Non-additive Type Of Gene Action Research Articles

Fertility restoration, combining ability effects and heterosis in sunflower (Helianthus annuus L.) using different CMS sources

Combining ability studies were made in sunflower (Helianthus annuus L.) using line x tester analysis with two diverse CMS lines PET-1 and ARG-1 and 12 testers. Analysis of variance revealed significant differences among the genotypes i.e., parents and hybrids. Non-additive type of gene action was found important for expression of all the charactersstudied. Studies on identification of effective restorer linesrevealed that out of 12 inbreds,fourturned out to be restorers for both PET-1 and ARG-1, while eight behaved as maintainers. Among the lines, PET-1 was found to be good general combiner forseed yield and oil content. Testers HAM-161, RHA-273 and HAM-174 have also exhibited desirable general combining ability effect for seed yield and several other characters. The cross combination ARG-1 x RHA-273 and ARG-1 x RHA-274 were found to be promising for most ofthe characterssuch as seed yield, plant height, number of leaves, capitulum diameter, stem girth and 100-seed weight. Besides PET-1source, other source viz., ARG-1 used in the present investigation was equally efficient in expressing their fullest potential of yield and yield contributing characters. Most of the crosses involving high x low general combining parents, exhibited high sca effects for various traits.

Elucidating Genetic Variability of Brassica napus L. Progenitors and Their Crosses for Enhanced Qualitative Traits

Evaluation of the breeding population is crucial for the selection of a superior genotype. Hence, the present study was conducted to assess genetic variation among five Brassica napus L. parents and their diallel hybrids to identify the best-performing parents and crosses. Heterosis and inbreeding depression were also assessed for the qualitative traits. Among the parental genotypes, Ancestor 2702 was identified as the best general combiner for protein (1.41%) and oleic acid content (1.21%). 2702×DUNCLED was the best specific combiner for oil content (0.78%), while 2702×2722 was recognized as best cross for linoleic acid content (1.3%). Similarly, DUNCLED×2702 was the best reciprocal cross for oil content (2.4%) and linoleic acid content (0.4 %), while P1-801×2702 was considered the best cross for protein content (2.2%) and oleic acid (1.7%). All the qualitative traits revealed a broad sense of heritability and non-additive type of gene action, which indicated the later generation selection for further improvement. High oleic acid content, preferred negative mid and best parent heterosis for erucic acid, glucosinolate and moisture contents was reported for 2702×DUNCLED. The favorable cross combination for protein and oil content was 2702×2722, which also yielded the positive mid and best parent heterosis. Inbreeding depression for qualitative traits ranged from -20.8% to 22.9%. It was concluded that among all the genotypes, accession 2702 was the best general, specific and reciprocal combiner, and the best parent heterosis for all traits when crossed with genotypes DUNCLED, P1-119 and 2722. It is also suggested that the screened crosses be carried to further generations to improve the quality related traits of Brassica napus. L.

Evaluation of General and Specific Combining Ability for Yield and its Attributing Traits in Bread Wheat (Triticum aestivum L.)

In order to investigate the general and specific combining ability (GCA and SCA) and gene action for yield and its contributing traits in common wheat, 10 lines and 4 testers were crossed using line × tester mating design at the Crop Research Center of SVP University of Agriculture and Technology, Meerut, Uttar Pradesh, India. The experimental material was raised under Randomized Block Design with three repetitions during rabi season of 2019–20 and 2020–21. The variance due to cross vs parent was highly significant for all the traits. Estimates of SCA variance for harvest index, plant height, biological yield per plant, 1000 grain weight, days to 50% blooming, grain yield per plant, days to maturity and number of productive tillers per plant, were higher than those of GCA variance, depicting the prevalence of non-additive gene action. GCA variance was found to be higher than SCA variance for the remaining characteristics, reflecting additive gene action. Based on GCA four parents were found promising (UP1109, DBW187, HD3237, PBW226, RAJ3777). On the basis of SCA, 9 crosses (HD3237 × WR544, RAJ 3777 × HD3086, DBW187 × HD3086, DBW187 × PBW226, K9162 × WH1105, PBW373 × WH1105, K9162 × PBW226, UP2628 × WR544, UP1109 × PBW226) were identified good specific combiner for grain yield per plant. In present study non-additive type of gene action was more pronounced, which can be utilized by pedigree method, biparental mating and selection in later generation.

Heterosis and Combining Ability Studies in A 5x5 Diallel Crosses of Maize Inbred Lines

The present study was conducted to evaluate the genetic architecture of five diverse maize genotypes using combining ability analyses. General combining ability (GCA) mean squares were non-significant for grain yield and its related components. Specific combining ability (SCA) mean squares were highly significant for grain yield, the number of grains per row and cob girth while non-significant for days to tasseling, days to silking, plant height, cob height and cob length. These studies suggested the preponderance of non-additive type of gene action for grain yield, cob girth and number of grains per row and additive gene action for days to tasseling, days to silking, plant height, cob height and cob length. The genotypes MIL2020-51 and MIL2020-52 were good general combiners for grain yield, grains per row, cob height and plant height. These lines were the poorest general combiner for days to 50% tasseling and days to 50% silking which suggested that these genotypes had sufficient genes for inducing earliness. The crosses MIL2020-51 x MIL2020-54, MIL2020-52 x MIL2020-53, MIL2020-51 x MIL2020-55, MIL2020-53 x MIL2020-55and MIL2020-52 x MIL2020-55 were the best performing combinations for grain yield. These crosses involved good x good and good x poor general combiners. The reciprocal cross combinations MIL2020-55 x MIL2020-53, MIL2020-52 x MIL20220-51, MIL2020-54I x MIL2020-52, MIL2020-55 x MIL2020-51, MIL2020-54 x MIL2020-51and MIL2020-55 x MIL2020-54 showed large positive estimates for grain yield suggesting that cytoplasmic inheritance also had a role in the expression of grain yield. SCA variances were higher than GCA variances for grain yield, plant height, cob height, number of grains per row, cob girth and cob length which highlighted major role of non-additive genes in the inheritance of these traits. Additive gene action was found more important for number of days to 50% tasseling and number of days to 50% silking

​Combining Ability and Heterosis Analysis for Seed Yield and Yield Related Traits in Table Pea [Pisum sativum (L.) var. hortense]

Background: A study was carried out to estimate the general and specific combining abilities, as well as heterosis for seed yield and yield associated traits in pea lines. Methods: Twenty-eight cross combinations were generated using half-diallel mating design with eight parental lines. The mean values of seed yield and its contributing traits of parental lines and their offspring for each replication were used for statistical analysis viz., GCA, SCA and Heterosis. Result: The GCA and SCA were significant and indicating the presence of both additive and non-additive types of gene actions. AP-3, VL-7, Kashi_Nandini and PC-531 were identified as promising parents due to significant GCA effects on seed yield and other traits. Among the crosses Kashi_Nandini x PC-531, VL-7 x PMR-53, Arkel x Vl-7 and VL-7 x Kashi_uday hybrids were the most promising, with significantly higher SCA effects for seed yield and yield related traits. Seed yield showed significantly high heterosis ranged from -2.00% to 8.77 % (AP-3 x PC-531 and Arkel x PMR-53, respectively) and relative heterosis ranged from -0.75% to 14.10% (Kashi_uday x PC-531 and Arkel x PMR-53 respectively) significantly exhibited positive heterosis for seed yield over better parent and mid-parent.

Genetic basis and principal component analysis in cotton (Gossypium hirsutum L.) grown under water deficit condition.

Cotton is considered as the main crop in the agricultural sector of Pakistan. Water deficiency in this region in recent years has reduced the chances of high yields of cotton. Selection and creation of high-yielding varieties of cotton, even in water deficit conditions, is one of urgent tasks of today. For this purpose, 40 diverse genotypes of upland cotton were screened in normal and water deficit conditions in triplicate arrangement under split plot in a randomized complete block design. All the genotypes showed significant difference under both water regimes. Ten upland cotton accessions were screened out as water deficit tolerant (VH-144, IUB-212, MNH-886, VH-295, IR-3701, AA-802, NIAB-111, NS-121, FH-113, and FH-142) and five as water deficit sensitive (IR-3, CIM-443, FH-1000, MNH-147, and S-12) based on seed cotton yield and stress susceptibility index. These tolerant and sensitive genotypes were crossed in line × tester mating design. For further evaluation of genetic material, the seed of 50 F1 crosses and their 15 parents were field planted under normal and water deficit conditions during next cotton growing season. Traits related to yield under the study showed significant variations among the accessions and their half sibs. The results of the principal component analysis (PCA) exhibited that total variation exhibited by factors 1 and factor 2 were 55.55 and 41.95%, respectively. PCA transformed the variables into three factors, and only two factors (F1 and F2) had eigenvalue > 1. The degree of dominance revealed that all parameters were highly influenced by non-additive gene action under both water regimes. Furthermore, the line VH-295 and tester CIM-443 had better yield performance under water deficit stress. The cross-combinations, viz., VH-144 × S-12, NIAB-111 × IR-3, and VH-295 × MNH-147, were the best for yield contributing traits. These combinations may be helpful for germplasm enhancement on large scale under water scarcity. All the studied traits have non-additive types of gene action suggesting the usage of these genotypes in cotton hybrid development program against water deficit tolerance.

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

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

Gene action studies in cherry tomato for yield and yield attributing traits in open and protected environment

The present study was undertaken to learn more about the the nature and magnitude of gene action for various yield and yield attributing traits in cherry tomato. Ten different lines of cherry tomato were crossed in diallel fashion (excluding reciprocals) and tested for gene action investigations in open and protected environment. Analysis of variance of the components of genetic variation and their ratios and differences revealed that the additive variance component ( ) was significant for all the traits in the individual as well as pooled data analysis, except for number of primary branches plant-1 in E2. The dominance components ( and ) showed the significant difference for all the traits except for plant height in E2. This shows the involvement of both additive and non-additive type of gene action in the inheritance of the traits. Hence, reliance should be placed on reciprocal recurrent selection and the development of superior lines with several desirable genes.

Deployment of Brassica carinata A. Braun Derived Brassica juncea (L.) Czern. Lines for Improving Heterosis and Water Use Efficiency Under Water Deficit Stress Conditions.

Among Brassica species, Ethiopian mustard (Brassica carinata A. Braun) is known to tolerate most abiotic stresses, including drought. Drought caused by low and erratic rainfall in semi-arid regions consistently challenges rapeseed mustard productivity. Development of B. carinata-derived lines (CDLs) in Brassica juncea (L.) Czern. nuclear background, carrying genomic segments from B. carinata, are expected to tolerate moisture deficit stress conditions. The present study was, thus, aimed to establish the phenomenon “heterosis” for drought tolerance and water use efficiency by evaluating 105 hybrids developed from intermating 15 CDLs in half diallel fashion. Data on 17 seed yield and yield contributing traits were recorded under two different environments, viz., irrigated and rainfed conditions. Traits under study were found to be governed by both additive and non-additive types of gene action. Average degree of dominance was higher (>2) for yield and yield contributing traits, viz., secondary branches/plant, point to first siliqua on main shoot, total siliquae/plant, 1,000-seed weight, seed yield/plant, biological yield, harvest index, and seed yield/hectare under rainfed conditions, clearly indicating that higher productivity under drought conditions can be realised through the development of hybrids. Out of 15, highly significant general combining ability (GCA) effects for seven CDLs were observed under rainfed condition. Furthermore, nine and six hybrids expressed highly significant specific combining ability (SCA) effects and > 50% heterobeltiosis for yield contributing traits under rainfed and irrigated conditions, respectively. Water use efficiency (WUE) of parental CDLs and hybrids varied from 2.05 to 2.57 kg m–3 under rainfed, while 1.10 to 1.28 kg m–3 under irrigated conditions. Hybrids expressed higher WUE than parental lines under both water regimes. Furthermore, selection indices such as drought tolerance index (DTI) and mean relative performance (MRP) were identified to be efficient in the selection of productive CDLs and hybrids under drought conditions. Nine hybrids, identified as highly productive in the present study, can further be exploited for improving the yield of Indian mustard in drought-prone areas. Usefulness of interspecific hybridisation in the development of B. carinata-derived B. juncea lines for improving heterosis and WUE is, thus, well demonstrated through the present study.

Combining ability analysis for yield and yield components and quality traits in Indian mustard [Brassica Juncea L. (Czern & Coss)]

Combining ability analysis was performed in a 10× 10 half dialle cross in Indian mustard genotypes for yield and quality traitsduring 2017-18 and 2018-19 at the agriculture research farm R.B.(PG) college Mudi, Agra and IFTM university,Lodhipur Rajput Moradabad.In this study, 45 F1 hybrid and their parents were evaluated for 14 quantitative and qualitative traits. The parents used namely, NRCHB -101, DRMR- IJ- 31, Kanti, Urvashi, Pusa mustard- 25 (NPJ-112), Pusa mustard-26 (NPJ-113), Pusa mustard- 27 (EJ-17), CS- 54, RH- 406, RH -749. The results indicated that both additive and non-additive type of gene actions were responsible in expression of all the 14 characters. Parental genotypes viz., RH -749, RH -406 and CS -54, showed high GCA effects for seed yield per plant and most of the important characters except days to 50% flowering and days to maturity. The other parent’survashi, PM -27, DRMRIJ- 31, NRCHB -101 showed high GCA effects for the remainingtraits. Out of 45 crosses only three crosses RH- 406 × RH -749, PM- 26 × RH -406 and PM -26 × RH -406 had desirable and significant SCA effects with high per se performance for seed yield per plant in F1,s generation. The present study indicated that genetic improvement in the Indian mustard would be achieved by using selected promising crosses having significantly high SCA values coupled with high per se performances.

Line x tester mating design analysis with GMS based system for seed cotton yield, its component traits and fibre quality parameters in Asiatic cotton (Gossypium arboreum L.)

Sixteen parents and 28 F1 (14×2) genetic male sterility based cross combinations were evaluated in a line x tester mating design in Asiatic cotton (Gossypium arboreum). The statistical analysis was performed using the method developed by Kempthorne (1957) with the help of an OPSTAT computer program (developed by CCS Haryana Agricultural University, Hisar). Sufficient variability among hybrids and their parents was found as the mean squares of genotypes for all the traits including fibre quality investigated were significant. The total genetic variability was partitioned to general combining ability (GCA) and specific combining ability (SCA). The variance due to GCA was higher than SCA for fibre strength (g/tex) only. For other traits viz., seed cotton yield, plant height (cm), bolls per plant, boll weight (g), 2.5 % span length and micronaire value, the SCA was higher which reflects the role of both additive and non-additive types of gene action (dominant or epistatic). In the present study, additive variances were significant for a 2.5% span length, fineness and fibre strength and non-additive as well as additive gene effects for seed cotton yield, plant height, boll number, boll weight and ginning percentage. GCA was significant for male parents, G-27, DLSA-17, DLSA-8, PA-496, LD-713, LD-853 and LD-733 for seed cotton yield; G-27, DLSA-17, DLSA-8, PA-255, PA-304, PA-405, PA-496 and LD-713 for plant height; G-27, DLSA-202, PAIG-8/1, PA-464 and PA-496 for bolls per plant; G-27, DLSA-202, PAIG-8/1, PA-464 and PA-496 for boll weight; DLSA-202, DLSA-17, PAIG-8/1, PA-405, PA-464, LD-733 for ginning out turn (GOT%); DLSA-202, DLSA-17, DLSA-8, PA-255, PA-464, PA-496, LD-713 and LD-733 for 2.5% span length (mm); DLSA-17, DLSA-8, PA-255, PA-464, PA-496 and LD-713 for lower micronaire value having fineness and DLSA-17, PAIG-8/1, DLSA-8, PA-255, PA-304, PA-496 and LD-713 for fibre strength (g/tex) which were considered as good general combiners. Similarly among 28 cross combinations, SCA was positively significant for 9 crosses for seed cotton yield, 11 crosses for plant height, 7 crosses for boll number, 10 crosses for boll wt, 9 crosses for GOT(%), 15 crosses for 2.5% span length, 8 crosses for micronaire and 8 crosses for fibre strength.

Heterosis for seed, oil yield and quality of some different hybrids sunflower

Twenty-one hybrids of sunflower were produced by crossing 7 introduced cytoplasmic male sterile lines (CMS-lines) with 3 restorer lines (RF-lines) using line × tester mating design. The twenty-one hybrids, three restorers, seven maintainer lines (B-lines) were evaluated. The experiment was conducted in a randomized complete block design of three replications. Mean squares due to genotypes, parents (P), crosses (C), lines (L), testers (T), P vs. C, for stearic acid and line × tester for palmitic acid. The inbred lines and their F1 hybrids differed significantly in their mean values of the traits under study. The variances due to specific combining ability (SCA) were higher than general combining ability (GCA) variances for all the studied traits, showing non-additive type of gene action controlling the traits. Non-additive type of gene action can be utilized for varietal improvement through heterosis breeding. Heterosis values for seed yield plant−1 were positive and highly significant relative to both the parental mean (17.68–72.38%) and the better parent (−2.86–56.842%). Significantly and negative heterosis was recorded in the case of linoleic acid relative to the parental mean (−81.24 to −38.02%) and better parent (−66.24–22.87%). With oleic acid, the heterotic effect ranged from −14.18 to 39.59% (parental mean) and from −15.06 to 38.72% (better parent). Therefore, these results are valuable for the improvement of quantitative as well as qualitative traits in sunflower breeding material to fulfill the edible oil requirements.

ESTIMATION OF GENETIC VARIABILITY USING LINE X TESTER TECHNIC IN MAIZE AND STABILITY ANALYSIS FOR SUPERIOR HYBRIDS USING DIFFERENT STABILITY PROCEDURES

Fifteen inbred lines were crossed to three testers of maize to estimate combining ability effects for maturity and yield traits. The produce 45 crosses, S.C. 168 and T.W.C. Giza 368 were evaluated across two years at the Farm of Faculty of Agriculture, Moshtohor, Benha University in RCBD with 3 replicates. Mean squares due to year (Y) genotypes (G), crosses (C), testers (T), inbred lines (L), line x tester (LxT) and interaction variance for C, L, T and LxT with (S) were significant (P>0.05) for most studied traits. Non- additive gene action (δ2SCA) is more pervading in determining inheritance of the most traits. The non-additive type of gene action is fluctuated by year changed more than additive. The inbred lines M. 645a (L4), M. 653 (L5), and M. 674 (L11) showed desirable ĝi for early maturity and grain yield plant-1. The crosses M.221xM.653, M.221xM.655b, M.221xM.657, M.221xM.671, M.221xM.674 and M.221xM.677 exhibited out-yielded SC 168 reached 9.96%, 11.35%, 12.53%, 8.32%, 11.80% and 4.80%, respectively across years. TWC (SC M 200xM418)xM.653 and (SC M200xM418)xM.674 showed superiority than TWC 368 being 9.11% and 3.78%, respectively.The eight superior hybrids along with SC168, SC hytech 2066, TWC 368 and TWC 352 were evaluated in 2019 year at various environments using RCBD with 3 replicates to identify suitable adapted maize hybrids. The main effects of genotypes, environments and their GxE interaction were highly significant (P<0.01). Hybrids M. 221 x M. 674, M. 221 x M. 655b, SC hytech 2066 and SC 168 were the most crosses stable phenotypically and genetically across environments.

Genetic Analysis of Groundnut Genotypes for Quality Related Traits

Groundnut (Arachis hypogaea) is an important cash crop of Pakistan. Groundnut has nutritional features like calcium, phosphorous, iron, zinc, proteins vitamin E and vitamin B complex. Little work has been done so far on groundnut quality aspects. Keeping this in mind present study was conducted comprising of eight groundnut genotypes collected from Barani Agriculture Research Institute (BARI) Chakwal which were evaluated for quality traits and their inheritance mechanism during Kharif season, 2016. Biochemical analysis for different traits were performed like protein content, oil content, calcium, phosphorous, iron, amino acid and Aflatoxin. The collected data were subjected to statistical analysis for ascertaining the significance of traits. Genotype 11CG005 gave good performance regarding oil content, iron content while genotype 11CG004 performed best for protein content and calcium content and it was also in safer limits for aflatoxin content. For phosphorous content, genotype 10CG008 gave best performance whereas genotype 11CG003 showed better results for amino acid content. High heritability with high genetic advance was showed by oil content, calcium content and protein content which indicated additive type of gene action for these traits while aflatoxin, amino acid, phosphorus and iron showed moderate heritability with little genetic advance which indicated predominance of non-additive type of gene action for the studied traits. The study is helpful in generating detailed information on quality traits of groundnut that can be used in future groundnut breeding programs of the country.

Genetic analysis of pod yield and its contributing traits in cowpea (Vigna unguiculata L. Walp)

The present investigation was undertaken to study the type of gene action involved for green pod yield and its components in cowpea and to estimate the general combining ability and specific combining ability of parents and crosses, respectively. The significance of both gca and sca variance for most of the characters indicated that both additive as well as non-additive types of gene actions were involved in the inheritance of these traits. The gca effects of parents suggested that 2014/COPBVAR-4, 2012/COPBVAR-2, 2014/COPBVAR-5 and Kashi Kanchan were good combiners for different yield components like number of flowers per cluster, number of pods per cluster, per cent pod set, number of pods per plant and days to last harvest. The Arka Garima, 2014/COPBVAR-5 and 2014/COPBVAR-4 were good general combiner for days to 50% flowering and Kashi Kanchan, 2014/COPBVAR-5 and 2012/COPBVAR-2 for green pod yield per plant. No single parent was found to be good for all the traits. Based on specific combining ability effects of the hybrids, the cross combination2014/COPBVAR-5 x Gomti was found to be the best combination both for number of pods per plant and green pod yield per plant. The other best specific combinations were 2012/COPBVAR-3 x Pusa Komal, 2012/COPBVAR-5 x Pusa Komal and 2012/COPBVAR-2 x Arka Garima with high positive sca effects and high mean for green pod yield per plant. These promising parents can be used in future breeding programmes and the crosses may be exploited for isolation of transgressive segregants from the segregating generations of these crosses for further improvement of pod yield in cowpea.

Assessment of heterosis and inbreeding depression for agro-morphological traits in bread wheat

A study was conducted for the assessment of heterosis and inbreeding depression for grain yield and its contributing traits in bread wheat using a 13 × 13 diallel fashion excluding reciprocals. The analyses of heterosis over mid parent (MP), better parent (BP) as well as the standard check (SC; NW 1014) were carried out in 78 F1 and F2 crosses and inbreeding depression in F2 crosses. Biological yield exhibited maximum degree of SC, BP and MP heterosis (46.96%, 39.98% and 31.78%), followed by grain yield (35.27%, 27.58% and 20.52%), respectively. The crosses viz., PBW 343 × HI 1563 (PH, ET, TGW, BY); PBW 343 × K 8962 (PH, ET, SPS, GNPS, TGW, BY); RAJ 3765 × UP 2490 (PH, SL, SPS, GNPS, TGW, BY); UP 2490 × CBW 38 (SL, ET, SPS, GNPS, TGW, BY) and NW 2036 × UP 2490 (SPS, GNPS, TGW, BY) expressed significant standard heterosis (&gt;50%) for grain yield and some other yield components. All these crosses had significant performance in both generations (F1 and F2) hence, can be exploited for the development of high yielding lines and/or isolation of desirable transgressive segregants. Thus these crosses combinations may be used for developing superior genotypes. The crosses viz., PBW 343 × RAJ 3765 (-26.17), RAJ 3765 × HP 1744 (-20.66), NW 1014 × CBW 38 (-19.95), RAJ 3765 × CBW 38 (-10.31), HP 1744 × CBW 38 (-9.71) and UP 2425 × CBW 38 (-5.87) express negative significant inbreeding depression for grain yield and also exhibited &gt;15% heterosis over three parents, indicating non-additive type of gene action in the inheritance of these characters and therefore these crosses could be used for further improvement of grain yield in bread wheat. DOI.org/ 10.25174/2249-4065/2019/89648

Gene action and combining analysis for kernel yield and its attributing traits in maize [zea mays (l.)]

Eight maize (Zea mays L.) genotypes were crossed in a half diallel mating design.The 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 girth, whereas, the specific combining ability effects were found highly significant for all the characters except anthesis-silking interval. The low ratio (<1.0) of GCA to SCA variance for sixteen traits indicated that non-additive type of gene action was predominant in the expression of yield and component traits. Based on estimates of general combining ability effects revealed that four parents BLD-11 (5.19), CML-338 (4.28), VL-1032 (1.68) and VL-109178 (1.25) were found good general combiners because they registered significant and positive gca effects. The estimates of sca effects revealed that 23 hybrids were exhibited significant positive sca effects. The spectrum of differences in sca effects for this trait ranged from -2.70 (CBE-98 × CML-338) to 27.57 (CBE-98 × MRCN-3) and the top most three  hybrids for kernel yield per plant on the basis of specific combining ability effects were CBE-98 × MRCN-3 (27.57), CBE-98 × BLD-11 (23.16) and CBE-26 × BLD-11 (21.20).

Gene Actions and Combining Ability Analysis for Some Seed Characters in Citrullus Mucosospermus (Fursa)

In order to suggest breeding strategies to improve Citrullus mucosospermus (Fursa), 4 × 4 complete diallel cross design involving Bebu, Wlewle small seeds 1 (Wss1), Wlewle small seeds 2 (Wss2) and Wlewle small seeds 3 (Wss3) genotypes was used to assess combining ability and gene actions involved in the inheritance of six seed traits. The F1 direct and reciprocal crosses plus the parental inbred lines coming from these cultivars were grown in a randomized complete block design with three replications. The results indicated the existence of genetic variation between parental lines for all investigated seed traits. Combining ability analysis exhibited the involvement of both additive and non-additive types of gene actions in the expression of all studied traits, suggesting, doing the selection in C. mucosospermus heterogeneous populations for improving these seed traits. Non-additive gene actions were predominant in the inheritance of investigated traits indicating the possibility of the heterosis exploitation or the postponement of selection to later generations for improving genetically these traits. Bebu appeared the best general combiner for Mass of fresh seed, Mass of dry seed, Mass of 100 seeds, seed length and seed width while, Wss1 and Wss2 are the best combiners for percentage of seed integuments. Therefore, parental lines Bebu, Wss1, Wss2 and crosses with high significant specific combining ability effects are proposed for their incorporation in C. mucosospermus breeding programs. The presence of both GCA and SCA effects suggests the use of recurrent reciprocal selection to improve C. mucosospermus seed traits.

Gene action conditioning resistance traits to spotted stem borer, Chilo partellus, in grain sorghum

Understanding the mode of gene action conditioning traits of interest in sorghum is important for effective and efficient plant breeding programs. The objective of this study was to establish the nature of gene action for components that contribute to resistance to spotted stem borer, Chilo partellus, in grain sorghum. The experimental material consisted of seventeen sorghum lines with varying levels of resistance to C. partellus. Genetic analyses were performed using a line x tester method using Genstat statistical software. There was significant variation among the F1 for C. partellus resistance and grain yield. The general combining ability (GCA) for deadheart damage was significant (P ≤ 0.01) implying that this trait was governed by an additive type of gene action. Specific combining ability (SCA) for exit holes and stem tunneling were significant (P ≤ 0.01) suggesting that these characters were conditioned by both additive and non-additive types of gene action. Lines ICSA 472, ICSA 464, ICSB 474 contributed high levels of resistance to hybrids while IESV 93042 SH, IS 21879 and IESV 91131 DL were good sources of genes for high grain yield. This observation implied that grain yield and stem borer resistance traits should be considered in development of C. partellus resistant sorghum since a resistant line doesn’t necessarily yield high and vice versa. Generally, results of this study indicated that it would be possible to breed for high C. partellus resistance from this set of germplasm for cultivation by farmers in areas where the insect pest causes epidemics.