SCA Effects Research Articles

Combining ability studies for physiological and yield traits in maize (Zeamays L.) across three environments

The present study was conducted to assess the general combining ability effects of parents and specific combining ability effects of crosses for yield and yield contributing traits in maize hybrid development. Combining ability studies were conducted in10 X 10 half diallel fashion at Prayagraj to determine GCA and SCA effects of parents and single crosses respectively. The economic heterosis (hc) revealed that the hybrids CM124 x LM-13, HKI-193-2 x CM 129, DMR-QPM-28 x CM- 124, HKI-193-2 x POP 445 and CML 41 x POP 445 showed positive significant results across the three environments E1, E2 and E3. The combining ability study indicated that the parents, HKI-193-2 (P10)LM 13(P6) and line CM 129 (P5) can be considered as good general combiners and genetically worthy parents, as they contributed favourable genes for grain yield. The parent CML- 41 (P9) was a good general combiner for the trait chlorophyll content in all three environments, while the parent LM 13 (P6) was a good source for favourable alleles for leaf area index since they had significant positive gca effects.The parents HKI-193-2 (P10)LM 13(P6)can be considered as good general combiners for protein content.The pooled analysis of variance over three environments revealed the mean sum of squares due to genotypes was significant for the characters studied. The hybrid CM- 124 x LM-13 showed good specific combining ability effects for grain yield,days to 50 % tasseling, days to 50 % silking, days to 50% maturity, 100 seed weight, chlorophyll content, leaf relative water content, leaf area index, leaf area ratio and protein content.The hybrid HKI-193-2 x CM 129 showed good specific combining ability effects for grain yield, days to 50% maturity, one hundred seed weight, leaf area index, leaf area ratio and starch content.

Understanding Gene Action, Combining Ability, and Heterosis to Identify Superior Aromatic Rice Hybrids Using Artificial Neural Network

The aromatic rice represents a smaller but independent rice collection, the quality of which is considered to be highly acceptable. Farmers are interested in growing aromatic rice due to high premium market price. The prime objective of this study was to enhance genetic improvement of aromatic rice. Combining ability analysis (GCA and SCA) and gene action are studied in a set of 7 × 7 half-diallel crosses. Twenty-one hybrids along with their seven parents were assessed in randomized complete block design. Different quantitative characters were used to estimate the magnitude of heterosis. GCA and SCA significance for all traits revealed the importance of both additive and nonadditive genetic components. Several genes determine quantitative traits, with each gene having very little impacts and being easily influenced by environmental factors. Pusa Basmati-1 and Govindobhog were the best combiners among the seven parents. In terms of per se performance, heterosis, and SCA effects on seed yield per plant and important yield qualities, the crosses BM-24 Deharadun Pahari, Baskota × Tulaipanji, and Pusa Basmati-1 × Tulaipanji may be of interest. Because of its interconnected processing properties, ANN can play a critical role in this experiment. As a result, the current study was carried out to collect data and validate it using an artificial neural network (ANN) on the combining ability, gene action, and heterosis involved in the expression of diverse fragrant rice features. Using ANN, the validation of the result was done and it was found that the overall efficiency was approximately 99%.

Heterotic Groupings, Perse Performance and Standard Heterosis of Quality Protein Maize (Zea Mays L.) for Yield and Yield Contributor Traits Adapted at Mid Altitude of Ethiopia

For an organized cross breeding program, information on heterotic grouping, perse performance, and commercial heterosis of newly introduced maize lines is required. Therefore, the present study was conducted to determine the heterotic group, commercial heterosis, perse and crosses mean performance of newly introduced from IITA-Nigeria and CIMMYT- Zimbabwe quality protein maize inbred lines. 36F1 progenies generated from the four testers and nine lines, and including four standard checks a total of 40 entries, and thirteen inbred lines were planted by using Alpha lattice design with three replications at Bako National Maize Research Center and Jimma Agricultural Research center in 2019/20 main cropping season. The combined analysis over the two locations showed there were significant differences at (P<0.01) or (P<0.05) between the genotypes in grain yield, and yield contributors of the studied traits. In this study, lines that showed positive SCA when crossed with tester A were assigned to the opposing heterotic group (group B), and vice versa, based on the significance of the SCA effects. This also suggests that these inbred lines could be placed in the same heterotic group as AB. From the study, L5 had the highest yield (3.6 t/ha) of the inbred lines, followed by L2 (3.13t/ha) and L7 (2.53t/ha) respectively were identified. Regarding to the crosses, Eight promising crosses, L2xT4, L3xT4, L4xT4, L5xT2, L6xT3, L7xT2, L9xT1, and L9xT4, with higher yield than the checks, were identified. For grain yield, about twelve crosses nine crosses showed positive and significant advantages over the standard check BH545 with range of (33.3% to-24.2%) were also observed. Multilocation evaluation, tryptophan and lysine content of these genotypes must be re-evaluated to confirm the findings of this study and to use in recurrent breeding program or for directly release of the promised crosses. In general, molecular based heterotic grouping is more effective in clarifying ............

Elucidating combining ability, gene action and heterosis for yield and yield contributing traits in finger millet (Eleusine coracana L. Gaertn)

In order to explore the genetic architecture of finger millet through combining ability studies, the present investigation was carried out using 20 hybrids which were produced using five lines and four testers in a Line x Tester mating design. Among the parents, the line GPU 48 and the tester KMR 301 were found to be the good general combiners with significant per se for most of the traits studied. Hybrids viz., GPU 48 x KMR 301, GPU 48 x PR 1506, PYR1 x KMR 301 and Udurumallige x PR 1506 showed significant positive values for per se performance, sca effect, mid parent heterosis and better parent heterosis for grain yield per plant. The cross GPU 48 x KMR 301 derived from high x high general combining parents exhibited higher positive significant value for all the three types of heterosis for grain yield per plant. The hybrids GPU 48 x KMR 301, GPU 48 x PR 1506, PYR1 x KMR 301 and Udurumallige x PR 1506 were good specific combiners for yield and yield contributing traits. In all these crosses, at least one good general combining parent is involved which indicates that good general combiners serve as the best tool in enlightening the crop yield by manipulating the genetic architecture. Combining ability variances indicated that even if GCA and SCA variances were profound, SCA variances were higher than GCA variances for all the characters studied representing the predominance of non-additive type of gene action in the inheritance of traits under present study. Keywords: Finger millet, Combining ability. per se, GCA, SCA and Heterosis

Deciphering combining ability for yield and its components under saline environment in rice (Oryza sativa L.)

Line x tester analysis was performed with six lines and four testers and resulted 24 hybrids along with parents were evaluated for salinity conditions. Analysis of variance showed significant differences between lines, testers and crosses for all the parameters except 1000 grain weight. SCA mean squares were substantially larger than GCA mean squares, showing a prevalence of dominance gene action in parents and hybrids for tolerance to salinity conditions. Among the lines and testers, KPS 10642, KPS 10640, KPS 10651, RNR 11718 and CSR 36 were proven to be a good combiners for increasing yield under salt stress conditions. The hybrids viz., KPS 10651 x CSR 36, KPS 10651 x RNR 11718, KPS 10642 x KPS 2874, KPS 10651 x CSR 23, KPS 10640 x CSR 36, KPS 10640 x CSR 23, KPS 10642 x RNR 11718, KPS 10642 x CSR 36 and KPS 10642 x CSR 23 were found to be good specific combiners. The crosses KPS 10651 x RNR 11718, KPS 10642 x KPS 2874, KPS 10651 x CSR 36, KPS 10651 x CSR 23 and KPS 10640 x CSR 36 demonstrated significant results with respect to mean and sca effects. Keywords: Rice, combining ability, hybrid, line × tester, salinity

Identification of promising parental lines and hybrids in sweet corn (Zea mays L. saccharata)

Information on combining ability and standard heterosis are  crucial for the success of any hybrid breeding program. The present study was conducted in sweet corn involving crossing of twenty inbreds as female lines and five inbreds as testers in line × tester mating fashion during kharif, 2019. Resulted 100 F1s were evaluated in rabi, 2019-2020 for twelve yields and its attributing traits. Analysis of variance for combining ability revealed the existence of wider variability in the material studied exhibiting significant differences due to lines, testers, hybrids and various interactions. Non-additive gene action was observed pre-dominant for all the traits. Inbreds SCGP-88, SCGP-111, SCGP-36-3-1, SCGP-91, BSL-4, SCGP-44-2, VNR-SC-24, VNR-SC-23, SCGP-66-1 and SCGP-61-1-4 were identified as good general combiners. Crosses viz., SCGP-207-1  SCGP-44-2, SCGP-54  VNR-SC-29, SCGP-42  SCGP-80, SCGP-82  SCGP-80 and SCGP-66-1  SCGP-44-2 were identified as promising hybrid combinations based on per se performance, sca effects and standard heterosis over the commercial checks. Keywords: Sweet corn, Line x Tester, Hybrids, Combining ability, Heterosis.

Combining ability and heterosis studies in cotton (Gossypium hirsutum L.) for yield and fibre quality traits

Cotton is India’s most important cash crop and it is used for agricultural and industrial purposes for all over the world. The greatest way for identifying superior hybrids and best combiners of parents is by L×T design. For analyzing the combining ability and heterosis for various yield attributing variables as well as quality traits, the parents viz., four lines and four testers were crossed to produce sixteen hybrids. MCU5 × KC3 cross contributed to positive, highly significant heterosis for the traits viz., the number of sympodial branches, lint index and the number of bolls per plant, along with highly significant values of sca for the traits viz., the number of sympodial branches, seed cotton yield per plant and micronaire. CO14 × NDLH1938 had a highly significant sca effect for the trait of upper half mean length along with significant heterosis for the traits, viz., boll weight and seed cotton yield per plant. Therefore, MCU5 had the best gca value for the upper half mean length among the four lines. The KC3 tester had a high gca value, indicating that it contributes to additive genes among the four testers. For some traits, not all good combiners have good sca effects. In the majority of the qualities investigated, non-additive or dominant gene action was seen. Heterosis breeding can be used to exploit the amount of available vigour.  Keywords: Combining ability, G. hirsutum. L., intraspecific hybrids, heterosis, Cotton.

Combining Ability and Heterosis for Seed Yield and Yield Components in Indian Mustard [Brassica juncea (L.) Czern and Coss

Background: Indian mustard is an important oilseed crop which occupies premier position in Indian agriculture. Developing high yielding genotypes is a major breeding objective in Indian mustard. Present study was conducted at Experimental Farm of Ranaghat, Nadia, West Bengal, during 2017 to 2019. Methods: Line x tester analysis of seven lines and five testers was carried out to identify the high heterotic crosses and their relationship in terms of GCA and SCA in Indian mustard. The parents and F1 hybrids were evaluated in RBD with three replications. Result: The analysis of variances revealed significant differences of genotypes for all characters studied, indicating sufficient genetic variability for the characters. The estimates of SCA variances were higher than GCA variance the characters indicating that dominance variance was more than the additive variance. The ratio of variance due to general and specific combining ability was less than unity for all the traits that indicated the non-additive gene action was predominant over additive gene action. Five lines, viz. PM 24, PM 25, PM 30, Pusa Agrani, JD-6 and one tester, Pusa Bold were deemed to be the good general combiner for seed yield and yield attributing traits. On the basis of high heterosis over mid parent as well as better parent and significant SCA effects for seed yield per plant and its component traits, hybrids namely, JD-6 x Pusa Bold, PM 30 x Seeta, PM 25 x Pusa Bold, PM 24 x Kranti and PM 22 x Sarama were found to be very promising for further exploitation in breeding program.

Diallel analysis among new yellow maize inbred lines for grain yield and other agronomic traits

Yellow maize (Zea mays L.) is one of the important sources of animal feed in Egypt. The national maize programmes uses conventional crop breeding methodology, which depends on the development inbred lines of maize from open pollinated varieties or other heterogeneous sources. The objective of this study was to assess the general and specific combining ability for nine yellow maize inbred lines and their crosses for grain yield and other morphological traits, under Egyptian conditions. Nine new yellow maize inbred lines, derived from different yellow maize sources, were crossed in a half diallel mating scheme in 2020 summer season, at Gemmeiza Agricultural Research Station Gharbia Governorate in Egypt. The resulting 36 crosses, along with two commercial check hybrids (SC 168 and Pioneer SC 3444), were evaluated at three locations, i.e. Gemmeiza, Mallawy and Sids Agricultural Research Stations of the Agricultural Research Center (ARC), in 2021 summer season in Egypt. Overall, the additive gene effects played a major role in the inheritance of days to 50% silking, plant and ear heights; while the non-additive gene effects were mostly responsible for controlling the inheritance of grain yield. The parental inbred lines (P1 and P2) possessed significant (P<0.05) negative estimates of GCA effects for days to 50% silking towards earliness. The best general combiners were inbred lines P2 and P6 for plant and ear height, and these inbred lines would be good combiners for breeding to short hybrids and low ear placement. Crosses (P1xP9 and P3xP4) had desirable SCA effects and significantly out-yielded the two checks.

Combining abilities and heterotic patterns for heat tolerant traits in tomatoes (Solanum lycopersicum)

AbstractThis present study was undertaken to (i) assess the performance of hybrids under heat stress, (ii) determine the combining abilities of parental lines and their crosses, and (iii) identify the most efficient heterotic grouping method to classify the lines. We evaluated two sets of hybrids generated using the NC II design and a partial diallel mating design. Most crosses outperformed their parents and the best commercial hybrids for fruit weight per plant (FWP), fruit set (FS), fruit weight (FW), and the number of fruits per plant (NFP) under heat stress. The specific (SCA) and the general (GCA) combining ability variances were significantly higher than zero. The crosses Fla.7171 × P005 and CLN2026D × ATS020 had positive SCA effects and high per se performance for FW and FWP. BJ01 was the best combiner for FWP, NFP, and FS. The SNP‐based heterotic grouping was 28% more efficient than the heterotic grouping based on the GCA of multiple traits method and classified the lines into three groups. These findings provide a foundation for speeding up heat‐tolerant hybrid in tomatoes.

Optimizing use of U.S. Ex-PVP inbred lines for enhancing agronomic performance of tropical Striga resistant maize inbred lines

BackgroundTemperate maize inbred lines with expired Plant Variety Protection Act certificates (Ex-PVP) are potential sources of desirable alleles for tropical germplasm improvement. Up to now, the usefulness of the Ex-PVP inbred lines as a potential source of novel beneficial alleles for Striga hermonthica resistance breeding to enhance genetic gain in tropical maize has not been reported.ResultsThis study was thus conducted to characterize the combining ability of 24 Ex-PVP inbred lines in crosses with two tropical Striga resistant inbred testers under Striga-infested and non-infested conditions and across three locations for 2 years. Many testcrosses between Ex-PVP inbred lines and the first tester (T1) produced competitive or significantly higher grain yields compared to the hybrid between the two resistant testers under Striga infested and non-infested conditions and across multiple test locations. Also, most of the testcrosses with positive heterosis for grain yield and negative heterosis for Striga damage and emerged Striga count involved T1 as a tester. Our study identified six Ex-PVP inbred lines with positive GCA effects for grain yield under Striga infested and non-infested conditions and across multiple test locations. Amongst these, inbred lines HB8229-1 and WIL900-1 also displayed negative GCA effects for emerged Striga count and Striga damage rating. The inbred line HB8229-1 showed positive SCA effects for grain yield with T2, whereas WIL900-1 had positive SCA effects for grain yield with T1. Over 70% of the Ex-PVP inbred lines were consistently assigned to specific heterotic groups using yield-based classifying methods (mean grain yield and SCA effects).ConclusionsThese results could facilitate systematic introgression of the Ex-PVP inbred lines into the existing Striga resistant heterotic groups in IITA. The Ex-PVP inbred lines with positive GCA effects and producing high grain yields in hybrid combinations could be useful parents for enhancing Striga resistance and agronomic performance of tropical maize hybrids.

Combining ability and heterosis for yield and grain quality characters in rice (Oryza sativa L.)

Twelve F1 crosses derived from four lines and three testers, crossed in L x T mating design were utilized to estimate the combining ability and heterosis for 17 yield and grain quality traits and also to detect the superior crosses for the breeding program. Analysis of variance showed significant differences among all the traits under study except for plant height in lines. In the case of testers, the traits viz., the number of tillers per plant, the number of productive tillers per plant, hundred seed weight, single plant yield, alkali spreading value, amylose content, gel consistency, kernel length, kernel length breadth ratio, kernel length after cooking and kernel breadth after cooking showed significant values. The SCA variance was higher than the GCA variance for all the characters under study except the alkali spreading value indicating the predominance of non-additive gene action in the inheritance of all the characters. The parents TKM 13, CO 52, ADT 52 and IRBB 21 were adjudged as good general combiners with respect to single plant yield. Hence, these parents can be exploited through pedigree breeding to obtain better recombinants by selection in later generations. Based on the results of per se performance, standard heterosis, and sca effects, the hybrids viz., CO 52 × IRBB 60 and ADT 52 × IRBB 21 were identified as the best specific combiners and these could be used for future breeding. Keywords: Combining ability, Heterosis, SCA, GCA, Rice

Selection of Suitable Pearl Millet Hybrids for Arid and Semi-Arid Conditions through Combining Ability Analysis

Present investigation was carried out to study combining ability effects for grain yield and its component traits in 77 hybrids of pearl millet. From the results of GCA effects, it was revealed that a number of parents namely, ICMA 98222, ICMA 93333, ICMA 30199, ICMA 30201 (female parents), and BIB 481-500, BIB 561-570 and BIB 571-581 (male parents) were found to be good general combiner for grain yield and most of its component characters. On the basis of GCA effects, lines ICMA 98222, ICMA 88004, ICMA 93333, ICMA 30199, ICMA 30201 and testes BIB 571-580, BIB 561- 570, BIB 511- 520, BIB 481- 500, BIB 531- 540 were good general combiner for more than nine yield contributing characters. The SCA effects of the crosses namely, ICMA 97111 x BIB 561- 570, ICMA 98222 x BIB 481- 500, ICMA 88004 x BIB 501- 510 and ICMA 93333 x BIB 551-560 were significant and were identified as superior for seed yield and related traits over the environments. Therefore, these parents and hybrids were recommended for utilization in development of promising populations as well as hybrid development.

Genetic Variability and Combining Abilities for Earliness to Nut Yield and Nut Weight in Selected Cashew (Anacardium Occidentale L.) Clones

ABSTRACT Introduction of exotic clones into the pedigree of commercial cashew clones could constitute a viable strategy to overcome the current low early nut yield and nut weight of the crop in West Africa. The aim of this study was to assess the combining abilities of Beninese, Brazilian and Ghanaian clones for early nut yield and nut weight. Twelve F1 hybrids were evaluated in the field for five traits such as stem diameter increment, canopy spread, nut yield, nut weight and cropping efficiency. Significant difference (p ≤ .01) was observed for most of the traits. Nut weight varied from 5.3 to 10.1 g/year, whilst nut yield ranged from 666.1 to 872.8 kg/ha/year among the top five crosses in the third to fifth year after planting. The Beninese (BE) progenies were comparable to the Ghanaian (SG) progenies for early nut yield but inferior to the Ghanaian and Brazilian (A) progenies for nut weight. Pearson correlation coefficient estimate (r = 0.74; p ≤ .01) suggest that, selecting for canopy spread in the north-south direction might improve early nut yield. GCA effects were more important than SCA effects. Narrow-sense heritability was moderate and exceeded 50% for all the traits. BE203 and SG224 showed positive GCA for early nut yield, whereas A2 and SG273 showed positive GCA for nut weight. Our study suggest that the Brazilian, Beninese and Ghanaian clones had different merits as potential parents for early nut yield and nut weight and could constitute a suitable genetic resource for improving cashew productivity.

Heterosis and combining ability in diverse A and R lines of pearl millet tested in Western Rajasthan

The present study was conducted to estimate the combining ability and heterosis in pearl millet hybrids. Forty five pearl millet hybrids were developed using three male sterile lines (A line) with fifteen restore lines (R line) through the Line x Tester mating approach and were evaluated during kharif, 2018. Analysis of variance revealed that the mean square of treatments showed significance for all the traits. For days to 50 % flowering and days to maturity, lines viz., ICMA 93333, ICMA 97111, BIB 186, BIB 193 and BIB 281 had negative gca effect so these lines can be used as parents for hybrid development under harsh environmental conditions. Based on sca effect, heterosis and per se performance, crosses ICMA 97111 x BIB 208, ICMA 93333 x BIB 186 and ICMA 88004 x BIB 283 were identified as potential crosses for commercial exploitation of heterosis in pearl millet. Keywords: Pearl millet, male sterile lines, Line x Tester, Combining ability and heterosis

Genetic studies for isolation of superior parents and hybrids for a further breeding programme in safflower (Carthamus tinctorious L)

Combining ability analysis discriminates the parents and crosses, provides information about the breeding method to be adopted for genetic improvement of a specific character. Thirty hybrids obtained by mating two females with fifteen males in L × T fashion were evaluated in RBD along with parents to estimate the combining ability of parents and crosses for seed yield and yield contributing traits. The parents and hybrids significantly differed amongst themselves for different characters, viz., days to maturity, 100 seeds weight, capsules per plant, branches per plant, seed yield, seed volume weight and oil content. Among the males, GMU-590, GMU-2273, GMU-2830 and GMU-589 and the females, AKS CMS-3B had good gca effects for seed yield and some other yield contributing traits. However, GMU-7573 and GMU-2830 were found best general combiners for the trait oil content. All these selected parents may be utilised in a different breeding programme for genetic enhancement of the trait involved. The hybrids AKS CMS-2A × GMU-1731 and AKS CMS-3A × GMU-7448 were identified as good combinations for seed volume weight and capsules per plant. Whereas the hybrids AKS CMS-3A × GMU-2273 and AKS CMS-2A × GMU-6891 were effective for seed filling percentage and seed yield per plant. Three promising hybrids viz., AKS CMS-3A × GMU-7448, AKS CMS-3A × GMU-2273 and AKS CMS-2A × GMU-6891 were designated as promising hybrids as they had good per se performance and significant sca effects for seed yield per plant and most of its contributing characters which can be utilized for heterosis breeding and release of new hybrids at commercial level after thorough multilocation testing. Further, the hybrids AKS CMS-3A × GMU-7448, AKS CMS-3A × GMU-590 and AKS CMS-3A × AKS-589 involving one or both good general combining parents with non-significant sca effects for many studied characters which may be utilized to isolate desirable segregants in progressive generations for identification and release of new varieties by hybridizing the ‘B’ lines of concerned CMS line with similar males again. Keywords: Safflower, line × tester, general combining ability, specific combining ability, seed yield

Heterosis response and combining ability (variance and effect) analysis for seed yield and its components in Indian mustard (Brassica juncea L.) under timely sown condition

Diallel analysis excluding reciprocal crosses comprising of seven parents and their 21 specific hybrids was carried out to identifyhigh heterotic combinations and their relationship in terms of general and specific combining ability (GCA and SCA) in Indian mustard. Highest economic heterosis for yield was observed in crosses namely; NRCHB-101 x Pusa M-21, Urvashi x Pusa Bold, NRCDR-2 x Urvashi, Maya x Pusa Bold, and Maya x NRCDR-2. The economic parents Urvashi, Pusa Bold, NRCHB-101, Pusa M-21, NRCDR-2, Maya and RGN-73 were the best parents for majority of the characters with Urvashi and Pusa Bold being the best economic parents for seed yield/plant and its contributing characters as their GCA and per se performances were high. Analysis of variance for GCA and SCA signified differences for majority of the characters. Ratio of GCA and SCA variances was below unity for majority of the characters except Days to 50% flowering and Days to maturity, which suggested superior role of non-additive genetic variance in the inheritance of these traits. The crosses namely Maya x NRCDR-2, Maya x Pusa Bold, NRCDR-2 x Urvashi, NRCHB-101 x Pusa M-21 and Urvashi x Pusa Bold showed high per se performance as well as SCA effects for seed yield and its contributing characters. The above best parents and best crosses could be used in hybridization and heterosis breeding respectively.

Genetic analysis of parental lines and identification of heterotic hybrid combinations in rice (Oryza sativa L.)

Thirty hybrids along with their parents (B and R lines) and standard checks viz., MTU 1001 and 27P63 were evaluated for grain yield and related traits to study combining ability and heterosis in rice. The mean performance of the hybrids for most of the characters was found higher than that of parents. The analysis of variance revealed significant differences among lines, testers and hybrids for most of the characters studied. SCA variances were found lower than GCA variances for most of the characters and average degree of dominance was far from unity indicating the predominance of additive gene action for these traits. However, for effective bearing tillers and spikelet fertility the average degree of dominance was very near to unity inferring the predominance of non-additive genetic components for these traits. The gca effects revealed that the lines, RNR 25783 and RP 5980-109-12-9-27 had significant gca effects in desired direction for yield and yield attributing traits whereas the tester, CMS 59A was a good general combiner. SCA effects showed that the hybrid, JMS 13A × RNR 19361 was found to be good specific combiner for grain yield per plant and spikelet fertility. Similarly, the hybrids, CMS 59A × SYE 503-78-34-2, CMS 46A × WGL 347 and JMS 13A × RP 5980-109-12-9-27 were identified as good specific combiner for grain yield and yield contributing characters. Based on heterotic estimates, five hybrids viz., CMS 59A × RNR 25783, CMS 59A × WGL 14, JMS 13A × RNR 25783, CMS 59A × RNR 25776, JMS 13A × RP 5980-109-12-9-27 were identified as promising with more than 5% and 20% yield advantage over hybrid and varietal checks, respectively.

Study of line x tester analysis for combining ability in bhendi (Abelmoschus esculentus)

The present investigation was carried out at Plant Breeding Farm, Faculty of Agriculture, Annamalai University, Chidambaram during July 2019 to September 2020 in a set of 9 parents (six lines and three testers) by making 18 cross combinations. Ten economically important traits viz. days to first flower, plant height, number of branches per plant, number of fruits per plant, fruit length, fruit weight, fruit yield per plant, number of seeds per capsule, hundred seed weight and seed yield per plant were studied for per se performance, general combining ability, specific combining ability effects and gene action. The present investigation also recorded preponderance of non-additive gene action for all the characters. The results showed that the hybrids TCR-2056 × Punjab Padmini (80.05) and Dharmapuri Local × Punjab Padmini (56.24) were superior hybrids as they showed high per se performance and significant SCA effects. So, they can be used for producing promising hybrids. The cross Panruty Local × Parbhani Kranthi (27.06) showed high mean and significant SCA effects. So, it can be used for producing high seed yield and some of its related traits could be used as heterotic hybrids.

Gene action and combining ability analysis for kernel yield and its attributing traits in maize [Zea mays (L.)

Combining ability estimates were studied for kernel yield, its components and morphological traits in nine maize parents and 36 F1 hybrids generated from cross in half diallel mating design. Analysis of variance for combining ability revealed that mean sum of squares due to general combining ability were found significant for all the traits except cob length and cob girth, whereas, the specific combining ability effects were found highly significant for all the characters except cob length, cob girth and anthesis - silking interval. Based on estimates of general combining ability, two parents viz., WNC 40228 (6.17) and WNC 31702 (5.47) were found as good general combiners because they registered significant and positive gca effects. The estimates of sca effects revealed that 13 hybrids were exhibited significant positive sca effects. The top most three hybrids for kernel yield per plant on the basis of specific combining ability effects were Z 485-50 x Z 485-11 (22.77), WNC 40228 x BLD - 105 (20.13) and WNC 40228 x Z 485-11 (17.47). The low ratio (<1.0) of GCA to SCA variance for fourteen traits indicated that non-additive type of gene action was predominant in the expression of yield and component traits. Keywords: Maize, geneal combining ability, specific combining ability, hybrid, kernel yield