Analysis of genetic effects and heritabilities for amylose content of indica rice in different environments

An understanding of the genetic effects of em-bryo genes for rice quality traits is of impor-tance for rice quality improvement. Analysisof embryo, endosperm, cytoplasmic, and ma-ternal genetic effects and genotype×environ-

Genetic parameter evaluation for growth and cold resistance traits of the giant freshwater prawn Macrobrachium rosenbergii

The giant freshwater prawn Macrobrachium rosenbergii distributed from tropical to subtropical regions,is a warm-water species,and its survival temperature is 14-35°C,which greatly limits its culture cycle and culture area in China.Therefore,it is urgent to cultivate a new high quality,high yield variety with improved cold-resistance,but the genetic parameters for cold-resistance traits are unknown in M.rosenbergii.In this study,the cold-resistance of adult M.rosenbergii populations was tested using the indoor artificial cooling method.Individuals were selected from 139 families of Shufeng G3 generation and cultured for 200 days.A linear mixed model was constructed by ASReml-R to evaluate the genetic parameters of the cold-resistance trait(cooling degree hours,CDH)and growth traits(body weight,BW,and body length,BL)based on the restricted maximum likelihood(REML)method.The results show that the heritability of CDH was low(0.12±0.05),while the growth traits(BW and BL)had low to moderate heritability,with 0.20±0.06 for BW and 0.06±0.04 for BL.The phenotypic and genetic correlation between BW and BL was significantly positive,but significantly negative phenotypic and genetic correlations were detected between CDH and BW and between CDH and BL.Furthermore,the analysis of the differences between cold-resistance and phenotypic traits showed that the female reproductive status,exoskeleton hardness and claw number of adult prawns had a great influence on the cold-resistance of M.rosenbergii(P<0.05),indicating that adults with claws and hard exoskeletons are preferred as parents in subsequent breeding selection.The present results can be attributed to the selection and breeding of a new cold-resistant variety of M.rosenbergii.

Exploring the genetic control of sweat gland characteristics in beef cattle for enhanced heat tolerance

Background Thermal stress in subtropical regions is a major limiting factor in beef cattle production systems with around$369 million being lost annually due to reduced performance.Heat stress causes numerous physiological and behavioral disturbances including reduced feed intake and decreased production levels.Cattle utilize various physiological mechanisms such as sweating to regulate internal heat.Variation in these traits can help identify genetic variants that control sweat gland properties and subsequently allow for genetic selection of cattle with greater thermotolerance.Methods This study used 2,401 Brangus cattle from two commercial ranches in Florida.Precise phenotypes that contribute to an animal's ability to manage heat stress were calculated from skin biopsies and included sweat gland area,sweat gland depth,and sweat gland length.All animals were genotyped with the Bovine GGP F250K,and BLUPF90 software was used to estimate genetic parameters and for Genome Wide Association Study.Results Sweat gland phenotypes heritability ranged from 0.17 to 0.42 indicating a moderate amount of the phenotypic variation is due to genetics,allowing producers the ability to select for favorable sweat gland properties.A weighted single-step GWAS using sliding 10 kb windows identified multiple quantitative trait loci(QTLs)explaining a significant amount of genetic variation.QTLs located on BTA7 and BTA12 explained over 1.0%of genetic variance and overlap the ADGRV1 and CCDC168 genes,respectively.The variants identified in this study are implicated in processes related to immune function and cellular proliferation which could be relevant to heat management.Breed of Origin Alleles(BOA)were predicted using local ancestry in admixed populations(LAMP-LD),allowing for identification of markers'origin from either Brahman or Angus ancestry.A BOA GWAS was performed to identify regions inherited from particular ancestral breeds that might have a significant impact on sweat gland phenotypes.Conclusions The results of the BOA GWAS indicate that both Brahman and Angus alleles contribute positively to sweat gland traits,as evidenced by favorable marker effects observed from both genetic backgrounds.Understanding and utilizing genetic traits that confer better heat tolerance is a proactive approach to managing the impacts of climate change on livestock farming.

Genetic variability and trait association analysis in linseed(Linum usitatissimum L.)for yield and related traits

Diversity information mining about a crop for different attributes is an essential step for effective breeding programs.The present investigation evaluates the quantum of genetic variability and determines the relationship among the important agro-economic traits based on two years of phenotypic data of 210 accessions of linseed.The traits,capsule weight per plant,capsule per plant,husk weight per plant,and seed weight per plant exhibited comparatively higher genetic coefficient of variation(GCV)and phenotypic coefficient of variation(PCV).In contrast,oil content and seed per capsule exhibited a lower value.The high magnitude of broad sense heritability was observed for all traits except seeds per capsule and husk weight per plant.The trait,capsules per plant,plant height,and days to 50%flowering showed high genetic advance coupled with high heritability.Hierarchical cluster analysis grouped 210 accessions into six distinct clusters.Out of 210,144(68.57%)accessions were grouped into three clusters(I,II,and III),in which cluster-III was the largest,containing 64 accessions followed by cluster II and cluster-I.The highest inter-cluster distance was observed between clusters-I and V(127.85),while the lowest was between clusters-II and IV(27.09).The positive correlation of capsule weight per plant with the seed weight per plant and a negative correlation with the days to 50%flowering indicates that high yielding linseed varieties with early flowering/maturity could be developed through direct and indirect selection.Further,seed yield and oil content could be enhanced together as indicated by ghe positive association among these two important traits.In this study,high yielding accessions with moderate to high oil content such as GP36,GP31,GP14,GP54,GP26,GP24,GP34,GP21,GP37 and GP27 and early flowering(less than 70 days)accessions such as GP2,GP26,GP27,CG33,CG44,CG42,CG132,and CG31 identified as potential genetic materials that could be exploited for developing early maturing varieties with high yield.In addition,information’s on various genetic parameters will help breeders to devise suitable breeding methodology for linseed genetic improvement for targeted traits.

Heterosis Analysis in Endogenous Substances in Root Bleeding Sap of Sorghum

Despite hybrid dominance contributing to the genetic improvement of crops,little is known about heterosis and inheritance patterns of endogenous substances in sorghum(Sorghum bicolor(L.)Moench)root bleeding sap.In this study,six sterile and six restorer lines of sorghum and 36 hybrid sorghum combinations formulated as incomplete double-row crosses were selected as test materials,and heterosis,combining ability,heritability,and their interrelationships of root bleeding sap endogenous substances in different hybrid sorghum combinations and their parents were investigated.The results showed that the root bleeding sap of the F1 generation of hybrid sorghum had a high heterosis in both soluble sugar content and amino acid content at the flowering stage,and the average high-parent heterosis was 129.34%and 74.57%,respectively.Indole-3-acetic acid(IAA),cytokinins(CTK),gibberellic acid(GA_(3)),abscisic acid(ABA),soluble sugar,amino acid,and root bleeding intensity were mainly affected by non-additive genetic effects of the genes.Soluble protein was affected by additive genetic effects of the genes and had a high narrow heritability(75.50%),which could be selected at low generations in breeding.The combining ability analyses showed that the sterile lines 521A and 170A,and the restorer lines Ji318R and 0–30 were promising parents with high general combining ability.Correlation analysis showed that all endogenous substances of root bleeding sap were positively correlated with the sum of parental general combining ability(GCA)at highly significant levels,and IAA,CTK,GA_(3),ABA,soluble sugar,amino acid,and root bleeding intensity were positively correlated with male GCA at significant or highly significant levels.Therefore,the GCA of the restorer lines root bleeding sap endogenous material or the sum of both parents’GCA can be used to predict the performance of wounding endogenous material in the F1 generation of hybrid sorghum.Overall,this study results can help elucidate heterosis mechanisms of root bleeding sap endogenous material and improve sorghum quality.

Selection criteria of MPOB-Angola germplasm collection for yield improvement of the oil palm

Oil palm germplasm collected from Angola,Africa in 1991 were subjected to genetic variability potential studies.The collection was planted in the form of open-pollinated families as trials at the Malaysian Palm Oil Board(MPOB)Kluang Research Station,Johor,Malaysia,in 1994.Dura palms from 52 families and tenera palms from 44 families of MPOB-Angola were evaluated for their bunch yield and bunch quality components.The objectives of this study were to determine the genetic variability among the families and performance of MPOB-Angola germplasm for yield improvement.The analysis of variance(ANOVA)revealed highly significant differences between the dura and tenera families for most of the traits,suggesting the presence of high genetic variability,which is essential for breeding programmes.Among the duras,family AGO 02.02 displayed the best yield performance,with a high fresh fruit bunch,oil yield and total economic product at 240.40,29.46 and 37.93 kg palm^(-1)year^(-1),respectively.As for the teneras,family AGO 03.04 recorded the highest FFB yield and oil yield at 249.25 and 45.22 kg palm^(-1)year^(-1),respectively.Besides that,several families with big fruit sizes or producing a mean fruit weight of 14-17 g were also identified.Both dura and tenera from AGO 01.01 recorded the highest oil to bunch(O/B)of 17.76%and 28.65%,respectively.These findings will facilitate the selection of palms from the MPOB-Angola germplasm for future breeding programmes.

Estimation of heritabilities of disease resistance to Edwardsiella tarda and genetic correlations between resistance and growth traits in Chinese tongue sole (Cynoglossus semilaevis)

Chinese tongue sole(Cynoglossus semilaevis)is an important marine flatfish which is widely cultured in coastal areas in China.Infectious bacterial diseases such as Edwardsiella tarda imposed serious threats to this species.A potential strategy to prevent this disease is to select resistance strains.The aim of the present work was to estimate the genetic variation of disease resistance to E.tarda and to evaluate the genetic correlations between resistance traits and growth traits.Three types of models were fitted by using different trait definitions(binary,continuous and categorical).After a 9-day challenge test,the overall survival was 75.4%(ranging from 6.4%to 100%in families),and at test day 6,the overall survival was 50.7%.We set test day 6 and 9 as cut-off point times respectively.The heritabilities of survival traits were ranging from 0.10 to 0.36.Considerably higher heritability values were obtained at day 6 than at day 9,regardless of which model or trait definition used(except Trait 2 in LIN).The genetic correlations between disease resistance traits and growth traits(i.e.body weight and total length)were low and not significant from zero(−0.12–0.24).There is a substantial re-ranking of families when defined resistance as categorical and continuous traits compared to binary trait.These results confirm the existence of genetic variation for resistance against E.tarda and weak genetic correlations indicate that joint genetic improvement of E.tarda resistance and growth is scarcely available.

High-fat diet and oral infection induced type 2 diabetes and obesity development under different genetic backgrounds

Background:Type 2 diabetes(T2D)is an adult-onset and obese form of diabetes caused by an interplay between genetic,epigenetic,and environmental components.Here,we have assessed a cohort of 11 genetically different collaborative cross(CC)mouse lines comprised of both sexes for T2D and obesity developments in response to oral infection and high-fat diet(HFD)challenges.Methods:Mice were fed with either the HFD or the standard chow diet(control group)for 12 weeks starting at the age of 8 weeks.At week 5 of the experiment,half of the mice of each diet group were infected with Porphyromonas gingivalis and Fusobacterium nucleatum bacteria strains.Throughout the 12-week experimental period,body weight(BW)was recorded biweekly,and intraperitoneal glucose tolerance tests were performed at weeks 6 and 12 of the experiment to evaluate the glucose tolerance status of mice.Results:Statistical analysis has shown the significance of phenotypic variations between the CC lines,which have different genetic backgrounds and sex effects in different experimental groups.The heritability of the studied phenotypes was estimated and ranged between 0.45 and 0.85.We applied machine learning methods to make an early call for T2D and its prognosis.The results showed that classification with random forest could reach the highest accuracy classification(ACC=0.91)when all the attributes were used.Conclusion:Using sex,diet,infection status,initial BW,and area under the curve(AUC)at week 6,we could classify the final phenotypes/outcomes at the end stage of the experiment(at 12 weeks).

Comparison of genetic impact on growth and wood traits between seedlings and clones from the same plus trees of Pinus koraiensis

To evaluate the relationships among clones and open pollinated families from the same plus trees and to select elite breeding materials,growth,and wood characteristics of 33-year-old Pinus korainsis clones and families were measured and analyzed.The results show that growth and wood characters varied significantly.The variation due to clonal effects was higher than that of family effects.The ratio of genetic to phenotypic coefficient of variation of clones in growth and wood traits was above 90%,and the repeatability of these characteristics was more than 0.8,whereas the ratio of genetic to phenotypic coefficient of variation of families was above 90%.The broad-sense heritability of all characteristics exceeded 0.4,and the narrow-sense family heritability of growth traits was less than 0.3.Growth characteristics were positively correlated with each other,but most wood properties were weakly correlated in both clones and families.Fiber length and width were positively correlated between clones and families.Using the membership function method,eleven clones and four families were selected as superior material for improved diameter growth and wood production,and two families from clonal and open-pollinated trees showed consistently better performance.Generally,selection of the best clones is an effective alternative to deployment of families as the repeatability estimates from clonal trees were higher than narrow-sense heritability estimates from open pollinated families.The results provide valuable insight for improving P.koraiensis breeding programs and subsequent genetic improvement.

A promising resilience parameter for breeding:the use of weight and feed trajectories in growing pigs

Background Increasing resilience is a priority in modern pig breeding.Recent research shows that general resilience can be quantified via variability in longitudinal data.The collection of such longitudinal data on weight,feed intake and feeding behaviour in pigs has been facilitated by the development of technologies such as automated feeding stations.The goal of this study was to investigate resilience traits,which were estimated as deviations from longitudinal weight,feed intake and feeding behaviour data during the finishing phase.A dataset with 324,207 records between the age of 95 and 155 days on 5,939 Pietrain pigs with known pedigree and genomic information was used.We provided guidelines for a rigid quality control of longitudinal body weight data,as we found that outliers can significantly affect results.Gompertz growth curve analysis,linear modelling and trajectory analyses were used for quantifying resilience traits.Results To our knowledge,this is the first study comparing resilience traits from longitudinal body weight,feed intake and feeding behaviour data in pigs.We demonstrated that the resilience traits are lowly to moderately heritable for deviations in body weight(h2=2.9%–20.2%),in feed intake(9.4%–23.3%)and in feeding behaviour(16.2%–28.3%).Additionally,these traits have good predictive abilities in cross-validation analyses.Deviations in individual body weight and feed intake trajectories are highly correlated(rg=0.78)with low to moderate favourable genetic correlations with feed conversion ratio(rg=0.39–0.49).Lastly,we showed that some resilience traits,such as the natural logarithm of variances of observed versus predicted body weights(lnvarweight),are more robust to lower observation frequencies and are repeatable over three different time periods of the finishing phase.Conclusions Our results will help future studies investigating resilience traits and resilience-related traits.Moreover,our study provides first results on standardization of quality control and efficient data sampling from automated feeding station data.Our findings will be valuable for breeding organizations as they offer evidence that pigs’general resilience can be selected on with good accuracy.Moreover,this methodology might be extended to other species to quantify resilience based on longitudinal data.

Statistical Method for Block in Replication Design and Its SAS Program

Large-scale genetic population used for genetic breeding researches covers a large area in the field experiment,and the effect of local control would be gradually weakened.The block in replication(BIR)design is suitable for large population,which is applied to the field experiment of genetic population.The statistical methods of analysis of variance(ANOVA)and heritability estimation in single and multiple environments were derived and implemented using the statistical analysis system(SAS)program for the analysis of BIR.As a work example,a comparison of statistical analysis between BIR design and the completely random block(CRB)design were conducted for the protein content from a panel containing 455 soybean germplasms.The results indicated the different estimates of average heritability in multiple environments.The research results provided technical support for the application of BIR design in genetics and breeding studies.

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

A solid understanding of the efficiency of early selection for fiber dimensions is a prerequisite for breeding slash pine(Pinus elliottii Engelm.)with improved properties for pulp and paper products.Genetic correlations between size of fibers,wood quality and growth properties are also important.To accomplish effective early selection for size of fibers and evaluate the impact for wood quality traits and ring widths,core samples were collected from360 trees of 20 open-pollinated Pinus elliottii families from three genetic trials.Cores were measured by SilviScan,and the age trends for phenotypic values,heritability,early-late genetic correlations,and early selection efficiency for fiber dimensions,such as tangential and radial fiber widths,fiber wall thickness and fiber coarseness,and their correlations with microfibril angle(MFA),modulus of elasticity(MOE),wood density and ring width were investigated.Different phenotypic trends were found for tangential and radial fiber widths while fiber coarseness and wall thickness curves were similar.Age trends of heritability based on area-weighted fiber dimensions were different.Low to moderate heritability from pith to bark(~0.5)was found for all fiber dimension across the three sites except for tangential fiber width and wall thickness at the Ganzhou site.Early-late genetic correlations were 0.9 after age of 9 years,and early selection for fiber dimensions could be effective due to strong genetic correlations.Our results showed moderate to strong positive genetic correlations for modulus of elasticity and density with fiber dimensions.The effects on fiber dimensions were weak or moderate when ring width or wood quality traits were selected alone.Estimates of efficiency for early selection indicated that the optimal age for radial fiber width and fiber coarseness was 6-7 years,while for tangential fiber width and wall thickness was 9-10 years.

Nutritional and nutraceutical variability in neglected niger(Guizotia abyssinica(L.f.)Cass.)accessions from Eastern Ghats of India

The exploitation of neglected niger accessions plays a crucial role in future breeding programs aimed to enhance the quality.Present study evaluated the genetic variation in nutritional and nutraceutical compositions of 30 indigenous niger accessions originating from Eastern Ghats of India,and compare them with three improved varieties of the locality.The proximate compositions(g/100 g)showed significant variations,with moisture ranging from 1.36 g to 4.95 g,ash from 1.06 g to 5.45 g,fat from 28.53 g to 44.11 g,protein from 8.84 g to 18.18 g,carbohydrate from 11.21 g to 35.09 g,fiber from 16.32 g to 26.62 g,and energy from 407.32 kcal to 526.84 kcal.Niger seeds are rich in phenol 41.10–82.20 mg/g,flavonoid 5.32–15.98μg/g,antioxidant 13.59–31.08%across the accessions.Principal component analysis revealed that the first two axis explained 41.8%of the total variation,indicating significant differences among genotypes.The heritability and genetic advance in percent of mean(GAM)ranged from 61.11%to 99.91%and 12.5%–89.1%among the traits across the populations.High heritability and GAM recorded in vitamin C,ash content,antioxidant capacity,flavonoid and phenol suggests that these traits may be important for niger breeding program.Altogether,some indigenous niger accessions such as Mangardora,Ganjeipadar and Kolabnagar had exceptionally rich in fat,protein and energy contents and are nutritionally superior compared to improved variety of the locality.Further,exceptional rich in flavonoid,antioxidant capacity and vitamin C was recorded in Manahar,Badapada and Mahadeiput.These nutrition rich accessions have ample opportunities for future breeding programs aimed to enhance the quality and hold great potential in food industry for making high value functional food.

A study of the influence of genetic variance and sex on the density and thickness of the calvarial bone in collaborative cross mice

Background:Bone microarchitecture is affected by multiple genes,each having a small effect on the external appearance.It is thus challenging to characterize the genes and their specific effect on bone thickness and porosity.The purpose of this study was to assess the heritability and the genetic variation effect,as well as the sex effect on the calvarial bone thickness(Ca.Th)and calvarial porosity(%PoV)using the Collaborative Cross(CC)mouse population.Methods:In the study we examined the parietal bones of 56 mice from 9 lines of CC mice.Morphometric parameters were evaluated using microcomputed tomography(μCT)and included Ca.Th and%PoV.We then evaluated heritability,genetic versus environmental variance and the sex effect for these parameters.Results:Our morphometric analysis showed that Ca.Th and%PoV are both significantly different among the CC lines with a broad sense heritability of 0.78 and 0.90,respectively.The sex effect within the lines was significant in line IL111 and showed higher values of Ca.Th and%PoV in females compared to males.In line IL19 there was a borderline sex effect in Ca.Th in which males showed higher values than females.Conclusions:These results stress the complexity of sex and genotype interactions controlling Ca.Th and%PoV,as the skeletal sexual dimorphism was dependent on the genetic background.This study also shows that the CC population is a powerful tool for establishing the genetic effect on these traits.

Heritability of Main Yield Traits in Red-seed Watermelon and Their Correlation Analysis

[Objectives]This study was conducted to provide a reliable theoretical basis for the correct formulation of breeding programs for red-seed watermelon and the effective breeding of hybrid offspring.[Methods]With local varieties and inbred lines of red-seed watermelon as test materials,the generalized heritability of fruit number per plant,single-fruit weight,single-fruit seed number,single-fruit seed weight,seed kernel weight,1000-seed weight,kernel-producing ratio,seed production ratio and seed volume were estimated by variance analysis;and the heritability,genetic variation coefficients,and correlation of the nine yield traits in 43 red-seed watermelon varieties were studied.[Results]The generalized heritability of fruit number per plant,single-fruit weight,single-fruit seed number,single-fruit seed weight,seed kernel weight,1000-seed weight,kernel-producing ratio,seed production ratio and seed volume were 12.86%,80.14%,75.96%,74.39%,48.01%,17.12%,24.97%,18.60%,and 37.07%,respectively.The heritability of single-fruit weight,single-fruit seed number and single-fruit seed weight was higher,and early-generation individual selection could achieve a better effect on them;and 1000-seed weight and kernel-producing ratio had a higher coefficient of genetic variation,indicating a high selection potential.[Conclusions]Indirect selection could be achieved for traits such as the single-fruit seed number,single-fruit seed weight,seed kernel weight,and seed volume by selecting the single-fruit weight.In the process of red-seed watermelon breeding,traits with high heritability can be selected in early generations of hybrids,thus playing the role of early-generation orientation.

Genetic Variability, Heritability and Correlation of Some Morphological and Yield Components Traits in Potato (Solanum tuberosum L.) Collections

The study was conducted with the main objective to evaluate the genetic variability, heritability, and clustering pattern exploration of morphological and yield related traits in potato (Solanum tuberosum L.) collections in the bimodal rainfall agroecological zone of Cameroon using a Randomized Complete Block Design (RCBD) with three replications. The data obtained on morphological and yield traits were subjected to analysis of variance (ANOVA). The results showed that the viability rate of the collections varied from 77.78% to 96.55% respectively for the Maffo and Desiree collections, while the greatest number of tubers per plant varied from 4 to 18 respectively for Synergie and Desiree. The emergence rate varies from 60% to 1.66% respectively for Maffo et Doza collections. However, Desiree presents the highest TL (96.55) while Maffo shows the lowest value (77.78%). The yield per hectare varied from 1.14 to 9.3 t/h for Maffo and Doza respectively. For all the characteristics observed, Phenotypic Coefficients of Variation (PCV) were higher than Genotypic Coefficients of Variation (GCV) suggesting the role of environment in the expression of traits under observation. The highest GCV and PCV 47.55 and 58.94 respectively were observed for Diameter at the collar (DC). Most of the traits showed high GAM (>20%)) except Average Tuber Length (ATL) with a moderate value (19.8). In terms of vegetative development, the Desiree variety showed the highest performance. Based on the growth and yield results, Doza seems to be the most recommendable crop in the study area.

Genetic Analysis on the Lambing Effects of Ewe Inner Mongolia Cashmere Goat

[Objective] The aim of this study was to explore the genetic law of litter size of Inner Mongolia Cashmere Goat.[Method] A total of 22 721 litter records from 3 044 mothers were statistically analyzed.[Result] As shown by the least square variance analysis,the sex,parity and birth type had significant effect on lamb birth weight.As indicated by restricted maximum likelihood method,the parity,population and maternal effect influenced litter size significantly.The birth weight heritability of single lamb,twins and total was 0.16,0.40 and 0.17,respectively.[Conclusion] The study provided a certain basis for the establishment of Inner Mongolia Cashmere Goat line with superior reproductive performance.

不同肥料对桉树幼苗营养及生长的影响

采用单因素随机区组试验设计,分析了包衣缓释专用肥(B)、水蒸气造粒专用肥(Z)、硫酸造粒专用肥(S)及有机-无机肥(L)对桉树(Eucalyptus L Herit.)幼苗叶片营养及生长的影响。结果表明,施肥8个月后,不同肥料处理均能有效促进桉树幼苗的生长,与对照相比,对地径增加的幅度从大到小的排序为有机-无机肥(27.49%)、包衣缓释专用肥(25.99%)、蒸气造粒肥(24.30%)、硫酸造粒肥(14.59%);对苗高增加的幅度从大到小的排序为包衣缓释专用肥(65.68%)、有机-无机肥(60.36%)、硫酸造粒肥(59.76%)、蒸气造粒肥(58.58%)。有机-无机肥处理的桉树幼苗叶片的全氮、全磷、全钾含量分别比对照提高了15.00%、4.02%、6.57%;包衣缓释专用肥处理的桉树幼苗叶片全氮、全磷含量分别比对照增加4.44%、1.86%,而2种常规无机专用肥处理8个月后已基本失去供肥能力,桉树幼苗叶片全氮、全磷、全钾含量均低于对照或与对照持平。

Estimates of Heritability and Genetic Correlations for Growth Traits in Chinese Shrimp Fenneropenaeus chinensis

[Objective] The aim was to estimate the heritability and genetic correlations of growth traits of Chinese shrimp Fenneropenaeus chinensis so as to provide basis and technical parameters for the breeding and selecting of Chinese shrimp.[Method] 51 full-sib families（including 35 half-sib families）of the Chinese shrimp F.chinensis were obtained by artificial insemination.Four growth traits of these families were measured,including body length,cephalothorax length,abdorminal segment length and body weight.According to quantitative genetics theory,the heritability of each growth trait,genetic and phenotypic correlation among these traits was statistically studied.[Result] The heritability was 0.36-0.51 for body length,0.14-0.24 for cephalothorax length,0.25-0.50 for abdominal segment length,and 0.04-0.29 for body weight.High and positive genetic correlations were obtained among growth traits.The genetic correlation between body weight and abdominal segment length was the highest（0.92）,followed by body length and abdominal segment length（0.91）,body length and body weight（0.88）,body weight and cephalothorax length（0.87）,abdominal segment length and cephalothorax length（0.86）,while the genetic correlation between body length and cephalothorax length was the lowest（0.83）.[Conclusion] The phenotypic correlation of body length,cephalothorax length,abdorminal segment length and body weight of Chinese shrimp F.chinensis were from 0.80 to 0.90 with extremely significant difference（P0.01）among the four growth traits by t-test.

Genetic Effects and Heterosis in Plant Height and Internode Traits of Japonica-Indica Hybrid Rice

[Objective] This study aimed to investigate the genetic effects and heterosis of plant height and internode traits of japonica-indica hybrid rice. [Methed] Incomplete diallel crosses were made between six japonica CMS lines and nine indica widecompatibility restorer lines; the genetic effects of plant height and internode traits of japonica-indica hybrid rice were analyzed using the additive-dominance genetic model. [Result] The ple, nt height, panicle length and the length of internode 1 of japonica-in- dica hybrid rice were mainly controlled by the additive effects; but the length of in- ternode 3, internode 4 and internode 5 were mainly controlled by dominance effects. Both the narrow sense heritability and broad sense heritability of plant height, panicle length, number of elongated internodes and length of most internodes reached signifi- cance level. The positive phenotypic correlation, genetic correlation, additive correla- tion and dominance correlation between plant height and panicle length, number of e- longated internodes and internode length were significant; and most of the other paired traits were significantly positively correlated. Heterosis analysis showed that the positive heterosis value over mid-parent and positive heterosis value over better- parent of the length of internode 3, internode 4, internode 5 and internode 6 reached significant level, and the heterosis value over mid-parent of plant height reached extreme significance level. [Conclusion] This study will provide reliable theoretical basis for the genetic improvement and heterosis utilization of plant height and internode traits in japonica-indica hybrid rice.