Combining ability analysis in bitter gourd (Momordica charantia L.) for potential quality improvement

Combining ability analysis provides useful information for the selection of parents, also information regarding the nature and magnitude of involved gene actions. Crops improvement involves strategies for enhancing yield potentiality and quality components. Targeting the improvement of respective characters in bitter gourd, combining ability and genetic parameters for 19 characters were estimated from a 6×6 full diallel analysis technique. The results revealed that the variances due to general combining ability (GCA) and specific combining ability (SCA) were highly significant for most of the important characters. It indicated the importance of both additive and non-additive gene actions. GCA variances were higher in magnitude than SCA variances for all the characters studied indicating the predominance of the additive gene effects in their inheritance. The parent P2 (BG 009) appeared as the best general combiner for earliness; P1 (BG 006) for number of fruits, average single fruit weight and fruit yield; P4 (BG 027) for node number of first female flower and days to seed fruit maturity; P3 (BG 011) for fruit length and thickness of the fruit flesh; P5 (BG 033) for 100-seed weight; and P6 for number of nodes per main vine. The SCA effect as well as reciprocal effect was also significant for most of the important characters in different crosses.

Genetic combining, heterosis analysis for horticultural traits in tomato (Solanum lycopersicum L.) using ToLCV-resistant lines and molecular validation of Ty genes

Tomato is a pivotal vegetable crop worldwide concerning human nutrition, economy and in service to biotechnology. Tomato leaf curl virus (ToLCV) is a begomovirus transmitted through the whitefly (Bemisia tabaci) and is responsible for severe losses in tomato production. In this context, the current investigation was carried out to determine heterotic combiners with high yield, resistance to ToLCV and mode of gene action for economically important traits. For this, 11 prescreened inbred lines were crossed in a half diallel fashion to generate 55 F1 hybrids. The 55 crosses with 11 parents and commercial checks were evaluated for different horticultural traits and resistance to ToLCV. The molecular validation with SCAR markers TG0302 and SCAR1 confirmed the presence of ToLCV-resistant genes in parents and their crosses. The hybrid IIHR-2902 × IIHR-2852 showed the presence of both Ty-2 and Ty-3 alleles in the homozygous state. The estimation of σSCA2 and σGCA2 was significant. It also indicated that the genetic control of target traits was under additive and non-additive gene effects. The values of σA/D2 along with σGCA2/σSCA2 found to be less than unity indicates the preponderance of non-additive gene action in the expression of the studied traits except for percent disease incidence. The parental line IIHR-2919 was the best combiner for fruit and yield traits. The cross combinations IIHR-2913 × IIHR-2898 exhibited significantly higher economic heterosis for yield along with the presence of Ty-2 and Ty-3 genes. The study paves the way for breeding high yielding and ToLCV-resistant hybrids in tomato.

Estimation of Gene Action for Seed Yield and Component Traits using Generation Mean Analysis in Pigeonpea [Cajanus cajan (L.) Millspaugh]

Background: For improvement of quantitative traits the information on nature of gene action is an important asset for plant breeders. However, the information on gene action for yield and its attributes is scanty in pigeonpea crop. Methods: The present experiment was carried out during kharif 2018-2020 at GBPUAT, Pantnagar, Uttarakhand. The experimental material consisted of six generations of three crosses viz., PADT-16 × PUSA 992, PADT-16 × UPAS 120 and PADT-16 × PAU 881. The observations were recorded on nine morphological characters. The gene action was estimated by three parameters model of Jinks and Jones if scaling tests were non significant and six parameters model of Hayman if scaling tests were significant. Result: For majority of traits in all three crosses, epistatic gene action was present as scaling tests were found to be significant. However, for traits number of primary branches, number of secondary branches and number of seeds per pod in cross PADT-16 × UPAS 120 a simple additive/dominance model was found to be adequate. In general, magnitude of dominance was found to be higher as compared to corresponding additive gene action. The high magnitude of dominance indicated that heterosis breeding is rewarding in these characters.

Genetic studies of different agronomic, quality and yield contributing traits in Gossypium hirsutum L.

An experiment of 4 × 4 diallel was carried out to study the gene action of different yield and yield contributing traits of four advanced cotton cultivars using Mather and Jinks approach. Significant variation was present for all the characters (P< 0.01). The data on recorded parameters revealed that most of the traits were fully or partially fit for genetic interpretation. Additive gene action (D) was significant and pre-dominant for all the characters while seeds per locule showed dominance effect of H1& H2, and it was confirmed by the value of degree of dominance (H1/D 0.5). The value of H2/4H1 and h2 (measures the direction of dominance) demonstrated asymmetrical division of dominant genes for all traits, except ginning out turn (G.O.T) percentage and fiber length, in parental material. All the studied traits showed high value of narrow sense heritability (h2NS), however seeds per locule possessed low heritability. The genetic analysis revealed that all the characters could be improved by progeny and pedigree selection, whereas hybrid dynamism could be exploited in the trait like seeds per locule.

Heterosis and combining ability studies by Line × tester analysis for fruit biochemical, morpho-physiological, and yield traits governing shelf life in tomato (Solanum lycopersicum L.)

Improving tomatoes keeping quality is crucial for reducing post-harvest losses. Knowledge on heterosis, and combining ability is pre requisite for breeding high yielding and good shelf life heterotic hybrids. An investigation was undertaken with each of 3 lines, testers, and 9 hybrids to identify desirable parents and crosses for 20 fruit biochemical, morpho-physiological, and yield traits and to elucidate nature of gene action for shelf life and its contributing traits through Line × Tester analysis. The lines contributed to most of hybrids variability than testers and fruit quality traits had higher degree of SCA variance as compared to GCA variance. pH, ascorbic acid, fruit firmness, and plant height governed by additive gene action. Lycopene, titratable acidity, TSS, calcium, magnesium, pericarp thickness, pulp content, locule number, fruit length, diameter, weight, shelf life, number of branches, number of clusters, number of fruit/cluster, and yield/plant were under the control of non-additive gene action. All the lines and Arka Saurabh were best general combiners and IIHR 2349 × Arka Vikas, IIHR 2349 × Arka Saurabh, IIHR 2358 × Arka Ahuti and IIHR 2357 × Arka Ahuti were the best specific combiner in producing heterotic hybrids. IIHR 2349 × Arka Vikas and IIHR 2349 × Arka Saurabh were promising hybrids for high yield and shelf life. The crosses involved both parents with high, one parent with high and other with low and both parents with low good overall general combining ability status respectively indicated the additive, non-additive and epistatic gene action in fruit quality and yield traits inheritance.

Combining Ability and Gene Action for Yield Improvement in Kenaf (Hibiscus Cannabinus L.) Under Tropical Conditions Through Diallel Mating Design

Nine morphologically distinct kenaf genotypes were hybridized to produce 36 hybrids following a half diallel mating design. The combining ability and gene action of 15 yield and yield components were assessed in hybrids and their parents across two environments. Except for the mid diameter and plant height traits, there were highly significant differences (p ≤ 0.01) between both the analysis of variance of environments and the interaction of genotype and environment. For the inheritance of these traits, additive gene effects were considerable, and the expression of these additive genes was heavily influenced by the environment. Significant differences were found for all studied traits for GCA except top diameter, and SCA except plant height and top diameter, implying the presence of both additive and non-additive gene action for the inheritance of the concerned characters. For all features except top diameter and number of nodes, the magnitude of GCA variation was significantly higher than that of SCA variance, indicating the additive gene's predominance. The parental lines P1, P3 and P4 were determined to be outstanding general combiners for fibre yield and yield-related parameters. Considering combining ability and genetic analysis study together, the crosses P1 × P4, P1 × P9, P2 × P3, P2 × P5, P4 × P6, P4 × P7, P4 × P9, P5 × P8, and P7 × P9 were found promising for their heterotic response to higher fibre yield, stick yield, seed yield and and could be useful by adopting proper strategies for future improvement in kenaf breeding programmes.

Genetic Analysis of Yield and its Attributes in Bread Wheat (Triticum Aestivum L. Em. Thell) Under Irrigated and Rainfed Conditions

Experiments were conducted to study the genetics and combining ability for yield and its attributes under Irrigated (E1) and Rainfed (E2) conditions using F1 hybrids derived from Line X Tester mating design by crossing eleven lines with three testers. Significant differences were observed among all the genotypes for all the traits in both E1 and E2 environments as well as in pooled analysis. The σ2gca/σ2sca ratio indicated predominance of non-additive gene action for all the characters in both environments. Therefore, this component of variance can be utilize in breeding programme through exploitation of heterosis and the selection process for identification of superior plant type should be postponed to further generations like F4 or F5. VL3001 and KACHU*2//WHEAR/SOKOLL was identified as good general combiner in irrigated condition (E1) and in rainfed condition (E2), respectively for maximum number of traits. Parent VL3001 was also identified as good general combiner for maximum number of traits in case of pooled analysis. Cross BECARD/KACHU × WH1080, BOW/VEE/5/ND/VG9144//KAL/BBB/YACO/4/CHIL/6/CASKOR/3/… × WH1080 and C306 × WH1142 was identified as good specific combination for maximum number of traits in irrigated condition (E1), rainfed condition (E2) and in pooled analysis, respectively.

Study of Combining Ability and Heterosis in Quality Protein Maize using Line x Tester Mating Design

Background: High protein content with good quality maize is likely to gain wider acceptance if hybrids are produced that have agronomic performance similar to normal hybrids and retain an enhanced nutritional quality. Thus, an attempt was made to develop quality protein maize hybrids for the benefit of different sections of society depending on maize. Methods: During the Rabi season of 2016-17 (hybrids were obtained crossing ten inbred lines and four testers following Line x Tester mating design) and 2017-18 (evaluation of hybrids and parents involved along with two commercial checks based on different agro-morphological traits). Result: Highly significant differences were observed among lines, testers and crosses. Combining ability revealed SCA variances was higher indicating preponderance of non-additive gene action. The contribution of line x tester interaction was higher suggesting parents used in this study can provide high heterotic cross combinations. The parents CML 508, CML 163-D and CML 169 were superior general combiners, indicating their efficacy as parents in future maize breeding programs. Heterosis identified superior yield advantage of the crosses namely, CML508 x CML154-2, CML170 x CML169 and CML163-D x DMRQPM103 over the standard commercial checks HQPM1 and 900 M Gold.

GENETIC VARIABILITY FOR GRAIN NUTRIENTS CONTENT IN COASTAL RICE COLLECTIONS OF BANGLADESH

Overcoming malnutrition through biofortification breeding in rice is aimed to assist nutritional food security in Bangladesh. So to select parents for nutritional improvement, estimation and exploitation of mineral nutrients reserves of rice grain and their variability assessment in different genotypes is essential. Eighty-five (85) T. aman rice genotypes collected from different coastal regions of Bangladesh were evaluated at the Advanced Plant Breeding laboratory, GPB of BSMRAU to estimate the grain nutrients content and to elucidate their genetic variability among the genotypes. Considerable significant variation (0.1% level of probability) was noted among the genotypes for studied different grain nutrient contents and yield per hill. The mean values of N, P, K, Ca, Mg, Na, Zn, Fe, Cu, Mn and grain yield/ hill were 10788.24 mg/kg, 804.85 mg/kg, 3798.58 mg/kg, 13795.29 mg/kg, 2778.87 mg/kg, 3771.17 mg/kg, 7.25 mg/kg, 5.01 mg/kg, 1.05 mg/kg, 1.90 mg/kg and 433.29 g, respectively. Box and whisker plots analysis were done to represent data graphically for better understanding. Histogram was used to present the frequency distribution of genotypes for N, P, K, Ca, Mg, Na, Zn, Fe, Cu, Mg and Grain yield/hill content in 85 diverged rice genotypes All the traits had equality in genotypic and phenotypic variances with high heritability and high genetic advance which indicated preponderance of additive gene effects for these traits. The genotype R080 (Chinigura) contained the highest content of grain P, Fe and Cu. The R030 (Mota Dhan), R040 (Dudh Kalam) and R019 (Chikon Dhan) were noted for the highest Ca, Mg and Na content, respectively. The maximum N and Zn content were observed in R029 (Dudh Kolom) and R075 (Gopal Bogh), respectively. R083 (Lal Dhan) was marked for the highest grain yield/ hill and K content. Genetic variability parameters, heat map analysis and neighbor joining clustering methods indicated these genotypes including R079 can be considered for biofortification program and used as parents for the improvement of those grain nutrients in rice breeding.

Genetic Analysis of Some Genotypes of Indian Mustard (Brassica juncea L.) for Yield and Yield Attributing Traits

The current investigation was carried out to examine the selection criteria for yield improvement in selected genotypes of Indian mustard. Twenty-four genotypes of Indian mustard were evaluated for seed yield and yield attributing characters with randomized block design with three replications. The analysis of variance showed significant differences among all the 24 genotypes against all the characters. The phenotypic and genotypic coefficient of variation were higher for most of the traits like seed yield per plant, number of secondary branches per plant and number of siliquae per plant. High heritability coupled with high genetic advance in percent of mean was registered for number of siliquae per plant, number of primary and secondary branches per plant, plant height, 1000 seed weight, siliqua length per plant and seed yield per plant suggesting predominant role of additive gene action for expression of these traits. The correlation study revealed that seed yield per plant was positively and significantly correlated with number of primary and secondary branches per plant, number of siliquae per plant, siliqua length per plant and 1000 seed weight at both phenotypic and genotypic level. The traits namely, number of secondary branches per plant recorded as highest positive direct effect followed by number of seeds per siliqua, number of siliquae per plant and plant height. Therefore, they may be carried out further evaluation in multilocational trials, biotic and abiotic stress like environmental conditions to check their stability and adaptability.