Winter wheat yield improvement by genetic gain across different provinces in China

The replacement of winter wheat varieties has contributed significantly to yield improvement worldwide,with remarkable progress in China.Drawing on two sets of data,production yield from the National Bureau of Statistics of China and experimental yield from literature,this study aims to(1)illustrate the increasing patterns of production yield among different provinces from 1978 to 2018 in China,(2)explore the genetic gain in yield and yield relevant traits through the variety replacement based on experimental yield from 1937 to 2016 in China,and(3)compare the yield gap between experimental yield and production yield.The results show that both the production and experimental yields significantly increased along with the variety replacement.The national annual yield increase ratio for the production yield was 1.67%from 1978 to 2018,varying from 0.96%in Sichuan Province to 2.78%in Hebei Province;such ratio for the experimental yield was 1.13%from 1937 to 2016.The yield gap between experimental and production yields decreased from the 1970s to the 2010s.This study reveals significant increases in some yield components consequent to variety replacement,including thousand-grain weight,kernel number per spike,and grain number per square meter;however,no change is shown in spike number per square meter.The biomass and harvest index consistently and significantly increased,whereas the plant height decreased significantly.

Genetic gain and inbreeding from simulation of different genomic mating schemes for pig improvement

Background Genomic selection involves choosing as parents those elite individuals with the higher genomic estimated breeding values(GEBV)to accelerate the speed of genetic improvement in domestic animals.But after multi-generation selection,the rate of inbreeding and the occurrence of homozygous harmful alleles might increase,which would reduce performance and genetic diversity.To mitigate the above problems,we can utilize genomic mating(GM)based upon optimal mate allocation to construct the best genotypic combinations in the next generation.In this study,we used stochastic simulation to investigate the impact of various factors on the efficiencies of GM to optimize pairing combinations after genomic selection of candidates in a pig population.These factors included:the algorithm used to derive inbreeding coefficients;the trait heritability(0.1,0.3 or 0.5);the kind of GM scheme(focused average GEBV or inbreeding);the approach for computing the genomic relationship matrix(by SNP or runs of homozygosity(ROH)).The outcomes were compared to three traditional mating schemes(random,positive assortative or negative assortative matings).In addition,the performance of the GM approach was tested on real datasets obtained from a Large White pig breeding population.Results Genomic mating outperforms other approaches in limiting the inbreeding accumulation for the same expected genetic gain.The use of ROH-based genealogical relatedness in GM achieved faster genetic gains than using relatedness based on individual SNPs.The GROH-based GM schemes with the maximum genetic gain resulted in 0.9%-2.6%higher rates of genetic gainΔG,and 13%-83.3%lowerΔF than positive assortative mating regardless of heritability.The rates of inbreeding were always the fastest with positive assortative mating.Results from a purebred Large White pig population,confirmed that GM with ROH-based GRM was more efficient than traditional mating schemes.Conclusion Compared with traditional mating schemes,genomic mating can not only achieve sustainable genetic progress but also effectively control the rates of inbreeding accumulation in the population.Our findings demonstrated that breeders should consider using genomic mating for genetic improvement of pigs.

First Report of a Successful Development of Yam Hybrids(Dioscorea alata L.)from Lyophilized and Long-Term Stored Pollens

Various biological constraints including erratic and asynchronous flowering between male and female plants hinder successful hybrid development and genetic gains in greater yam breeding programs.Therefore,pollen storage has gained much attention to facilitate artificial pollinations and increase the genetic gains.This 4-year study aimed at developing a practical long-term pollen storage technique for the successful development of yam hybrids.Fresh pollens were collected from two Dioscorea alata males,then lyophilized(two lyophilization treatments were applied),followed by storage at room temperature(24℃–25℃)for 12 months.Moreover,the lyophilized and stored pollens were tested for viability by crossing with four female varieties.Our results showed that lyophilization is effective for achieving viable pollens after 12 months of storage.Treatment 1(48 h drying)showed higher pollen germination and fertility rates than Treatment 2(72 h drying).Although we observed a reduction in viability of lyophilized pollens after 12 months of storage,we generated hybrid seedlings with success rates from 12%to 21%compared to 21%–31%when using fresh pollens.Paternity testing based on molecular genotyping confirmed the hybrid status of the obtained seedlings,which grew well in a greenhouse.Lyophilization is a practical approach for a long-term storage of greater yam pollen samples.This protocol will positively impact yam breeding programs particularly in developing countries.

Comparative Analysis of Improving Effects of 12 Maize Populations with Improved S_1 Selection Method

ln this study, 12 maize populations were improved with the improved S1 selection method, aiming to increase the improvement efficiency of maize popula-tions. The results showed that number of rows per spike, number of grains per row and 100-grain weight were the three important component traits of maize yield. The highest genetic increment was found in Mengqun 2, fol owed by Mengqun 4, Mengqun 1 and other 7 maize populations. Negative genetic increment was shown in Mengqun 3 and 3 introduced foreign maize populations. Some changes were shown in spikes, plant traits and genetic diversity of maize populations. Based on our results, we concluded that Mengqun 2, Mengqun 4, Zhongzong 7, Mengqun C and Mengqun A could be directly used for the line breeding by selfing for their higher genetic increment of yield and better improvement effects of other agricultural traits. Compared with these 5 populations, the improvement potential of other maize populations was limited for their lower genetic increment.

Growth performance and physiological parameters of the second generation selected and control groups of Pinctada martensii

In May of 2007,the second generation selected （SS） and control （SC） groups of pearl oyster Pinctada martensii were established by selecting 10% breeders with the largest and mean shell length,respectively,from the first generation selected group.Growth performance of the SS and SC groups were compared on the basis of measurement data at Days 8,18,60,95,195 and 365.On Day 365,100 individuals （60.0–75.0 mm at shell length） were sampled from each group and then subjected to the experiment where physiological parameters such as filtrate rate,oxygen consumption and ammonia excretion were measured at 15,20,25 and 30°C.The results show that the SS group had significantly larger mean shell length and shell height than the SC group at Days 8,18,60,95,195 and 365 （P 0.05）.The genetic gains at different ages varied from 6.0% to 17.0% for shell length and 5.7% to 14.6% for shell height,respectively.At 15,20,25 and 30 ° C,the SS groups had significantly larger filtrate rate than the SC group （P 0.05）.At 15 and 25 °C,the differences in oxygen consumption rate between the SS and SC groups were not significant （P 0.05）.At 20 and 30 °C,however,the oxygen consumption rate of the SS group was significantly larger than the SC group （P 0.05）.At 15,20,25 and 30 °C,there were no significant differences in ammonia excretion rate between the SS and SC groups （P 0.05）.The present results indicate that there existed considerable genetic variability in the base population and a further selection could be likely fruitful.Mass selection for faster growth might produce animals that had higher intake of metabolizable energy by virtue of faster filtrating behavior.

Variation in cone and seed characters in blue pine (Pinus wallichiana) across natural distribution in western Himalayas

We analyzed 17 seed sources （seed stands） ofPinus wallichiana for variations present in cone and seed characters, scattered over natural distribution in north-west Himalayan states （Uttarakhand and Himachal Pradesh） of India. The significant variations were observed in cone weight, cone length, cone width, seed length, seed width, seed weight, seed germination, radicle length, and plumule length among different seed sources of the species. Significant positive correlation between seed weight, cone weight and cone width showed that seed weight in the species depend more on the cone size. Seed germination was also positively correlated with seed weight, cone weight and radicle length in the study. The estimates of variability with regard to genetic parameters for seed weight, seed germination, cone length, cone width, cone weight showed wide range of variation in the study. Seed weight showed high heritability values coupled with maximum genetic gain. Traits with such values indicate presence of good amount of heritable additive components and are under strong genetic control. The findings of the study revealed that seed sources expressed both phenotypic and genotypic differences in the seed and cone traits which might be due to the differences in genetic make up of various seed sources and environmental factors i,e. genotypic and environmental interaction, The study suggests that the seed weight should be given the top priority for the further improvement of this species.

Variability in cone,seed and seedling characteristics of Pinus kesiya Royle ex.Gordon

Investigations were made to determine the nature and extent of variations present for 10 morphological characters of cone,seed and seedlings of 17 plus trees（PTs）of Pinus kesiya growing in eastern Himalayas（Meghalaya state） of India.The significant variations has been observed in cone weight,cone length,cone diameter,seed length,seed diameter,seed weight,number of seeds per cone,seed germination,seedling height and seedling collar diameter among different PTs of the species.Significant positive correlation（p ／ 0.01） between seed weight,cone length and cone diameter showed that seed weight in P.kesiya depend more on the cone size.Seed germination is found positively correlated（p ／ 0.01） with seed weight,seed diameter,cone size and number of seeds per cone in the study.Among geographical factors,latitude and altitude are found positively correlated（p ／ 0.05） with cone weight and seed diameter,respectively.The genetic parameters for seed,cone and seedlings of PTs of P.kesiya also showed a wide range of variability in terms of variance,coefficient of variability,broad sense heritability,genetic advance and genetic gain.Seed weight,seeds per cone and seedling diameter showed high heritability values（[75） coupled with maximum genetic gain.Traits with such values indicate the presence of good amount of heritable additive components and are under strong genetic control.The findings of the study revealed that PTs expressed both phenotypic and genotypic differences in the seed,cone and seedling characters,which may be attributed to the differences in genetic makeup of various PTs and environmental factors i.e.genotypic and environmental interaction.The presence of high variability in P.kesiya PTs for different characters provide further opportunities to improve the population in subsequent generations so as to establish this species as an important timber tree to be grown on less fertile and degraded soils in its distributional ranges.

Genetic variability and divergence studies in pod and seed traits of Pongamia pinnata(L.) Pierre., accessions in Bay Islands

In this study, we assessed the variability in pod, seed traits and oil content of 24 accessions of Pongamia pinnata collected from different parts of the Andaman and Nicobar Islands, India. The experiment was conducted at the Central Agricultural Research Institute, Port Blair during 2010 to 2011. The variability studies for pod and seed traits revealed that, the accession CPT-6 collected from New Wandoor in South Andaman recorded the maximum values for eight traits viz. pod length （75.51 mm）, pod width （34.62 mm）, pod thickness （17.55 mm）, 100 pod weight （770.33 g）, seed width （21.23 mm）, 100 seed weight （377.00 g）, oil percentage （43.92%） and germination percentage （94.7%）. However, the maximum seed length （26.46 mm） was recorded from CPT 2 and the maximum pod-seed ratio was obtained from CPT 13 and CPT 4 （2.50 and 2.44 respectively）. The phenotypic and genotypic coefficients of variations were also close to each other for all traits, but the 100 pod and seed weight exhibited higher phenotypic and genotypic coefficient of variation than the other traits. Estimates of broad sense heritability ranged from 0.30 （for seed length） to 0.95 （pod length） and genetic ad- vance as percent of the mean ranged between 11.66% and 57.40% with seed length giving the lowest value and 100 pod weight giving the high- est value. Both the phenotypic and genotypic correlation between pod length, pod width, pod thickness, 100 pod weight, seed width and 100 seed weight and between pod thickness, 100 pod weight, seed width, 100 seed weight and germination percentage were found to be strong. On the basis of non hierarchical Euclidian cluster analysis, 24 accessions were grouped into six clusters. The maximum numbers of seven accessions were included in cluster VI. The maximum intra cluster distance （10.238）shown by cluster VI and the maximum inter cluster distance （17.021） between V and HI followed by III and II （15.942）. Among the six clus- ters formed the cluster III recorded maximum oil percentage, 100 pod weight, 100 seed ,weight, pod length, pod thickness, pod width, seed width and. germination percentage, while cluster V recorded maximum pod seed ratio and germination percentage. The present findings suggest that the crossing between accessions of cluster V and cluster III will result in a wide spectrum of variability in subsequent generations.

Response to Selection for Fast Growth in the Second Generation of Pacific Oyster (Crassostrea gigas)

Mass selection for fast growth was conducted in three Pacific oyster (Crassostrea gigas) stocks from China, Japan and Korea using previously established lines (CS1, JS1, and KS1). To determine whether continuous progress can be achieved by selection for growth, the progeny of three second-generation Pacific oyster lines was selected for shell height and evaluated via a 400-day farming experiment. When harvested at the end of the experiment, the selected crosses of CS2, JS2, and KS2 lines grew by 9.2%, 10.2% and 9.6% larger than the control crosses, respectively. During grow-out stage, the genetic gain of three selected lines was (10.2 ± 1.4)%, (10.4 ± 0.3)%, and (8.4 ± 1.6)%, respectively; and the corresponding realized heritability was 0.457 ± 0.143, 0.312 ± 0.071 and 0.332 ± 0.009, respectively. These results indicated that the selection for fast growth achieved steady progress in the second generation of oyster. Our work provides supportive evidence for the continuity of the Pacific oyster selective breeding program.

A STUDY ON THE GEOGRAPHIC VARIATION ANDSELECTIONOFTHEBEST PROVENANCE OF LARIX OLGENSIS

On the basis of the results from the geographic provenance test of nine years old /arix olgensis in Liangshui Natural Reserve of our university, a study on the geographic varition and the primary selection of the best provenance of torix oIgensis was carried out. The main results are as follows: 1. The different provenances of Larix olgensis have rich and wide genetic variation, and exist a linear correlation with latitude and longitude in collection area. General trends are enumerated below: Provenances at lower latitude and more west longitude have lighter thousand seed weight. short growth period, higher increment, wide branches, rich leaves and crown as well as worst adaptabi llity. It is a dual-way variation along with two directions of latitude and longitude, and also embodies a change gradually in climate condition from south to north. The temperat ures in seed production site, especially the mean temperature in January and≥10℃ accumulated temperature, are important factors that produce geographic variation for larix olgensis. 2. The variation of different provenances in periodic biological phenomena and growth rhythm trends are that: ① both of the provenances from Changbai Mt. (Ⅲ) and Dashitou(Ⅳ) at low latitude belong to the centralized growth type, and have shout growth period, the difference between these two provenances is that the provenance from Changbai Mt. grows well in all time, Dashitou provennce is well only in later period; ②the provenance from Baidao Mt. (Ⅱ) at middle latitude belongs to even growth type and has longer grpwth period, this provenance has higher increment in early and later periods relatively; ③ Xiaobeihu provenance at high latitude is a growth type among Ⅱ Ⅲ and Ⅳ provenances and has a general growth period, the provenance grows better in middle time and worse in later time. 3. The best provenance in Liangshui Natural Reserve and its meighbourhood is Dashitou Procenance. which growth in height. diameter and volume has exceeded 16. 28%, 46. 27%, 30. 58%, 78. 20, 82. 00% as well as 392. 00% by comparison with the mean value of the contrast and the worst provenance respectively, The result from the height growth of three, five. seven and nine years old Larix olgensis by using the method of order correlation analysis demonstrates that it is possible to make early selection of the provenance. Meanwhile. data from juvenile and mature of larix olgensis plantation also prove the reliability of the early selection. 4. The provenance heritabilities of nine years old larix olgensis in Liangshui Natural Reserve are follows:The heritability of the height growth (h2)is 0. 79; The heritability of the diameter breast height (h2) is 0. 791; The geretic gain is 24. 5%and 40. 36% respectively.

Progeny Test on the Natural Populations and Selection of Excellent Populations from Fraxinus Mandshurica

Fraxinus mandshurica is one of the ancient relict flora species originated from the Tertiary period, which is mainly produced in the eastern mountains in Northeast China. It has an important scientific value for studying the Tertiary flora and the Quaternary glacial climate. In order to make rational use of the natural genetic resources of F. mandshurica , and to increase the scientific and technological added value of improved varieties, this study used the method of positional observation of fixed standard fields to discuss the genetic variations of tree height and DBH of the natural populations and its open-pollinated progenies, systematically analyze the heritability and genetic gains in growth characters based on the analysis of progeny test, growth dynamic and heredity effects. The populations with good growth, stress resistance and adaptability were selected. The results showed that there were extremely significant difference in the growth characters among the natural populations, and the coefficients of variance for tree height （22.99%） were smaller, while the coefficients of variance for DBH （41.37%） were larger. On the other hand, there were extremely significant differences in the growth characters among the open-pollinated progenies, and the interaction between these progenies and the blocks was significant. Meanwhile, the growth characters had strong heritability, high genetic gain, and remarkable heredity effects. The heritability of tree height and DBH were 0.825 and 0.781, and the genetic gains were 15.16% and 25.85%, respectively. Therefore, Shanhetun （SHT） and Xinglong （XIL） were determined to be excellent natural populations both in the growth, resistance and adaptation with growth traits as the main evaluation index, which could be widely applied in the advanced generation improvement breeding.

Genetic evaluation of twenty seed sources of Asparagus racemosus

A field trial of 20 seed sources of Asparagus racemosus was conducted at the Forest Research Institute, Dehradun, Uttarakhand, India to evaluate their performance of different economic traits. Genotypic variance, phenotypic variance, genotypic coefficient of variance （GCV） and phenotypic coefficient of variance （PCV） for number of shoots, shoot height, shoot weight, number of roots, root length, root diameter and root weight were calculated. Maximum genotypic and phenotypic variance was observed in shoot height among the shoot - related traits and root length among the root - related traits. For the shoot height, genotypic variance, phenotypic variance, genotypic coefficient of variance, phenotypic coefficient of variance were 231.80, 3924.80, 61.26 and 1037.32, respectively, where those of the root length were 9.55, 16.80, 23.46 and 41.27, respectively. The maximum genetic advance and genetic gain were obtained for shoot height among the shoot-related traits and root length among the root-related traits. Index values were developed for all the seed sources based on the four most important traits, and Panthnagar （Uttrakhand）, Jodhpur （Rajasthan）, Dehradun （Uttarakhand）, Chandigarh （Punjab）, Jammu （Jammu and Kashmir） and Solan （Himachal Pradesh）, were promising seed sources for root production.

Culling phenotypically inferior trees in seed production area enhances seed and seedling quality of Acacia auriculiformis

Improvement in seed and seedling quality of Acacia auriculiformis after culling phenotypically inferior trees was studied in a 6-year old seed production area （SPA）. A 5-ha plantation was identified, of which 2.3 ha was converted into SPA. The initial stocking, 1 612 trees·ha^-1, was thinned down to 982 trees·ha^-1 based on growth characteristics. The following fruiting season, seeds were collected from 10 randomly selected trees in culled and non-culled stands, and seed physical characters, germination and seedling traits were assessed. Seed weight, seed thickness and percentage germination increased by 32.1%, 4.43% and 22.37%, respectively in the culled stand compared to the non-culled stand. Culling also increased the speed of germination, seedling dry weight and seedling vigor index. Heritability values were high for seed weight （0.974） and seed thickness （0.948） while medium values were observed for percentage germination （0.577） and total dry weight （0.534）. Predicted genetic gain was 11.13% and 11.22% for seed weight and percentage germination, respectively. The actual gain was 32.1, 51.9 and 22.9% for seed weight, percentage germination and total dry matter, respectively. In conclusion, SPAs established by culling inferior trees could serve as sources of good quality seeds for reforestation programs until genetically improved seeds are made available.

INTRASPECIFIC GEOGRAPHIC VARIATION AND PRIMARY SELECTION ON THE BEST PROVENANCE OF PINUS SYLVESTRIS VAR. MONGOLICA

This paper summarizes the result from the provenance test of eight years old Pinus sylvestris var. mongolica in Liangshui Natural Rcserve comprehensivcly. The main contents include:(1) the geographic variation of the growth characters of Pinus sylvestris var.mongolica.tends to negative change gradually at latitude and has obvious climatic nature, (2) no significant difference exists in the morphological adaptability and resistant characteristics and so on; (3)on the basis of the geographic variation study on the growth characteristics, the provcnances of Pinus sylvestris var. mongolica were classificd into two geographic populations and two subpopulations as follows:the northern population of the Daxing'an Mountain (Ⅰ) and the southern population of the Daxing'an Mountain as wcll as the Xiaoxinglan Mountain (Ⅱ),which includcs Honghuarii subpopulation and Kalunshan subpopulation (Ⅱ-2). (4) the height growth rhythm was analyzed according to the divided population and subpopuIation; (5) the best provcnance was selected for the Liangshui Natural Rescrve and its neighborhood accord ing to the results from SSR test of the growth characteristics (the breast height diameter and height of eight year old trces), the possibility of the carly provcnance sclection was also verified by the method of order correlation analysis on the height growth of three. five, scvcn and eight years old provenances.

Variability in growth characteristics for different genotypes of Eucalyptus tereticornis (SM.)

Eighteen clones of Eucalyptus tereticornis （Sm.） were evaluated for three years by adopting randomized block design for various growth parameters at Hoshiarpur, Punjab, India and compared with two checks. Significant variations were recorded for height, diameter at breast height （DBH） and clear bole height （CBH）. The broad sense heritability was low to moderate for both height and CBH. The genetic gain for height and CBH increased substantially pe se with the increase in age of trees. The average genetic gain for thres years was recorded maximum for height （159.60%） followed by DBH （110.97%） and CBH （70.34%）. Clone 17 attained maximum DBH over other genotypes for second and third year followed by clones 14 and 11. Clone 5 showed an upward trend for DBH and maintained its superiority for CBH as the age of the tree increased. Similarly, clone 11 changed its ranking from 9th to 8th to 3rd for DBH and from 9th to 4th to 2nd for CBH, respectively for the age of one, two and three years. Nonetheless, clones 6 and 10 per- formed poorly for all the characters studied. Clones 17, 14 and 5 were found to be the most promising clones for commercial deployment.

Within-and between-population variations in seed and seedling traits of Juglans mandshurica

In order to quantify within-and between-population variation in seed and seedling traits of Juglans mandshurica and reveal the relationship among genetic and environmental variations and select elite families,samples of 50 J.mandshurica families from five natural populations in Liaoning Province,northeast China,were taken to measure seed and seedling traits.The results show that all seed traits varied significantly among families within the population,but only kernel weight and kernel rate showed significant variations among populations.Average values of single seed weight,length,width,lateral diameter,and average size,and kernel weight and rate were 10.1 g,43.0 mm,29.2 mm,28.1 mm,33.4 mm,and 2.2 g and 22.5%,respectively.Significant variations were observed in seedling height and root collar diameter among families and interaction between families and blocks,but the block effects on height and root collar diameter were insignificant.Average values of height and root collar diameter were 94.0 cm and 8.7 mm,respectively.Family heritability of traits ranged from 0.6 gm(kernel weight)to 0.9 mm(seedling height).Correlation analysis showed a strong relationship among seed traits but a weak correlation between seed and seedling traits.Cluster analysis grouped the five natural populations of J.mandshurica into three significant clusters with different characteristics.The general combining ability analysis showed that most traits in one family(WD11)were higher,suggesting parental traits were excellent for selecting elite parent clones.Using the comprehensive evaluation method,five families with better seed traits and five families with better seedling traits were selected as elite materials with 10%selection rate.The genetic gains of these elite materials for seed weight,kernel weight,average seed size,kernel rate,seedling height,and root collar diameter were 13.1%,10.3%,4.1%,2.4%,29.7%,and 21.1%,respectively.

Growth and heritability estimates among clones of Dalbergia sissoo Roxb. in a clonal seed orchard

The study of genetic variability is a prerequisite for any tree improvement program. Screening of clones showing the effect of dominance in growth and tree form is essential to identify productive clones, matched to sites. Our study performed in a clonal seed orchard at Lacchiwala of India, represented by 31 clones of Dalbergia sissoo （Shisham） Roxb. from diverse locations revealed significant variability at the 0.1% level of significance in various morphological traits. At the age of 13 years, clone 196 （Gonda） revealed maximum height of 20.2 m and a girth at breast height of 74.2 cm. The five identified clones viz. 196, 198, 192, 123 and 235 were well adapted to the climatic conditions of this zone, hence survived well and showed good performance compared to other clones. Heritability estimates of 87%, 83% and 80% for height, crown width and crown length respectively coupled with high genetic gains indicated strong genetic control of these variables. A correlation matrix of various growth attributes revealed positive correlation among these attributes. On the basis of the entire set of growth variables, the clones were grouped into two major clusters with three subgroups.

Ecological Coupling Analysis and Genetic Effect Evaluation of Quantitative Characters in Lonicera edulis

Lonicera edulis is a perennial berry shrub that prefers the cold and wet climate, with high nutritional and medicinal value. In this study, ecological cou- pling capability of L. edulis with light, heat, water and soil resources in cold regions was investigated to analyze comprehensively ecological effects of quantitative characters and genetic effects of parents, aiming at providing a theoretical basis for the breeding, introduction and domestication of fine varieties of L. edulis in cold regions of China. The results showed that fruit characters in L. edulis exhibited certain variations among different habitat types. To be specific, fruit vertical diame- ter varied slightly, fruit horizontal diameter varied greatly and seed number varied maximally, with the average variance coefficients of 9.38%, 11.92% and 20. 64%, respectively; in addition, fruit characters in L. edtdis exhibited moderate herilability, moderate genetic gain and low level of genetic differentiation; the heritability of fruit vertical diameter, fruit horizontal diameter and seed number was 0.825, 0. 559 and 0. 627, respectively; the genetic gain of these three fruit characters was 7.53%, 5.72% and 11. 94%, respectively, resulting in significant economical benefits.

Implementation of Breed-Specific Traits for a Local Sheep Breed

In recent decades, a considerable number of local breeds have been replaced by high-yielding breeds for reasons of profitability. Many local breeds are now threatened by extinction and the loss of their native genetic diversity. The need to conserve breeds and their genetic diversity has a major importance due to the necessity for genetic change within and between populations. Novel approaches have to be explored and extended to maintain this genetic diversity. The aim of this study was the identification and implementation of breed-specific traits for a small, local sheep breed in northern Germany. The data comprised pedigree information, estimated breeding values (EBVs) of several conventional traits, and phenotypic information from a field experiment for two novel traits: 1) average daily gain under extensive circumstances (ADGE) and 2) ultrasonic measurements of muscle-fat ratio (UMFR). The experimental design included a dataset of 47 progeny from 14 pure-bred rams of German White-Headed Mutton (GWM). The methodical approach was divided into four parts: 1) the analysis of the breeding programme, 2) the identification of breed-specific traits, 3) the estimation and correlation of novel breeding values, and 4) the consequences of implementing these novel traits. Genetic parameters and correlations were conducted by applying linear mixed models. The estimates for the heritability (repeatability) were between 0.70 and 0.83 (0.42 and 0.46). The genetic correlation was positive (0.61) and in accordance with the phenotypic correlation (0.62). Average daily gain under intensive circumstances (ADGI) was moderately positive correlated with muscularity (0.60), as opposed to ADGE, which was moderately negative correlated with muscularity (-0.68). The EBV of ADGE was also moderately positive correlated with UMFR (0.64). Genetic response for ADGE enhanced to values of 481.09 g/day, 639.97 g/day, >700 g/day and >850 g/day for different selection intensity scenarios. Corresponding rates of inbreeding were 1.4%, 2.7%, 5.1%, and 7.9% after 10 years of selection. Genetic response for UMFR increased to 0.92, 1.34, 2.41, and >2.75, whereas remaining rates of inbreeding increased to 1.1%, 2.2%, 5.1%, and 7.9%. ADGI and ADGE were tendentially negatively correlated (-0.11), which strengthen the assumption of a biased ADGI. ADGE has a positive influence on meat-quality aspects (UMFR). Optimal use of reference sires with predefined selection intensity achieves genetic response for ADGE and UMFR with simultaneously acceptable rates of inbreeding.

Genomic selection in plant breeding:Key factors shaping two decades of progress

Genomic selection,the application of genomic prediction(GP)models to select candidate individuals,has significantly advanced in the past two decades,effectively accelerating genetic gains in plant breeding.This article provides a holistic overview of key factors that have influenced GP in plant breeding during this period.We delved into the pivotal roles of training population size and genetic diversity,and their relationship with the breeding population,in determining GP accuracy.Special emphasis was placed on optimizing training population size.We explored its benefits and the associated diminishing returns beyond an optimum size.This was done while considering the balance between resource allocation and maximizing prediction accuracy through current optimization algorithms.The density and distribution of single-nucleotide polymorphisms,level of linkage disequilibrium,genetic complexity,trait heritability,statistical machine-learning methods,and non-additive effects are the other vital factors.Using wheat,maize,and potato as examples,we summarize the effect of these factors on the accuracy of GP for various traits.The search for high accuracy in GP—theoretically reaching one when using the Pearson’s correlation as a metric—is an active research area as yet far from optimal for various traits.We hypothesize that with ultra-high sizes of genotypic and phenotypic datasets,effective training population optimization methods and support from other omics approaches(transcriptomics,metabolomics and proteomics)coupled with deep-learning algorithms could overcome the boundaries of current limitations to achieve the highest possible prediction accuracy,making genomic selection an effective tool in plant breeding.