Diallel Experiment Research Articles

HETEROSIS AND COMBINING ABILITY STUDIES IN PEARL MILLET

The present research was carried out to assess combining ability and heterosis through a complete 5x5 diallel experiment for grain yield and related parameters in Pearl millet (Pennisetum glaucum L.). GCA effects were highly significant for days to 50% flowering, panicle length and plant height while non- significant for grain yield per plant, no. of productive tillers and panicle girth. SCA effects were highly significant for grain yield and non- significant for rest of the characters. These studies suggested that non- additive gene action was more important regarding the inheritance of grain yield while additive gene action had major role in the inheritance of days to 50% flowering, no. of productive tillers, panicle girth, panicle length and plant height. The parent MGP-84 was good general combiner for the parameters studied. 15RBS-01 was good general combiner for all the characters except days to flowering. The crosses, MGP-84 x 13RBS-09, MGP-304 x 15RBS-01, MGP-84 x 13RBS-10, 13RBS-10 x 15RBS-01, 13RBS-09 x 15RBS-01, MGP-84 x 15RBS-01 and MGP-84 x MGP-304 were the best combinations for grain yield which involved good x good and good x poor general combiners. SCA variance for grain yield was higher than GCA variance indicating that non-additive gene action had major role in its inheritance. GCA variances for days to flowering, productive tillers, panicle girth, panicle length and plant height were higher than SCA variances which suggested that additive gene action had played key role in the inheritance of these traits

Combining Ability and Heterosis for Some Yield Component Traits in a 10x10 Diallel Cross of Rice (Oryza sativa L.)

A ten – parent diallel experiment was carried out at the Teaching and Research Farms of the Federal University of Agriculture, Makurdi, Nigeria, to estimate combining ability and heterosis in rice. The design was a 10x10 alpha lattice with three replications and data was collected on plant height (PH), tiller numbers/plant (TN), leaf length (LL) and width (LW), days to flowering (DF), panicle length (PL), panicle exsertion (PE), spikelet numbers/panicle (SN), 100 seed weight (100SW) and days to maturity(DM). A preponderance of both additive and non – additive gene action with both negative and positive GCA, SCA and % heterosis was observed in the control of yield component traits in the studied rice varieties and their hybrids. Non – additive variance was higher, except for DF, SN and DM where additive variance was higher compared to non – additivity. Six parents, namely MGD 101, FARO 44, FARO 52, FARO 57, STRASSA 58 and IR 72 recorded the highest GCA values for most of the traits and the least values in terms of days to flowering and maturity. These parents were the most frequent in crosses with the highest SCA effects and % heterosis for Tiller number, Leaf length, leaf width, panicle length and Spikelet numbers/panicle. Crosses involving these six parents also recorded the least SCA effects and % heterosis for days to flowering and maturity. Based on the results of GCA, SCA and % heterosis, backcross breeding of F1s to their respective parents (the six parents), was recommended for improvement of yield component traits.

Exploring Heterosis in Melon (Cucumis melo L.).

Heterosis is the superiority of an F1 hybrid over its parents. Since this phenomenon is still unclear in melon, a half diallel experiment based on eight genetically distant breeding lines was conducted in six environments of Central Italy, assessing commercially important traits: yield, total soluble solids (TSS), and days to ripening (DTR). To estimate the additive (general combining ability; GCA) and the non-additive gene effects (specific combining ability; SCA), yield was analyzed by Griffing’s methods two and four, and the results were compared to the GGE (Genotype plus Genotype by Environment interaction) biplot methodology; TSS and earliness were evaluated only by Griffing’s method four. Overall, GCAs were significantly more relevant than SCAs for all examined traits. Least square means (LsM), mid-parent heterosis (MPH), best-parent heterosis (BPH), as well as Euclidean and Mahalanobis’ distances were calculated and compared with the genetic distance (GD). As a few correlations were found statistically significant (only for TSS), it was difficult to predict the value of a hybrid combination only by knowing the genetic distance of its parents. Despite this, heterosis was observed, indicating either the presence of epistatic effects (additive × additive interactions) and/or an underestimate of SCAs embedded within Griffing’s method. The significant Env × Entries source of variation suggests development of hybrids in specific environments. The results are discussed with a breeding perspective.

Diallel Analysis of Sweet Potato [Ipomoea batatas (L.) Lam] Genotypes for Combined Beta Carotene and Dry Matter Content in Southern Guinea Savanna, Nigeria

Roots of orange-fleshed sweet potato varieties currently available in Nigeria contain high quantities of β-carotene or pro-vitamin A but have high moisture content. These varieties have been found to be a cheap and crucially important remedy for vitamin A deficiency. The cream or white-fleshed varieties, on the other hand, have a sweet taste with high dry matter content, giving a dry texture, a quality trait preferred in Nigeria. Development of sweet potato genotypes that can combine these two important quality traits is the objective of this breeding work. A diallel experiment using six parental sweet potato genotypes crossed in all possible combinations were carried out and thirty progenies were evaluated for beta carotene (β-carotene) and dry matter content in Landmark University, Omu Aran, Kwara State, Nigeria. The 30 F1 progenies along with their parental lines were planted in the same field trial. The trial was laid out in 6 x 6 triple lattice in two replications. Highly significant (P≤ 0.01) differences were observed among the genotypes for the traits. The average β-carotene content among the progenies was 2.86 (mg/100g.f.w) while the dry matter cttgontent had a mean value of 31.89%. The cross progenies 199024.2 x Excel had the highest beta carotene (14.37mg/100g.f.w) content with the highest dry matter content (40.10%) and are therefore recommended for further evaluation.

Study on performance evaluation and crossbreeding effects for juvenile body weights in duck

A 3×3 complete diallel experiment was made using three populations of ducks namely indigenous duck (D), Khaki Campbell (K) and White Pekin (W). Standard feeding and management practices were followed. Body weight at first day, 1, 3, 5 and 7th week of age were recorded. Data were analysed to derive the differences between genetic groups. The traits showing significant difference were used for the analysis of combining ability. Heterosis per cent was also calculated. Significant differences between different genetic groups were observed for all the traits studied. Body weight at 7 weeks of age were 995, 1069, 2145, 1185, 1707, 1316, 1815, 1633 and 1559 g, respectively. W recorded significant higher body weight amongst the purebreds irrespective the age. Body weights were higher in the crosses having White Pekin as one parent. Significant general combining ability (GCA), specific combining ability (SCA) and reciprocal effect (RE) were observed for all the traits indicating importance of additive genetic effects, non-additive genetic effects and maternal/sex linked effects. Heterosis per cent decreased with the advancement of the age. The study indicates that for meat purpose KW and DW are useful as they recorded higher body weight, whereas for medium weight type duck WD and WK are the preferred crosses and may be used as dual purpose duck. For smaller duck DK and KD are the best choice which may be used for egg laying purpose.

Role of Cis, Trans, and Inbreeding Effects on Meiotic Recombination in Saccharomyces cerevisiae.

Meiotic recombination is a major driver of genome evolution by creating new genetic combinations. To probe the factors driving variability of meiotic recombination, we used a high-throughput method to measure recombination rates in hybrids between SK1 and a total of 26 Saccharomyces cerevisiae strains from different geographic origins and habitats. Fourteen intervals were monitored for each strain, covering chromosomes VI and XI entirely, and part of chromosome I. We found an average number of crossovers per chromosome ranging between 1.0 and 9.5 across strains ("domesticated" or not), which is higher than the average between 0.5 and 1.5 found in most organisms. In the different intervals analyzed, recombination showed up to ninefold variation across strains but global recombination landscapes along chromosomes varied less. We also built an incomplete diallel experiment to measure recombination rates in one region of chromosome XI in 10 different crosses involving five parental strains. Our overall results indicate that recombination rate is increasingly positively correlated with sequence similarity between homologs (i) in DNA double-strand-break-rich regions within intervals, (ii) in entire intervals, and (iii) at the whole genome scale. Therefore, these correlations cannot be explained by cis effects only. We also estimated that cis and trans effects explained 38 and 17%, respectively, of the variance of recombination rate. In addition, by using a quantitative genetics analysis, we identified an inbreeding effect that reduces recombination rate in homozygous genotypes, while other interaction effects (specific combining ability) or additive effects (general combining ability) are found to be weak. Finally, we measured significant crossover interference in some strains, and interference intensity was positively correlated with crossover number.

SASHAYDIALL: A SAS Program for Hayman's Diallel Analysis.

Different methods of diallel crossing are commonly used in plant breeding. The diallel cross analysis method proposed by Hayman is particularly useful because it provides information, among others, on additive and dominance effects of genes, average degree of dominance, proportion of dominance, direction of dominance, distribution of genes, maternal and reciprocal effects, number of groups of genes that control a trait and exhibit dominance, ratio of dominant to recessive alleles in all the parents, and broad-sense and narrow-sense heritability. In this paper, we fully describe a SAS-based software SASHAYDIALL for performing a complete diallel cross analysis based on Hayman’s model with or without reciprocals. We demonstrate the use of SASHAYDIALL with two data sets; one is a published diallel cross data set with reciprocals in cabbage (Brassica oleracea L.), and the second is a data set from a multilocation diallel cross trial in maize (Zea mays L.) without reciprocals. With SASHAYDIALL, diallel experiments conducted in single sites can be analyzed to estimate various genetic parameters, and this analysis is extended over locations or environments to assess genetic effect × environment interaction. SASHAYDIALL is user-friendly software that provides detailed genetic information from diallel crosses involving any number of parents and locations.

Combining ability and heterosis analysis for mineral elements by using cytoplasmic male-sterile systems in non-heading Chinese cabbage (Brassica rapa)

Brassica vegetables are an important source of dietary nutrition. The nutritional quality of mineral elements is becoming one of the most important studied traits because of the year-round supply of vegetables in China. However, there are few reports about breeding and utilisation of mineral elements in non-heading Chinese cabbage (Brassica napus L.). Using two newly reported CMS (cytoplasmic male-sterile) lines of non-heading Chinese cabbage, we conducted incomplete diallel experiments to analyse heterosis, combining ability and cytoplasmic effects for mineral elements such as calcium (Ca), iron (Fe), magnesium (Mg) and zinc (Zn). Heterosis analysis of mineral elements indicated that the crossing combinations A1 (hau CMS) × C03, A2 (eru CMS) × C03 and A2 × C11 exhibited desirable positive effects of mid-parent heterosis and high-parent heterosis in terms of mineral element content that could be exploited for commercial purposes. Analysis of general combining ability (GCA) effects of the parental lines indicated that the tester C11 was superior for the improvement of the four mineral elements; CMS line A1 had greater GCA effects than CMS line A2 for Ca and Fe. The hybrid combinations A2 × C11, B × C05 and B × C12 showed positive specific combining ability (SCA) effects for the four mineral elements on overall performance. The analysis revealed that cytoplasmic effects of hau CMS and eru CMS were both positive for Ca and Fe, and that A1 had more obvious cytoplasmic effects than did A2. These results indicated that the two isonuclear, alloplasmic CMS lines of non-heading Chinese cabbage might be useful for improving the nutritional quality traits of cruciferous vegetables and for heterosis utilisation.

Optimal Block Designs for Diallel and Double Cross Experiments

ABSTRACT: Methods of construction of optimal block designs for a diallel cross and double cross experiments are proposed for even value of p of parental lines. The proposed designs are obtained by using unreduced balanced incomplete block designs.

Effects of open- and self-pollination treatments on genetic estimations in maize diallel experiment

This study investigated the effects of open- and self-pollination treatments on genetic estimations and kernel biochemical content in a maize diallel experiment. A 7×7 complete reciprocal diallel set (7 parents and 42 hybrids) was used as plant material. Measured traits were: kernel weight per plant, protein content, oil content and carbohydrate content. General combining ability (GCA), specific combining ability (SCA), maternal effects (MAT), non-maternal effects (NMAT) and heterosis values were compared in open- and self-pollination treatments for measured traits. Results showed that the pollination treatments had a significant effect on all investigated traits. Parental lines and hybrid combinations gave different responses. Parents had relatively higher protein and oil content in self-pollination but hybrids had lower values in self-pollination compared with open-pollination. A considerable number of genotypes showed significant differences for genetic estimations (GCA, SCA, MAT, NMAT) and heterosis between open- and self-pollination treatments. Overall, findings suggest that evaluation of kernel quality traits should be made on selfed ear samples; however, evaluation for yield should be carried out on open-pollinated samples.

Estimation of genetic mechanism of stomatal traits influencing grain yield in hexaploid wheat (Triticum aestivum L.)

Efforts to improve wheat plant have been made at various plant characters. Yield component breeding and modification of the plant architecture offer possibilities to develop more efficient breeding systems for increased grain yield. A 6 × 6 diallel experiment was conducted to determine the genetic mechanism of stomatal traits influencing grain yield in hexaploid wheat. Graphical representation indicated the over-dominant type of gene action for 1000-seed weight, seed yield per plant, leaf venation, stomatal size, epidermal cell size and stomatal frequency suggesting that selection would be difficult in early segregating generation. Hence heterosis breeding may useful for genetic improvement for these traits. Non allelic interactions were found to be absent for all traits. The genotype Aas-11 contained maximum dominant genes for epidermal cell size while genotype 9515 for 1000grain weight and seed yield per plant. The genotype 9516 possessed maximum dominant genes for leaf venation. Whereas, genotype Iqbal-2000 carried maximum dominant genes for stomata size.

Genetic analysis of some agronomic traits in groundnut (Arachis hypogaea L.)

A 10×10 half diallel experiment was conducted on groundnut (Arachis hypogaea L.) to ascertain the gene action and genetic parameters of ten traits including 50% flowering, no. of pods per plant, plant height, harvest index, pod index, 100 pod weight, 100 kernel weight, pod size, diseases infection and yield per plot. The experiments were carried out in the Department of Genetics and Plant Breeding, Bangladesh Agricultural University (BAU), Mymensingh during the cropping season of 2010-2011. The estimates of gene effects indicated that significance of both additive and non-additive variance for pod size, 100 pod weight and diseases infection among the traits and presence of over dominance satisfying assumptions of diallel except dormancy. However, both the additive and non-additive gene affects together importance to control of most quantitative traits in the groundnut. The average degree of dominance (H1/D) 1/2 (H1 = dominance variance, D = additive variance) was higher than one, indicating over dominance for all the traits. The narrow-sense heritability was high for 50% flowering (38%), harvest index (35%), pod size (52%), 100 pod weight (35%) and yield per plot (41%) indicating that great genetic gain could be achieved for them. DOI: http://dx.doi.org/10.3329/ijarit.v3i2.17841 Int. J. Agril. Res. Innov. & Tech. 3 (2): 31-35, December, 2013

General combining ability (GCA), specific combining ability (SCA) and reciprocal effects on average daily gain in body weights at various ages of rabbit in northern guinea savannah zone of Nigeria

Complete diallel experiment was carried out involving three rabbit breeds (Chinchilla {CHC}, New Zealand White {NZW} and Californian White {CAW}). Data on post weaning average body weight gain were analysed by complete diallel analysis after first been corrected for significant effects of season of birth and sex of animal using the least squares constants. The variations due to general combining ability (GCA) as well as specific combining ability (SCA) were highly significant (P 0.01) indicating absence of maternal effect. The GCA effect was positive and considerably high for CHC and NZW but negative for CAW. The crosses of NZW and CHC with CAW rabbit had positive and high SCA effect. The findings from this study further revealed positive GCA effect in the two breeds (NZW and CHC) in respect of post weaning growth performance up to 90, 120 and 150 days of age. This was contrary to the negative GCA effect in CAW breed. The results suggested that the growth performance of NZW and CHC breeds far exceeded that of CAW breed of rabbit. When crossed with CAW breed, NZW and CHC showed positive SCA effects for the tested trait. On the basis of these findings, crossbreeding of CAW with NZW as well as with CHC was advocated.

Genetics of yield and related traits in groundnut using diallel analysis

A 10×10 diallel experiment was conducted on groundnut (Arachis hypogaea L.) to explore the genetic mechanism of yield and its related traits. The data obtained from the experiment were subjected to analysis of variance. The analysis of variance indicated highly significant differences among the parents and their hybrids in F1 generation for all the character were studied in the experiment. The observations were recorded on 50% flowering, plant height, harvest index, pod size, 100 pod weight, 100 kernel weight, diseases infection and yield per hectare, respectively. It reveals that additive and non-additive gene action was involved in the inheritance of this character. Hayman’s ANOVA in accordance with Morley Jone’s modification reveals that both additive (a) and dominance (b) components were significant and exclusively control this character. Graphical analysis revealed non additive gene action with overdominance for harvest index, 100 pod weight, 100 kernel weight and pod index. Additive gene action with overdominance was found for pod size and diseases infection. Genetic analyses of traits confirm the involvement of additive and non-additive gene effects in governing the inheritance of these traits. No epistatic effects were found for all the traits under consideration. From these results, it could be concluded that selection for all the traits under study would be effective in early generation within limits of this experiment.

Performance evaluation and crossbreeding effects for body weight and conformation traits in different breeds of ducks

A 3×3 full diallel experiment was carried out using 3 breeds of ducks, viz. Indigenous duck (D), Khaki Campbell (C) and White Pekin (P), to evaluate the juvenile body weights and conformation traits and to estimates different crossbreeding genetic parameters in 609 ducklings from nine genetic groups. Significant differences between different genetic groups were observed for all the traits measured. Direct genetic effects, maternal effects and heterosis were significant for all the traits studied. Heterosis was in desirable direction for all the traits. Overall results revealed that crossbreds performed significantly higher than the purebreds. C × P recorded highest body weight amongst the crossbreds at 8 weeks of age. Heterosis (%) estimates for 8 week body weight, shank length and keel length were positive. Since both additive and non-additive genetic effects are important for the juvenile traits, establishment of pure lines with specialized sire and dam lines followed by crossing is ideal for the production of different crosses for the commercial duck farming.

Genetics of yield and related traits in bread wheat over different planting dates using diallel analysis

An 8x8 diallel experiment was conducted on bread wheat (Triticum aestivum L.) to ascertain the genetic mechanism of yield and its related traits. The observations were recorded on days to heading, productive tillers plant-1, number of grains spike-1, grain yield plant-1 and 1000-grain weight. The experiment was planted in randomized complete block design in three replicates. F-test declared significantly different means for all traits. Analysis of genetic components revealed significant additive (D) and dominant (H) genetic variations for days to heading, productive tillers plant-1, number of grains spike-1, grain yield plant-1 and 1000-grain weight under all three environments. Under normal planting both additive (D) and dominant (H) components were significant for productive tillers plant-1 and grain yield plant-1, while under late planting significant additive (D) and dominant (H) components were found for number of grains spike-1. Graphical analysis revealed additive gene action with partial dominance for days to heading and 1000-grain weight under early and normal planting. Negative intercepts of regression lines indicated non-additive gene action with over dominance for days to heading and 1000-grain weight under late planting, for productive tillers plant-1 and grain yield plant-1 under normal planting and for grains spike-1 under late planting. Genetic analyses of traits confirm the involvement of additive and non-additive gene effects in governing the inheritance of these traits. Key words: Diallel analysis, genetic analysis, breed wheat, yield components of wheat.

Genetics of Aluminum‐induced Callose Formation in Maize Roots, a Selection Trait for Aluminum Resistance

ABSTRACTAcid soils and associated aluminum toxicity could limit maize (Zea mays L.) production on more than 3950 million hectares worldwide. Callose formation in root tips is a reliable indicator of Al‐induced cell damage. We studied the modes of gene action determining callose formation in root tips using two diallel mating experiments involving a total of 33 maize inbred lines grown in 25 μM Al nutrient solution. Highly significant differences were found among parents, crosses, general combining ability (GCA), specific combining ability (SCA) effects, and for the contrast of parents vs. crosses in both diallel experiments. These results indicate that additive and nonadditive gene effects were important in the expression of callose content.

Yield Variation among Clones of Lowbush Blueberry as a Function of Genetic Similarity and Self-compatibility

Two types of field hand crosses (pairwise touching-neighbor and a full 5 × 5 diallel, Griffing's Model 2, Method 3) were performed in combination with genetic similarity estimations of mating partners using expressed sequence tag–polymerase chain reaction molecular markers to elucidate genetic factors underlying yield variations among clones (genotypes) of lowbush blueberry (Vaccinium angustifolium) in two managed fields in Maine. Genetic similarity values for touching pairs ranged from 0.308 to 0.765. Based on pairwise touching-neighbor crosses, no evidence was found for yield being affected by genetic similarity. However, self-fertility of clones was a significant positive predictor of outcross yields. The calculation of lethal equivalents, derived from selfing to outcross ratios, showed a large range in genetic load among clones and a higher average load than that previously reported in the related highbush blueberry (V. corymbosum). The diallel experiment revealed significant general and specific combining ability for all three post-pollination yield traits measured (proportion fruit set, mean mature seed per pollination, and mean berry weight per pollination). Narrow-sense heritability estimates for all three yield traits were moderately high (h2 = 0.58, 0.46, and 0.56, respectively). It is concluded that phenotypically screening for self-compatible clone yield attributes could be useful in identifying germplasm candidates for breeding and propagation.

Genetic Analysis of Yield and Its Components of B. napus Hybrids Using Resynthesized Rapeseed Lines

Resynthesized rapeseeds obtained by crossing the diploid parents Brassica rapa and Brassica oleracea have significant potential in hybrid breeding because of their higher genetic basis compared with Brassica napus cultivars. In this study, an 8 × 8 complete diallel experiment using four B. napus cultivars (BN) and four resynthesized rapeseed lines (RS) as parents was designed to study heterosis and genetic inheritance for yield components. The results showed that heterosis for yield per plant, the number of pods per plant and number of seeds per pod were high, with means 32.77, 24.49 and 15.71%, respectively. Diallel analysis showed that both additive and dominant effects were significant for yield and yield components. All traits, except for 1 000-seed weight, were significant for b1 mean squares and exhibited directional dominance. Dominant genes had positive effects on yield per plant, pods per plant and 1000-seed weight, and negative effects on seeds per pod ( r = −0.86, −0.62, −0.41, and 0.47, respectively). Narrow-sense heritability for yield per plant, pods per plant, and 1 000-seed weight and seeds per pod were 66, 31, 46 and 78% for the four traits, respectively. The F 1 hybrids showed considerable yields compared to B. napus cultivars when B. napus cultivars and resynthesized rapeseeds were used as parents (NR hybrids), with many more pods per plant and lower seeds per pod compared with the rapeseed cultivars, indicating that the resynthesized rapeseed may be applicable in current hybrid breeding programs.

Influence of nitrogen application on grain yield and end use quality in segregating generations of bread wheat (Triticum aestivum L)

Variation in bread making quality of wheat (Triticum aestivum L) is a major consideration for suppliers and bakers. Grain protein concentration, protein quality, ash content and carbohydrates are major quality attributes of bread wheat. Breeders and their cereal chemist colleagues use predictors of these end use quality factors in the early generations to develop improved cultivars. Six populations of bread wheat derived from a previous diallel experiment were evaluated under three rates of nitrogen fertilizer for grain yield and end use quality. Increasing nitrogen (N) rates from low (40 kg fad-1. N) to high (120 kg fad-1. N) had an accelerating significant effect on grain yield and quality in F2 and F3generations. Desirable quality types along with high grain yield were defined within the C3, C4 and C6 populations. The population C6 exhibited the highest flour protein (13.8%) and the lowest flour ash (0.42%) as well as good grain yield as compared with the check variety and other populations. In F3 populations, 1000-kernel weight was an effective selection criterion for grain yield in pop. C3, C4 and C6 but it caused reduction in flour protein in pop. C1. Grain protein concentration showed an increasing trend in F3 generation, confirming the positive relationship with grain yield. The expected response to selection of F3 populations under high N level were 8.81% for grain yield, 8.0% for flour protein 5.74% for gluten and 4.98% for carbohydrates. The SDS-PAGE of grain storage proteins was performed in order to analyze molecular weight of gluten subunits (GS) and investigate genetic diversity among the selected populations. The population C6 exhibited the highest unique bands (5 from 7 bands) under high N level and followed by the population C4. The high N level generally increased total high-molecular weight-GS content in wheat grain, although different patterns of response to N rate were observed between populations. Key words: Bread wheat, segregating populations, nitrogen, protein electrophoresis.