Traits In F2 Population Research Articles

Analysis of inter-varietal hybridization in rice (Oryza sativa L.) indicate transgressive segregation

Traits under continuous stabilizing selection may yield transgressive phenotypes in suitable cross combinations. Farmers maintained Njavara (Oryza sativa L. landrace Njavara), a poor yielding medicinal rice landrace in Kerala state over centuries for medicinal applications using short duration (60-70 days) as a selection criterion. This implies that the heading date together with several of the yield related traits, which are co-controlled by pleiotropism, were under constant stabilizing selection in Njavara. We examined the level of transgression in 13 yield related traits in F2 populations raised from crosses between Njavara and a high yielding hybrid variety Jyothi. The cross yielded transgressive phenotype in all of the 13 traits in F2 populations. Difference in the genetic architecture between Njavara and Jyothi due to the difference in the selection pressure experienced by them may have contributed to the excessive transgression observed in the study. The results highlight the value of unattractive poor yielding land races in providing alleles to lift yield barrier in high yielders, and suggest the need to examine the genetic architecture of the trait of interest in parental lines for better genetic advancement in crop improvement programmes.

Inheritance Analysis for Quantitative Traits in F2 Populations of Mustard Genotypes Grown Under Heat Stress Environments

Genetic variability is the basic requirement for improving crops which further leads to progress in crop breeding. This study was carried out to determine the inheritance pattern of various agronomically important traits in F2 populations of mustard genotypes. The objective of this study was to determine the genetic variability for agro-morphological traits under control conditions (CC) and heat stress environments (HS) and provide the future strategies to improve this important oilseed crop. The experiment was conducted at the Botanical Garden, Sindh Agriculture University, Tandojam. During 2022-23, a total of 27 genotypes including nine parental mustard genotypes and eighteen F2 progenies were grown under control and heat stress conditions. The experiment was laid out in a randomized complete block design with three replications. The analysis of variance for the genotypes, treatments, and F2 progenies revealed significant differences (P≤0.05) in most of the studied characters, highlighting the importance of genetic variations in the evaluated breeding materials of mustard for stress breeding. When estimating heritability for different characters, including seed yield plant-1, it was found that F2 crosses showed varying levels of heritability for different characteristics, ranging from low to moderate and high. This implies that careful selection may be conducted for traits that have low heritability, especially for seed yield.; however, those characters which showed high heritability would be selected at early generation stage to improve the characters.

Genetic variability studies for yield and yield-related traits in F2 populations based on UASD Bt Cotton Event No.78

Genetic variability studies for yield and yield-related traits in F2 populations based on UASD Bt Cotton Event No.78

Analysis of genetic variability and correlation for yield and its attributing traits in F2 population of rice (Oryza sativa L.)

For designing of the breeding programme, analysis of genetic variability and character correlation is crucial in crop improvement. The aim of this experiment was to estimate genetic variability parameters and trait association for 13 quantitative traits which were measured in F2 segregating populations of six crosses containing nine parents. All the F2 populations showed significant GCV and PCV values for productive tillers per plant, grains per panicle, grain yield per plant and straw yield per plant, indicating that these traits may be improved through selection. Plant height, productive tillers per plant, grains per panicle, grain yield per plant and straw yield per plant showed high heritability coupled with high genetic advance, indicating that these traits were controlled by additive gene action and have a good chance of improvement through pure line selection. Grain yield per plant exhibited a strong positive correlation with plant height, panicle length, grains per panicle, straw yield per plant, productive tillers per plant and harvest index in all the six F2 segregating populations. The F2 population of the cross GR 17 × NVSR 2740 demonstrated that more GCV and PCV, high heritability with high genetic advance for the majority of the traits which can be improved by selection. Keywords: Rice, F2 population, Variability, heritability, genetic advance and correlation

Identification of QTLs for Yield and Associated Traits in F2 Population of Rice

Identification of QTLs for Yield and Associated Traits in F2 Population of Rice

Genetic variability and association study of yield attributing traits in F2 populations of American cotton

Cotton is one of the most important fiber crops, grown all over the world. Genetic variability is a crucial factor from evolutionary point of view for crop species. It defines the adaptation of populations by allowing them to alter their genetic constitution in changing environment. Genetic variability in Gossypium hirsutum is declining due to selection pressure, hence causing low yield. Present study was conducted to evaluate ten parental genotypes with their F2 generations to uncover their genetic potential for yield by accessing genetic variability, heritability, genetic advance and association between fiber, yield and yield linked traits. High values of phenotypic and genotypic coefficient of variance were observed for node of first fruiting branch, monopodia per plant, boll weight, fiber strength and yield per plant. All morphological and fiber quality traits represented broad sense heritability ranging from 51% to 90%. High value of genetic advance was shown by plant height and yield per plant. Positive association of yield per plant was recorded for traits such as plant height, node of first fruiting branch, monopodia per plant, number of bolls per plant, seeds per boll, and ginning out turn. Additionally, F2 progeny of CIM-534×MNH-814 had high yield per plant along with maximum number of bolls per plant and seed per boll. So, such F2 progeny can further be explored to improve yield and yield contributing traits.

Genetic Analysis on Yield and Yield Components Traits in the Segregating Populations of Blackgram[Vigna mungo (L.) Hepper

The magnitude of variability and association among various traits in F2 populations of three crosses viz., MDU 1 x TU68, VBN6 x TU68, and VBN8 x TU68 of blackgram were studied. The experiment was conducted at the National Pulses Research Centre, Vamban, during Rabi 2019. The genotypic coefficient of variability was lower than the values of phenotypic coefficient of variability, which revealed the influence of the environment in deciding the expression of these populations.The traits viz., plant height, number of branches per plant, number of clusters per plant, number of pods per plant, and seed yield per plant has recorded high heritability and high genetic advance as per cent of mean for the majority of the crosses. It indicated that these traits were less influenced by the environment and possessed with high magnitude of genetic variability. Association studies revealed that the traits viz., number of clusters per plant, and number of pods per plant in all the three crosses recorded significant and positive association with seed yield per plant. Hence, based on the present investigation, it can be concluded that the number of clusters per plant and number of pods per plant should be given due importance in framing the selection indices for seed yield improvement in blackgram. However, separate selection indices are required for each population as the association of traits differs among populations.

Studies on character association and path analysis studies for yield, grain quality and nutritional traits in F2 population of rice (Oryza sativa L.)

Rice is a major cereal crop from the consumption point of view, dietary energy and nutrition source for more than half of the world’s population. Rice is rich in starch but deficient in major micronutrients. Present experiment consists of F2 mapping population for high grain zinc content, with 312 entries studied for 15 different traits. Correlation study indicated that, grain zinc and iron content were significant and positive. So there is a scope for simultaneous improvement of both traits. Grain yield per plant showed a non-significant and negative association with zinc and iron content. Plant height, total tillers per plant, the number of effective tillers per plant, panicle length, 1000 grain weight, fertile grains per panicle, kernel breadth, L/B ratio has significant and positive correlation and positive direct effects with grain yield per plant.

Assessment of genetic variability and heritability for grain yield and its associated traits in F2 populations of bread wheat (Triticum aestivum L.)

Assessment of genetic variability and heritability for grain yield and its associated traits in F2 populations of bread wheat (Triticum aestivum L.)

A chromosome-wide QTL mapping on chromosome 2 to identify loci affecting live weight and carcass traits in F2 population of Japanese quail

A chromosome-wide QTL mapping on chromosome 2 to identify loci affecting live weight and carcass traits in F2 population of Japanese quail

Relationship between esterase isozymes and some agronomic traits in F2 populations derived from the crossing of Milyang 23 and Ashahi

Esterase isozymes in the leaf blade were observed in the F2 populations derived from the cross combination between a japonicaindica hybrid rice variety with EIZ 1 (EST 1 , EST 2 S , EST 3 F ) and a japonica rice variety with EIZ 6 (EST 1 , EST 2 O , EST 3 S . The esterase isozyme of the 6A (EST 2 S band was controlled by a dominant allele, while the esterase isozymes of 12A (EST 3 S and 13A (EST 3 F ) bands were controlled by codominant alleles. No linkage relation was indicated while between EST 2 and EST 3 . The presence of esterase isozyme of 13A (EST 3 F ) band is related to the grain shedding habit and esterase isozyme of 13A (EST 3 F ) band itself is somewhat related to the cracking characteristics of the abscission layer. The presence of esterase isozyme of 6A (EST 2 S ) band is related the days to heading and it might due to the panicle length and ratio of fertility. There was no difference in the plant height, culm length, and number of tillers per hill between EIZ in the F2 population. Therefore, there were the relationships between esterase isozymes and some agronomic traits in rice plants.

IDENTIFICATION OF DISEASE TOLERANCE LOCI TO PHYTOPHTHORA PALMIVORA IN CARICA PAPAYA USING MOLECULAR MARKER APPROACH

Papaya diseases such as root rot and aerial blight caused by Phytophthora palmivora, powdery mildew caused by Oidium caricae, and fruit anthracnose caused by Collectotrichum gloeosporioides, and leaf black spot caused by Asperisporium caricae, reduce yields and increase production costs due to the lack of genetically resistant cultivars. Among these diseases, Phytophthora is particularly devastating because it becomes established in wet, rainy weather when the fungicides are ineffective. The goal of this study is to identify and develop molecular markers linked with P. palmivora tolerance in Carica papaya. We used an F2 population derived from an F1 of the most tolerant Hawaiian cultivar Kamiya, crossed with a highly susceptible cultivar SunUp, to evaluate genetic reaction to Phytophthora infection using a laboratory leaf inoculation, followed by a fruit inoculation. These same progeny were scored for DNA markers associated with resistance using methods of amplified fragment length polymorphism (AFLP) and several polymorphic bands linked with tolerance traits in F2 population has been identified. These markers are further characterized to form sequence characterized amplified region markers. Breeders could utilize these markers to select papaya varieties that carry a P. palmivora-tolerant phenotype. These markers may also assist in the identification and cloning of genes involved in plant defense mechanisms, which would further elucidate the defense mechanisms towards oomycete pathogens.