Heterosis and Genetic Diversity of Yield and Its Some Components in F1 of Sunflower Inbred Lines

Fall season 2020, six inbred lines of sunflower were crossed by half-diallel crosses to obtain 15 single hybrids. The genotypes (parents and first-generation hybrids -F1) were planted in randomized comlete block design (RCBD) with three replications in a field/Babylon Governorate during the spring season 2021. The study aimed to estimate Heterosis of the first generation hybrids from the mean of the parents for the traits; stem diameter, head diameter, number of seeds per head, weight of 100 seeds, seed yield and oil yield per plant. Furthermore, estimation of genetic distance among genotypes using cluster analysis. The results of the analysis of variance showed that there were significant differences at the probability level (0.01) for all the studied traits of the parents and the first generation hybrids. The two hybrids (I×Q) and (Q×C) were distinguished a high significant positive heterosis for most of the traits measured. The cluster analysis showed that the two genotypes that include hybrids (Q×C) and (Q×F) had the highest Euclidean distance (175.92 and 183.66) respectively. This indicated to high degree of genetic diversity between the two hybrids and the rest of the studied hybrids, which it positively reflected on the performance of the hybrids for the studied traits. The results of Principal Component Analysis (PCA) and Dendrogram showed that (Q) genotype was far from the rest of the genotypes and isolated to a single group, whereas the remaining genotypes separated into groups to two separed branches, especially the two genotypes (C( and )Q). The reason may be due to the distinguish genetic difference of these interested genotypes which have the ablility to transfer from parents to the its progenies, which resulted from a presence of the clear genetic distance between them, while, other genotypes lacks the of this genetic variation case.

Parental Diversity and Its Relationship with Performance of F1 Hybrid in Rice (Oryza sativa L.)

The present investigation was carried out including 10 parents and their 45 half diallel crosses with the objective to study the relationship between heterosis and diverse genotype. The Mahalonobis D2values resulted in grouping of 10 parents into 3 clusters. Cluster I was comprised of four genotypes, cluster II comprised of five genotypes while, cluster III was found monogenotypic. Cluster II and Cluster III had maximum mean values for 4 traits. Highest intercluster distance was also observed in these 2 cluster followed by cluster I and III . Maximum intra cluster distance was observed in cluster II followed by cluster I. The highest contribution in the manifestation of total genetic divergence was exhibited by grain iron content followed by grain zinc content. The relationship between parental diversity and heterosis indicated that majority of crosses belong to moderate divergence class. The cross P4×P5 exhibiting better parent heterosis for maximum traits also exhibited at par mean performance for 5 traits including grain yield per plant over the better parent. For grain zinc content, two crosses from high and low while, nine crosses from moderate divergence classes reported positive significant heterosis and SCA effects. For grain iron content, 1 cross with high, 2 crosses with moderate while four crosses with low divergence classes reported significantly positive heterosis and SCA effects.

Estimation of Heterosis in Okra [Abelmoschus Esculentus (L.) Moench] for Fruit Yield and Its Components Through Line × Tester Mating Design

Estimation the magnitude of heterosis for yield and yield contributing parameters of Okra was conducted. Fifty-four F1 hybrids were generated by line x tester mating design. These F1s along with 21 parents and commercial check (Mhyco-10) were evaluated in a randomized block design with two replications. Analysis of variance with respect to yield and quality characters in parents and hybrids were highly significant. This indicates the existence of high variation in parents and hybrids for different characters studied. Out of 54 cross combinations, seven crosses revealed the significant and positive heterosis over better parent. While 11 crosses showed positive and significant heterosis over economic parent. It is pertinent to mention that the crop has potential to produce the heterotic cross combinations and such crosses can be used for further improvement of this crop. Five crosses, namely L43 × T44, L22 × T36, L22 × T44, L53 × T36 and L31 × T23 were found to be potential for the production of fruit yield per plant and other desired characters. The high heterosis and per se performance was found in hybrid L43 × T44 over both better parents and standard check for fruit yield per plant. This indicates that the cross can be exploited commercially. Bangladesh J. Bot. 50(3): 531-540, 2021 (September)

THE EVALUATION OF CONFECTIONERY SUNFLOWER HYBRIDS BY ECONOMIC CHARACTERS

As a result of the evaluation, we identified experimental hybrids VK905 A × L171465 and VK934 A × L171465, which exceeded the standard by the thousand-seed weight and by the productivity, respectively. In most part of the studied hybrid combinations, we observed the positive heterosis and the positive dominance of the thousand-seed weight; but the negative heterosis predominated in case of seed huskness.

Genetic basis of negative heterosis for growth traits in chickens revealed by genome-wide gene expression pattern analysis

Background Heterosis is an important biological phenomenon that has been extensively utilized in agricultural breeding. However, negative heterosis is also pervasively observed in nature, which can cause unfavorable impacts on production performance. Compared with systematic studies of positive heterosis, the phenomenon of negative heterosis has been largely ignored in genetic studies and breeding programs, and the genetic mechanism of this phenomenon has not been thoroughly elucidated to date. Here, we used chickens, the most common agricultural animals worldwide, to determine the genetic and molecular mechanisms of negative heterosis. Results We performed reciprocal crossing experiments with two distinct chicken lines and found that the body weight presented widely negative heterosis in the early growth of chickens. Negative heterosis of carcass traits was more common than positive heterosis, especially breast muscle mass, which was over − 40% in reciprocal progenies. Genome-wide gene expression pattern analyses of breast muscle tissues revealed that nonadditivity, including dominance and overdominace, was the major gene inheritance pattern. Nonadditive genes, including a substantial number of genes encoding ATPase and NADH dehydrogenase, accounted for more than 68% of differentially expressed genes in reciprocal crosses (4257 of 5587 and 3617 of 5243, respectively). Moreover, nonadditive genes were significantly associated with the biological process of oxidative phosphorylation, which is the major metabolic pathway for energy release and animal growth and development. The detection of ATP content and ATPase activity for purebred and crossbred progenies further confirmed that chickens with lower muscle yield had lower ATP concentrations but higher hydrolysis activity, which supported the important role of oxidative phosphorylation in negative heterosis for growth traits in chickens. Conclusions These findings revealed that nonadditive genes and their related oxidative phosphorylation were the major genetic and molecular factors in the negative heterosis of growth in chickens, which would be beneficial to future breeding strategies.

Gene Action Studies in Cowpea Inbreds and Hybrids with Varying Levels of Heterosis

Background: Cowpea is an important pulse crop grown worldwide that fits well in a variety of cropping systems. Improvement in yield and related characters along with reduced duration are desirable traits in this crop. The study of heterosis reveals the type of gene action involved which enables the plant breeder to adopt suitable breeding methodology for its improvement. Methods: The present investigation was carried out with 10 parent partial diallel design to analyse the gene action and estimate of heterosis with respect to nine yield related traits in cowpea.Result: Highly significant variances observed for all the traits indicated that hybrids and parents were different from each other for the traits under study and that variability in the breeding materials was attributed to additive and non-additive gene effects. Perusal of the data revealed significant positive heterosis for all yield related traits and significant negative heterosis for days to 50% flowering indicating earliness. Among the twenty five crosses studied, VS9 x VS43, VS24 x VS45 and VS44 x VS47 had significant heterosis for maximum number of characters. Both gca and sca variances were significant for all the characters indicating both additive and non-additive gene actions controlling the various traits. The additive variance was much higher than dominance variance for the characters days to 50% flowering, pod length, pod breadth, pod weight, pods per plant and cluster, pod yield per plant, seeds per plant and length of harvest period suggesting the preponderance of additive gene action.

Heterobeltiosis and Economic Heterosis for Grain Yield Related Traits of Boro Rice (Oryza sativa L.)

Rice is a staple food for more than half of the world’s population and to increase the yield potential of rice would be a key factor for mitigating global demands of about 810 million tons of rice by 2025. To exploit the economic importance of heterosis, quantitative valuation was carried out in a randomized complete block design with three replications for 16 agronomic traits of 5x5 half diallel populations during boro season of 2017-2018. Diallel populations were generated by using five selected parents (P1: BRRI dhan28, P2: BRRI dhan74, P3: BINA dhan10, P4: IR59418-7B-21-3 and P5: BRRI dhan67) where, P1 was considered as standard check to estimate the economic heterosis. Analysis of variance revealed highly significant variability among the genotypes for most of the traits except grain length and length-breadth ratio. The results showed that none of the hybrid combination performed better for all the traits over the three types of heterosis. The highest relative heterosis was recorded in P3×P4 followed by P4×P5 for grain yield plant-1, filled grains panicle-1, effective tillers plant-1. Majority of the cross combinations (>60%) revealed highly significant positive heterosis for grain yield plant-1 over mid parent. Heterobeltiosis for grain yield plant-1 was observed significant for 50% cross combinations and could be utilized in hybrid breeding. Whereas, more than 70% crosses exhibited undesirable negative standard heterosis for grain yield plant-1. Only two cross combinations (P3×P5 and P3×P4) among ten revealed significant positive economic heterosis for grain yield plant-1 and those could be exploited in rice breeding. Int. J. Appl. Sci. Biotechnol. Vol 9(1): 45-53

Evaluation of staygreen sunflower lines and their hybrids for yield under drought conditions

The experimental material for the present study comprised of 28 inbred lines (including two checks) which were developed by mutation and hybridization among the lines from AICRP trials MARS, UAS, Dharwad and on the basis of SPAD readings and stay green nature, they were considered as drought tolerant lines. These lines were used for the present experiment and were evaluated under both normal and moisture stress condition in rain out shelter to study their root characteristics. Among 28 inbreds evaluated, eight inbred lines i.e. DSR-13, DSR-19, DSR-23, DSR-24, DSR-37, DSR-66, DSR-107 and DSR-132 were identified as drought tolerant nature which exhibited least reduction in their yield under moisture stress condition. Simultaneously hybridization programme was also initiated during summer 2018 using these 28 inbred lines as testers (males) and 5 CMS lines as female lines in Line × Tester fashion. Among 140 hybrids developed, only 40 F1 hybrid combinations were further analyzed for heterosis and combining ability studies along with four checks RHA 6D-1, RHA 95C-1, KBSH-53 and Cauvery Champ. Most of the hybrid combinations showed significant negative heterosis for flowering indicating earliness, and also all the combinations showed a positive heterosis for plant height indicating tallness dominant over dwarf checks. The combinations CMS 7-1-1 A × DSR-37 (624 kg/ha), CMS-853A × DSR-19 (624 kg/ha), and CMS-853A × DSR-23 (619 kg/ha) exhibited significant maximum heterosis for seed yield (kg ha−1) over the checks KBSH-53 (496.50 kg/ha) and Cauvery Champ (486.50 kg/ha) showing maximum seed yield per hectare.

Evaluation of selection material and forecasting of heterosis in the early stages of sugar beet (Beta Vulgaris l.) Plants

To conduct successful selective work aimed at high-yielding sugar beet hybrid creation, it is important to study the source material, its diversity and economically valuable features and patterns of their inheritance. The physiological approach and the development of ways to improve and estimate the population, based on physiological and biochemical indicators contribute to a deeper understanding of the production process. Therefore, the main goal of our work was to conduct a comparative physiological and biochemical evaluation of the production process of different sugar beet genotypes. Research objects were the MS hybrids with different combining ability and inbred lines of the I1 – I4 sugar beet generation. Research methods: physiological, biochemical and statistical. Genotypic features of multi-seeded diploid pollinators by physiological and biochemical parameters of individual metabolic links in the early stages of plant ontogenesis were established and the influence of inbreeding on photosynthetic productivity of plants was revealed. In simple MS hybrids obtained with the participation of combinational (by sugar content) O-type line comparing to one MS tester, a high positive heterosis in PHA and sugar content and a positive correlation between those traits were found. In hybrid combinations created by crossing combinational diploid pollinators compared to one MS tester showed positive heterosis in leaf surface area, chlorophyll content (a + b) and sucrose in the roots.

Determining the Genetic Action of Water and Nitrogen Utilisation Efficiency in Maize (Zea mays L.)

A study to observe and record the mode of gene action involved in some quantitative and physiological traits of three maize hybrids using generation mean analysis was conducted at Abu Garash Farm, Faculty of Agriculture, Damascus University, during two growing seasons (2018 and 2019). Genotypes were compared using Randomised Complete Block Design (RCBD) with three replicates. Significant differences in all studied traits for six populations within each cross were found. There was significant positive heterosis relative to intermediate and better parents for most studied traits of hybrids, except in nitrogen utilization efficiency. Most of the genetic parameters were significant for the three hybrids, indicating the importance of epistasis in the inheritance of studied traits. The dominance gene effect was more pronounced than the additive gene effect in the inheritance for all traits. The values of the phenotypic coefficient of variance were greater than the values of the genotypic coefficient of variance, indicating the effect of environmental factors on the expression of the studied traits. High narrow-sense heritability values were associated with high genetic advance for nitrogen use efficiency and biological yield per plant. It is recommended that selection in early segregating generations of the studied hybrids is useful.