Significant GCA Research Articles

Combining Ability and Gene Action for Grain Yield and Attributing Traits in Maize (Zea mays L.) Subjected to Drought Stress

Background: Maize production is subdued by many impediments that cause yield minimization. Among various biotic and abiotic stress factors, one significant cause of yield reduction in maize is drought stress. Methods: A set of 15 inbreds which were crossed with 3 narrow base testers in line × tester mating design, and resulting 45 F1s along with the parent inbreds and 3 commercial checks were then, in RCBD, subjected to drought stressed and well-watered conditions to assess their genetic worth during spring 2021. Result: The ANOVA unraveled significant mean sum of squares due to lines, testers and line × tester in pooled analysis for all the ten traits. The inbred EI-2188-2 followed by EI-2448 and EI-03-3 contained fair per se performance and significant high GCA effects over the environments for grain yield/plant, proline content and cob length whereas the cross EI-2448-1 × EI-2156 was found most promising hybrid with significant and high SCA effects across the environments regarding grain yield/plant, proline content and cob girth. Prevalence of non-additive type of genetic variance in governing most of the traits suggests adoption of heterosis breeding will be rewarding for improving yield and drought tolerance. Heterotic pooling of the highlighted inbreds and utilization of the superlative hybrids in further breeding programmes for drought tolerance is proposed.

Study on gene action, combining ability and heterosis for different traits in Indian mustard (Brassica juncea L. Cxern & Coss)

Abstract Combining ability and heterosis was investigated in mustard hybrids obtained from 7 × 7 half diallel cross. Twenty one F1s along with seven parents were evaluated in Randomized Complete Block Design. The combined analysis of variance revealed very significant differences among the parents for all morphological variables with the exception of secondary branches and siliqua length, indicating wide diversity among the parental material used in the present study. Significant GCA and SCA variance indicated additive and non-additive gene action across all the characters. The SCA variance components were larger than the GCA variance components for most traits indicating the prevalence of non-additive gene effects. Jawahar mustard × PM-30, showed a significantly positive SCA and better parent heterosis for seed yield per plant whereas five hybrids (Kranti × PM-30, Gujarat Mustard-3 × Pusa Mahak, Jawahar Mustard × PM-30, Jawahar Mustard × Pusa Mahak and PM-30 × Pusa Mahak) exhibited significant positive SCA effect for number of siliqua/ plant. Jawahar Mustard × PM-30, Varuna×Jawahar Mustard, Gujarat Mustard-3 × PM-30, exhibited highly significant heterosis over the mid-parent. Keywords: Brassica juncea, GCA, SCA, gene action, Heterosis

Deciphering the estimates of combining ability and heterosis for selecting superior parents and hybrids in rice (Oryza sativa L.)

Twenty F1s, parents and checks viz., MTU 1010 and RNR 15048 were assessed for grain yield and its contributing attributes to study combining ability and heterosis. The mean of hybrids was greater than that of the parents except for days to 50% flowering and plant height. For majority of the investigated characters, the analysis of variance indicated considerable variations among parents and hybrids. Degree of dominance was more than unity for majority of traits including grain yield. For the examined characters, SCA variances were equal to GCA variances, indicating the dominance of additive and non-additive gene activity. The traits days to 50 % flowering, plant height, panicle length, test weight, kernel length and kernel length/breadth ratio showed additive gene action whereas the remaining traits showed non-additive gene action. The gca effects revealed that among the lines IR 72 had significant gca effects in desired direction for yield and yield attributing traits. Among the 20 hybrids, MTU 1001 x Akshyadhan was found to be a good specific combiner for grain yield per plant. Similarly, the hybrids NLR 34449 x IR10N270 and IR 72 x IR10N270 were found to be good specific combiners for grain yield and yield contributing characters. The standard heterosis of these three hybrids was positively significant over the check varieties MTU 1010 and RNR 15048. Based on mean, sca and heterosis estimates, MTU 1001 x Akshyadhan, NLR 34449 x IR10N270 and IR 72 x IR10N270 were identified as promising hybrids. Keywords: Combining ability, gene action, heterosis and hybrid rice

Exploitation of heterosis in chilli using genetic male sterile lines for red fruit yield with special reference to high rainfall conditions

High-quality red/dry chilli for spice, pharmaceutical and medicinal purposes is a major goal in chilli breeding. The male sterile lines have greater potential for the exploitation of heterosis in chilli to achieve this objective. Genetic male sterile lines with special traits like destalking and ability to withstand high rainfall were involved in heterosis breeding to identify hybrids for commercial and industrial purposes. Forty F1 hybrids were developed by crossing 4 diverse GMS lines with 10 testers using Line × Tester mating design to estimate heterosis, combing ability and gene action. The experiment involving 14 parents and 40 F1s, along with standard variety ‘CH-27’ was laid out in α-lattice square design in three replications during summer 2020 and 2021. The GMS lines MS 9-2 and MS 26-1 along with testers DPCh 10, VVG, DPCh 40 and Him Palam Mirch-2 showed significant GCA for marketable red/dry fruit yield and majority of their component traits. Ten F1 hybrids were identified with superiority for fruit yield based on mean performance, significant heterosis and SCA effects, providing an opportunity to utilize them in value-added products and dried spice purposes viz., MS 9-2 × HPM-2, MS 11-2 × DPCh 40, MS 9-2 × DPCh 40 and MS 9-2 × DPCh 101 with erect fruiting habit and that of MS 9-2 × DPCh 10, MS 26-1 × DPCh 10, MS 9-2 × PBC 535, MS 26-1 × VVG, MS 29-2 × DPCh 10 and MS 26-1 × DPCh 22- C with pendent fruits. The non-additive gene action was predominant in the expression of fruit yield, total red fruits/plant, oleoresin and capsanthin. A significant positive correlation among SCA, economic heterosis and per se performance is an indicative to identify superior hybrids. Multi-location testing of these hybrids shall pave way to exploit them commercially by making them available to the farmers.

Strategic genetic amelioration of quality protein maize (QPM) germplasm and its utilization in hybrid breeding

Abstract Use of diverse germplasm for generating heterotic hybrids is the foremost requirement in maize. The present study was conducted by using a diverse set of inbred lines and the line × tester method was applied to identify best performing lines and to group QPM inbred lines into different heterotic groups. The test crosses, developed by following line (66) × tester (CML 161 and CML 165) mating design, were evaluated during winter 2013, rainy 2014 and 2015 seasons at Begusarai and Ludhiana, respectively. Based on the specific combining ability, the lines were categorized into two heterotic groups. Out of 66 novel inbreds, 18 lines with significant SCA with CML165 were classified in group A, 16 inbreds with significant SCA with CML161 were classified in group B and 20 inbreds with significant GCA were classified in group (AB). Nine inbred lines were selected based on their positive GCA values and pedigree crosses were developed in rainy season in 2017. Three crosses were made in heterotic group A and four crosses were in group B for synthesizing new inbred lines by using pedigree method. Heterotic grouping based inbred evaluation trial and biochemical analysis were carried out to estimate per se yield potential of developed lines and to estimate tryptophan content. QIL-4-2491 (Group-A) and QIL-4-2401 (Group-B) were the top yielders. A total of 25 crosses were made among the heterotic groups (A and B) by using 22 lines from groups A and B and three best performing hybrids were identified.

General and Specific Combining Ability for Fruit Yield Using Diallel Population of Ridge Gourd (Luffa acutangula (Roxb.) L.)

An experiment was conducted using 7 x 7 diallel population of ridge gourd to study the general and specific combining ability (GCA and SCA) of parents and their hybrids for 17 yield traits in a randomized complete block design with three replications. Data on 17 characters were subjected to analysis of GCA and SCA variances and their effects. The GCA and SCA variance were found highly significant for all the characters except days to first female flowering. Low magnitude of σ²g/σ²s ratio was observed for all the traits other than days to first male flowering, days to first female flowering, fruit length (cm), fruit width (mm), individual fruit weight (g). On the other hand, σ²g/σ²s ratio was more than 1.0 for days to first male flowering, days to first female flowering, fruit length (cm), fruit width (mm) and individual fruit weight (g). The general combining effects (GCA) of the parents revealed that none of the parent was found to be good general combiner for all the characters. However, in the present investigation, parent P3 was observed to be one of the best general combiner as it has shown significant GCA effects in desirable direction for number of fruits per plant and fruit yield per plant. It also observed significant GCA effects for parameters related to earliness viz., days to first male flowering, node number of first female flower and days to first harvest. Similarly, parent P5 was also good general combiners for fruit length, fruit width and individual weight of fruit, parent P6 and P7 were also good general combiners for fruit length, individual weight of fruit except fruit width. The parent P2 and P4 were also good general combiners for number of fruits per plant. The estimate of SCA effects revealed that none of the crosses was consistently superior for all the characters. The highest yielding hybrid (P3 x P4) had registered the highest SCA effect for fruit yield per plant. Similarly, the cross combinations P6 x P7, P3 x P6, P3 x P7, P1 x P5, P2 x P6, P4 x P5 were observed as good specific combinations for fruit yield per plant. The hybrid P2 x P6 was good specific combiner for days to first male flowering, hybrid P3 x P4 for sex ratio followed by P4 x P5 and P5 x P7. Hybrid P1 x P4, P6 x P7, P3 x P6 and P2 x P4 were found as good specific combinations for fruit length, P4 x P6 and P3 x P4 for fruit width. The hybrids P3 x P6, P6 x P7, P3 x P4, P2 x P4 and P1 x P5 were observed as good specific combinations for individual fruit weight.

Combining Ability and Hybrid Breeding in Tunisian Melon (Cucumis melo L.) for Fruit Traits

A half-diallel cross study of seven melon inbred lines was carried out. The seven parents and their 21 F1 hybrids were evaluated for precocity of maturity, average weight per fruit, and fruit quality (fruit size, rind thickness, and soluble solids). The Diallel analysis was investigated for breeding values of these melon genotypes via general and specific combining ability, relationships between general and specific combining ability, and heterosis for the evaluated traits. The analysis of variance of the traits evaluated indicated highly significant differences among genotypes, suggesting the presence of adequate genetic variation for breeding. Additive genetic effects were most important with respect to fruit weight, while genetic dominance and epistasis effects mainly controlled fruit quality traits (fruit size, rind thickness, and TSS). Parent 1 (P1) and parent 3 (P3) had significant positive general combining ability effects for fruit weight. Also, P3 had positive general combining ability effects for fruit length and diameter, and cavity diameter. P3 was found to show maximum significant GCA in the desirable direction for all the traits except for TSS. Evaluation of heterosis (%) revealed that hybrid P1 × P3 can be considered as the best-performing hybrid for average fruit weight, TSS, and precocity, which also exhibited the highest positive and significant SCA effect for these traits. These results suggested that, among the melon genotypes studied, there is the potential to generate superior new varieties in hybrid production.

Estimation of Combining Ability in Bread Wheat Using Line X Tester Analysis

The present investigation was undertaken to study the combining ability for yield and its components in F1 generation of wheat through Line × tester analysis. Experiment was conducted with 3 replications and 39 genotypes consisting 9 lines viz., HD 2851, HD 2893, HD 3226, PBW 677, HD 3086, PBW 725, Phule samadhan, Phule unnat, GW 273 and 3 testers viz., Faisalabad 2005, HW 2045, PBW 343 and their 27 crosses made in L × T mating fashion in randomized block design at experimental research farm, Lovely Professional University, Phagwara, Punjab during 2023-24. The genotypes (parents and crosses) exhibited highly significant variation for all traits studied indicating the presence of genotypic differences among these twelve genotypes under investigation. The mean square of parent vs crosses was found to be highly significant for all traits studied expect 1000 grain weight. Further partitioning of crosses mean squares i.e., Line × tester analysis showed highly significant for all traits studied. Line × tester analysis is used in predicting the effects of the general combining ability of parents and specific ability combining of their crosses The lines PBW 725, GW 273 and tester PBW 343 exhibited significant GCA for grain yield. The lines PBW 725, HD 2893 and Phule unnat which performed good combining ability effects for biological yield per plant were also good combiners. Among the cross combination PBW 725 × PBW 343 showed significant positive SCA for grain yield and biological yield per plant, whereas, PBW 725 × Faisalabad 2005, HD 2893 × HW 2045 and GW 273 × PBW 343 was a good specific combiner for 1000 grain weight.

GENETIC STUDIES FOR SOME YIELD-RELATED TRAITS IN OKRA (ABELMOSCHUS ESCULENTUS L.)

Okra is a traditional vegetable famous for its nutritional value. It is a perfect villager's vegetable due to its robust nature, dietary fiber, and seed protein balance of both tryptophan and lysine. The research was carried out in the research area of the Department of Plant Breeding and Genetics, University of Agriculture Faisalabad. Cross combinations among 3 lines (Patel, Selection Super Green, and 19234) and 3 testers (IQRA-III, Perbhani Karanti, and Sabz Pari) were developed by using line × tester design. Crossed seeds along with parents were grown in the field under Randomized Complete Block Design (RCBD) with three replications. Data for various morphological traits was collected and analyzed statistically through analysis of variance and used to assess GCA, SCA, and gene action. Genotype 19234 exhibited maximum significant GCA (-11.4) for plant height in the negative direction and genotype Selection super Green proved a good general combiner for fruit weight, fruit diameter, and first flowering node, exhibiting values of 3.21, 1.191, and -0.89. IQRA-III (3.00), Patel (2.00), and Perbhani Karanti (1.11) exhibited significant GCA for number of fruits per plant. Line 19234 observed a good general combiner for crude fat (0.28), ash (5.43), and protein (0.39). Cross combination Patel × Perbhani exhibited the highest SCA for the number of fruits (7.78) followed by Selection Super Green × Sabz Pari (4.78) hence can be exploited for heterosis breeding. Cross combination Selection Super Green × Perbhani Karanti exhibited the highest significant SCA for plant height (-7.60) and Selection Super Green × IQRA-III displayed the maximum significant SCA value (2.26) for crude fat. Line Patel proved a good general combiner for most of the yield-related traits. Based on GCA and SCA, line 19234 can be used to enhance quality traits and cross combination Patel × Perbhani Karanti can be used to increase the number of fruits per plant.

Genetic potential and inheritance pattern of agronomic traits in faba bean under free and infested Orobanche soil conditions

BackgroundOrobanche is an obligate parasite on faba bean in the Mediterranean region, causes considerable yield losses. Breeding tolerant faba bean genotypes to Orobanche is pivotal to sustain production and ensuring global food security, particularly considering the challenges posed by population growth. In the present study, seven faba bean lines and four testers were used in a line×tester mating design during 2020–2021 and 2021–2022 growing seasons. The eleven parents and their 28 F1 crosses were evaluated under Orobanche free and naturally infested soils.ResultsThe results demonstrated considerable variations among the evaluated genotypes, wide diversity among the parental materials, and heterotic effects for all studied agronomic traits under Orobanche-free and infested soils. Orbanche infestation displayed a significant adverse impact on all the studied agronomic traits. The genotypes Line1, Line2, Line3, and Line5 displayed superior performance under Orobanche-infested conditions and recorded the highest values of all studied agronomic traits. Additionally, Line1, Line2, Line3, Line5, and Line7 exhibited desirable significant GCA for most evaluated traits under the two infestation conditions. The obtained crosses displayed significant negative or positive heterosis for studied agronomic characters such as plant height, number of branches per plant, number of pods per plant, number of seeds per plant, and seed weight per plant were observed. Furthermore, specific cross combinations such as Line2×Sakha3, Line3×Nubaria5, Line7 × Nubaria5, Line6×Nubaria1, Line5×Sakha3, Line1×Sakha3, and Line1 × Nubaria5 exhibited superior performance in seed yield and contributing traits under Orobanche-infested conditions. Moreover, these specific crosses showed superior efficacy in reducing dry weight of Orobanche spikes. The results obtained from GGE biplot analysis closely aligned with those from the line×tester procedure, affirming the significance of GGE biplot as a valuable statistical tool for assessing genotype combining ability in line× tester data. Both additive and non-additive gene actions were reported to be predominantly involved in the inheritance of the studied agronomic traits in faba bean.ConclusionsThe detected genetic diversity within the evaluated faba bean genotypes and their developed crosses exhibits substantial potential for improving faba bean productivity under Orobanche-infested conditions. The parental genotypes, Line1, Line2, Line3, Line5, and Line7, were identified as effective and promising combiners. Moreover, the developed crosses Line2×Sakha3, Line3×Nubaria5, Line7×Nubaria5, Line6×Nubaria1, Line5×Sakha3, Line1×Sakha3, and Line1×Nubaria5 could be considered valuable candidates for developing high-yielding and tolerant faba bean genotypes to Orobanche.

Identification of Potential Tropical Maize Inbred Lines with Early Maturity for Drought-Prone Environments

The present study was undertaken during October, 2020–January, 2021 at Maize Research Centre, Professor Jayashankar Telangana State Agricultural University, Rajendranagar, Hyderabad, Telangana state, India to identify potential inbred lines and hybrids with early maturity and high yield through combining ability analysis and heterosis. Six lines and four testers were crossed in L×T design to obtain 24 crosses. Evaluation of these crosses and their parents for combining ability revealed significant differences due to lines, testers and their crosses indicating the existence of wider variability among the material used in the study. Maize line MGC 434 (91 days), two testers GP-170 and PFSR-56 (91 days), and one hybrid MGC-445×PFSR-132 (83 days) were identified as early duration genotypes. Four lines MGC-444 (-3.13), MGC-440 (-2.71), MGC-439 (-1.96) and MGC-445 (-0.46) with significant negative GCA effects were identified as best general combiners for early maturity. Eight hybrids, MGC-439×BML-14 (-4.99), MGC-445×PFSR-56 (-4.65), MGC-461×PFSR-56 (-3.65), MGC-445×PFSR-132 (-3.60), MGC-434×BML-14 (-2.32), MGC-439×GP-170 (-2.10), MGC-440×PFSR-56 (-2.07) and MGC-440×GP-170 (-1.01) with significant negative SCA effects were considered as best cross combinations with early maturity. The inbred parents and cross combinations with early maturity identified in the study can be utilized for development of hybrids suitable to drought prone environments.

Heterosis and Diallel Analysis for Grain Yield, Yield Attributes and Physiological Traits in Barley (Hordeum vulgare L.)

The present study was carried out during November–April, 2019–2020 and 2020–21 with eight diverse barley genotypes and their developed 28F1s (half diallel, excluding reciprocals) to ascertain gene effects, hetrosis and correlations for grain yield, yield attributes and physiological traits under water limited conditions of Bundelkhand region. Days to heading and days to maturity exhibited general mean values of 86 days and 127 days, respectively. The parental genotypes, DWRB180, RD2794 and RD2899 showed early spike emergence and maturity. The cross combinations, namely DWRB160 /DWRB180, DWRB180/RD2907 and BH946/RD2552 were promising for flag leaf length and width. The GCA effects were significant and prevalent for all the characters, except days to heading, plant height and tillers count. The parents, DWRB160 (5.29**) and BH902 (1.59**) depicted high GCA effects for 1000 grain weight. The parents, DWRB180, RD2552, and BH946 exhibited significant positive GCA effects for leaf area index and chlorophyll fluorescence, whereas the genotypes, RD2907, BH946 and RD2899 showed higher GCA effects for chlorophyll content. Grain yield exhibited significant positive correlations with flag leaf width (0.60**), tillers per meter (0.35*), grains per spike (0.39*), harvest index (0.53**), chlorophyll content (0.69**), leaf area index (0.49**) and chlorophyll fluorescence (0.68**). The parents, BH946, DWRB180 and RD2907 and the hybrids, RD2552/DWRB180, BH902/RD2794, DWRB160/DWRB180 and BH946/RD2907 were found promising for yield and yield attributes in the dry agro-ecology of Bundelkhand region. The crosses, DWRB160/BH902 and DWRB160/BH946 can be explored for developing superior segregants for malt barley breeding.

GENETIC EVALUATION FOR SEED YIELD AND ITS COMPONENT TRAITS IN SUNFLOWER (HELIANTHUS ANNUUS L.) USING LINE × TESTER APPROACH

Sunflower is a vital oilseed crop, but yield improvement remains a major objective. Exploring germplasm and exploiting non-additive gene action can help overcome yield limitations and identify superior parental lines and crosses for hybrid development through GCA and SCA. Four parental lines (A-1, A-2, A-3, and A-4) were crossed with three testers (B-1, B-2, B-3) in a line × tester fashion to generate F0 seeds. These seeds were planted using a randomized complete block design (RCBD) with three replicate plots in the field to ensure unbiased results. Data on various growth and yield parameters is collected and analyzed using Analysis of variance and combining ability analysis. Lines A-3 and A-4 and tester B-3 demonstrated consistently positive GCA effects for several traits, signifying their broad genetic value for hybrid development. The hybrid A-4 × B-1 emerged as the top performer, exhibiting exceptional SCA effects in days to flowering, seed yield per head and height of the plant, indicating exceptional compatibility between these parental lines. Lines A-3 and A-4 displayed significant positive GCA effects for key parameters like head diameter and seed yield. Tester B-3 also contributed to enhanced yield traits in hybrid combinations. Lines A-3 and A-4, tester B-3, and hybrid A-4 × B-1 emerged as promising parents for sunflower hybrid development due to their superior GCA and SCA effects. These findings offer valuable resources for future breeding programs that enhance sunflower yield and productivity.

Combining ability analysis of Cucurbita moschata D. in Côte d'Ivoire and classification of promising lines based on their gca effects.

Cucurbita moschata varieties grown in Africa have very low yield. They have been neglected, and totally ignored in agricultural research programs. However, interest in their fruits, seeds, flowers and leaves is growing nowadays due to their nutritional and medicinal potentials. That growing interest has prompted plant breeders and agronomists to develop research programs for their improvement. A complete diallel cross analysis of four parental lines, Long, Zouan-H, Oval, and Soubre and their twelve F1 hybrids, was carried out in a farming environment at the University Nangui Abrogoua, Abidjan, Côte d'Ivoire. The four parental lines and the F1 hybrids were evaluated for their general performances, combining abilities, potency ratio and heterosis effects. The investigated traits included plant height, and eleven fruit- and seed-related characters. The analysis of variance showed significant differences for all traits studied. In addition, the diallel model yielded highly significant gca effects of the female parents. The gca effects of the male parents were significant for all traits except plant height, length of the fruit, width of the fruit and length of the seed. Highly significant sca effects were observed in the crosses for all the traits. Strong maternal effects were observed for the weight and diameter of the fruit, weight of the pulp, number of seeds per fruit, weight of the fresh seeds and 100-seed weight. The general predictive ratio approached the value 1 for all the traits except weight of the fresh seed and width of the dry seed. Most of the characters under this study are predominantly determined by the effects of additive genes. But, weight of the fresh seed and width of the dry seed may be controlled by non-additive genes. Mid-parent heterosis was significant for all measured traits in the crosses, except the length of the fruit. And better-parent heterosis was significant for all traits except plant height, number of fruits per plant and length of the fruit. Gene expression is described by a super-dominance for many traits, and partial dominance for some other traits in all twelve F1 hybrids. Classification of the parental lines based on the effects of their general combining ability grouped the Soubre lines as promising contributors to fruit yield. The parental lines Long and Oval formed another group likely on the basis of the small size of their fruits, the small pulps, the smaller number of fruits per plant and the large number of seeds per fruit. However, Long would be a candidate parent for the development of cultivars with longer vegetative growth. The parental line Zouan-H formed the third group and it was mostly characterized by its large number of seeds per fruit and relatively large fruits.

Combining ability and gene action studies in castor (Ricinus communis L.)

The present study of combining ability and gene action studies will be helpful in identifying better combiners to yield superior hybrids along with selection protocol for the trait of interest. Analysis of variance studies revealed that significant variation exists in the material understudy. Higher estimates of SCA variance were observed than the GCA variance except for seed yield indicating preponderance of non-additive gene action in governing the traits. Significant gca effects were observed in SKP-84 and ICS-142 for seed yield and PPL-1001, SKI-215, DCS86, PCS-327 and Kiran for oil content. Significant sca effect was observed for the crosses viz., M-574 x Kiran, PPL1001 x SKI-215 and SKP-84 x JI-244 for total yield.

Combining ability and gene action studies for yield and fibre traits in Gossypium arboreum using Griffings numerical and Haymans graphical approach

BackgroundFor the purpose of utilising hybrid vigour to produce possible hybrids with a suitable level of stability, the knowledge of gene activity and combining ability is a crucial prerequisite before choosing desirable parents. The present study was carried out with six parents crossed in full diallel fashion and generated 30 F1 hybrids. These hybrids were evaluated in two replications in Randomized Block Design at Department of Cotton, TNAU for combining ability and gene action. Diallel analysis was carried out according to Griffing’s method-I (parents + F1 + reciprocals) and model-I and Hayman’s graphical approach by using INDOSTAT software.ResultsAnalysis of variance for combining ability indicated that mean square values of GCA, SCA and reciprocals were highly significant for all the traits except for the uniformity index. RG763 and K12 showed highly positively significant GCA effects for most of the yield traits while PA838 and K12 for fibre quality traits, so they were found as best general combiners. PAIG379 × K12 and PDB29 × K12 for yield traits, and PDB29 × PA838, RG763 × PA838, and CNA1007 × RG763 cross combinations for fibre quality traits could be recommended for future breeding programms.ConclusionThe results of both Griffing’s and Hayman’s approaches showed that non-additive gene action predominates as SCA variance was bigger than GCA variance, so heterosis breeding is thought to be a more fruitful option for enhancing GCA of many traits.

Heterosis and Combining Studies for Growth, Yield and Quality Traits in Garden Pea (Pisum sativum L.)

The present study entitled “Line × Tester analysis in garden pea” was undertaken to estimate the extent of heterosis and combining ability effects for growth, yield and quality traits in pea. Experimental materials comprise five lines viz., Arka Uttam, IIHR-48, IIHR-34, IIHR-41, Arka Tapas and three testers viz., Arka Ajith, Arka Sampoorna and Arka Priya with their fifteen crosses along with one check Arka Pramodh. The parents and hybrids were randomized separately and sown using a Randomized Block Design with two replications during 2019-20. The results revealed that the female parent Arka Tapas recorded a significant GCA effect for most growth and yield parameters. The cross Arka Tapas × Arka Priya exhibited a high percentage of mid-parent (38.74 %), better parent (16.70 %) and heterosis over the commercial check (9.96 %) for the character pod yield per hectare.

Hybrid breeding for fall armyworm resistance: Combining ability and hybrid prediction

AbstractFall armyworm (FAW, Spodoptera frugiperda) emerged as a major lepidopteran pest destroying maize in sub‐Saharan Africa. A diallel mating design was used to generate 210 experimental hybrids from 21 lines. Experimental hybrids and four checks were evaluated in two locations. Commercial checks suffered higher foliar and ear damage compared to the top 15 hybrids. Mean squares associated with the genotypic variation were higher than genotype‐by‐environment interactions for foliar and ear damage traits. Heritabilities were moderate to high. Significant correlations were observed between grain yield (GY) with ear rot (−0.54) and ear damage (−0.45). Positive and significant GCA effects were observed for GY in seven parental lines, which were developed from multiple insect resistance breeding programmes. CKSBL10153 has the highest GCA value for GY and shows significant GCA effects for foliar and ear damage traits. These lines were identified as the ideal combiners for GY and FAW resistance and are therefore recommended for utilization as testers in the development of FAW‐resistant three‐way cross‐hybrid maize with correlated response for increased GY. GCA and marker‐based prediction correlations of GY were 0.79 and 0.96, respectively. Both GCA effects and marker‐based models were effective in predicting hybrid performance for FAW resistance.

Heterosis and combining ability vis‐à‐vis association for green fruit yield and component traits involving male sterile lines in chilli (Capsicum annuum) under wet temperate zone of North Western Himalayas

AbstractFourteen genetically diverse inbred lines comprising of four genic male sterile lines and 10 often pollinated lines as testers were crossed following ‘line × tester’ mating design to generate 40 F1s. These F1s, parents and check ‘CH‐27’ were evaluated in α‐lattice square design, replicated thrice during summer seasons of 2020 and 2021. The male sterile line DPChMS 9‐2 was good general combiner for marketable fruit yield and eight other component traits while testers namely, DPCh 10, PBC 535, VVG, Him Palam Mirch‐2 and DPCh 40 showed significant GCA for majority of yield related traits. The hybrids DPChMS 9‐2 × HPM‐2, DPChMS 9‐2 × DPCh 40, DPChMS 9‐2 × DPCh 101, DPChMS 9‐2× VVG and DPChMS 26‐1× HPM‐1 were the most desirable based on specific combining ability (SCA) and economic heterosis for fruit yield and other important traits. Heterosis was positively correlated with SCA indicating prediction of potential hybrids can be made based on both these parameters simultaneously. Present study provides an opportunity to exploit top hybrids for stability and commercial cultivation.

English

Twenty-one crosses developed from the frame of line × tester analysis along with ten parents were grown in two replicates experiment. Data on days to flowering, days to maturity, plant height, number of pods/plant, number of primary branches, number of secondary branches, number of tertiary branches, number of seeds per pod and seed yield per plant (g), revealed high significant differences exist among lines, testers and crosses for all traits studied. The ratio value of general combining ability variance to specific combining ability variance suggests the preponderance of non-additive type as well as additive gene action for some traits. Genotype Pusa-362 was the best general combiner for days to flowering. Genotype ICCL-87322 was identified as the best general combiner for the number of seeds per plant. Genotype BG329 was identified as the best general combiner for seed yield per plant (g) followed by KPG-59. Genotype PG-92-4 recorded desirable and significant GCA across five traits consistently. Cross PG-92-4 X Pant-186 recorded five significant SCA in the positive direction for secondary branches, number of tertiary branches, number of pods per plant, seed yield per plant and hundred seed weight. This cross is considered the most important compared to other materials under study. The proportional contribution of line × tester interaction was evident for most of the traits followed by the contribution of maternal lines. Days to flowering, days to maturity, primary branches, secondary branches, tertiary branches, pod per plant, seed per pod and seed yield per plant (g) recorded higher SCA variance suggesting non-additive gene action exit in expressing of these traits. The presence of a high SCA effect suggests that heterosis breeding can be exploited. Selection for those characters should be undertaken in later generations when these traits are fixed in homozygous lines. Key words: Chickpea, Cicer reticulatum, combining ability, gene action, heritability.