Exploitation Of Heterosis Research Articles

Combining ability and gene action analysis in okra (Abelmoschus esculentus L. Moench)

The present research was conducted in Okra to study combining ability and gene action in a set of 28 F1s developed by crossing seven lines and four testers. The experiment was laid out in a Randomized Block Design with three replications and observations were recorded on 12 traits viz. days to 50% flowering, days to first picking, number of internodes, number of branches plant-1, fruit length at maturity and harvest, number of fruits plant-1, number of seeds fruit-1, seed index, fruit weight, yield per plant and plant height. The results revealed that two lines viz., VRO-4 and Sel-2 were excellent general combiners for most of the traits in both positive and negative direction as per desirable traits. Cross VRO-6 x Varsha Uphar recorded highly significant SCA effects for eight traits and GAO-5 x GJO-3 for yield trait. Variance due to GCA was less than SCA, and the GCA/SCA ratio was less than unity indicating preponderance of non-additive gene action for all the traits. This suggested the feasibility of exploitation of heterosis. Keywords: Gene action, Fruit yield, Okra, GCA and SCA

Exploitation of heterosis in chilli using genetic male sterile lines for red fruit yield with special reference to high rainfall conditions

High-quality red/dry chilli for spice, pharmaceutical and medicinal purposes is a major goal in chilli breeding. The male sterile lines have greater potential for the exploitation of heterosis in chilli to achieve this objective. Genetic male sterile lines with special traits like destalking and ability to withstand high rainfall were involved in heterosis breeding to identify hybrids for commercial and industrial purposes. Forty F1 hybrids were developed by crossing 4 diverse GMS lines with 10 testers using Line × Tester mating design to estimate heterosis, combing ability and gene action. The experiment involving 14 parents and 40 F1s, along with standard variety ‘CH-27’ was laid out in α-lattice square design in three replications during summer 2020 and 2021. The GMS lines MS 9-2 and MS 26-1 along with testers DPCh 10, VVG, DPCh 40 and Him Palam Mirch-2 showed significant GCA for marketable red/dry fruit yield and majority of their component traits. Ten F1 hybrids were identified with superiority for fruit yield based on mean performance, significant heterosis and SCA effects, providing an opportunity to utilize them in value-added products and dried spice purposes viz., MS 9-2 × HPM-2, MS 11-2 × DPCh 40, MS 9-2 × DPCh 40 and MS 9-2 × DPCh 101 with erect fruiting habit and that of MS 9-2 × DPCh 10, MS 26-1 × DPCh 10, MS 9-2 × PBC 535, MS 26-1 × VVG, MS 29-2 × DPCh 10 and MS 26-1 × DPCh 22- C with pendent fruits. The non-additive gene action was predominant in the expression of fruit yield, total red fruits/plant, oleoresin and capsanthin. A significant positive correlation among SCA, economic heterosis and per se performance is an indicative to identify superior hybrids. Multi-location testing of these hybrids shall pave way to exploit them commercially by making them available to the farmers.

Unlocking the mystery of heterosis opens the era of intelligent rice breeding.

Heterosis refers to the phenomenon where the first filial offspring (F1) from genetically diverse parents displays advantages in growth rate, yield, and adaptability compared with its parents. The exploitation of heterosis in rice breeding has greatly increased the productivity, making a significant contribution to food security in the last half of the century. Conventional hybrid rice breeding highly relies on the breeder's experience on random crossing and comprehensive field selection. This process is time-consuming and labor-intensive. In recent years, rice hybrid breeding has encountered challenges stemming from limited germplasm resource, low breeding efficiency, and high uncertainty, which constrain the progress in yield increase, coupled with difficulties in balancing grain yield, quality, and resistance. Understanding the genetic basis of rice heterosis could lead to significant advancements in breeding concepts and methods. This will fully unleash the advantages of heterosis. In this review, we focus on the research progress of the genetic dissection of crop heterosis and briefly introduce some key advancements in modern intelligent breeding of rice hybrid.

Exploitation of heterosis for fruit yield and its attributing traits in brinjal (Solanum melongena L.)

Exploitation of heterosis for fruit yield and its attributing traits in brinjal (Solanum melongena L.)

Heterosis Exploitation in Brinjal against Fruit Borer Infestation under Semi-arid Climates of Gujarat

Heterosis Exploitation in Brinjal against Fruit Borer Infestation under Semi-arid Climates of Gujarat

Identification and fine mapping of Brmmd1 gene controlling recessive genic male sterility in Brassica rapa L

Recessive genic male sterility (RGMS) provides an effective approach for the commercial exploitation of heterosis, especially in Brassica crops. Although some artificial RGMS mutants have been reported in B. rapa, no causal genes derived from these natural mutants have been identified so far. In this study, a spontaneous RGMS mutant Bcajh97-01A derived from the ‘Aijiaohuang’ line traced back to the 1980 s was identified. Genetic analysis revealed that the RGMS trait was controlled by a single locus in the Bcajh97-01A/B system. Bulk segregant analysis (BSA) in combination with linkage analysis was employed to delimit the causal gene to an approximate 129 kb interval on chromosome A02. The integrated information of transcriptional levels and the predicted genes in the target region indicated that the Brmmd1 (BraA02g017420) encoding a PHD-containing nuclear protein was the most likely candidate gene. A 374 bp miniature inverted-repeat transposable element (MITE) was inserted into the first exon to prematurely stop the Brmmd1 gene translation, thus blocking the normal expression of this gene at the tetrad stage in the Bcajh97-01A. Additionally, a co-segregating structure variation (SV) marker was developed to rapidly screen the RGMS progenies from Bcajh97-01A/B system. Our findings reveal that BraA02g017420 is the causal gene responsible for the RGMS trait. This study lays a foundation for marker-assisted selection and further molecular mechanism exploration of pollen development in B. rapa.

Development of near homozygous lines for diploid hybrid TPS breeding in potatoes

Diploid inbred-based F1 hybrid True Potato Seed (DHTPS) breeding is a novel technique to transform potato breeding and cultivation across the globe. Significant efforts are being made to identify elite diploids, dihaploids and develop diploid inbred lines for heterosis exploitation in potatoes. Self-incompatibility is the first obstacle for developing inbred lines in diploid potatoes, which necessitates the introgression of a dominant S locus inhibitor gene (Sli) for switching self-incompatibility to self-compatibility. We evaluated a set of 357 diploid clones in different selfing generations for self-compatibility and degree of homozygosity using Kompetitive Allele Specific PCR (KASP) Single Nucleotide Polymorphism (SNP) markers. A subset of 10 KASP markers of the Sli candidate region on chromosome 12 showed an association with the phenotype for self-compatibility. The results revealed that the selected 10 KASP markers for the Sli gene genotype could be deployed for high throughput rapid screening of self-compatibility in diploid populations and to identify new sources of self-compatibility. The homozygosity assessed through 99 KASP markers distributed across all the chromosomes of the potato genome was 20–78 % in founder diploid clones, while different selfing generations, i.e., S0, S1, S2 and S3 observed 36.1–80.4, 56.9–82.8, 59.5–85.4 and 73.7–87.8 % average homozygosity, respectively. The diploid plants with ∼80 % homozygosity were also observed in the first selfing generation, which inferred that homozygosity assessment in the early generations itself could identify the best plants with high homozygosity to speed up the generation of diploid inbred lines.

Gene Action and Heterosis Studies for Yield and its Attributes in Bitter Gourd (Momordica charantia. L) under Temperate Ecologies

Thirty crosses developed through Line x Tester mating design along with their parents were evaluated for combining ability, heterosis and gene action for yield and its attributes in bitter gourd. The experimental material was evaluated in RCBD design with three replications at three different locations viz., Vegetable Experimental Farm, Division of Vegetable Science, SKUAST-Kashmir, Shalimar Srinagar (E1); Faculty of Agriculture, Wadura, Sopore (E2) and KVK Malangpora, Pulwama (E3). The mean squares due to parents vs crosses were significant for all the traits, which indicated the possibility of sufficient amount of heterosis exploitation for these traits. The \(\sigma\)2sca was found to be more than \(\sigma\)2gca for all the traits under study which indicated the preponderance of non-additive gene action for the traits. Both the variances (\(\sigma\)2gca and \(\sigma\)2sca ) were significant for most of the traits which reflects the importance of both additive and non-additive gene effects in the inheritance of these traits. The lines viz: NDBG-4, NDBG-1, NDBG-5, Pant Karela-1 and NDBG-7 were found to be good general combiners for most the economic traits. The extent of heterosis exhibited by crosses were estimated over standard parent (Arka Harit). The crosses viz: Pant Karela-1 × Arka Harit, NDBG-4 × Arka Harit, NDBG-1 × Arka Harit, NDBG-7 × Jounpuri, NDBG-5 × Jounpuri, NDBG-5 × Local bitter gourd, Pant Karela-1 × Jounpuri, NDBG-4 × Local bitter gourd and NDBG-4 × Local bitter gourd showed high standard heterosis for yield and yield attributes. These crosses can be exploited as desirable hybrids for yield.

A higher-yield hybrid rice is achieved by assimilating a dominant heterotic gene in inbred parental lines.

The exploitation of heterosis to integrate parental advantages is one of the fastest and most efficient ways of rice breeding. The genomic architecture of heterosis suggests that the grain yield is strongly correlated with the accumulation of numerous rare superior alleles with positive dominance. However, the improvements in yield of hybrid rice have shown a slowdown or even plateaued due to the limited availability of complementary superior alleles. In this study, we achieved a considerable increase in grain yield of restorer lines by inducing an alternative splicing event in a heterosis gene OsMADS1 through CRISPR-Cas9, which accounted for approximately 34.1%-47.5% of yield advantage over their corresponding inbred rice cultivars. To achieve a higher yield in hybrid rice, we crossed the gene-edited restorer parents harbouring OsMADS1GW3p6 with the sterile lines to develop new rice hybrids. In two-line hybrid rice Guang-liang-you 676 (GLY676), the yield of modified hybrids carrying the homozygous heterosis gene OsMADS1GW3p6 significantly exceeded that of the original hybrids with heterozygous OsMADS1. Similarly, the gene-modified F1 hybrids with heterozygous OsMADS1GW3p6 increased grain yield by over 3.4% compared to the three-line hybrid rice Quan-you-si-miao (QYSM) with the homozygous genotype of OsMADS1. Our study highlighted the great potential in increasing the grain yield of hybrid rice by pyramiding a single heterosis gene via CRISPR-Cas9. Furthermore, these results demonstrated that the incomplete dominance of heterosis genes played a major role in yield-related heterosis and provided a promising strategy for breeding higher-yielding rice varieties above what is currently achievable.

Genetic variability of maize (Zea mays) germplasm from Iran: genotyping with a maize 600K SNP array and genome-wide scanning for selection signatures

Context Maize (Zea mays L.) is one of the most economically important plants of the cereal family; it has value as human food, livestock feed, and as a component of industrial products. Aims This study focused on genetic diversity and existence of genetic divergence among promising maize inbred lines in Iran. Methods A commercial maize 600K SNP (single-nucleotide polymorphism) array was used to inspect genetic variability among 93 maize inbred lines. Key results The rate of transition mutation was twice as high as transversion mutation, and the density of detected SNPs was greater close to telomere regions of maize chromosomes. Considering the fluctuation of observed, expected and total heterozygosity and fixation index values across maize chromosomes, as well as polymorphism information content values, there is a high level of genetic variability among the studied maize panel. In addition, discriminant analysis of the principal components revealed four subpopulations in which the subpopulation ‘Line’ was distinct from other subpopulations and had no genomic overlap with them. Selection signature analysis revealed 177 regions harbouring 75 genes that differentiate among subgroups. Detected genes had a role in the mitogen-activated protein kinase signalling pathway, spliceosome, protein processing in endoplasmic reticulum, and hormone signal transduction. Conclusions We conclude that remarkable genetic diversity and differentiation exists among the studied maize subpopulations. The most differentiated SNPs among the subpopulations were associated with important biological processing genes and pathways. Implications The findings provide valuable insights for future maize breeding programs through exploitation of heterosis, as well as marker-assisted selection.

Estimation of heterosis for yield and its contributing traits in Brassica juncea L.

Brassica is an economically important genus consisting of oilseeds, vegetables, and forage crops. Brassica juncea L. is commonly known as Indian mustard. The current investigation was carried out with ten diverse parents, and 45 crosses in a half-diallel mating design. A total of 55 genotypes (45 F1 + 10 parents) were investigated for 14 traits, yield, yield characters, and oil content during rabi 2021-22 and 2022-23. All crosses along with their parents were assessed in RBD with three replications. Analysis of variance for combining ability showed that significant variation was present among 45 crosses and their parents. The cross DRMRIJ-31× BRIJRAJ showed positive significant mid-parent heterosis (30.76%) and better parent heterosis (30.20%), while the cross DRMR150-35 × RH-406 showed positive significant economic heterosis over both the checks (44.68% and 35.25%) respectively. The best crosses for yield/plant NRCDR-02 x PUSABOLD, NRCDR-02 x RH-761, NRCDR-02 x JM-2 and NRCDR-02 x BRIJRAJ exhibited positive and significant heterosis. Hence, these identified hybrids could be used for exploitation of heterosis after evaluating and testing with large multilocations.

Diallel analysis of maize inbred lines for estimating superiority and combining ability

The phenomenon of heterosis has provided the most important genetic tools for crop yield improvement. Identification of specific parental combinations capable of producing the highest level of heterotic effects in F1 has immense value for commercial exploitation of heterosis. The objective of this study was to assess the combining ability variances and superiority in twenty one combinations developed by crossing seven maize (Zea mays L.) inbred lines in half diallel fashion design. The resulting 21 hybrids, along with two check hybrids, were evaluated in Randomised Complete Block Design, in three locations during 2022 season in Egypt. The results showed that both additive and non-additive gene actions were important in controlling all the measured traits. The General Combining Ability (GCA) variance was found to be greater than Specific Combining Ability (SCA) variance, indicating predominance of additive and additive by additive gene effects in the inheritance for all studied traits. Cross P2×P3 significantly out yielded the best check (SC. 168) for the grain yield trait. The parental inbred lines, P1, P2 and P3, possessed significant desirable (GCA) effects for the grain yield trait. The cross combinations (P1×P5),(P2×P7), (P3×P7),(P4×P5),(P4×P6) and (P6×P7) showed significant positive sca effects for grain yield. Cross P2×P3 (10.32**) obtained superiority (%) relative to the check hybrid SC.168 for grain yield. On the other hand, five crosses viz. (P1×P3), (P1×P5), (P2×P3), (P2×P5) and (P3×P5) expressed positive superiority (%) over the check hybrid SC.3444 for same trait. Thus, these crosses could be recommended to be released as commercial hybrids by Maize Research Programme after further evaluation and testing in multi-locations in Egypt.

Establishment of new convenient two-line system for hybrid production by targeting mutation of OPR3 in allopolyploid Brassica napus

Abstract The two-line pollination control system, which usually depends on the utilization of thermosensitive or photoperiod genic male-sterile lines, has been widely used in various crops. However, this system is susceptible to instability issues caused by uncontrollable weather fluctuations. A stable and handy two-line pollination control system is highly desirable in many crop species for heterosis exploitation. Oxophytodienoic acid reductase 3 (OPR3) was proven to be involved in jasmonate biosynthesis. In the present study, CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeat) was utilized to mutate two OPR3 homologs in Brassica napus. After two OPR3 homologs were simultaneously mutated, mutants exhibited complete male sterility, and fertility could be easily restored by exogenous MeJA treatment. Hybrids produced from crosses between the opr3 sterile lines and normal varieties exhibited heterosis. This new two-line system based on OPR3 mutation provides higher stability and convenience than traditional systems. By using exogenous MeJA treatment to restore fertility, the system enables more precise control of male fertility transition, which has great potential to significantly contribute to the maneuverable production of hybrid seeds in rapeseed as well as other Brassica species crops.

Estimation of Combining Ability for Flowering and Yield Attributes in Bhendi (Abelmoschus esculentus (L.) Moench)

The present study on general combining ability effects and specific combining ability effects involves seven parents viz., G1 (Arka Anamika), G2 (Aruna), G3 (Varsha Uphar), G4 (Pusa-5), G5 (MDU-1), G6 (Kashi Kranti), G7 (Ankur-41) with their 21 F1 hybrids through half-diallel mating system. The present investigation was undertaken using Randomized Block Design with three replications. The combining ability effects were estimated for seven characters viz., days to first flowering, days to first fruit harvest, fruit length, fruit girth, fruit weight, number of immature seeds per fruit and fruit yield per plant. The results showed that gca effects of parents and sca effect of hybrids were significantly differed. The SCA variance was higher than the GCA variance that indicates the presence of preponderance of non-additive gene action for all the seven traits i.e., presence of preponderance of non-additive gene action for all characters except number of nodes per plant. Among the parents, G3 was found to be a good general combiner based on the per se performance and gca effects for its flowering and yield traits. Among the 21 F1 hybrids, the crosses G3 x G5 and G4 x G6 were superior on the basis of per se performance and sca effect for flowering and yield attributes. Hence, these hybrids were used for further exploitation of heterosis.

Identification of sources of male sterility in the Colombian Coffee Collection for the genetic improvement of Coffea arabica L.

In coffee (Coffea arabica L.), male sterility is a prerequisite for the exploitation of heterosis since it provides an efficient and reliable method for the production of hybrid seeds. Given its relevance, the objective of this study was to identify male-sterile genotypes within the Colombian Coffee Collection that can be used in genetic improvement. For this purpose, Ethiopian germplasm and progenies derived from hybrids between C. arabica x C. canephora were explored between 2017 and 2021. In the first stage, genotypes without visual presence of pollen were preselected in the field, followed by selection through staining and verification of male sterility and female fertility through directed crosses (directed, reciprocal and selfing). In this stage, 9,753 trees were explored, preselecting 2.4% due to visual absence of pollen. The staining of structures allowed us to confirm the lack or sporadic production of pollen in 23 individuals of Ethiopian origin. The results of the directed crosses led to the identification of 11 male-sterile and 12 partially male-sterile genotypes belonging to 15 accessions. In all cases, the individuals were characterized by the presence of anthers but with an absence or low content of pollen, which is why the male sterility is possibly of the sporogenic type. The female receptivity values were between 2.9% and 72.6%, being higher than 30% in five genotypes. These genotypes are a valuable tool for the genetic improvement of C. arabica with the potential to facilitate the use of heterosis and to allow a deeper understanding the development of male gametophytes in the species.

Combining ability analysis for seed yield and its attributes in Indian mustard [Brassica juncea (L.) Czern and Coss

The hybrids were developed by adopting diallel mating design excluding reciprocals involving ten diverse Indian mustard genotypes during rabi 2007-08. The resultant 45 hybrids along with their parents were evaluated in a Randomized Block Design with three replications under four environments viz., timely sown at Sardarkrushinagar (E1) and Ladol (E2), and late sown at Sardarkrushinagar (E3) and Ladol (E4), during rabi 2008-09. Combining ability analysis on pooled basis, revealed importance of both additive and non-additive genetic variances for the control of various traits. However, the ratio σ2 gca/σ2 sca indicated preponderance of non-additive gene action for days to 50% flowering, days to maturity, seed yield/plant and oil content, while additive gene action was preponderant for rest of the traits. The parents RK 9501, GM 1 and GM 2 were good general combiners, whereas, the crosses 'RK 9501 x GM 2', 'GM 1 x GM 3' and 'GM 3 x SKM 139' were found to be the best specific combinations for seed yield/plant and some of the important yield contributing traits. However, on the basis of per se performance, exploitable heterosis and significant sca effects for seed yield/plant and some of its important components, the above hybrids were considered to be the most promising for exploitation of heterosis.

Analysis of Heterotic Potential for Yield and Its Contributing Traits in Wheat (Triticum aestivum L.)

Fifty-six genotypes were evaluated comprising 45 hybrids, 10 parents and 1 standard check (HD2968) were evaluated in a randomized block design (RBD) with three replications for 12 traits viz. Days to 50 % flowering, days to maturity, plant height, number of tillers per plant, spikelets per spike, ear length, spike density, number of ears per plant, number of grains per ear, seed index, grain yield per plant and harvest index to study the magnitude and direction of heterosis for yield and earliness in wheat. Significant heterosis was found over mid parent and commercial checks for all the traits studied in desirable direction. The findings revealed highly significant differences between parents and F1’s as well as among parents for the majority of attributes. In the present research investigation, the number of days taken for 50 % flowering and days to maturity was selected as indicative of earliness. Among 45 crosses, K1317 x HD2967 expressed negative significant heterosis over mid parent and standard check respectively, for days to 50% flowering while Cross HD3059 x DBW3059 revealed highly significant negative heterosis for days to maturity. In present research, the highest positive and significant heterosis over mid parent was exhibited by cross DBW187 x HI153 followed by DBW187 x DBW3059, HD3294 x DBW3059. The cross DBW187 x DBW3059 followed by DBW187 x HD3059, HD3294 x K1601 shows highly positive heterotic percent for grain yield per plant over standard check. These hybrids may further be tested over various locations before release for commercial cultivation. High estimates of heterosis obtained in hybrid combinations revealed considerable genetic divergence among the parental lines and reveals good scope for commercial exploitation of heterosis in wheat.

Genetic Analysis of Rice (Oryza sativa L.) Genotypes Under Wet Direct Seeding Condition

Present investigation was carried out with 35 rice genotypes under wet direct seeding condition at Regional Agricultural Research Station, Jagtial, PJTSAU, Telangana, India during kharif (June to October), 2016. High GCV and PCV values for important yield contributing traits viz., 1000 grain weight (24.41, 24.62) and number of grains panicle-1 (26.17, 29.30) were observed. High heritable and genetic advance values for 1000 grain weight (98.30, 49.86) and number of grains panicle-1 (79.80, 48.16) indicated the role of additive genes and these traits can be improved by simple selections. Effective bearing tillers m-2recorded low values of heritability (25.40) and genetic advance (5.19) suggesting the exploitation of heterosis for improvement of this important yield character. Effective bearing tillers m-2 (0.7097**), plant height (0.5014**) and panicle length (0.3219**) exhibited significant correlations with yield, hence direct selection for these traits could improve the yield. Highest inter cluster distance was observed between clusters IV and VI (27.75) followed by III and VI (24.69), IV and V (22.34) and III and V (22.23) thus high heterotic hybrids can be developed by making crosses between genotypes of the clusters. 1000 grain weight (44.2%) contributed highest towards total divergence followed by days to 50% flowering (40.17%) and plant height (10.76). Genotypes from cluster V and VI can be used as parents in breeding programme for development of extra early varieties. Cluster II and IV recorded lowest means for plant height and hence genotypes from these clusters can be used as parents for development of dwarf varieties desirable for wet direct seeding condition.

ROS accumulation-induced tapetal PCD timing changes leads to microspore abortion in cotton CMS lines

BackgroundCytoplasmic male sterility (CMS) is the basis of heterosis exploitation. CMS has been used to hybrid production in cotton, but its molecular mechanism remains unclear. CMS is associated with advanced or delayed tapetal programmed cell death (PCD), and reactive oxygen species (ROS) may mediate this process. In this study, we obtained Jin A and Yamian A, two CMS lines with different cytoplasmic sources.ResultsCompared with maintainer Jin B, Jin A anthers showed advanced tapetal PCD with DNA fragmentation, producing excessive ROS which accumulated around the cell membrane, intercellular space and mitochondrial membrane. The activities of peroxidase (POD) and catalase (CAT) enzymes which can scavenge ROS were significantly decreased. However, Yamian A tapetal PCD was delayed with lower ROS content, and the activities of superoxide dismutase (SOD) and POD were higher than its maintainer. These differences in ROS scavenging enzyme activities may be caused by isoenzyme gene expressions. In addition, we found the excess ROS generated in Jin A mitochondria and ROS overflow from complex III might be the source in parallel with the reduction of ATP content.ConclusionROS accumulation or abrogation were mainly caused by the joint action of ROS generation and scavenging enzyme activities transformation, which led to the abnormal progression of tapetal PCD, affected the development of microspores, and eventually contributed to male sterility. In Jin A, tapetal PCD in advance might be caused by mitochondrial ROS overproduction, accompanied by energy deficiency. The above studies will provide new insights into the cotton CMS and guide the follow-up research ideas.

Genetic Variability of Floral and Agronomic Characteristics that Influence Outcrossing Rate Percentage of Cytoplasmic Male Sterile Rice

Developing high-yielding hybrid rice varieties is much needed to ensure food security to meet the requirement of the increasing population across the world. Cytoplasmic male genetic sterility system is a valuable technology for the exploitation of heterosis and production of high-yielding hybrid rice with better grain quality. Large-scale commercial exploitation of hybrid vigor in rice largely depends on the availability of good CMS (Cytoplasmic Male Sterile) lines. A total of eighteen traits of five CMS lines of rice were evaluated to study the variability and correlation between floral and other yield-contributing traits with outcrossing rate using Randomized Complete Block Design with three replications. High significant variation was observed among the genotypes for all the studied traits. High GCV (Genotypic Coefficient of Variance) and PCV (phenotypic Coefficient of Variance) coupled with high heritability and high genetic advance in percent of mean were observed for number of panicles per plant, filled grain, flag leaf breadth, stigma length and breadth, filament length and outcrossing rate which indicated the broad genetic base, less environmental influence, and these traits are under the control of additive gene action. character association and path analysis indicated that number of grains per panicle, filled grains per panicle, stigma length, and breadth possessed both positive significant correlation and positive direct effects on outcrossing rate therefore, selection for the traits mentioned above will certainly bring in the improvement of the outcrossing percentage of the lines, which in turn enhances the seed quantity of the hybrid.