Full Diallel Research Articles

Combining ability analysis of yield and biomass allocation related traits in newly developed wheat populations

Increasing biomass allocation to the root system may increase soil-organic carbon stocks and confer drought adaptation in water-limited environments. Understanding the genetic bases and inheritance of biomass allocation is fundamental for drought tolerance breeding and soil health. The objective of this study was to determine the general and specific combining ability, maternal effects and the mode of gene action controlling the major yield and biomass allocation related traits in wheat to identify good combiners for breeding and enhanced carbon sequestration. Ten selected wheat genotypes were crossed in a full diallel mating design, and 90 F2 families were generated and evaluated in the field and greenhouse under drought-stressed and non-stressed conditions. Significant differences were recorded among the tested families revealing substantial variation for plant height (PH), kernels per spike (KPS), root biomass (RB), shoot biomass (SB), total plant biomass (PB) and grain yield (GY). Additive gene effects conditioned PH, SB, PB and GY under drought, suggesting the polygenic inheritance for drought tolerance. Strong maternal and reciprocal genetic effects were recorded for RB across the testing sites under drought-stressed conditions. Line BW162 had high yield and biomass production and can be used to transfer favourable genes to its progeny. The parental line LM75 maintained the general combining ability (GCA) effects in a positive and desirable direction for SB, PB and GY. Early generation selection using PH, SB, PB and GY will improve drought tolerance by exploiting additive gene action under drought conditions. Higher RB production may be maintained by a positive selection of male and female parents to capture the significant maternal and reciprocal effects found in this study.

Study of Combining Ability Analysis in Cherry Tomato (Solanum lycopersicum var. cerasiforme)

The study aimed to show the best effect of the general combining ability (GCA) and specific combining ability (SCA) for parents and their hybrids of the studied traits. The study included two main successive seasons. In the first season, cherry tomato pure lines were selected that were introduced from the Tomato Genetics Resource Center (TGRC) at University of California, Davis in USA, 5 pure lines were selected which were the most genetically Distant which are (LA4451, LA4753, LA3334, LA1221 and LA4689) and its code (1, 2, 3, 4 and 5) respectively and entered into Full Diallel crossing program to produce individual crosses. The second season included an experiment to compare genotypes (5 parents + 20 cross-hybrids. and its reciprocal hybrids) according to RCBD design with three replications. The results were as follows: parents 1 showed a general significant ability to combine in the desired direction in terms of fruit set percentage and fruit weight, while the superiority of parent 4 in terms of plant yield and total yield. The parent 5 was superior in the number of flowers in the inflorescence, the number of total flowers of the plant and the number of fruits, whereas the hybrid (5×1) showed superiority in the number of flowers in the inflorescence 35.667, number of total flowers 259.66, the percentage of the set 15.69 and the number of fruits 86.83. (1×4) appeared significant effect of (SCA) were shown significant and desirable in the traits average fruit weight 1.47, plant yield 0.55 and total yield 0.69.

Biochemical and Yield Component of Hybrid Chili (Capsicum annuum L.) Resulting from Full Diallel Crosses

Chili (Capsicum annuum), economically important, is one of the world’s most popular horticultural plants. Functional biochemical components, such as polyphenol content, antioxidants, and α-glucosidase inhibitory properties, are found in chili. The purpose of this study was to evaluate a chili hybrid that resulted through full diallel crosses for its yield components, total phenolic (TPC) and flavonoid content (TFC), antioxidants, and α-glucosidase inhibitory (AGI) activities. The Folin-Ciocalteu and AlCl3-colorimetric assays were, respectively, used for TPC and TFC analyses. Using 2,2-diphenyl-1-picrylhydrazy (DPPH) and ferric reducing antioxidant power assay (FRAP) techniques, the antioxidant activity of a sample was determined. The bioassay of α-glucosidase inhibition was used to evaluate the antidiabetic activity of the sample. The twenty-five genotypes (hybrid and parent) have diverse yield components and biochemical contents. The highest fruit weight per plant was found in IPB074005 (1008.85 g). IPB114367 showed a high AGI (80.25%), antioxidant FRAP (43.42 µmol TE g−1 DW), TFC (3.97 mg QE g−1 DW), and TPC (37.51 mg GAE g−1 DW). These findings suggested that hybrid plants that suppress α-glycosidase and oxidative stress may prevent diabetes and its complications. This vital information could help design replacement drugs and diabetes diets.

Natural genetic variation in a dopamine receptor is associated with variation in female fertility in Drosophila melanogaster.

Fertility is a major component of fitness but its genetic architecture remains poorly understood. Using a full diallel cross of 50 Drosophila Genetic Reference Panel inbred lines with whole genome sequences, we found substantial genetic variation in fertility largely attributable to females. We mapped genes associated with variation in female fertility by genome-wide association analysis of common variants in the fly genome. Validation of candidate genes by RNAi knockdown confirmed the role of the dopamine 2-like receptor (Dop2R) in promoting egg laying. We replicated the Dop2R effect in an independently collected productivity dataset and showed that the effect of the Dop2R variant was mediated in part by regulatory gene expression variation. This study demonstrates the strong potential of genome-wide association analysis in this diverse panel of inbred strains and subsequent functional analyses for understanding the genetic architecture of fitness traits.

Estimation of Hybrid Vigor for Flowering and Yield Cherry Tomato Hybrids

The experiment was carried out in the greenhouses of the extension farm in Diyala governorate for the seasons (2020-2021) and (2021-2022), where ten strains of cherry tomatoes imported from the Tomato Genetic Resources Center (TGRS) at the University of California Davis Institute were planted in the first season. Tomatoes were selected (5 ) pure lines (LA4451, LA4753, LA3334, LA3538 and LA4689) and their symbols (1, 2, 3, 4 and 5), respectively, and entered into a Full Diallel crossing program to produce individual hybrids, and in the second season it included an experiment to evaluate the genotypes (5 parents + 20 hybrids) according to the RCBD design and with three replications, and the results were as follows: Genotypes: There was a significant effect of genotypes, as the parent (1) outperformed in the average fruit weight, per plant yield and total yield (8.41 g, 2.72 kg and 3.40 tons), respectively. The parent (2) outperformed the contract (94.11). parent (5) was superior in the number of flowers in the inflorescence, the number of total flowers and the number of fruits per plant (82.66 inflorescences. plants, 937.00 flowers. plants, and 512.33 fruits. plants). The hybrid (1×4) was also significantly superior in the percentage of the fruit set (95.13), the average fruit weight, the yield of one plant and the total yield (13.45 g, 4.66 kg and 5.82 tons, respectively). While the hybrid (2×5) was superior in the number of total flowers (941.33 flowers). Hybrid (5×2) outperformed in the number of flowers in the inflorescence (90.00 flowers). The superiority of the hybrid (5×4) in the number of fruits (521.33 fruits). Genetic analysis: The hybrid (1×5) showed desirable and significant hybrid vigor for the characteristics of the number of flowers in the inflorescence, the number of total flowers and the number of fruits in the plant). It was also found that the hybrid (5×2) showed a significant hybrid strength for the two traits (one plant yield and total yield). While the hybrid (2×5) and (5×1) recorded the strength of the hybrid for one trait for each of them (the percentage of the knot and the average weight of the fruit) respectively for the best parents.

Heterosis breeding for yield and its attributes in brinjal (Solanum melongena L.)

A study on heterosis in brinjal was carried out during the year 2019-20 at the Department of Genetics and Plant Breeding, Annamalai University. Seven genotypes were hybridised in full diallel fashion and the resultant 42 hybrids were evaluated along with parents in RBD. The mean squares of the 11 traits revealed significant differences among the entries. The hybrid ICO-345590 x Arka Kusumkar recorded high heterobeltiosis for fruit yield per plant and its associated traits except for fruit grith, fruit length, plant height, and days to first harvest. High standard heterosis was recorded by the hybrid ICO-344674 x ICO-383119 for plant height, ICO-344674 x Arka Kusumkar for days to first harvest, Arka Kusumkar x ICO-345590 for fruit length and ICO-345590 x ICO-545862 for fruit girth. The application of heterosis in brinjal will aid in the production of superior cross combinations, which will help meet the expanding demand for brinjal due to its bioactive properties. Keywords: brinjal, heterosis, fruit yield, diallel.

Diallel analysis of length and shape of rice using Hayman and Griffing method

Abstract Length and shape of rice are important physical qualities that determine public acceptance of a variety and determine the price. Improvement of length and shape of rice requires information on the genetic parameters of these traits. Diallel analysis is one of the methods usually used to estimate the genetic parameters of a trait. The purpose of this study was to estimate the genetic parameters of length and shape of rice using full diallel analysis. The plant material used was a full diallel cross-population of six rice genotypes, namely, Basmati Pakistan, Basmati Delta 9, Inpago Unsoed 1, Inpari 31, Koshihikari, and Tarabas. Thirty-six genotypes consisting of parents, F 1 and F 1reciprocal, were planted using a randomized block design with three replications. The data of rice grain length and length:width ratio were used for diallel analysis using the Hayman and Griffing method-1. The results showed additive and non-additive gene action influencing the length and shape of rice. The effect of the additive gene action was greater than the non-additive gene action, while both broad-sense heritability and narrow-sense heritability were high, revealed that the selection of these traits at the early generation using the pedigree selection method may be considered. Length and shape of rice were not affected by the female parent cytoplasm so that F 2 and F 2reciprocal populations may be combined into one population the next generation.

Estimation of mean performance of parents and their hybrids for yield related traits in Gossypium hirsutum L.

Cotton (Gossypium hirsutum L.) is an important fiber crop and plays an important role in Pakistan's economy as a cash crop. Cotton crop is cultivated primarily for fiber. The main objective of all cotton breeders is the production of a new variety with high yield and fiber quality. The current experiment was be conducted in the research area of Department of Plant Breeding and Genetics, University of Agriculture Faisalabad. Crosses were made of four varieties AGC-999, IR-3701, VH-37 and AS-01 by full Diallel mating design in the greenhouse during winter season. Evaluation of 12 crosses and 4 parental varieties were proceeded in the field during Kharif season of 2019 under RCBD (Randomized completely blocked Design) design with three replications. The data for agronomic characters and yield related traits as plant height, number of branches, number of bolls, number of nodes, seed cotton yield, ginning out turn, seed index and lint index was recorded. Mean data of seed cotton yield for all the genotypes indicated that the parent AS-01 provided the maximum yield (93.73 grams) among the parents while AGC-999 × IR-3701 had the maximum yield (82 grams) among the crosses. While VH-37, VH-37 × AS-01 and AS—01 × AGC-999 had the minimum value among parents and crosses respectively. These genotypes

Diallel analysis of kernel weight and grain‐filling traits in maize grown under contrasting nitrogen supply

AbstractUnderstanding the inheritance of maize (Zea mays L.) kernel weight (KW) under contrasting nitrogen (N) supply is crucial for obtaining high KW across diverse N conditions. This work evaluated broad‐sense heritability (H2), general combining ability (GCA), and specific combining ability (SCA) under contrasting N levels for (i) KW and kernel number per plant and (ii) grain‐filling traits represented by the duration of lag and effective filling phases, kernel growth and desiccation rates, maximum water content and volume, and moisture content at physiological maturity. A six‐parent full diallel cross generated via Griffing's method 3 was tested under high (N200) and low (N0) N supply in 2 years (Y). For the various traits: (i) F1 hybrid, and F1 by Y and/or N interactions were significant (p < 0.05); (ii) GCA was significant at both N levels and affected (p < 0.05) by the Y effect; (iii) SCA was important (p < 0.05) only at N200; and (iv) GCA sum of squares was higher than those of SCA (except for KW). For KW and grain‐filling traits, H2 and GCA/SCA ratios were higher at N0 than at N200, suggesting low‐N environments would be more advantageous for developing genetic selection. Lag‐phase duration (LPD), kernel desiccation rate (KDR), and kernel maximum water content (KWCMAX) had higher H2 (≥0.70) and GCA/SCA ratio than KW, particularly under N0. Thus, the highest KW hybrid (LP2×LP662) was composed of inbreds with high GCA for LPD, KDR and KWCMAX, revealing superior KW hybrids could be selected from the GCA of mentioned traits.

Combining ability studies of grain Fe and Zn contents of pearl millet (Pennisetum glaucum L.) in West Africa.

Micronutrient malnutrition is a major challenge in Africa, where half a million children die each year because of lack of micronutrients in their food. Pearl millet is an important food and fodder crop for the people living in the Semi-Arid regions of West Africa. The present study was conducted to determine the stability, combining ability, and gene action conditions of the high level of Fe and Zn content in grain and selected agronomic traits. Hence, eight genotypes were selected based on the availability of grain Fe and Zn contents and crossed in a full diallel mating design. Progenies from an 8 × 8 diallel mating along with the parents were evaluated in an alpha lattice design with three replications in three locations for two years. The parental lines Jirani, LCIC 9702 and MORO, had positive significant general combining ability (GCA) effects for grain Fe concentration, while Jirani and MORO had positive significant GCA effects for grain Zn concentration. For the specific combining ability (SCA), among the 56 hybrids evaluated, only the hybrids LCIC 9702 × Jirani and MORO × ZANGO had positive significant SCA effects for grain Fe concentration across locations, and for grain Zn concentration, the hybrids Gamoji × MORO, LCIC 9702 × Jirani, and ICMV 167006 × Jirani had positive significant SCA effects. The reciprocal effects were significant for grain Zn concentration, grain yield, flowering time, plant height, test weight, and downy mildew incidence, suggesting that the choice of a female or male parent is critical in hybrid production. Grain Fe and Zn concentration, flowering time, plant height, panicle length, panicle girth, panicle compactness, and downy mildew incidence were found to be predominantly under additive gene action, while grain yield and test weight were predominantly under non-additive gene action. A highly positive correlation was found between grain Fe and Zn concentrations, which implies that improving grain Fe trait automatically improves the grain Zn content. The stability analysis revealed that the hybrid ICMV 167006 × Jirani was the most stable and high-yielding with a high level of grain Fe and Zn micronutrients.

Identification of Newer Stable Genetic Sources for High Grain Number per Panicle and Understanding the Gene Action for Important Panicle Traits in Rice

Rice is an important food crop extensively cultivated worldwide, and rice's grain yield should be improved to meet future food demand. Grain number per panicle is the main trait that determines the grain yield in rice, and other panicle-related traits influence the grain number. To study the genetic diversity, 50 diverse Indian-origin germplasm were evaluated for grain number per panicle and other panicle traits for two consecutive seasons (Rabi 2019 and Kharif 2020). The maximum genotypic and phenotypic coefficient of variation was obtained for the number of spikelets and filled grains per panicle. The genotypes were grouped into eight clusters with Mahalanobis' D2 analysis and six groups using Principal component analysis. Based on, per se, performance for grain number per panicle and genetic distances, six parents were selected and subjected to full diallel mating. The genotypes CB12132, IET 28749, and BPT 5204 were the best general combiners for the number of filled grains per panicle and other panicle branching traits, viz., the number of primary and secondary branches per panicle. The hybrid BPT 5204 × CB 12132 identified as the best specific combination for most of the studied panicle traits. The additive gene effects were high for the number of filled grains per panicle, the number of primary branches, and secondary branches, whereas non-additive gene action was high for the number of productive tillers and grain yield per plant. The information obtained from this study will be useful in rice breeding programs to improve panicle traits, especially the grain number, which would result in higher grain yield.

Heritability of temperature-mediated flower size plasticity in Arabidopsis thaliana

Phenotypic plasticity is a heritable trait that provides sessile organisms a strategy to rapidly mitigate negative effects of environmental change. Yet, we have little understanding of the mode of inheritance and genetic architecture of plasticity in different focal traits relevant to agricultural applications. This study builds on our recent discovery of genes controlling temperature-mediated flower size plasticity in Arabidopsis thaliana and focuses on dissecting the mode of inheritance and combining ability of plasticity in the context of plant breeding. We created a full diallel cross using 12 A. thaliana accessions displaying different temperature-mediated flower size plasticities, scored as the fold change between two temperatures. Griffing's analysis of variance in flower size plasticity indicated that non-additive genetic action shapes this trait and pointed at challenges and opportunities when breeding for reduced plasticity. Our findings provide an outlook of flower size plasticity that is important for developing resilient crops for future climates.

Inheritance of Secondary Metabolites Associated With Cowpea Resistance to Flower Bud Thrips

Plant secondary metabolites are part of defense mechanism that form host plant resistance. Understanding the inheritance of secondary metabolites is preliquisite for conducting an effective plant breeding program. The objective of this study was to determine the mode of inheritance of secondary metabolites associated with resistance of cowpea to flower bud thrips. Five cowpea genotypes with varying level of resistance to flower thrips were crossed in full diallel method 1. The F2 were evaluated for secondary metabolites and flower thrips damage in field and screen house. The results confirmed genotype TVU-3804 as resistant, and TVU-9820 and TVU-201 as susceptible to flower bud thrips. Flavonoids, antioxidants, proteins and reducing sugars had significant (p < 0.001) GCA and SCA effects indicating the importance of additive and dominance effect in controlling resistance of flower bud thrips. In addition, significant reciprocal observed for crosses such as Lori Niebe × Sanzi and Sanzi × TVU-3804 for flavonoids and antioxidants is an indication that maternal effect is key in governing resistance of cowpea to thrips. The broad sense heritability was low for secondary metabolites except flavonoid which had moderate value, an indication that delaying selection to a later generation would yield better results while breeding for resistance to flower thrips based on secondary metabolites. The results of this experiment showed that it is possible to use secondary metabolites to breed for improved cowpea resistance to flower bud thrips.

Understanding self-incompatibility and exploring the reproduction biology in Linnaeoideae – with a focus in Abelia – to accelerate cultivar development

Despite being in cultivation for more than 135 years, relatively few cultivars of Abelia have been developed and are commercially available. Cultivar development has been limited by self-incompatibility and crossing barriers with other species. To help overcome these barriers, self-incompatibility systems were investigated in Abelia chinensis R. Brown, Abelia macrotera var. engleriana (Graebner & Buchwald) Rehder, Abelia xgrandiflora (Rovelli ex André) Rehder, and Vesalea floribunda M.Martens & Galeotti. A full diallel cross with self-pollinations was performed in greenhouse-grown plants on recently opened flowers. Styles were removed one and two days after pollination, fixed in a solution of ethanol and glacial acetic acid (3:1) for at least 24 hr, transferred to a solution of 4 N NaOH for 24 hrs to soften the tissues, and then stained with 0.1% decolorized aniline blue with 0.1 M K3PO4. Stained styles were analyzed for pollen tube growth under an inverted epifluorescent microscope. Pollen tubes were inhibited in the upper half of the style on self-pollinations and reached the base of the style on cross-pollinations suggesting the presence of gametophytic self-incompatibility in Abelia and Vesalea. In vitro pollen germination was evaluated in A. chinensis, A. macrotera var. engleriana and Diabelia serrata (Siebold & Zuccarini) Landrein. The most effective germination medium consisted of 10% sucrose, 0.01% H3BO3, 0.02% CaCl3 and 0.5% agar with a pH of 7. Pollen did not germinate in liquid medium and sucrose concentrations of 15, 20 or 25% were not effective. Three samples of pollen from different dehiscent anthers of recently opened flowers from greenhouse-grown plants were placed on top of a slide containing germination medium. Slides were placed on a petri dish with a wet paper towel to ensure 100% humidity and cultured in light at 28.5 ± 0.5 °C. Germination of 100 pollen grains was evaluated at 2 hrs and 24 hrs after culture. Overall, Abelia macrotera var. engleriana had the highest germination, with 80% of the grains germinating after 24 hrs of culture. Diabelia serrata had 49.8% germination, while A. chinensis exhibited very low germination in the three different pH levels tested. In vitro germinated pollen grains of A. chinensis, A. macrotera var. engleriana, and Diabelia serrata were examined for number of nuclei. Pollen was stained for one hour with 0.25 mg∙L−1 or 0.5mg∙L−1 of a 4′, 6-diamidino-2-phenylindole (DAPI) solution and evaluated under a fluorescent microscope. Observations indicate the presence of three nuclei in pollen in Abelia and Diabelia. This is the first report of a self-incompatibility system in Abelia and Vesalea, and pollen nuclei in Abelia and Diabelia.

Estimation of Heterosis and Combining Ability for Improving Yield, Sweetness, Carotenoid and Antioxidant Qualities in Pumpkin Hybrids (Cucurbita moschata Duch. Ex Poir.)

A full diallel mating design was used to hybridize seven pumpkin inbred parental lines, yielding 42 F1 hybrids, including reciprocals. The generated F1 hybrids, parental lines and commercial check hybrid were evaluated in two environments to investigate the per se performances, combining ability effects and magnitude of heterosis over mid-parent, better-parent and commercial check hybrids for yield, yield attributed, sweetness, total carotenoid and antioxidant traits, using a randomized complete block design with three replications. The analysis of variance for most of the examined traits revealed highly significant differences (p ≤ 0.01) for GCA, SCA, reciprocal, maternal and non-maternal variances and their interaction with the environment. Since the inheritance of yield and its contributing fruit quality, and antioxidant traits is governed by non-additive gene action, it suggests heterosis breeding would be useful in obtaining further improvements in pumpkin. From the experiment, it was found that the paternal lines P1 (Gold Butter 315) for dry matter content and DPPH (%), P4 (Asian pumpkin) for total carotenoid content, P6 (Sarawak) for fruit number per plant and P7 (Australia-1) for single fruit weight, fruit flesh thickness, yield per plant and total soluble solid were shown to be good general combiners. In respect to per se performance, combining ability effects and magnitude of heterosis over mid-parent, better-parent and commercial check, the cross P2 (928 Fuxiang) × P1 (Gold Butter 315) and P4 (Asian pumpkin) × P5 (Sarawak) for single fruit weight and yield per plant, the cross P5 (Sarawak) × P2 (928 Fuxiang) for fruits number per plant, P1 (Gold Butter 315) × P7 (Australia-1) and P1 (Gold Butter 315) × P6 (Sarawak) for total soluble solid and dry matter content, P7 (Australia-1) × P2 (928 Fuxiang) for total carotenoid content and P3 (Ser Bajadi) × P1 (Gold Butter 315) for DPPH (antioxidant) were identified to be highly significant positive specific combiners and the highest performers, and these crosses may be exploited as commercial hybrids.

Interacting host modifier systems control Wolbachia-induced cytoplasmic incompatibility in a haplodiploid mite.

Reproductive parasites such as Wolbachia spread within host populations by inducing cytoplasmic incompatibility (CI). CI occurs when parasite‐modified sperm fertilizes uninfected eggs and is typified by great variation in strength across biological systems. In haplodiploid hosts, CI has different phenotypic outcomes depending on whether the fertilized eggs die or develop into males. Genetic conflict theories predict the evolution of host modulation of CI, which in turn influences the stability of reproductive parasitism. However, despite the ubiquity of CI‐inducing parasites in nature, there is scarce evidence for intraspecific host modulation of CI strength and phenotype. Here, we tested for intraspecific host modulation of Wolbachia‐induced CI in haplodiploid Tetranychus urticae mites. Using a single CI‐inducing Wolbachia variant and mitochondrion, a nuclear panel was created that consisted of infected and cured near‐isogenic lines. We performed a highly replicated age‐synchronized full diallel cross composed of incompatible and compatible control crosses. We uncovered host modifier systems that cause striking variation in CI strength when carried by infected T. urticae males. We observed a continuum of CI phenotypes in our crosses and identified strong intraspecific female modulation of the CI phenotype. Crosses established a recessive genetic basis for the maternal effect and were consistent with polygenic Mendelian inheritance. Both male and female modulation interacted with the genotype of the mating partner. Our findings identify spermatogenesis as an important target of selection for host modulation of CI strength and underscore the importance of maternal genetic effects for the CI phenotype. Our findings reveal that intraspecific host modulation of CI is underpinned by complex genetic architectures and confirm that the evolution of reproductive parasitism is contingent on host genetics.

Estimation of parameters of genetic variation of spring durum wheat (Triticum durum Desf.) on the basis of “number of grains from the main spike”

Aim. To assess the combining ability, features and nature of the inheritance of the trait “number of grains from the main spike” in varieties of spring durum wheat for their further involvement in breeding programs. Methods. The investigations were carried out at the V. M. Remeslo Institute of Wheat of NAAS of Ukraine. Varieties (‘Zhizel’, ‘MIP Raiduzhna’, ‘Kharkivska 27’, ‘Kharkivska 39’, ‘Spadshchyna’, ‘Kuchumovka’, ‘Tera’) of domestic breeding were involved in crossings according to the full diallel scheme (7 ´ 7). Parental components and F1 were studied in the field in 2016, 2017. Results. The analysis of variance of combining ability showed a significant advantage in general combining abili­ty (GCA) effects. The mean square of the specific combi­ning ability (SCA) was significantly inferior to the GCA, but was significant in both years of the study. Consistently high GCA effects in 2016, 2017 were determined in the variety ‘Tera’ (gi = 1.35; 2.37). Non-alelic gene interaction was not found, which made it possible to analyze the main parame­ters of genetic variation. In two years of investigations, in the phenotypic manifestation of the number of grains from the main spike, dominant effects (H1 and H2) survived over additive ones (D). The average degree of dominance indicated overdominance (H1/D). The indicator of the ave­rage degree of dominance in loci () also indicated overdominance. Dominance was significantly oriented. Dominant effects of genes increased the number of grains, while recessive effects decreased them. At least one group of genes has been identified that has led to dominance. In general, dominant genes (F > 0) or groups of genes dominated quantitatively in cultivar investigated. A high coefficient of heritability in a broad sense (H2 = 0.88; 0.90) indicates a significant phenotypic conditionality to genetic factors. The coefficient of heritability in a narrow sense (h2 = 0.31; 0.38) indicates the average contribution of the additive effects of genes over the dominant ones. Conclusions. The identified breeding and genetic features on the basis of the “number of grains from the main spike” trait make it possible to predict the effectiveness of selections aimed at increasing the trait in the newly hybrid material. However, due to the predominance of dominant effects and overdominance in the genetic control of a trait, selection in later generations will be more effective. Varieties ‘Kharkivska 27’, ‘Kharkivska 39’ and ‘Tera’ should be used as genetic sources to increase the trait “number of grains from the main spike”.

Evaluation of combining abilities and heterosis effect for a better selection of hybrid barley

Heterosis effect and the combining ability are two main indices of hybrids performance. Predicting hybrid performance and heterosis effect is an important approach in the breeding of hybrid barley. In order to i) combine the local and introduced genetic material; ii) study the combining abilities of parents and hybrids; and iii) analyze the relationships between the heterosis effect, the combining ability and the performance of hybrids, the present research has been initiated. In this study, five cultivars of barley (Hordeum vulgare L.) were crossed according to a full diallel plan comprising P² combinations. The twenty hybrids F2 were assessed by the general combining ability analysis (GCA); by the specific combining ability (SCA) as well as by the calculation of the heterosis effect of six agronomic characters, namely, the weight of the spike (WE), the number of grains per spike (NGE), the weight of a thousand grains (WTG), plant earliness at flowering (PRF), plant harvest index (IR) and plant productivity (P P). The results indicate that GCA for all parameters was significant except for the WE trait while SCA was significant for three of the six traits studied: WTG, IR and PRO. The GCA/SCA ratio revealed that non-additive effects were the main effect on traits assessed in the hybrids F2. Heterosis was significantly correlated with SCA for all traits tested, indicating that non-additive effects were the main effect of heterosis. Hybrids from two parents with a high GCA have consistently shown better SCA and better hybrid performance. Indeed, the selection of parents should be mainly based on their GCA.

Examining the Inheritance of Watermelon Fruit Traits by Hayman's Graphical Approach.

Watermelon traits such as yield and other agronomic traits are highly environmentally sensitive and regulated by multiple genes; therefore, by understanding the genetic structure, the heritability and genetic influence of different traits can improve them. Five watermelon lines were crossed in a 5 × 5 full diallel parental design to estimate the genetic effect and heritability of fruit traits. Treatments were evaluated on the farm using a random complete block design. Analysis of the results showed a significant difference between genotypes, which was observed for all the studied traits at the probability level of 1%. Hayman's graphical method showed that the contribution of the nonadditive effects was more important than that of the additive effect to control most of the traits. Fruit maturation and pericarp thickness traits were regulated by incomplete dominance gene effects, and other traits were regulated by overdominance effects. The trait heritability varied between at least 0.013 and 0.352 for the fruit weight and fruit number, respectively. Results demonstrated that some traits can be modified based on the heterozygosity and production of hybrid variety methods, while the hybrid and selection in an advanced generation method can be suggested in watermelon breeding programs to breed other traits.

Toward Systematic Breeding of Asian Sea Bass, Lates calcarifer (Bloch, 1790), in Malaysia: Status, Challenges and Prospects for Future Development

Asian sea bass, Lates calcarifer (Bloch, 1790), is one of the most farmed marine fish in Malaysia since the 1970s and is predominantly cultured at present. Although it has been farmed for some time, there is no systematic breeding programme in place. Local hatcheries rely heavily on wild and imported broodstock. However, imported stocks do not guarantee improved quality and even increase the chances of introducing pathogens into the country. Availability of superior breeding stocks, efficient dissemination and control of seed production could greatly assist in increasing Asian sea bass production. This paper presents the status of Asian sea bass production, its culture history in Malaysia and the current broodstock development programme implemented by the Fisheries Research Institute, particularly in the 11th Malaysia Plan from 2015 to 2020. In brief, broodstock from Malaysia, Thailand and Indonesia were used as base population and were mated using full diallel method to produce cohorts. Three pairs of the selected broodstock were used for each cross and spawning performance was evaluated. The growth performances of the first generation (F1) offsprings were assessed in different culture systems. Physico-chemical water quality parameters such as dissolved oxygen, temperature, pH and salinity were maintained at optimal levels during all stages of the experiment. Results indicate that the growth performance of F1 improved by more than 60 % in terms of weight gain compared with the base population. The project demonstrated the benefits of using selective breeding to enhance the production of Asian sea bass.