selection is efficient according to all adopted criteria, and the age of around three years is the most recommended, given the high efficiency and accuracy rate in the indication of trees and families. The addition of competition covariates at the end of the cycle improves early selection efficiency for almost all studied criteria.