Type Of Gene Action Research Articles

HALF DIALLEL ANALYSIS OF SEVEN PEA CULTIVARS FOR SEED YIELD AND ITS COMPONENTS FOR F4 GENERATION UNDER SULAIMANI CONDITION

The present study was carried out at Qlyasan locations, in Kurdistan Region-Iraq, Agricultural Research Station, College of Agricultural Engineering Sciences-University of Sulaimani, according to half diallel mating system using seven pea cultivars (1-Avolla, 2-Americana, 3-Jeza, 4-Joneor, 5-Pack land, 6-Arvena and 7-Samara) with 21 F4 crosses. The genotypes were planted in a completely randomized block design with three replications. Highly significant mean squares due to genotypes were recorded indicating the presence of sufficient variability among genotypes for all traits. The mean squares due to gca and sca were significant for all the studied traits. The highest positive heterosis values estimated as the F4s deviation from mid parental values recorded by the cross 2×6 and 4×5 for almost all traits. Maximum positive gca effect values for seed weight plant-1, biological yield plant-1 and pods number plant-1 were recorded by parent 4, while parent 2 showed the best value for some components. The cross 4×5 was the best sca combiner for seed weight plant-1 and some its components including pods number plant-1, pod weight plant-1 and seed number pod-1. The type of gene action as controlled the inheritance of all characters was over dominance except 100-seed weight. Heritability in broad sense was found to be high for all treats except seed number pod-1 which was moderate, while at narrow sense it was high for average pod weight, pod length, seed weight pod-1 and 100-seed weight.

Mean Performance, Type of Gene Action, Combining Ability and Superiority Percentage of some New White Maize Inbred Lines in Top Crosses

Mean Performance, Type of Gene Action, Combining Ability and Superiority Percentage of some New White Maize Inbred Lines in Top Crosses

Studies on genetic variability and response to selection for quantitative and qualitative traits over environments in brinjal (Solanum melongena L.)

The present study was conducted during the Rabi-2017-18 over three environments with 21 hybrids and their seven parents. The characters viz., the number of fruits per cluster, fruit width (cm), fruit length to girth ratio, average fruit weight (g) and the total number of fruits per plant recorded high GCV and PCV values and differences between these two parameters also less indicates presence of high genetic variability for these traits among the genotypes. Heritability and genetic advance as per cent mean for aforesaid traits also recorded high values; it means direct selection for these characters may be an effective and further evaluation for knowing the type of gene action actually involved in the phenotypic expression of these traits may be confirmed by estimating GCA and SCA variances by using any mating design.

Generation Mean Analysis and Molecular Markers for Drought Tolerance in Wheat during Germination and Seedling Stage

Generation mean analysis for drought tolerance was studied in wheat cross-1 (Pavon-76 X Gemmeiza-7) and cross-2 (ICR-DH18 X Pavon-76). The genotypes were evaluated under control and drought stress (15% polyethylene glycol 6000) at germination and seedling stage for seven traits. The additive–dominance model is adequate for explaining the inheritance of root and shoot lengths under both treatments and root fresh weight under drought stress in cross-1, and shoot length in both treatments and root length under drought stress in cross-2, while being inadequate in the other traits in the two crosses treatments. The additive-dominance and epistatic interaction effects recorded for germination percentage, root and shoot fresh and dry weights in both crosses suggested postponement of plant selections till the later generations for plant traits with such type of gene action. Epistasis absence and the contribution of considerable additive genetic variance in root and shoot lengths and root fresh weight indicating that recurrent selection in early segregating generations could be effective to select wheat lines with enhanced early tolerance to drought stress. Only two SSR primers and two TRAP primer pairs generated polymorphic bands from the tested genotypes. Four positive molecular markers were detected for drought tolerance. The UPGMA clustering analysis revealed correlation between drought tolerance genotypes and the studied molecular markers. The markers identified herein would allow implementing marker-assisted selection to screen wheat segregating populations for drought tolerance.

GENERATION MEAN ANALYSIS OF TWO BREAD WHEAT CROSSES UNDER NORMAL AND LATE SOWING DATE CONDITIONS

Parents (P1&P2), F1, F2 and first generation of backcrosses (BC1&BC2) of two bread wheat crosses i.e., Sids 12 x Gemmeiza 11 (C1) and Misr 2 x Sids 1 (C2), were grown in two experiments {normal sowing date 20th Nov. (N) and late sowing date 20th Dec. (L)}. This study was conducted at the Experimental Farm of Shandaweel Agric. Res. Station, ARC during 2015/2016, 2016/2017 and 2017/2018 seasons. The study aimed to estimate non-allelic interaction, scaling tests (A,B,C and D), coupled with three and six types of gene action and to determine the adequacy of genetic model controlling the genetic system of the inheritance for seven economic traits of bread wheat. Scaling test showed the presence of non-allelic interactions for all studied taits, except number of spikes/plant in cross 1 under late sowing. The relative importance of dominance and additive effects differ for traits and crosses under normal and late sowing conditions. Dominance effects were generally more important than additive for all studied traits in both crosses under the two sowing dates, except for days to heading in cross 2 under late sowing, number of spikes/plant in cross 1 under late sowing and biological yield in cross 1 under normal sowing. This explains that dominant genes play a major role in the inheritance of these traits beside the additive one. Dominance × dominance gene interaction was higher in magnitude than additive × dominance and additive × additive in most traits, indicating that these traits are greatly affected by dominance and non-allelic interactions. Therefore, it is advisable to delay selection to late segregating generations with increased homozygosity. Positive highly significant heterosis over better parent values was observed for all studied traits in both crosses under the two sowing dates, except for plant height in cross 1 under late sowing and cross 2 under normal sowing, number of kernels/spike in cross 1 under both sowing dates and grain yield/plant in cross 1 under normal sowing. Broad and narrow sense heritabilities and genetic advance ranged from moderate to high in most cases. These results indicated that selection in segregating generations could be effective to develop early maturing lines that have high yielding ability under heat stress conditions (late sowing date).

GENETIC ANALYSIS FOR EARLINESS AND GRAIN YIELD OF BREAD WHEAT (Triticum aestivum L.) UNDER HEAT STRESS

This investigation aimed to study mean performance, genotypic variances, types of gene action and heritability for earliness, yield and components in four bread wheat crosses using six populations i.e. (P1, P2, F1, F2, BC1 and BC2) under different thermal conditions. Wheat crosses populations were sown on 19th November and 3rd January at the Experimental Farm, Faculty of Agriculture, Zagazig University, Egypt in a randomized complete block design in 2017/2018 season. Scaling test provide evidence of non-allelic interaction in controlling all studied characters in the four crosses on both sowing dates except No. of spiklets/spike in the 3rd and 4th crosses and grain yield/plant in the 2nd and 3rd crosses on normal sowing date, indicated the presence of epistasis and the digenic model proved to be satisfactory in explaining the inheritance of the previous characters in the corresponding crosses. Narrow-sense heritability estimates recorded high values (>50%) for days to heading in the 1st and 2nd crosses on normal sowing date and the 3rd cross on both sowing dates; days to maturity in the 1st and 4th on normal sowing date and the 3rd cross on both sowing dates, No. of tillers/plant in the 3rd cross on both sowing dates and the 2nd and 4th crosses on normal sowing date; No. of spiklets/spike in all crosses on both sowing dates except the 1st and 2nd crosses on normal sowing date; No. of grains/spike in the 2nd cross on both sowing dates, the 4th cross on normal sowing and the 1st cross on late sowing date; weight of grains/spike in the 2nd cross on both sowing dates and the 3rd on normal sowing date, 1st and 4th crosses on late sowing date and grain yield/plant in the 1st cross on both sowing dates and the 3rd and 4th crosses on late sowing date.

Genetics analysis for earliness and yield traits using Ogura CMS in snowball cauliflower (Brassica oleracea var. botrytis)

A study was undertaken to determine the components of genetic variance and gene action effects in snowball cauliflower (Brassica oleracea var. botrytis L.) lines through line × tester analysis involving 5 Ogura CMS lines and 7 male fertile testers. The mean squares due to lines and testers were significant for most of the characters under study, except for gross plant weight, polar diameter, equatorial diameter, curd weight, curd yield and harvest index and for line × tester, it was significant for leaf length, leaf width, number of leaves per plant, plant height, days to 50% curd initiation and days to 50% curd maturity. Pre-dominance of dominance component of variance was observed for leaf length, number of leaves per plant, plant height, days to 50% curd initiation, marketable curd weight and marketable curd yield. The traits studied had narrow differences among GCV, PCV and broad sense heritability values, suggesting low effect of environment on the expression of phenotype for most of vegetative traits. The variance due to general (σ2gca) and specific combining abilities (σ2sca) were highly significant indicating the importance of both additive (σ2A) as well as non-additive (σ2D) type of gene actions. However, the ratios of σ2gca/ σ2sca (<1) and σ2A/σ2D (<1) revealed the preponderance of non-additive variance for the inheritance of traits studied except for days to 50% curd initiation and harvest index. The results of the experiment suggest the possibility of improvement of these traits through recurrent selection and hybridisation.

Partial diallel and potential of super sweet corn inbred lines bt 2 to obtain hybrids

ABSTRACT The aims of this study were to determine the potential of S4 super sweet corn inbred lines for hybrid synthesis, identify the predominant types of gene action and correlations among different traits, significant for breeding programs. The 81 hybrids obtained from a partial diallel 9x9 and three checks were evaluated. A complete randomized block design, with three replicates, and two sowing seasons was used. We could notice significant hybrid effects, general combining ability (GCA) of GI and GII groups and specific combining ability (SCA) in relation to evaluated traits, highlighting the existence of hybrids with superior performance and the expression of additive and non-additive effects. The inbred lines: L1, L3, L6 and L9 (GI) and L1’, L7’ and L9’ (GII) showed the best GCA and SCA estimates, being present in the nine selected hybrids with superior and competitive performance in relation to the checks. The estimated correlations indicate that, for a breeding program aiming to increase grain productivity, evaluating, at least, the dehusked ears, prioritizing genotypes with larger ear diameters and longer ear lengths is important.

DETERMINATION HETEROSIS AND COMBINING ABILITY FOR TRAITS YIELD AND YIELD COMPONENTS IN THE FABA BEAN (VICIA FABA L.)

Study was conducted genotypes of faba bean half diallel crosses were done in winter season 2016. All genotypes (parents and hybrids) were planted in winter season 2017, in one of the agricultural fields in the Al-Sufiya region at latitude 33.28? north and longitude 43.33? east of Anbar province, using R.C.B.D. design with three replicates. Studied traits were pod length, number of pods per plant ,number of seeds per pod, seeds100 weight and seed yield. Results showed significant differences between the mean of parents and the mean of their hybrids for all studied traits. The parent (Spanish) was superior and had the highest mean of the pod length 16.610 cm, number of pod plant 15.493 pod plant-1, number of seeds pod 5.873 seed pod-1 and seed yield 124.110 g plant-1. While the parent (Dutch) recorded the highest mean for trait seed100bweight reached 142.580g. As for the means of the hybrids, hybrids (Spanish×Dutch) showed the highest mean significant for traits the pod length 24.120 cm, number of pod plant 20.420 pod plant-1 and the seed yield 212.330 g.plant-1. While the hybrid (Iraqi×Italian) gave the highest significant mean of the number of seeds pod 6.267 seed pod-1 and non-significantly from the hybrid (Spanish×Dutch). Hybrids (Iraqi×Turkish) showed the highest mean for trait seeds100 weight 176.340 g. Hybrid (Turkish×American) was superior and had the highest value of heterosis in number of pods plant 39.560%. While hybrid (Iraqi×Italian) recorded the highest value of the heterosis number of seeds pod reached 69.83% , The highest value of the heterosis in two trait seed100 weighed and seed yield was by the hybrid (Iraqi×Turkish) gave 30.820% and 78.238% sequentially. And that the variance components of the general ability to the specific ability components were less than one for all traits. This indicates the type of gene action for dominance genes in the control of the heritability of these traits.

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.

Generation mean analysis for yield and submergence tolerance in high yielding varieties of rice (Oryza sativa L.)

An investigation in rice (Oryza sativa L.) was carried out by utilizing two cosmopolitan rice varieties of Tamil Nadu namely ADT 43 and Improved White Ponni along with the donor submergence tolerance FR13A to reveal the genetics and gene action for submergence tolerance. The generation mean study was done by developing six generations viz., P1, P2, F1, F2, B1 and B2 for two cross combinations namely ADT 43 × FR 13A (Cross 1), IWP × FR 13A (Cross 2). Gene action studies for submergence tolerance through generation mean analyses revealed that all the yield and yield component traits under submergence condition were mostly influenced by dominance gene action, except for number of filled grains per panicle, total number of grains per panicle and spikelet fertility in cross 1. Regarding 1000 grain weight epistatic gene action was predominant in cross 1. In cross 2, dominant gene action alone was predominant for the trait number of productive tillers per plant whereas, the epistatic gene effects were predominant for the traits number of filled grains per panicle and total number of grains per panicle. The traits, days to flowering, plant height, number of tillers per plant, spikelet fertility, 1000 grain weight and single plant yield were controlled by additive, dominance followed by epistatic gene action. The generation mean analysis also revealed that number of filled grains per panicle, 1000 grain weight and single plant yield in cross 2 under submergence condition were much influenced by different types of gene action viz., additive, dominance and epistasis with complementary epistatic interaction. These crosses would be utilized for yield improvement through single plant selection in segregating generations. To obtain desirable segregants, the appropriate breeding method would be bi-parental mating or one or two cycles of recurrent selection followed by pedigree breeding will be effective and useful method to obtain expected improvement in rice under submergence tolerance.

Combining ability and gene action studies for seed yield and its components in sesame (Sesamum Indicum L)

A line x tester analysis using two lines and ten testers was carried out to study the combining ability and gene action in sesame for seed yield and 14 quantitative traits. Analysis of variance for combining ability revealed significant differences among the mean squares due to lines were non significant for all the characters except days to 50% flowering and weight of capsules and in case of lines x testers it found significant for most of the character except days to 50% flowering, length of capsule, weight of capsule, number of capsule per leaf axil and oil content which indicated the existence of genetic diversity among the hybrids. General and specific combining ability variances showed the involvement of both type of gene actions in the inheritance of these characters. Among the lines G.Til-2 and among testers DS 21, RT 127, RT 346 and NIC 17274 were good general combiners for seed yield per plant and some of its contributing traits. The cross combination G.Til 3 × RT 127, G.Til 3 × DS 21, G.Til 3 × RT 346, G.Til 2 × RMT 175, G.Til 2 × HT 2, G.Til 2 × DS 10, G.Til 2 × RMT 166, G.Til 2 × RMT 186 and G.Til 3 × NIC 17274 showed significant and positive sca effect for seed yield per plant and involvedpoor x good, good x poor, poor x poor and good x good general combiners for majority of characters indicating the presence of dominance x additive and additive x additive type of gene interactions. These crosses have been identified as best hybrids for improving seed yield per plant and could be evaluated under different environment to confirm their superiority.

English

The bruchid, Callosobruchus maculatus (F.) is one of the most destructive pests and causes substantial losses to cowpea during storage in tropical and subtropical regions. The development of successful breeding strategy requires knowledge on gene action and trait inheritance in local and improved sources. In this study, the mode of inheritance, the types of gene action and maternal effects of cowpea resistance to bruchid was investigated. Nine parental lines and their 72 F2 segregating populations, created in a full diallel Griffing’s method 1 approach, were evaluated for resistance to bruchid attack in a randomized complete block design (RCBD) with three replications. Data were recorded on number of eggs laid by the bruchid (NE), adult bruchid emergence (NEI), median development period (MDP) and Dobie Susceptibility index (DSI) was computed. Genotype had highly significant effects on NE, NEI and MDP and DSI. General combining ability (GCA) effects of parents, specific combining ability (SCA) effects of crosses, and maternal and reciprocal effects were highly significant for all the traits. The ratios of GCA to SCA for all the traits were greater than 50% suggesting the preponderance of additive over non-additive gene action in the expression of the traits. Narrow sense heritability estimates were 64.12, 77.69 and 80.99% for NE, NEI and MDP, respectively. Parents 2419, TVu-2027 and IT84s-2246 were identified as promising general combiners for resistance to bruchid and the seven best selected crosses based on their SCA and DSI values were, IT84s-2246 × 2419, 2419 × MU9, TVu-2027 × SECOW2W and 2419 × IT90K-76, 2419 × WC69, 2419 × SECOW5T and 2419 × SECOW2W. The selected parents and/or crosses could be valuable genetic materials for breeding cowpea resistance to bruchid in Uganda or similar environments. Key words: Additive gene action, heritability, median development period, reciprocal effects.

Gene Action and Combining Ability for Seed Yield and its Components in Eight Sesame Genotyps Diallel Crosses

In order to study the combining ability, type of gene action and partition the components of the genetic variance to its constituents of additive and dominance gene effects using half diallel cross for eight genotypes to produce twenty eight sesame crosses. Two field experiments were carried out during two summer growing seasons 2016 and 2017 at Arab El-Awammer Research Station, Assuit, Agricultural Research Center. Results showed that mean squares due to both general (GCA) and specific (SCA) combining ability were highly significant for all characters, indicating the importance of both additive and non-additive gene effects in the inheritance of studied traits. The ratio of GCA/SCA indicated that the largest part of the total genetic variability due to the additive and additive x additive was very important than the non-additive gene effects in the genetic variability for all studied traits. Estimates of GCA for eight parents revealed that P8 was good combiner for plant height, length of fruiting zone, seed yield/plot and number of days to 50% flowering, while P1, P2 was good combiner for number of capsules/plant, seed yield/plant and 1000-seed weight. Significant SCA effects were observed for some crosses, cross (P1xP5), (P1xP7) and (P2xP3) were the best ones for seed yield/plant. Additive D and dominance (H1 and H2) genetic variation were significant for plant height and seed yield/plot. The D parameter estimating the additive effect was highly significant and was larger in magnitude than the dominance parameters (H1 and H2) in the all studied traits indicating that the type of gene action is partial dominance. The positive and negative alleles were unequally distributed among the parents. All studied traits had a high values for the broad sense than the narrow sense heritability. Graphical analysis revealed that the regression lines cuts Wr axis above origin point, indicating partial dominance for all the studied characters.

Combining ability and Heterosis analysis for grain yield and yield associated traits in Pea (Pisum sativum L.)

This experiment was conducted to determine the general and specific combining abilities and heterosis for grain yield and yield associated traits in pea as a source of protein through line x tester analysis. Grain yield and its inheritance were carried out for investigation through a 12 x 3 line x tester analysis. Experimental materials comprising 15 parents and their 36 hybrids. The materials were planted in a randomized block design with three replications. The general combining ability and Specific combining ability effects were significant indicating the presence of both additive and non-additive types of gene actions. Heterosis was determined as the superiority over mid parent heterosis as well as better parent (HBP). Grain yield showed highly significant heterosis ranging from -36.29 to 8.77and relative heterosis ranged from -25.85 to 13.19 respectively.

GENETIC BEHAVIOR OF YIELD AND FIBER TRAITS IN SOME BARBADENSE COTTON CROSSES

This investigation was carried out at Sakha Experimental Station, Agricultural Research Center during four seasons 2013, 2014, 2015 and 2016. Five populations (P1, P2, F1, F2 and F3) for the four barbadense cotton crosses namely (Uzbekstan1 x C.B 58), (TNB x C.B 58), (BBB x C.B 58) and (Giza 94 x Giza 45) were used in this investigation to study the genetic behaviour of yield and its components and fibre traits. The aim of the present investigation was to study heterosis, inbreeding depression and type of gene action in four intra-specific crosses to obtain additional information about some genetic parameters to help the breeder to select effective breeding methods. The results showed that the potence ratio estimates indicated overdominance for seed cotton and lint yield/plant, boll weight, lint percentage and number of bolls/plant, while the quality traits exhibited partial dominance. Highly significant positive heterotic effects relative to mid-parent and better parent were obtained for seed cotton yield, lint cotton yield and number of bolls/plant, while it was for lint percentage. The inbreeding depression effects were highly significant for the number of bolls/plant, seed cotton yield and lint cotton yield. Highly significant values of additive and dominance were found for seed cotton yield, lint cotton yield and number of bolls/plant. Dominance effects for Micronaire value and fibre length were of greater magnitude than additive effects. Highly significant epistasis values were found for additive x additive and dominance x dominance with complementary action with non-additive effect. High broad-sense heritability values were calculated for all studied traits, while narrow sense heritability values were of low values for seed cotton and lint cotton yield. on the other hand the fibre quality traits exhibited high values in three crosses as well as the heritabilities of regression

Combining Ability, Heterosis, and Heritability of Storage Root Dry Matter, Beta-Carotene, and Yield-related Traits in Sweetpotato

Orange-fleshed sweetpotato (OFSP) is an effective, low-priced, and sustainable source of β-carotene (provitamin A). However, most OFSP varieties have low storage root dry matter content (DMC), which influences their acceptance by small-scale farmers and hence needs to be improved. The objective of the study was to determine the combining ability, type of gene action, heterosis and heritability of storage root DMC, β-carotene content, and yield-related traits of selected sweetpotato clones for further evaluation and breeding. Crosses were conducted using a 7 × 7 half-diallel mating design and a total of 28 genotypes (seven parents and 21 crosses) were evaluated at four locations in Ethiopia using a 7 × 4 alpha lattice design with two replications. The performance of the genotypes was significantly different (P < 0.01) across the four locations for storage root DMC, β-carotene content, sweetpotato virus disease (SPVD) reaction, storage root yield, and harvest index (HI). The general combining ability (GCA) and specific combining ability (SCA) mean squares were significant (P < 0.01) for all traits except the SCA effect of storage root DMC. The GCA to SCA variance ratios were 0.96, 0.94, 0.74, 0.96, and 0.97 for storage root DMC, β-carotene content, SPVD, fresh storage root yield, and HI, respectively, indicating that the inheritance of these traits was controlled mainly by additive genes. Progenies of crosses involving Ukerewe × Ejumula, Ukerewe × Pipi, Resisto × Pipi, and Ejumula × Pipi exhibited high levels of positive heterosis for storage root DMC. Similarly, progenies of crosses including Resisto × Pipi and Resisto × Ogansagan had higher positive heterosis for fresh storage root yield, reflecting the breeding value of these parents. Relatively high narrow sense heritability (h2) was obtained for β-carotene content (79.8%) and HI (48.6%). However, the h2 estimates of storage root DMC, SPVD, and fresh storage root yield were relatively low at 19.0%, 14.9%, and 20.4%, respectively. Crosses with high β-carotene content such as Ukerewe × Resisto, Resisto × Ogansagan, Eumula × Pipi, and NASPOT 1 × Temesgen exhibited high storage root DMC. These families also had medium-to-high mean fresh storage root yield. Therefore, progenies derived from these families are good candidates to develop improved OFSP varieties with high storage root DMC.

APTITUD COMBINATORIA GENERAL Y ESPECÍFICA DE CARACTERES AGRONÓMICOS EN LÍNEAS DE MAÍZ (Zea mays L.) DE BAJA ENDOGAMIA

Knowing the type of gene action that controls agronomic traits is essential for the planning and development of a maize genetic improvement program. The objective of this study was to determine the genetic components of general combining ability (GCA), specific combining ability (SCA) and reciprocal effects (ER) involved in the expression of agronomic traits in a set of S3 maize lines. F1 crosses and their progenitors were evaluated at two planting dates: March 18 and May 28, 2014. The following agronomic traits were recorded: plant height, days to male and female flowering, days to physiological maturity, general appearance of the plant, crop yield and some of its components. Statistical differences were found between genotypes for all the traits in the two planting dates. Regarding the effects of GCA and SCA, significant differences were found for all the traits, with a predominance of GCA on SCA for days to male and female flowering, days to physiological maturity, plant height and yield. However, the most important component regarding general appearance of the plant and crop yield was SCA. The ER were significant in plant height, days to female flowering and general appearance of the plant. TNM-5 and TNM-4 lines showed high GCA in yield and its components, and greater precocity. In crosses with high and positive estimators in all the traits evaluated, lines with high ACG estimators and with low and negative effects intervene.

Genetic Analysis for Fruit Yield and Quality Attributes in Some Processing and Fresh Market Tomato Genotypes

ABSTRACTHigher demands for improved fruit yield and processing qualities for Tomato (Solanum lycopersicum L.) could be met through heterosis breeding. It is important to identify the parental line combination performing better for economically important quality traits. The experiment was composed of seven tomato inbred lines (two processing and five fresh market) and 21 F1 hybrids produced by crossing of them in a 7 × 7 half-diallel fashion. The nature and type of gene actions were analyzed to determine how they were involved in inheritance of fruit per plant, yield per plant, average fruit weight, total soluble solids, fruit juice pH, titratable acidity, sugar acid ratio, fruit juice content, shape index, and pericarp thickness. Most characters were predominantly controlled by nonadditive gene actions. Employing hybrid breeding for improving characters could be effective. The crosses ‘Metadel × Marglobe’, ‘Bishola × CLN2037E’, ‘Roma VF × ARP Tomato d2’, ‘Roma VF × CLN2037E’, ‘ARP Tomato d2 × Marglobe’, and ‘Eshete × CLN2037E’ showed positive and highly significant specific combining ability (SCA) effects for number of fruit per plant and fruit yield per plant. This indicated that the crosses could be used for developing high-yielding varieties. The crosses ‘Metadel × Roma VF’, ‘Bishola × Roma VF’, ‘Roma VF × Eshete’, and ‘ARP Tomato d2 × Marglobe’ exhibited positive, significant SCA effects for total soluble solids and negative, significant SCA effects for fruit juice pH. These crosses could be utilized as hybrids with better processing qualities. The crosses ‘Metadel × Marglobe’, ‘Bishola × Eshete’, ‘ARP Tomato d2 × CLN2037E’, and ‘Eshete × Marglobe’ exhibited positive, highly significant SCA effects for sugar-to-acid ratio, indicating that they could be used in hybridization for developing lines with better fruit flavor.