Superior Inbred Lines Research Articles

Genome assembly of KA105, a new resource for maize molecular breeding and genomic research

Superior inbred lines are central to maize breeding as sources of natural variation. Although many elite lines have been sequenced, less sequencing attention has been paid to newly developed lines. We constructed a genome assembly of the elite inbred line KA105, which has recently been developed by an artificial breeding population named Shaan A and has shown desirable characteristics for breeding. Its pedigree showed genetic divergence from B73 and other lines in its pedigree. Comparison with the B73 reference genome revealed extensive structural variation, 58 presence/absence variation (PAV) genes, and 1023 expanded gene families, some of which may be associated with disease resistance. A network-based integrative analysis of stress-induced transcriptomes identified 13 KA105-specific PAV genes, of which eight were induced by at least one kind of stress, participating in gene modules responding to stress such as drought and southern leaf blight disease. More than 200,000 gene pairs were differentially correlated between KA105 and B73 during kernel development. The KA105 reference genome and transcriptome atlas are a resource for further germplasm improvement and surveys of maize genomic variation and gene function.

Effect of three cycles of recurrent selection for yield in four Spanish landraces of maize

Landraces of maize (Zea mays L.) have a variability not found in the elite hybrids due to the bottleneck during selection. There is a renewed interest in using that variability, incorporating alleles for specific traits, or widening the general variability of elite germplasm. In Europe, there is also an interest in the direct use of local landraces by farmer’s associations seeking agriculture that preserves crop diversity. Pre-breeding programs are aimed to reduce the yield gap among landraces and improved materials. In the Misión Biológica de Galicia we have carried out three cycles of a S1 recurrent selection program for yield on four local landraces from Northwestern Spain with the objective of obtaining improved populations that might be cultivated by farmers and that could be used as sources of superior inbred lines. One hundred plants were selfed in each landrace and the S1 families were evaluated in a 10 × 10 simple lattice. The 20 S1 families with the highest grain yields were randomly intercrossed to form the selected population of each landrace. After three cycles of selection, each population and its cycles of selection were evaluated in three locations for two years. All the populations had a consistent yield gain in the first cycle of selection. However, the response in later cycles differed among the populations: one population had a continuous increase of 21% per cycle while two populations had a reduced yield in the last cycles. Our results highlight the need to include secondary traits to avoid unintentional indirect effects. We conclude that, in pre-breeding programs, it could be worthy to use large effective numbers to prevent inbreeding depression, particularly when the objective is the direct use of improved landraces. Another conclusion is that recurrent selection does not seem to be as efficient on European germplasm as it is on Corn Belt varieties. Finally, obtaining valuable new germplasm requires a sustained, long-term effort.

Performance of Test Crosses of Maize Variety Sarhad White with Jalal and Kiramat for Morphological Traits

This research was carried out at Khyber Pakhtunkhwa Agricultural University Peshawar to evaluate the performance of maize inbred lines derived from maize variety Sarhad White regarding grain yield and morphological traits and identifying superior inbred lines based on test cross performance. Test crosses were evaluated in replicated trial along with two tester, one check and 16 parental inbred lines for comparison in a 7×7 partially balanced lattice square design with two replications. Results revealed highly significant differences among the genotypes for most of the traits. Jalal TC-230-a and TC-63-1 took the maximum days to tasseling and Jalal TC-101-2 showed maximum days to anthesis. Maximum day to silking and anthesis silking interval were recorded in Jalal TC-94. Maximum plant height was observed in Jalal TC-33 (164.5 cm) and Kiramat TC-9-6-1 (141.50 cm). Maximum 100 kernal weight was recorded in Jalal TC-101-2 (40.55 g). Kiramat TC-89-b produced the highest grain yield (6808 kg ha-1). From these results, it can be concluded that Kiramat TC-89-b, having highest yield, could be promoted for further selfing. Jalal TC-9-6, TC-9-6-1, TC-12-1, TC-63-1, TC-76-2b, TC-89b, TC-163, TC-205, TC-230a, TC-211 and Kiramat TC-9-6, TC-9-6-1, TC-12-1, TC-33, TC-76-2b, TC-89b, TC-94, TC-101-2, 150-c, TC-163, TC-230-a, 205, 211, 226-2 in addition to having satisfactory grain yield could be used for selfing. Among parental lines (selfed lines) 9-6-1, 9-6, 10-2, 226-2, 33, 63-1, 76-2, 163, 89-b, 205 and 211 were promising for grain yield and morphological traits.

Comparative Analysis of Pedigree-Based BLUP and Phenotypic Mass Selection for Developing Elite Inbred Lines, Based on Field and Simulated Data

Pedigree-based best linear unbiased prediction (pBLUP) is an effective method for genetic evaluation. The objective of this study was to assess the efficacy of pBLUP to develop superior inbred lines, using field and simulated data. This study was based on the data of 30,986 plants from six S0 generations and eight inbred progeny trials (S1–S4), performed over eight years. We measured the grain yield and the expansion volume (EV). We also simulated the EV and grain yield of 5000 plants (S0–S4) in two in silico populations, assuming 300 and 400 genes distributed across 10 chromosomes of 200 cM, respectively, and 10% of pleiotropic genes. We selected selfed plants based on the predicted additive value for EV by fitting the individual model in inbred population. The use of pBLUP provided total genetic gains in EV in the range of 1 to 45%, inversely proportional to the level of improvement of the population, and indirect changes in grain yield in the range of −17 to 3%. Only from the analysis of the in silico populations, assuming selection based on the true additive value and genetic gain computed from the genotypic values, there was evidence that pBLUP is superior to phenotypic mass selection.

Identification of Drought Tolerant Recombinant Inbred Lines and Estimation of Genetic Diversity by Clustering and Multivariate Analysis in Wheat RILs Populations

The current experiments were carried out in alpha lattice design at the Seed Breeding Farm, Department of Plant Breeding and Genetics, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, Madhya Pradesh state, India, during 2019−20 and 2020−21 crop seasons, using 236 RILs population. The aim of current experiment is to assessment of genetic diversity and identification of promising recombinant inbred lines for irrigated and restricted irrigated conditions through PCA and cluster analysis. The drought selection indices viz. Relative drought index, yield stability index, drought resistance index, mean productivity, stress tolerance index and yield index were performed from two year grain yield pooled data. The principal component analysis and cluster analysis were performed through drought selection indices. Drought selection indices viz. relative drought index, yield stability index, yield index were confirm strong positively associated with grain yield under restricted irrigated conditions while mean productivity, stress tolerance index and yield index were strong positively associated with grain yield under irrigated conditions. Moreover, high cluster mean, for grain yield under restricted irrigated condition with associated selection indices was confirmed by 77 inbred lines from cluster I. similarly 128 superior inbred lines were found for irrigated condition. The highest inter cluster distance was observed between cluster I and cluster III therefore the inbred line occupy by cluster I and cluster III were considered as most diverse lines and could be used in farther breeding program to achieve more recombination for drought tolerance.

Generation mean analysis in maize (Zea mays) for yields and yield attributing traits

The nature of gene action involved is mainly responsible for the genetic improvement of any crop. Generation means analysis for maize (Zea mays L.) yield and its traits for six generations, i.e. P1, P2 F1, F2, BC1 and BC2 of six crosses evaluated at Karnal. Significant individual and joint scaling tests indicated inadequacy of three parameter models and presence of epistasis in all characters indicating greater genetic variation in parents. However, only shelling percentage in HKI 209 × HKI 163 showed additive-dominance. The presence of duplicate form of non-allelic gene interactions was prominent, except for days to maturity and cob diameter in HKI 325-17AN × HKI 163, cob length in HKI 209 × HKI 163 and shelling percentage in HKI 1332 × HKI 163 where complementary gene action is recorded. It suggests selection from F3 generation onwards for character improvement. Dominance and duplicate type of epistatic effects were found to be more prominent for inheritance than additive effects alone for grain yield/plant, grains/cob, and plant height suggesting the reciprocal recurrent selection or bi-parental mating design to improve in these characters. In crosses where dominance was of major importance, the trait could be successfully utilized for the exploitation of hybrid vigour. Some significant additive and additive × additive effects were recorded in all of these crosses, and therefore gain from selection could be possible, fixable and heritable epistasis could be effectively used in the selection of superior inbred lines.

Strategies for Selecting Early Maturing Maize Inbred Lines for Hybrid Production under Low Soil Nitrogen and Striga Infestation

Development, testing and selection of superior inbred lines is crucial for the success of a hybrid program targeting Striga-infested and low soil nitrogen (low-N) environments. The practical value of inbred lines is determined by multiple traits, most of which are inter-dependent. The main objective of this study was to identify early maturing inbred lines based on multiple traits under optimal, low-N and Striga-infested environments for hybrid development and population improvement. One hundred early maturing inbred lines were evaluated under artificial Striga-infestation, low-N and optimal growing environments for two years at Kwadaso and Nyankpala in Ghana. The inbred lines exhibited high levels of genetic variability for grain yield and other agronomic traits desirable for Striga resistance and low-N tolerance. Under optimal growing conditions, days to silking (DS), ears per plot (EHARV) and days to anthesis (DA) had high direct effects on grain yield (GYLD). Days to silking and ears per plant (EPP) had the highest positive direct effects on GYLD, while DA had the highest negative direct effect on grain yield in low-N environments. Under Striga-infestation, the highest negative direct effect on GYLD was obtained with EASP. All the measured traits previously identified to have direct influence on grain yield were associated with it and could be used for indirect selection for improved grain yield under the contrasting environments. Forty-eight of the 100 inbred lines studied were identified as low-N tolerant and forty-nine as Striga resistant.

Heterotic pools in African and Asian origin populations of pearl millet [Pennisetum glaucum (L.) R. Br.

Forty-five African or Asian origin pearl millet populations bred either in Africa or Asia were investigated to generate information on heterotic pools. They were clustered into seven groups (G1 to G7) when genotyped, using 29 highly polymorphic SSRs. Fourteen parental populations representing these seven marker-based groups were crossed in diallel mating design to generate 91 population hybrids. The hybrids evaluated at three locations in India showed mean panmictic mid-parent heterosis (PMPH) and better-parent heterosis (PBPH) for grain yield ranging from − 21.7 to 62.08% and − 32.51 to 42.99%, respectively. Higher grain yield and heterosis were observed in G2 × G6 (2462 kg ha−1, 43.2%) and G2 × G5 (2455 kg ha−1, 42.8%) marker group crosses compared to the most popular Indian open-pollinated variety (OPV) ICTP 8203. Two heterotic groups, Pearl millet Population Heterotic Pool-1 (PMPHP-1) comprising G2 populations and Pearl millet Population Heterotic Pool-2 (PMPHP-2) comprising G5 and G6 populations, were identified based on hybrid performance, heterosis and combining ability among marker group crosses. Population hybrids from two heterotic groups, PMPHP-1 × PMPHP-2 demonstrated PMPH of 14.75% and PBPH of 6.8%. Populations of PMPHP-1 had linkages with either African or Asian origin populations, whereas PMPHP-2 composed of populations originating in Africa and later bred for Asian environments. Results indicated that parental populations from the two opposite heterotic groups can be used as base populations to derive superior inbred lines to develop high yielding hybrids/cultivars.

Estimation of Combining Ability and Gene Action for Yield and Yield Components in Maize (Zea mays L.)

A field experiment was carried out in one of the farms in the AL- Sufi area of Anbar Governorate. Six Inbred lines of corn (Zea mays L.) (Pio-36, Sy-52, Am-63, Zm-69, ART-B17, NAdh-26) were used in this study. These lines were introduced into program Half dillael in the spring season 2019 15 hybrids were obtained. These crosses and their parents were in the full season using a randomized complete block design with three replications in the autumn season, to analyze the general and specific combining ability and estimate their effects, hybridization and some genetic parameters. The results of the statistical analysis showed that there were high significant differences between the genotypes (parents + hybrids) for all the studied traits, and the (Pio-36) was the best in plant height and leaf area as it reached 163.67 cm and 536.3 cm 2 respectively. In the ear diameter, the (ART-B17) was the highest and it reached 5.49cm, and in the Weight 300 grains (NAdh-26) was the highest, and it reached 78.33g, while the yield plant high value with line (Pio-36) was 203 g. In hybrids, the hybrid 3x5 gave the highest average for the number of grains per row, and it was 36.4 grains per row, and at 300 grains, the Add this word (hybrid 4x5) gave the highest hybrids and it reached 84.67 g, and the 4x5 hybrid gave the highest individual plant yield, as it reached 285.2 g. plant−1. The of heritability in the narrow sense was low in all the studied traits, and the value of the average degree of dominance was greater than one in all the studied traits, which indicates the importance of the effect of the over dominance of genes. It is concluded from the study the possibility of using some superior Inbred lines in their speculations to derive individual hybrids.

Assessment of the Potential for Genomic Selection To Improve Husk Traits in Maize.

Husk has multiple functions such as protecting ears from diseases, infection, and dehydration during development. Additionally, husks comprised of fewer, shorter, thinner, and narrower layers allow faster moisture evaporation of kernels prior to harvest. Intensive studies have been conducted to identify appropriate husk architecture by understanding the genetic basis of related traits, including husk length, husk layer number, husk thickness, and husk width. However, marker-assisted selection is inefficient because the identified quantitative trait loci and associated genetic loci could only explain a small proportion of total phenotypic variation. Genomic selection (GS) has been used successfully on many species including maize on other traits. Thus, the potential of using GS for husk traits to directly identify superior inbred lines, without knowing the specific underlying genetic loci, is well worth exploring. In this study, we compared four GS models on a maize association population with 498 inbred lines belonging to four subpopulations, including 27 lines in stiff stalk, 67 lines in non-stiff stalk, 193 lines in tropical-subtropical, and 211 lines in mixture subpopulations. Genomic Best Linear Unbiased Prediction with principal components as cofactor, performed the best and was selected to examine the impact of interaction between sampling proportions and subpopulations. We found that predictions on inbred lines in a subpopulation were benefited from excluding individuals from other subpopulations for training if the training population within the subpopulation was large enough. Husk thickness exhibited the highest prediction accuracy among all husk traits. These results gave strategic insight to improve husk architecture.

Combining ability of physiological traits in forrage maize

ABSTRACT The exploitation of the existing genetic variability for the physiological traits related to the yield and quality of maize forage can assist in the development of superior inbred lines and hybrids. The objective of this work was to evaluate the general and the specific combining ability and the nature of gene effects of physiological and chemical traits of forage maize genotypes. Two groups of genotypes and 16 hybrids resulting from a 4x4 partial diallel scheme were evaluated. Group I consisted of two commercial hybrids (AG8025, P30B39) and two elite inbred lines (LEM2 and LEM3). Group II consisted of four experimental inbred lines originated from different populations of forage maize breeding program. In total, 24 treatments were evaluated, formed by the genotypes of both groups and the respective crossings. The traits evaluated were: CO2 assimilation (A), stomatal conductance (gs), internal CO2 concentration (Ci), transpiration (E), calculated activity of Rubisco (A/Ci) and efficiency of water use (A/E). Forage acid detergent fiber (ADF), neutral detergent fiber (NDF) and digestibility in situ were obtained. There was a predominance of non-additive gene effects for most of the chemical and physiological traits. Crossings LEM2 x 203-218.3, LEM3 x 201-107.2, LEM2 x 101-7.2 and LEM3 x 101-7.2 stood out regarding CO2 assimilation, and are indicated for future research considering the physiological traits. Inbred lines 101-7.2 and 203-218.3 presented high concentration of favorable alleles to increase carboxylation efficiency, in which inbred line 101-7.2 stood out for NDF, ADF and DIG. Inbred line 201-107.2 has a high concentration of favorable alleles for efficiency of water use. Physiological parameters can assist the selection of inbred lines and hybrids in maize breeding for forage purpose.

Comparison of non-parametric indexes to select soybean genotypes obtained by recurrent selection

In the final steps of a breeding program, it is necessary to evaluate several traits, which makes it difficult to select the superior genotypes. This study aimed to compare nonlinear indexes in the selection of superior soybean inbred lines obtained by recurrent selection. The experiment was carried out in Londrina, Paraná State, Brazil. During the 2010/11 and 2011/12 seasons, 67 soybean inbred lines and two commercial controls (BMX Potência RR and NK 7059 RR) were evaluated. The experimental design was a randomized complete block with three replicates. The evaluated traits were: days to maturity, agronomic value, lodging, first pod insertion height, and grain yield. A combined analysis of variance for seasons was performed and the sum of ranks index, ideotype distance index, and cultivars selection index were applied. All traits were significant for the genotypic source of variation and showed complex genotype × environment interactions. The selection indexes were consistent with each other. The ideotype and cultivar selection index showed higher concordance on indication of 15 superior inbred lines with a coefficient of coincidence of 80%. The inbred lines SR-03, SR-12, SR-22, SR-41, SR-49, SR-55, SR-61, and SR-62 were indicated for all indexes and are therefore considered superior to other inbred lines.

Genetic diversity and path analysis for nitrogen use efficiency of tropical popcorn (Zea maysssp.everta) inbred lines in adult stage

AbstractModern maize hybrid breeding is also focused on increasing nitrogen use efficiency (NUE) for grain production. The objectives of this study were to assess popcorn inbred lines forNUE, assess its genetic diversity forNUEand related traits, and investigate the relationship between vegetative and adult traits withNUE, under contrasting N levels. Nineteen inbreds were assessed forNUEand related traits under two contrasting N levels in a 2‐year experiment, using complete blocks with three replications. Path analysis was performed using the vegetative N uptake and utilization efficiency and two root traits and four adult traits. The inbred 05‐388 was the most efficient in N use under both N levels. The inbreds with higher N use and utilization efficiency, grain N content and post‐silking N uptake were allocated in the same cluster in both N conditions. Leaf chlorophyll content and post‐silking uptake can serve as target traits for identifying superior inbred lines forNUE. Vegetative N uptake and utilization efficiency, and total root length can be used for early selection of superiorNUEinbreds.

Multi-trait multi-environment Bayesian model reveals G x E interaction for nitrogen use efficiency components in tropical maize.

Identifying maize inbred lines that are more efficient in nitrogen (N) use is an important strategy and a necessity in the context of environmental and economic impacts attributed to the excessive N fertilization. N-uptake efficiency (NUpE) and N-utilization efficiency (NUtE) are components of N-use efficiency (NUE). Despite the most maize breeding data have a multi-trait structure, they are often analyzed under a single-trait framework. We aimed to estimate the genetic parameters for NUpE and NUtE in contrasting N levels, in order to identify superior maize inbred lines, and to propose a Bayesian multi-trait multi-environment (MTME) model. Sixty-four tropical maize inbred lines were evaluated in two experiments: at high (HN) and low N (LN) levels. The MTME model was compared to single-trait multi-environment (STME) models. Based on deviance information criteria (DIC), both multi- and single-trait models revealed genotypes x environments (G x E) interaction. In the MTME model, NUpE was found to be weakly heritable with posterior modes of heritability of 0.016 and 0.023 under HN and LN, respectively. NUtE at HN was found to be highly heritable (0.490), whereas under LN condition it was moderately heritable (0.215). We adopted the MTME model, since combined analysis often presents more accurate breeding values than single models. Superior inbred lines for NUpE and NUtE were identified and this information can be used to plan crosses to obtain maize hybrids that have superior nitrogen use efficiency.

Comparison of methods for the estimation of best parent heterosis among lines developed from interspecific sunflower germplasm

Pre-breeding and elite breeding are two steps in creating high yielding sunflower hybrids that differ in well established procedures and selection methods. However, a methodology that bridge efficient use of introgression lines as product of pre-breeding procedures and their crossing to elite inbreed lines, is not yet very well established. Therefore, the development of cost- and time-efficient methods for the determination of best parent heterosis and the use of best inbred lines in crosses with introgression lines for obtaining high-yielding and stable hybrids is highly desirable. In this regard, sixteen Cytoplasmic Male Sterile (CMS) inbred lines (A) derived from four heterogeneous interspecific lines originating from three annual: H. debilis silvestris (DEB-SIL), H. praecox runyoni (PRA-RUN), H. deserticola (DES) and one perennial H. resinosus (RES) wild species were evaluated. Seven agronomic traits were measured over a period of 2 years and 38 DNA loci were analysed, in order to compare four different methods for the estimation of best parent heterosis (BPH). New inbred lines were characterized by Principal Component Analysis (PCA) of morphological traits and Principal Coordinate Analysis (PCoA) of molecular marker data. Line × tester mating design was used to evaluate General Combining Ability (GCA), while Genetic Distance (GC) estimated by markers was evaluated as a predictor of BPH by Locally Weighted Sequential Smoothing (LOESS). Analysis of combining ability is one of the most important tools breeders use to identify superior inbred lines on the basis of their performance in hybrid combinations. Results obtained in this research show that PCA of morphological and PCoA of molecular marker data on parental lines are generally in agreement with GCA effects for examined traits. GD versus BPH relationships indicate that intermediate to high GD between parental lines was optimal for best heterotic effects of most traits. In this study, we show that the combination of the PCA of morphological data, PCoA of molecular marker data and GD between parental lines is fast and affordable, giving the most important information for parental choice of introgression and elite lines in sunflower breeding programs.

Combining ability and heterosis study in maize (Zea mays L.) Hybrids at different environments in Bangladesh

The aim of this study was to isolate superior inbred lines and better combining parents for suitable hybrids and to determine percent of heterosis using standard commercial checks in a 7 × 7 diallel analysis excluding reciprocals over five environments. The mean sum of square obtained from combined analysis of variance showed the presence of genetic variability among the crosses, environment and crosses × environment interaction for all of the characters under study. The variances for general combining ability (GCA) and specific combining ability (SCA) of variance were found significant for all the characters. However, relative magnitude of variances indicated that additive gene effects were more prominent for all the characters studied. GCA and SCA effects both showed significant interaction with environment for all the traits. This clearly suggested the need of selecting different parental lines for hybrids for different ecological situations. Parents P3, P5 and P6 were the best general combiner for high yield; parents P6 for earliness; and P1, P2 and P3 for dwarf plant type. The range of heterosis expressed by different crosses was from -13.04 to 5.25 % percent for grain yield. The better performing six crosses (P1 × P2, P1 × P5, P3 × P4, P3 × P6, P3 × P7 and P4 × P5) can be utilized for developing high yielding hybrid varieties as well as for exploiting hybrid vigour. These crosses also need to be evaluated further in multilocations.Bangladesh J. Agril. Res. 43(1): 125-134, March 2018

Quantitative studies on heterosis and inbreeding depression in maize (Zea mays l.)

The present investigation was carried out for studying heterosis and inbreeding depression of twenty eight hybrids (F1 ? s) and their F2 ? s made by crossing of eight maize inbreds in all possible cross combinations excluding reciprocal. Observations were recorded on ten quantitative traits viz., plant height (cm), ear length (cm), ear girth (cm), number of kernel rows per ear, number of kernels per row, 100 kernels weight (g) yield per plant (g), days to 50 % tassel emergence, days to 50% silk emergence and days to 50% maturity. Variable magnitude of heterosis was observed for different cross combinations for all the traits. Based on higher mean performance (94.33 to 118.67 g/plant) and higher heterotic response (11.95 to 30.48%) eleven crosses were selected. Response of inbreeding depression was significant in positive direction for most of the traits. Among these eleven crosses five crosses CM 300 x CML 142, CM 300 x CML 144, CM 300 x CML 150, CM 300 x CML 176 and CML 150 x CML 144 were selected having high heterotic value (12.31 to 30.48%) and lower inbreeding depression (less than 15%) for their utilization in maize improvement programme for the development of superior inbred lines.

Genomic Prediction Within and Across Biparental Families: Means and Variances of Prediction Accuracy and Usefulness of Deterministic Equations.

A major application of genomic prediction (GP) in plant breeding is the identification of superior inbred lines within families derived from biparental crosses. When models for various traits were trained within related or unrelated biparental families (BPFs), experimental studies found substantial variation in prediction accuracy (PA), but little is known about the underlying factors. We used SNP marker genotypes of inbred lines from either elite germplasm or landraces of maize (Zea mays L.) as parents to generate in silico 300 BPFs of doubled-haploid lines. We analyzed PA within each BPF for 50 simulated polygenic traits, using genomic best linear unbiased prediction (GBLUP) models trained with individuals from either full-sib (FSF), half-sib (HSF), or unrelated families (URF) for various sizes () of the training set and different heritabilities ( In addition, we modified two deterministic equations for forecasting PA to account for inbreeding and genetic variance unexplained by the training set. Averaged across traits, PA was high within FSF (0.41–0.97) with large variation only for and For HSF and URF, PA was on average ∼40–60% lower and varied substantially among different combinations of BPFs used for model training and prediction as well as different traits. As exemplified by HSF results, PA of across-family GP can be very low if causal variants not segregating in the training set account for a sizeable proportion of the genetic variance among predicted individuals. Deterministic equations accurately forecast the PA expected over many traits, yet cannot capture trait-specific deviations. We conclude that model training within BPFs generally yields stable PA, whereas a high level of uncertainty is encountered in across-family GP. Our study shows the extent of variation in PA that must be at least reckoned with in practice and offers a starting point for the design of training sets composed of multiple BPFs.

Identification of Superior Recombinant Inbred Lines for Seed Yield and Related Traits in Indian Mustard (Brassica juncea L.) from a Population Derived from Rohini × PBR-97

In the present study, a set of 230 recombinant inbred lines (RILs) was developed through a cross between high yielding commercially released Indian mustard cultivars Rohini and PBR-97. These RILs were evaluated in F6:7 generation during the rabi season of 2012–2013 for quantitative and qualitative traits. High genetic advance in conjunction with high heritability for seed yield/plant (43.81, 80.89%), biological yield (39.34, 88.77%), fruiting zone length (9.36, 70.21%), fibre (28.35, 72.63%) and glucosinolates content (68.75, 97.56%) indicated the effectiveness of selection for these traits. Plant height (0.207), number of seeds/siliqua (0.169), biological yield (0.615) and 1000-seed weight (0.160) were positively associated with seed yield. On the basis of seed yield/plant, 25 RILs were identified as highly promising and some of these lines may be considered for multi-location testing for varietal release or used as parents for breeding high yielding Indian mustard varieties. Moreover, the recombinant inbred population developed in the study may be used for molecular dissection of yield and yield related traits in Indian mustard.

Prediction and validation of double cross hybrids in maize (Zea mays L.)

The experiment comprised of six F1’s, which were selected based on the combinations of low yield × high yield and low ASI × high ASI. The selected six F1’s were crossed in full diallel mating design to synthesise 16 double crosses was estimated and validated on the basis of performance of their constituent single crosses. Out of 16 hybrids, DCH 15 recorded lower tasseling and silking days and hence it can be used further in breeding programme. While, DCH 13 recorded narrow mean for ASI are suggested for use in deriving superior inbred lines with a combination of narrow ASI and higher ear circumference and kernel rows ear-1.The expected yield performance of DCH 5 (125.88), DCH 8 (124.23), DCH 10 (123.96), DCH 15 (123.73), DCH 6 (122.77) and DCH 12 (120.76) out yielded best check, Hema (119.00) for grain yield plant-1respectively. DCH 12 predicted better for most of the characters viz., ASI, ear length, ear circumference, kernel rows-1 and 100 grain weight. While, DCH 15 predicted better for characters viz., days to tasseling, days to silking, plant height (cm), ear height (cm), kernels row-1 and shelling percentage. Therefore, these two crosses may be used as double cross hybrids for breeding programme. In both prediction methods, nearly 14 out of 16 double cross hybrids manifested significant differences between realised and predicted performance suggesting involvement of epistasis in genetic control of grain yield plant-1