Segregation Frequency Research Articles

Exploring Transgressive Segregation for Enhanced Yield in F2 Segregants of Sesame (Sesamum indicum L.)

The experiment involved F2 generation of three superior crosses of sesame: Thilak X Ayali 1, Thilathara X Ayali 2 and Thilak X Ayali 5, grown in a Compact Family Block Design. A total of 200 plants were grown with a spacing of 30 x 25 cm, and observations were recorded on yield related characters. Significant variation was found among most traits, except for capsule length, capsule width, number of seeds per capsule and the number of primary branches. The cross Thilathara X Ayali 2 exhibited a high frequency of transgressive segregants for multiple traits, particularly for seed yield per plant, making it highly promising for further breeding efforts. Plant height had the highest mean and range, showing considerable potential for selection. CV analysis revealed high variability for traits like the number of capsules per plant and seed yield per plant. In contrast, low variability and high stability was observed for traits like capsule length, number of seeds per capsule and days to maturity. Higher PCV and GCV were recorded for traits like days to first flowering, number of capsules per plant, and seed yield per plant, showing substantial genetic and environmental influences. Moderate PCV and GCV were found for plant height and days to maturity, while traits like capsule length, number of seeds per capsule, and capsule width had the lowest PCV and GCV, indicating limited genetic variation. Days to first flowering and days to maturity showed high heritability combined with high genetic advance, suggesting the preponderance of additive gene action and are ideal for simple selection. Traits like capsule length, capsule width, and number of seeds per capsule showed low heritability and genetic advance, making them less ideal for selection. The cross, Thilathara X Ayali 2 should be prioritized in future generations to recover desirable segregants, especially for economically important traits like seed yield.

The effect of object perception on event integration and segregation.

The perceptual system must integrate information from various points in time and space to interpret continuous sensory input into meaningful units, such as visual objects or events. To explore the relationship between the perception of spatial objects and temporal events, we modified the missing element task, a typical temporal integration task, by inserting a simple spatial object. The aim was to determine whether the perceptual processing of the object would have an impact on the frequency of temporal integration and segregation. Temporal integration was most successful when the missing element was located within the object, less successful when there was no object, and least successful when the missing element appeared outside the object. The advantage of the location of the missing element within the object was observed at display durations from 30 ms to 150 ms. Interestingly, the object provided the same benefit for integration and segregation despite their opposing perceptual demands. This study demonstrates the relationship that exists between the processing of temporal events and spatial objects, and shows how such spatial information can facilitate temporal integration.

New lentil variety RKL 58F-3715: a case study depicting the emergence of desirable transgressive segregants

Lentil is one of the world’s most important cool-season grain legumes. The frequency of natural recombinants and segregants under natural conditions is very low in lentil due to their cleistogamous flower. The present investigation depicted the emergence of desirable transgressive segregants obtained from spontaneous mutation. Exploiting these hypervariable mutants, a highyielding lentil variety RKL 58F-3715 (Kota Masoor 4; KM 4) was developed from the progeny of a natural variant. The identified single deviated plant from the seed production plot of DPL 62 was probably a spontaneous mutation. During generation advancement, the progenies showed hypervariable segregants, especially for seed morphological traits, such as size, shape, colour and texture. The breeding cycles following rigorous selection under modified pedigree and single seed descent delivered the high-yielding stable genotype KM 4. Hypervariable progenies were obtained from natural mutants, distinguished in morphological traits such as earliness, light foliage colour, and prominent tendrils from the parent variety. The national weighted mean over locations over the year of KM 4 for grain yield was 1865 kg/ha, with yield superiority of 22.80% over national check DPL 62. Considerable resistance against major diseases, i.e., wilt and rust, makes it a durable genotype for commercial cultivation in major lentil-growing areas of India.

Revealing the Inheritance of Qualitative Traits and Identification of Transgressive Segregants for Productivity Traits in Early Segregating Generation of Soybean [Glycine max (L.) Merril

The breeding effort was carried out to elucidate information on the inheritance of qualitative traits and identification of transgressive segregants for productivity traits in two crosses viz., DSb 23 x MACS 1575 (Cross 1) and DSb 23 x MACS 1460 (Cross 2) in soybean during Kharif 2020 at Botany Garden, Department of Genetics and Plant Breeding, University of Agricultural Sciences, Dharwad. The observations were recorded on nine traits viz., days to 50% flowering, days to maturity, plant height, pods per plant, 100 seed weight, seed yield per plant, hilum colour, leaf shape and flower colour. Test for goodness of fit revealed that the traits viz., flower colour and leaf shape are controlled by a single dominant gene (3:1) and hilum colour was controlled by two genes with complementary gene action (9:7). In general, the percent of transgressive segregants obtained for yield-related traits was in a range of 7-17%. The high frequency of favorable segregants was identified for pods per plant (15.33%), 100 seed weight (13.87%) and days to maturity (16.42%) in cross 1, and high frequency of favorable segregants in cross 2 were observed for days to 50% flowering (8.95%), plant height (13.75%) and seed yield per plant (14.17%). These segregants can be further utilized in the breeding programme to develop high-yielding varieties and morphological traits can be used as markers in molecular breeding.

Inheritance of dwarfism trait by winter wheat mutants induced in the Chornobyl NPP exclusion zone

Background. The development of short-stem cultivars is an effective way to increase the productivity of winter wheat grown under the intensive cultivation techno­logy. Dwarf mutants, induced in the exclusion zone of ChNPP, can preserve a productive potential of an initial cultivar and be of a breeding value. The knowledge of the inheri­tance regularities of stem length by dwarf winter wheat mutants makes it possible to choose the pairs for crossing better and predict a final result in hybrid generations earlier. Materials and methods. Hybrids F1 і F2 of Triticum aestivum L. were received by crossing medium-grown cultivar Sonechko with dwarf mutant lines UK 1145/10, UK 1147/10, and UK 1148/10, induced by the effect of the radionuclide contamination of the exclusion zone of ChNNP on the plants of ‘Albatros odeskyi’ cultivar. The nature of the trait inheritance in F1 was determined by the degree of phenotype dominance, the variability of plant height was determined by a variation coefficient. The segregation frequency of dwarf, low-, medium- and high-grown forms was accounted in the population of F2 plants. Results. By stem length, plants F1 exceeded the genotypes involved in hybridization, or were closer to parental forms with a greater manifestation of the trait. The real heterosis in the plant height decrease was shown in the F1 hybrid ‘Sonechko’ × UK 1147/10. The hybrid productivity elements are inherited by the type of a partial positive dominance and over-dominance. From 2.2 % to 3.6 % of high-grown forms, atypical for parents, were recorded in the population of F2. Conclusions. When the crossing combination includes a medium-grown cultivar of winter wheat and dwarf mutants, induced in the exclusion zone of ChNPP, a stem length in F1 is inherited by an intermediate type and partial positive dominance. Dwarf mutant UK 1147/10 can be valuable for breeding short stem winter bread wheat. A significant variation of such indicator as a degree of phenotype dominance by all studied features confirms a complicated nature of genetic determination of a plant height and the productivity elements of winter wheat, in the formation of which various types of gene interaction take part.

Genetic divergence study in greengram [Vigna radiata (L.) Wilczek

The present investigation was undertaken to obtain information on the nature and extent of genetic diversity among 60 greengram genotypes for yield related traits and quality traits by using Mahalanobis’s D2 statistics.  The genotypes were grouped into eleven clusters. Cluster I was found to be the largest  with 38 genotypes followed by cluster V with 13 genotypes and all the other clusters were found to be solitary, each containing a single genotype. Clusters VIII and XI had the maximum inter-cluster distance, followed by clusters IV and XI. Cluster XI had the highest mean values for yield and other yield attributing traits. Iron content contributed high towards total genetic diversity followed by protein content and test weight. Based on the mean performance and diversity studies, the genotypes COGG 18-17, LGG 460, Daftri vikas and IPM 1603-3 were found to be the best for further yield improvement in greengram. Utilizing the genotypes from the more divergent clusters as parents in breeding programmes will yield relatively good amount of heterosis in F1 and high frequency of transgressive segregants and genetic variability in subsequent generations can be acquired. Keywords: D2 statistic, Cluster analysis, Genetic Divergence, Greengram, Tocher’s method.

Stepwise recombination suppression around the mating-type locus in an ascomycete fungus with self-fertile spores.

Recombination is often suppressed at sex-determining loci in plants and animals, and at self-incompatibility or mating-type loci in plants and fungi. In fungal ascomycetes, recombination suppression around the mating-type locus is associated with pseudo-homothallism, i.e. the production of self-fertile dikaryotic sexual spores carrying the two opposite mating types. This has been well studied in two species complexes from different families of Sordariales: Podospora anserina and Neurospora tetrasperma. However, it is unclear whether this intriguing association holds in other species. We show here that Schizothecium tetrasporum, a fungus from a third family in the order Sordariales, also produces mostly self-fertile dikaryotic spores carrying the two opposite mating types. This was due to a high frequency of second meiotic division segregation at the mating-type locus, indicating the occurrence of a single and systematic crossing-over event between the mating-type locus and the centromere, as in P. anserina. The mating-type locus has the typical Sordariales organization, plus a MAT1-1-1 pseudogene in the MAT1-2 haplotype. High-quality genome assemblies of opposite mating types and segregation analyses revealed a suppression of recombination in a region of 1.47 Mb around the mating-type locus. We detected three evolutionary strata, indicating a stepwise extension of recombination suppression. The three strata displayed no rearrangement or transposable element accumulation but gene losses and gene disruptions were present, and precisely at the strata margins. Our findings indicate a convergent evolution of self-fertile dikaryotic sexual spores across multiple ascomycete fungi. The particular pattern of meiotic segregation at the mating-type locus was associated with recombination suppression around this locus, that had extended stepwise. This association between pseudo-homothallism and recombination suppression across lineages and the presence of gene disruption at the strata limits are consistent with a recently proposed mechanism of sheltering deleterious alleles to explain stepwise recombination suppression.

Breaking the tight genetic linkage between the a1 and sh2 genes led to the development of anthocyanin-rich purple-pericarp super-sweetcorn

The existence of purple-pericarp super-sweetcorn based on the supersweet mutation, shrunken2 (sh2), has not been previously reported, due to its extremely tight genetic linkage to a non-functional anthocyanin biosynthesis gene, anthocyaninless1 (a1). Generally, pericarp-pigmented starchy purple corn contains significantly higher anthocyanin. The development of purple-pericarp super-sweetcorn is dependent on breaking the a1–sh2 tight genetic linkage, which occurs at a very low frequency of < 1 in 1000 meiotic crossovers. Here, to develop purple-pericarp super-sweetcorn, an initial cross between a male purple-pericarp maize, ‘Costa Rica’ (A1Sh2.A1Sh2) and a female white shrunken2 super-sweetcorn, ‘Tims-white’ (a1sh2.a1sh2), was conducted. Subsequent self-pollination based on purple-pericarp-shrunken kernels identified a small frequency (0.08%) of initial heterozygous F3 segregants (A1a1.sh2sh2) producing a fully sh2 cob with a purple-pericarp phenotype, enabled by breaking the close genetic linkage between the a1 and sh2 genes. Resulting rounds of self-pollination generated a F6 homozygous purple-pericarp super-sweetcorn (A1A1.sh2sh2) line, ‘Tim1’. Genome sequencing revealed a recombination break between the a1 and yz1 genes of the a1–yz1-x1–sh2 multigenic interval. The novel purple-pericarp super-sweetcorn produced a similar concentration of anthocyanin and sugar as in its purple-pericarp maize and white super-sweetcorn parents, respectively, potentially adding a broader range of health benefits than currently exists with standard yellow/white sweetcorn.

Breeding Potential of Crosses Derived from Parents Differing in Overall GCA Status for Productivity per se Traits and Powdery Mildew Disease Response in Blackgram [Vigna mungo (L.) Hepper

Background: Predicting the breeding potential of crosses in terms traits means, genetic variability and frequency of desirable transgressive segregants in early segregating generations is crucial in breeding programme. Therefore, an experiment was carried out to assess breeding potential of crosses involved parents with varying overall gca status and contrasting responses to powdery mildew disease (PMD) in blackgram. Methods: Total of 40 F1s developed by following Line × Tester design; among, nine crosses were selected based on GCA status of parents and responses to PMD. F1, F2 and F3 along with parents of six and three crosses were evaluated for 10 productivity per se traits and responses to PMD separately during kharif, 2016 and rabi, 2016-17 respectively. The traits means, absolute and standardized range, PCV and frequency of transgressive segregants in F2 and F3 were compared to assess the breeding potential of the crosses. Result: F2 and F3 generations derived from six crosses (for productivity traits) and three crosses (for PDI) were differed for means, absolute and standardized range, PCV and the frequency of transgressive segregants. This is may be due to the contribution of diverse genes from female and male parent. Though considerable number of transgressive segregants were also identified in F2 and F3 of all the crosses, high frequency of desirable transgressive segregants was observed in crosses involved parents with overall high GCA status.

Breeding potential of crosses derived from genetically divergent parents differing for yield and its attributes in cowpea [Vigna unguiculata (L.) Walp

Handling of segregating populations arising from a large number of crosses in Plant Breeding is a challenging and vital task. Identification of potential of the particular cross will aid in the selection of superior segregants. In the present study, four crosses derived from parents contrasting for seed yield and most of its attributing traits was assessed by comparing the 11 quantitative traits, mean values, phenotypic coefficient of variation, standardized range and frequency of transgressive segregants in F2 and F3 generations in cowpea. Based on per se mean value , variances, standardized range and frequency of transgressive segregants in F2 and F3 generations derived from four crosses, PL-2 × NBC-39 was predicted to have better breeding potential followed by PL-5 × EC-402104 in terms of chances of isolating desirable recombinants in advanced generations. Increasing trend in mean values, variances, and frequency of transgressive segregants for most of the traits from F2 to F3 generations derived PL-2 × NBC-39 and PL-5 × EC-402104 supported the conclusion, although a decreasing trend was observed for standardized range in all four crosses. Identification of 10 best F3 plants in PL-2 × NBC-39 indicated the utility of mean values, variances, standardized range and frequency of transgressive segregants in predicting the performance of a cross to maximize the frequency of superior segregants in advanced generations. Key words:&nbsp;PCV, GCV, Transgressive segregation, Cowpea , Vigna unguiculata &nbsp; &nbsp;

Comparison of Genetic Parameters among Selfed Lines and Random Mated Population A (PDM 53 x PDM 4441) and Population B (HKI 1105 x HKI 323) and Identification of Transgressive Segregants

The present study was conducted to compare the genetic variability parameters among selfed lines of population A (PDM 53 x PDM 4441) and population B (HKI 1105 x HKI 323) and also random mated population A (PDM 53 x PDM 4441) and random mated population B (HKI 1105 x HKI 323) using original inbred parents and three commercial checks, HM-4 (National check), CPB 468 and TENDER (Private check). High heritability coupled with high genetic advance was observed for number of cobs per plant, husked cob weight, dehusked cob weight, baby corn yield with and without husk per plant among selfed populations and a similar trend was observed in random mated populations except for ear length and days to 50 % silking. In total the variability observed was more in random mated populations than selfed lines because allelic frequency differences occur in random mated populations and the pool of gametes originating from male and female is different when compared to the pollen source in selfed populations. The frequency of transgressive segregants were more in random mated Population A (PDM 53 x PDM 4441) and the most promising transgressive segregant identified can be used in the further breeding programmes.

Heritability and Genetic Advance as Genetic Indicators for Improvement in Two Cotton Crosses

The primary breeding goal for the Egyptian cotton breeding program is how to genetically improve both yield and fibre quality traits, while most of these agronomically traits are biometric traits. The objective of the present study is to evaluate variability and estimate frequency of transgressive segregants in order to isolate early superior individual plants which exceeding the better parent for some yield and fiber quality traits in two intraspecific cotton crosses in early transgressive segregating generation (F2 ). The F1 was highly significant superior than the better parent (Giza 97 and Giza 94) of the two crosses for all the studied traits except boll weight and lint %. Most of the studied traits in F2 generation showed high values of broad sense heritability coupled with low GAM % indicated that these traits controlled by non-additive gene action. All the studied traits had positive skewness sign except for lint %. Presley index and uniformity index for the two cotton crosses and upper half mean for cross II showed negative skewness. The negative skewness indicated that the population had more plants frequency with higher mean values than population mean and controlled by dominancy alleles. While, the traits that had positive skewness are controlled by additive gene action. The two cotton crosses showed transgressive segregants for all the studied traits. Cross I has higher transgressive index for yield traits than cross II, while cross II has the same trend for fiber quality traits than cross I. These results indicated that the both parents of the two cotton crosses had different alleles and genes governing the respective studied traits, which will help cotton breeder to combine beneficial alleles into a single genotype by rigorous selection process. This strategy could be used to improve many economic biometric traits by using better and stringent selection procedure to enhance Egyptian cotton productivity which is major concern in Egypt. The breeder can use transgressive segregation as an indicator of genetic variability to select the most superior plants.

Comparative Breeding potential of two crosses for response to late wilt disease (LWD) in maize (Zea mays L.)

Plant Breeders routinely develop a large number of crosses. This poses challenge to breeders in terms of prioritizing the crosses for advancing the generations. This necessitates testing the crosses to assess the breeding potential on BC1F1 and BC2F1 generations derived from two different crosses involving parents differing for response to late wilt disease resistance was assessed for response to late wilt disease. The recurrent parent that is common for both the crosses, is a seed parent of popular public bred maize hybrid “Hema”. In the present investigation, BC1F1 and BC2F1 generations of two crosses NAI-137 × MAI-345 and NAI-137 × 97B were assessed for their breeding potential for resistance to late wilt disease. The breeding potential was assessed based on the mean, variance and frequency of transgressive segregants. The BC1F1 and BC2F1 populations derived from the cross NAI-137 × MAI-345 expressed lower mean (for response to late wilt disease), wider absolute range and standardized range, and higher phenotypic coefficient of variation and frequency of transgressive segregants. Hence, backcross populations derived from the cross NAI-137 × MAI-345 was identified as the one with better breeding potential than that derived from NAI-137 × 97B.

Breeding potential of crosses derived from parents differing in fruiting habit traits in chilli (Capsicum annuum L.)

Crop breeders are frequently confronted with a challenge of shortlisting a few most likely to be productive early segregating generations in terms of high frequency of superior recombinant inbred lines from among a large number of segregating generations which are normally being developed to save substantial resources. The breeding potential of five F2 populations derived from parents differing for fruiting habit traits was assessed based on first- and second-degree statistics and frequency of transgressive segregants for number of fruits plant−1, average fruit weight and fruit yield plant−1 using 2016 and 2017 rainy season data. Based on higher mean, wider absolute range and standardized range, and higher phenotypic coefficient of variation and frequency of transgressive segregants, F2 population derived from JL × 8B was identified as the one with better breeding potential than that derived from other crosses.

Transgressive segregations in two pea F2 populations and their respective F2:3 families

Abstract: The objective of this work was to evaluate the variability present in two pea (Pisum sativum) F2 populations and their corresponding F2:3 families, as well as to determine, in both generations, the frequency of transgressive segregants in order to isolate early superior families. The study was conducted from a cross of green pea varieties (Ilca 5115 and Turf) and a cross of yellow pea varieties (Zavalla 15 and Amarilla). In both generations, morphological traits were evaluated. Phenotypic and genotypic variances, experimental error variance, genotypic and phenotypic coefficients of variation, broad-sense heritability, and transgressive segregants were determined. The green F2 population showed greater variation, whereas the yellow F2:3 families had higher average values for most traits. In the green F2:3 population, the percentage of transgressive segregants was greater or equal to 20, while, in the yellow one, no traits had a percentage greater than 20. High heritability values were obtained for most traits in both generations. Considering all traits, 45% of the transgressive segregants are found in the F2 populations and 42% of the F2 transgressive segregants in the F2:3 generation. The distribution of F2:3 families allows to select promising families according to the breeding program objectives.

Protocol for the Connected Speech Transcription of Children with Speech Disorders: An Example from Childhood Apraxia of Speech

Objective: While it is known that connected speech has different features to single-word speech, there are currently few recommendations regarding connected speech transcription. This research therefore aimed to develop a clinically feasible protocol for connected speech transcription. The protocol was then used to assist with description of the connected speech of children with childhood apraxia of speech (CAS), as little is known about their connected speech characteristics. Participants and Methods: Following a literature review, the Connected Speech Transcription Protocol (CoST-P) was iteratively developed and trialled. The CoST-P was then used to transcribe 50 connected utterances produced by 12 children (aged 6–13 years) with CAS. The characteristics of participants’ connected speech were analysed to capture independent and relational analyses. Results: The CoST-P was developed, trialled, and determined to have adequate reliability and fidelity. The frequency of inter-word segregation (mean = 29) was higher than intra-word segregation (mean = 4). Juncture accuracy was correlated with intelligibility metrics such as percentage of consonants correct. Conclusion: Connected speech transcription is challenging. The CoST-P may be a useful resource for speech-language pathologists and clinical researchers. Use of the CoST-P assisted in displaying CAS speech characteristics unique to connected speech (e.g., inter-word segregation and juncture).

Genetics of stripe rust resistance in two barley (Hordeum vulgare L.) genotypes

Stripe rust inflicted by the pathogen Puccinia striiformis Westend. f. sp. hordei Eriks can cause marked grain yield reduction and deterioration of the malting quality in barley. Two barley genotypes, DWRB137 (DWR28/DWRUB64) and DWRB143 (DWRB73/DWR83) were identified as resistant (R) for three stripe rust races viz., 57 (0S0), M (1S0) and Q (5S0) at seedling and adult plant stages. These genotypes were crossed with two stripe rust susceptible (S) barley cultivars, RD2035 and Lakhan to study mode of inheritance of stripe rust resistance. All the F1 plants showed resistance against stripe rust race, 57 (0S0) indicating that the resistance (R) is dominant. The F2 generations derived from the crosses namely, Lakhan/DWRB137, Lakhan/DWRB143, RD2035/DWRB137 and RD2035/DWRB143 were tested with inoculum of race, 57 (0S0) under artificially inoculated conditions. The observed frequency of segregants in each F2 generation fit well in a theoretical ratio of 3(R):1(S) (χ 2(T) less than 0.01) indicating that the resistance against the tested race is controlled by a single dominant gene in the genotypes, DWRB137 and DWRB143. To validate the F2 hypothesis, the F3 progenies were also tested under above described conditions and followed discrete segregation of 1 (R): 2 (Segregating): 1(S) ratio in all the four crosses. Test of allelism was also conducted to establish the identity of resistance gene(s) present in the resistant genotypes. The F2 population derived from DWRB137/DWRB143 (R × R) cross fit to 15(R):1(S) ratio showing that the two genotypes had different resistance genes.

Crypt fusion as a homeostatic mechanism in the human colon

ObjectiveThe crypt population in the human intestine is dynamic: crypts can divide to produce two new daughter crypts through a process termed crypt fission, but whether this is balanced by...

Analysis of meiotic segregation modes in biopsied blastocysts from preimplantation genetic testing cycles of reciprocal translocations

PurposeTo analyse the meiotic segregation modes of chromosomal structural rearrangements (PGT-SR) of reciprocal translocation in biopsied blastocysts from preimplantation genetic testing and to investigate whether any features of reciprocal translocation, such as carrier gender or the presence of acrocentric chromosomes or terminal breakpoints, affect meiotic segregation modes.MethodsComprehensive chromosomal screening was performed by next generation sequencing (NGS) on 378 biopsied blastocysts from 102 PGD cycles of 89 reciprocal translocation carriers. The segregation modes of a quadrivalent in 378 blastocysts were analysed according to the carrier’s gender, chromosome type and the location of chromosome breakpoints.ResultsThe results showed that 122 out of 378 blastocysts (32.3%) were normal or balanced, 209 (55.3%) were translocated chromosomal abnormalities, and 47 (12.4%) were abnormalities of non-translocated chromosomes. The proportion of translocated chromosomal abnormalities in translocations without acrocentric chromosomes was significantly higher than that in blastocysts from carriers with acrocentric chromosomes (14.8% versus 5.9%, P = 0.032). Translocation with acrocentric chromosomes exhibited a significantly higher proportion of 3:1 segregation (24.8% versus 5.1%, P < 0.0001) and a lower rate of 2:2 segregation (70.3% versus 87.0%, P = 0.00028) compared with the proportions in blastocysts from carriers without acrocentric chromosomes. The frequency of adjacent-2 segregation was significantly different in translocations with terminal breakpoints compared to the frequency in blastocysts from carriers without terminal breakpoints (6.7% versus 15.5%, P = 0.013).ConclusionsThis study indicates that the segregation modes in blastocysts were affected by the presence of acrocentric chromosomes and terminal breakpoints, but not by the carrier’s sex. Our data may be useful for predicting the segregation pattern of a reciprocal translocation and could support genetic counselling for balanced translocation carriers for PGT cycles using blastocyst biopsy.

Genetic divergence studies in blackgram (Vigna mungo (L.) Hepper

Divergence among 112 genotypes for yield and yield contributing traits was carried out by using mahalanobis D2 statistics. The maximum inter cluster distance was observed between cluster XII and IV (18.80) followed by cluster VI and IV (18.79). The maximum intra cluster distance was reported in cluster XII (14.74). The crosses which involve parents from these more divergent clusters will yield relatively good amount of heterosis in F1 and high frequency of transgressive segregants and genetic variability in subsequent generationsBased on the mean performance and diversity studies the genotypes KU 11–667, ABG 11–036, IC 436729 and IC 335331 were found to be the best for further yield improvement.