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ThesisItem Open Access Genetic analysis of quantitative traits and selection of transgressive segregants in crosses of sesame (Sesamum indicum L.)(Department of Plant Breeding and Genetics, OUAT, Bhubaneswar, 2022-11-04) Sahu, Dibyabharati; Mishra, Tapash Kumar; Pradhan, B.; Dash, M.; Samal, K. C.; Senapati, A. K.The present investigation on "Genetic analysis of quantitative traits and selection of transgressive segregants in crosses of sesame (Sesamum indicum L.)" was conducted in the EB-II, Department of Plant Breeding and Genetics, College of Agriculture, O.U.A.T., Bhubaneswar. The experimental materials comprising of nineteen genotypes were sown during Pre rabi 2018 in Randomized Block Design with three replications and evaluated for eight quantitative characters viz., days to 50 % flowering, plant height, no. of branches per plant, capsule length, no. of capsules per plant, no. of seeds per capsule, 1000-seed weight and seed yield per plant for the diversity analysis. In Summer, 2019, seven genotypes (OSM-22, Nirmala, Prachi, Amrit, VRI-1, Rama and PKDS-11) were selected and crossed in half diallel fashion to develop 21 F1s. In Pre rabi 2020, 21 F1 along with their 7 parents were evaluated in RBD design for study of gene action involved in inheritance of quantitative traits and the magnitude of heterosis expressed by the crosses. Four crosses viz. OSM22×Rama, OSM22×VRI-1, Nirmala×Prachi, Prachi×VRI-1 were selected on the basis of sca effect and carried forward to F2 in Kharif 2021 to study the transgressive segregants. Nineteen genotypes were grouped into five clusters based on D2 values following Tocher's method. Cluster III was the largest cluster consisting of seven genotypes followed by Cluster II and V consisting of four genotypes each. Combining ability analysis of the parents and crosses (developed through half diallel fashion) were done following the both graphical and numerical approaches. From Vr- Wr graph it was evident that overdominance was prevalent for four traits viz. plant height, number of branches per plant, number of seeds per capsule and seed yield per plant as the regression line passed below the origin for the above traits. But for rest three traits, partial dominance was prominent, as the regression line passed just above the origin. OSM-22 and Nirmala were the good combiners for seed yield and its component traits. The crosses like OSM-22 × Rama, OSM-22 × VRI-1, Nirmala × Prachi and Prachi × VRI-1 exhibited signifcant sca effect and good amount of heterosis for plant height, no. of capsules per plant and seed yield per plant. Out of the four selected crosses OSM-22 x Rama showed high transgressive segregants in F2 for seed yield and its component traits, indicating its further advancement in segregating generations to select good genotypes, to be developed as a variety.ThesisItem Open Access Pyramiding resistance genes for bacterial leaf blight (Xanthomonas oryzae pv. oryzae) into Pratikshya, a popular rice variety of Odisha(Department of Plant Breeding and Genetics, OUAT, Bhubaneswar, 2022-07-30) Pradhan, Madhuri; Debendranath, Bastia; Pradhan, Bansidhar; Samal, Kailash Chandra; Mishra, Mihira KumarPratikshya is a popular high-yielding rice variety of Odisha with good grain and cooking quality. However, this variety is highly susceptible to bacterial leaf blight disease which is endemic to many rice-growing areas of Odisha. The development of resistant varieties is the most effective and economic method to combat the losses due to this disease. The present investigation was carried out with the objective of the phenotypic screening of segregating population for bacterial leaf blight resistance and marker-based identification of line possessing bacterial leaf blight resistance genes xa5, xa13, and Xa21 individually or in the pyramided form in the population. Genomic DNA from the resistant parent (Swarna MAS) and susceptible parent (Pratikshya) were amplified using the three SSR markers viz., RM122, xa13prom, and pTA248 markers to see polymorphism in parental genotypes. It was concluded that all of the three bacterial leaf blight resistance genes xa5, xa13, and Xa21 conferring resistance were present in Swarna MAS and absent in susceptible parent Pratikshya. Cross was attempted between donor parent Swarna MAS and recipient parent Pratikshya and 26 F1 seeds were obtained. Out of 26, 18 true F1 plants were obtained and hybridized with the recurrent parent Pratikshya to produce BC1F1 seeds. Foreground selection was performed in 117 BC1F1 plants to select plants carrying xa5, xa13, and Xa21 genes in the lines, and 58 plants were found to have all three resistant genes. Selected resistant BC1F1 plants were backcrossed to the susceptible recipient parent Pratikshya to produce BC2F1 seeds. Foreground selection was performed in 170 BC2F1 plants to select plants carrying xa5, xa13, and Xa21 genes in the lines, and 40 plants were found to have all three resistant genes. Seeds from selected BC2F1 plants were planted in the next generation to obtain the BC2F2 population. 35 resistant plants from BC2F2 generation selected by phenotypic screening by artificial inoculation of Xoo inoculum. Seeds from resistant plants having similar agronomic characteristics to Pratikshya were raised to obtain the BC2F3 population. In the BC2F3 generation, thirty-five lines were raised from the cross Pratikshya x Swarna MAS during Rabi, 2019. When all the markers were comparatively studied in all the plants, 31 plants possessed all three genes that conferred resistance to bacterial blight in rice. Based on data generated by foreground selection, background selection was done using forty-five SSR markers in the BC2F3 population to check the recovery of the recurrent parent genome. In BC2F3 generation of the cross Pratikshya x Swarna MAS the recurrent parent genome in the thirty-one bacterial leaf blight-resistant plants ranges from 64.44% to 93.33%. Among the thirty-one bacterial leaf blight-resistant plants, five plants showed the highest recurrent parent genome recovery percentage in the range of 91.11 to 93.33%. The recurrent parent genome recovery percentage was observed to be 91.11% in Pratikshya x Swarna MAS (Plant No. 4), 91.11% in Pratikshya x Swarna MAS (Plant No. 51) and 93.33% in Pratikshya x Swarna MAS (Plant No. 54), 93.33% in Pratikshya x Swarna MAS (Plant No. 65), 93.33% in Pratikshya x Swarna MAS (Plant No. 92). Thirty-one three-gene pyramid lines at BC2F4 generation along with the donor and recipient parents were evaluated during Kharif, 2020. Using mean values of eight agronomic traits, the statistical analysis revealed that many lines did not show any significant variation as compared to Pratikshya for most of the characters. The mean of all characters was at par with Pratikshya in most of the lines and to that of the average of the population. The recipient parent, Pratikshya recorded a mean seed yield of 44g/plant, while the donor parent (Swarna MAS) recorded 49.4g/plant. Many lines showed seed yield higher than recurrent parent Pratikshya. In most of the lines mean seed yield/plant was at par with the recipient parent Pratikshya. The five lines having a parental genome recovery percentage of more than 90% were at par with Pratikshya for all the characters. The yield and agronomic traits of the three gene pyramid line in this study are similar to those of the recurrent parent, Pratikshya, indicating no yield penalty associated with the presence of three bacterial leaf blight resistance genes.ThesisItem Open Access Gene stacking for submergence tolerance and bacterial blight resistance in popular rice variety Ranidhan(Department of Plant Breeding and Genetics, OUAT, Bhubaneswar, 2022-10-27) Pradhan, Kartik Chandra; Bastia, Debendranath; Pradhan, Sharat Kumar; Pradhan, Banshidhar; Samal, Kailash ChandraRanidhan, a popular variety of Odisha state of India in the late maturity group but is affected by the adverse effects of the climate change as the variety is sensitive to submergence and susceptible to bacterial blight (BB) disease. An attempt was undertaken for transferring three BB resistance genes and Sub1 QTL into the variety through marker-assisted backcross breeding approach. Direct and closely linked markers were used for screening of the backcross progenies. CR Dhan 800 is the donor parent for Xa21, xa13 and xa5 BB resistance genes while Swarna-Sub1 for Sub1 QTL were used in the backcross breeding program. Foreground selection detected all the four target genes in 11 progenies in BC1F1 generation. The progeny containing all the target genes and more similar with Ranidhan was backcrossed and a total of 312 BC2F1 seeds were produced. Foreground selection detected all the four target genes in 10 progenies in BC2F1 generation. The progeny containing all the target genes and more similar with Ranidhan was backcrossed and a total of 286 BC3F1 seeds were generated. Foreground screening detected 12 BC3F1 plants carrying all the four genes. A total of 1270 seeds were obtained from the selfed plant of the best BC3F1 progeny. Screening of the progenies resulted in four plants with the four desirable genes (Sub1, xa5, xa13 and Xa21) in homozygous condition. Bioassay of the seven pyramided lines containing BB resistance genes was conducted against 8 different Xoo strains conferred very high levels of resistance to the predominant isolates. These pyramided lines also showed higher submergence tolerance than the recipient parent, Ranidhan. High grain yield was recorded from the pyramided lines, CRSB 159-87-69-942 (71.7 q) followed by CRSB 159-87-69-717 (69.9 q) and CRSB 159-87-69-546 (68.45 q). The pyramided lines were similar to the recipient parent in 11 yield, agro-morphological and grain quality traits. The similarity of these pyramided lines is achieved in 3 backcrosses. It is possible due to the use of two donor varieties, Swarna-Sub1 and CR Dhan 800 which were developed in the same mega variety background, Swarna through MAB and the recipient parent, Ranidhan is also developed from Swarna variety. Therefore, the best pyramided lines carrying the target genes for bacterial leaf blight resistance and submergence tolerance are almost alike the recipient parent and hence will be preferred over,‘Ranidhan’.ThesisItem Open Access Assessment of useful genetic variation for nutrient use efficiency in aus rice (Oryza sativa L.) using genome wide association studies(Department of Plant Breeding and Genetics, OUAT, Bhubaneswar, 2022-10-27) Panda, Siddharth; Bastia, Debendranath; Pradhan, Bansidhar; Anandan, Annamalai; Mohanty, Iswar Chandra; Mohanty, SimantaRice (Oryza sativa L.), the second most cultivated crop nurtures billions of lives including humans and animals. However, the modern high yielding rice genotypes have a low nutrient use efficiency i.e., <50% (of the total applied fertilizers). The breeding activities should focus on developing and/or improving genotypes that can survive under limited inputs utilizing the available resources to the optimum. The Bengal Assam Aus Panel consisting of 298 diverse lines of aus rice was used in this study to identify genetic loci involved in nutrient use efficiency with respect to nitrogen, phosphorus and iron. The nitrogen deficient study was conducted in the field where as phosphorus and iron study was conducted in hydroponics. The BAAP with its nearly 2 million SNP sequence information was processed for association studies with the phenotypic data collected in this study. The results highlighted the different traits contributing the maximum variability under nutrient deficient conditions. In case of nitrogen (N) deficient trial there was positive correlation between grain yield, panicle length and leaf width. Similarly, in case of phosphorus (P) and iron (Fe) deficient trial there was a positive correlation between root biomass and shoot growth. The putative candidate gene for enhancing nitrogen use efficiency via flag leaf width was; LOC_Os6g41750 (25024626 – 25034551 bp), panicle length; LOC_Os04g09900 (5318060 – 5326427bp), and grain yield per plant;LOC_Os11g39220 (23354149 – 23358318bp). Three accessions; DA24, DM56, and AUS210 were identified as superior donors from the better performing haplotype groups of the above mentioned traits. Phosphorus use efficiency was found to be associated with the putative candidate gene LOC_Os04g45370 (26831005 - 26831867bp) via root length, LOC_Os06g41840 (25016001 - 2502001bp) via shoot length, and LOC_Os03g25040 (14294507bp - 14297898bp) via shoot dry weight. Shada boro, Kele (AUS) and Kada 68-1 were the selected as superior donors for the selected traits. Iron use efficiency was associated with a common peak SNP for root volume and average root diameter, LOC_Os04g54200 (32286661bp to 32291459bp) as a putative candidate gene. The peak SNP for shoot length and number of leaves shared a peak and the putative candidate gene was identified as LOC_Os11g28360 (16316873 – 16321329bp). Only five accessions were common in the superior haplotype across the four traits. Among these five lines, Rata boro had the highest root volume (3.316cm3) and average root diameter (2.19mm). The shoot length was highest in Sada boro G1 (26.05cm) and the average number of leaves were 2.8. The variations explored at the SNP level and amino acids in this study can serve as a guide for further genomic studies. The nonsynomyous substitutions can be validated further through protein expression studies. The SNP haplotypes identified in this study can further be used in haplotype assisted breeding approach while the superior haplotype bearing lines can be used as donor for the respective traits.ThesisItem Open Access Genetic improvement of aromatic rice landraces through in vitro mutagenesis(Department of Plant Breeding and Genetics, OUAT, Bhubaneswar, 2022-05-17) Das, Subhashree; Pradhan, B.; Samantaray , S.; Sahu, Simanchal; Samal, K. C.Aromatic rice is a special group of rice with pleasant aroma and excellent taste. They have a consumer preference and generally fetch high price in domestic and international market. Around 18% of non basmati rice exported is traditional aromatic rice (USDA, 2020). There is steady increase in demand for milled quality rice from India in the international market as Indian aromatic rice varieties are best suitable for traditional dishes. There are a number of short and medium grain aromatic rice which includes aus type aromatic rice which is known as indigenous aromatic rice grown in India. The indigenous aromatic rice are characterized by tall plant stature, photoperiod sensitivity, susceptible to lodging and low yield. They possess unique genes tolerant to environmental stresses and high adaptability to low input conditions. In vitro mutagenesis using ethyl methane sulphonate (EMS) is being used in plant molecular biology as a tool to identify and isolate genes and to study their structure, function more precisely and utilize for crop improvement. Genetic improvement of crop plants through conventional breeding program can be made more effective if coupled with the current in vitro cell culture techniques of cellular and molecular biology. The present investigation was undertaken with 40 aromatic rice genotypes involving diversity study for selecting genotypes for in vitro culture, identifying responsive genotypes for in vitro mutagenesis using 0.2% EMS, macro mutants study, finding effectiveness and efficiency of the mutagen dose under different treatments in M2 generation, field observation and evaluation of M3 and M4 generations for identification of desirable mutant lines. High and moderate to high GCV, heritability and genetic advance was found in the characters like thousand grain weight, number of grains per panicle, effective tillers per plant, plant height, kernel length breadth ratio and single plant yield. 1000-grain weight, number of grains per panicle, kernel length breadth ratio, number of effective tillers per plant are found to be positively correlated while plant height, panicle length were found negatively correlated with yield, which have been used as criteria while selecting genotypes for genetic improvement of grain yield in indigenous aromatic rice. Both callus induction and shoot regeneration were found to be genotype dependent having specific media requirement for efficient callus induction and shoot regeneration. Murashige and Skoog (MS) medium with 2.0 mg/l 2,4-Dichlorophenoxyacetic acid (2,4-D) was most suitable for callus induction and half MS medium with 2.0 mg/l 6-Benzyl amino purine (BAP) gave more shoot regenerations in local aromatic rice genotypes. Genotype Basumati and Kalikati were found to be more responsive to mutagenesis by EMS than Gangabali and Karpurajeera. EMS (0.2%) at 4 hours treatment was found to be most effective. Higher mutation rate was recorded in the genotypes which showed diplontic selection (Basumati and Kalikati). Appreciable genotypic variation in the mutant population existed and 32 mutant lines with desirable traits were identified in the M3 generation by multireplicated trial and estimates of skewness and kurtosis. Eleven competitive mutant lines, showing higher grain yield in the replicated yield trial, having positive skewness and negative Kurtosis values were identified and selected in M4 generation to be utilized further to advance generations through selection to develop superior varieties.ThesisItem Open Access Mapping of genomic regions associated with vegetative stage drought tolerance in rice (Oryza sativa L.)(Department of Plant Breeding and Genetics), OUAT, Bhubaneswar, 2021-11-09) Singh, Sandeep Kumar; Jagadev, P.N.; Katara, J.L.; Pradhan, B.; Bastia, D.N.; Samal, K.C.Rice (Oryza sativa L.) is most widely consumed staple food for a large part of the world's human population, especially in Asia. The major rice growing areas are concentrated in central and eastern regions of India and rice crop is grown mostly under rainfed conditions. Drought stress is the predominant cause for rice yield reduction and production stability in rainfed and poorly irrigated rice ecosystems. Modern high yielding rice varieties are highly sensitive to drought stress at seedling, vegetative and reproductive stages and even mild drought stress can result in a significant yield reduction in rice. This ultimately results in economic loss to the farmers and considered as one of the main constraints that limit rice yield in rainfed and poorly irrigated areas. Incorporation of drought tolerance has always been a challenge to plant breeders, because of the complexity of the trait that involves several physiological and molecular mechanisms and different mechanisms often combine to confer drought tolerance. A large numbers QTLs have been mapped and identified for drought tolerance at reproductive stage in rice. However, very few numbers of QTLs/genes were reported till date for vegetative stage tolerance in rice. Therefore, the present study was undertaken to carry out the genetic analysis coupled with identification of QTLs for traits related to drought tolerance at vegetative stage in rice. One hundred eighteen lines of doubled haploids (DHs) from the cross of two indica genotypes, IR20 x Mahulata were evaluated under both net house (pot culture) and rainout shelter conditions, to generate phenotypic data. Genotyping of the mapping population was carried out by using STMS and SNP markers. The phenotypic and genotypic data were analyzed for identification of QTLs related to drought tolerance. The data was statistically analyzed to calculate various genetic parameters and finally identification of QTLs using inclusive composite interval mapping (ICIM). The analysis of variance showed substantial variation among the traits. Interestingly, RWC under both net house and rain out shelter conditions showed heritability of 98.8% and 99.5% coupled with 48.9 and 38.6 genetic advance respectively. Additionally, RWC had significant negative correlation with leaf tip drying and leaf rolling, thus direct selection based upon RWC, leaf rolling and leaf tip drying under drought condition could be a better option. A total of nine hundred eighty-three STMS and 1k RiCA SNP markers were screened for detecting parental polymorphism, out of which five hundred eleven markers found as informative markers that were used for genotyping of DH mapping population. Under drought screening at net house, thirteen QTLs have been identified for eight traits in eight different chromosomes, whereas eleven QTLs have been identified for six traits in seven different chromosomes for drought screening at rainout shelter. In chromosome number 2, single minor QTL named as qRWC-2.1 for RWC was identified in the interval of SNP marker chr02_35818319 & chr02_21060669 and STMS marker RM475 &RM207, under both net house and rain out shelter conditions respectively. Under both net house and rainout shelter, Chromosome 2 harbour maximum 6 QTLs, out of which 3 were major. Chromosome 5 contain maximum 5 major QTLs under both net house and rain out shelter conditions. These QTLs can be useful for enhancement of vegetative stage drought tolerance through marker-assisted breeding approach in rice.ThesisItem Open Access Characterization and genetic analysis in mungbean [Vigna radiata(L.)Wilczek] under cold stress(Department of Plant Breeding and Genetics), OUAT, Bhubaneswar, 2021-10-19) Dash, Sasmita; Lenka, Devraj; Pradhan, B.; Dash, Manasi; Tripathy, S. K.; Mohanty, S.Mungbean is the major cool season pulse crop in Odisha, but it is highly sensitive to low temperature resulting low productivity. To address the problem, a set of 230 mungbean genotypes were screened for cold tolerance based on germination percentage and seedling growth (root length) in growth chamber at 10oC against another same set of genotypes at 250C to serve as control. Cold stress had drastic affects on germination percentage and root growth compared to control. Elite cold tolerant genotypes identified were NM 94, Pant M-3, LGG 460 and T 32-3 with score 1(high cold tolerant) and KPS-2, Pusa bold, PusaVishal, Pusa 9672, OGG 12, CoGG 902 and NM 92 with score 3 (moderately cold tolerant) which can serve as important base materials in cold tolerance breeding. Besides, field experiments for the set of germplasm were carried out during Rabi 2018-19 at Bhubaneswar and Rabi 2019-20 at Jaypore (Odisha) to assess effect of low temperature of winter season on eight quantitative characters including seed yield per plant in addition to status for cold tolerance. Pooled analysis of variance revealed significant difference for Genotype (G), Location (L) as well as their inter se (GxL) interaction indicating presence of appreciable genotypic variability with high genotype x environment (location) interaction. Almost all above cold tolerant genotypes that scored 1 to 3 under cold stress, were also shown to thrive better with higher seed yield per plant (> 3.2g/plant) among 230 genotypes under low temperature in field condition. High heritability accompanied by high genetic advance was associated with the number of clusters per plant signifying the abundance of additive gene action leading to adequate scope for effective selection. Plant height (cm), number of pods per plant, pod length (cm), number of seeds per pod and 100-seed weight (g) correlated significantly with seed yield per plant. However, path analysis revealed number of pods per plant, number of seeds per pod and 100- seed weight as the major yield contributing characters in mungbean under low temperature stress. The findings would have immense value for restructuring the genetic architecture of the crop through judicial selection to develop cold tolerant breeding lines in future. Pooled analysis over two locations revealed the highest contribution of seed yield per plant followed by number of clusters per plant, 100-seed weight and number of pods plant towards genetic divergence. The total set of genotypes was grouped into nine clusters. Cluster IV was shown to be highly divergent from Cluster I, II, III and VI. Cluster IX showed high mean yield performance as it included almost all above high yielding cold tolerant genotypes except NM 94 which was clubbed in the divergent Cluster VI. Cluster IX maintained quite distance from Cluster IV and almost equally divergent from Cluster I, III, V and VI. Thus, cold tolerant x cold tolerant cross combination of NM 94(Cluster VI) with either LGG 460 or Pant M-3 or T 32-3 from cluster IX would be worth trying. Further, a few above promising cold tolerant genotypes (Pant M-3, NM 94, LGG 460 and T 32-3) vis-a-vis the most sensitive test entries (AKM 8802, OBGG 52 and ADT 14) were studied for physiological (germination percentage and root length under 10oC cold stress in growth chamber; leaf area index, cell membrance injury, biomass and relative water content under low temperature stress) and biochemical parameters (proline, catalase, peroxidase, superoxide dismutase and melondialdehyde content of seedlings under low temperature stress) to elucidate the inherent mechanism(s) for cold tolerance in mungbean. Germination percentage and root growth were extremely reduced in sensitive genotypes compared to tolerant entries under cold stress in growth chamber. Tolerant varieties almost maintained the leaf area index(LAI), biomass, cell membrane injury and relative water content (RWC) under cold stress (10+2oC, crop sown on 1st Dec.,2020) without much deviation from control (25+2oC, crop sown on 1st Sept.,2020). Among the tolerant varieties, NM 94 and LGG 460 were shown to be physiologically more active than Pant M-3 and T 32-3 under cold stress. Proline and antioxidant enzymes (CAT, POD and SOD) activity increased tremendously in tolerant genotypes compared to sensitive entries, while MDA revealed inverse trend justifying the biochemical basis of cold tolerance. Besides, an attempt was undertaken for molecular profiling and marker - trait association (MTA) for cold tolerance in a set of 11 selected cold tolerant (Pant M-3, NM 94, LGG 460, T 32-3, KPS2, Pusa Vishal, NM 92, Pusa bold, CoGG-902, Pusa 9672, OGG 12) and six cold sensitive genotypes (AKM 8802, Pusa-2, PDM 84-143, OBGG 52, Pusa 9072 and ADT 14). Out of 13 primers screened for polymorphism, five cold stress related SSR primers (BrgMs 5339-1 related to Brassica, BMD 35 and BMD 48 related to mungbean, and Az 13907 and Az 13274 from Adzuki bean) were finally selected for molecular analysis. Among the primers, BrgMs5339 and Az 13274 were estimated to have high PIC (>0.5) as well as Rp value (2.9- 3.2) and hence, seems to have merit in allelic diversity study and varietal identification. Phylogenetic analysis using above cold stress-related molecular markers, was potent enough to isolate a few elite cold tolerant divergent genotypes e.g., NM 94, NM 92, T 32-3 and LGG 460 which may be considered as valuable material for recombination breeding. MTA revealed significant association of BrgMs 5339_1 allele with cold tolerance score explaining 24.4% phenotypic variation, While Az 13274_2 revealed significant MTA with root length which is considered important parameter for cold tolerance. Besides, BrgMs 5339_1 as well as Az13274_3 had shown strong significant association with 100-seed weight under low temperature stress. The significant association of SSR marker(s) with cold tolerance revealed in this study, can be a way forward for Marker Assisted Selection (MAS) for cold tolerance breeding in this crop.ThesisItem Open Access Characterization of maize double haploid lines for heat stress tolerance and development of hybrids using line × tester analysis(Department of Plant Breeding and Genetics, OUAT, Bhubaneswar, 2020) Dash, Asit Prasad; Lenka, Devraj; Pradhan, B.; Baisakh, B.; Tripathy, S.K.; Parida, A.K.Among all the abiotic stresses, heat stress is now enhancing its severe impact causing yield loss in maize. The present investigation comprising both field and laboratory experiments was conducted to study the effect of heat stress on maize DH lines and to understand the genetic mechanism controlling yield and other important traits under heat stress. The field experiments were carried out at EB-II Section, whereas the laboratory experiments were conducted at the PG Laboratory, Department of Plant Breeding and Genetics, College of Agriculture, OUAT, Bhubaneswar. A set of 345 maize DH lines collected from CIMMYT, Hyderabad were evaluated for grain yield per plot and two of the most heat sensitive traits viz., leaf firing and tassel blasting in a randomized block design with 2 replications during Summer, 2016. A very high positive association was observed between the two heat sensitive traits. However, both the traits exhibited negative correlation with grain yield per plot. The genotypes were classified into five clusters through hierarchical cluster analysis. Twenty DH lines belonging to cluster III, cluster IV and cluster V with higher grain yield per plot and less leaf firing and tassel blasting were identified as tolerant genotypes, whereas five DH lines from cluster I with very low grain yield per plot and high leaf firing and tassel blasting were identified as susceptible genotypes to heat stress. The 25 selected DH lines were further evaluated for six physio-biochemical traits along with yield per plant during Summer, 2017. Yield per plant attained significant positive genotypic and phenotypic correlation with all the physio-biochemical traits. However, the highest positive association was observed with cell membrane stability, which was also reported with high heritability and genetic advance. Forty five F1s generated by crossing fifteen of the previously identified tolerant DH lines with three testers, were evaluated for yield and yield attributing traits during Summer, 2018 along with the parents and six checks. The cross ZL155181 × ZL155828 exhibited highest grain yield per plant, while the cross ZL155219 × ZL155828 possessed least value for maturity related traits. Selection for grain yield based on the secondary traits like plant height, ear height and 100 grain weight might be fruitful as they possessed significant positive correlation as well as positive direct effect with grain yield per plant. The traits viz., days to 50 percent tasseling, days to 50 percent silking, days to 75 percent dry husk, plant height, ear height, cob length, cob diameter, number of rows per cob, number of grains per row and 100 seed weight were found to be predominantly governed by non-additive gene action, whereas additive gene action was found to be the controlling factor for anthesis to silking interval. Grain yield per plant was found to be influenced by both additive and non-additive components of gene action in expression of the trait. From the overall status of GCA effects for yield and yield contributing traits, the DHs viz., ZL155115, ZL155181, ZL155247 and ZL155828 were identified as better parents for developing either synthetic varieties or an elite breeding population thorough appropriate breeding programme. The majority of the crosses exhibited positive significant relative heterosis and heterobeltiosis for yield and its attributing traits, indicating the dominant nature of genes controlling these traits. Eleven crosses illustrated high overall economic heterosis status as well as high SCA effect status. Most of these crosses were of H × L or L × H parental combinations indicating additive × dominance gene interaction. The promising crosses identified in the present investigation may be evaluated further for future use as heat tolerant varieties.ThesisItem Open Access Genetic, physiological and molecular basis of yield variation in tomato(Department of Plant Breeding and Genetics, OUAT, Bhubaneswar, 2021) Behera, Mamata; Jagadev, Prema Narayan; Pradhan, B.; Swain, S. K.; Das, Swarnalata; Samal, K. C.Tomato (Solanum lycopersicum L.; 2n=2x=24, Family; Solanaceae) is one of the dominant vegetable crops in India. The native place is South America, particularly Peru, Ecuador and Bolivia region. The nutritional values of tomato make it more useful in reducing cardiovascular risk, weight loss and controlling obesity, eye disorder, night blindness, urinary tract infection, liver disorder and diabetic problem. The increased erosion of plant genetic resources has resulted in reduction of genetic variability of cultivated species and their wild relatives. Hence genetic manipulation of the crop plants through appropriate breeding procedure can overcome such problems. For any type of crop improvement, presence of genetic variability in the population is a crucial factor. The present investigation was based on evaluation and characterization of 40 tomato genotypes under three environments to study Genetic, Physiological and Molecular Basis of Yield Variation in Tomato. Observations were recorded on 18 characters (13 morphological and 5 physiological characters) and subjected to yield variation analyses in tomato. The characters observed were days to flowering, plant height, number of branches per plant, number of clusters per plant, number of flowers per cluster, number of fruits per cluster, number of fruits per plant, average fruit weight, root length, root fresh weight, root dry weight, root volume, crop growth rate, relative growth rate, net assimilation rate, leaf area index, total chlorophyll content and fruit yield per plant. Studies on genetic variability, character association, path analysis, genetic divergence, molecular diversity and stability were performed to achieve the objectives of present research work. The analysis of variance (ANOVA) for 13 morphological characters recorded the presence of considerable amount of genetic variations among the traits under study. The pooled data analysis revealed that root volume, fruits per plant and average fruit weight showed high heritability coupled with high genetic advance which indicated the presence of additive gene effects, hence selection based on these characters could give effective results for selection of genotypes Similarly, the ANOVA for 5 physiological characters recorded the presence of significant variations among the genotypes. The pooled analysis revealed that crop growth rate, relative growth rate and total chlorophyll content showed high heritability coupled with high genetic advance which indicated the presence of additive gene effects are there and hence the selection based on these characters would be effective for selection of the genotypes Correlation analysis revealed high estimates of significant positive correlation between yield and number of clusters per plant followed by the characters like number of fruits per plant, number of fruits per cluster, average fruit weight, number of flowers/cluster, root fresh weight, root volume and root length at phynotypic level. Path analysis revealed that maximum direct contribution toward yield was manifested by number of fruits per plant followed by average fruit weight and root volume. The characters like number of fruits per plant exhibited highest indirect effect on yield via number of clusters per plant followed by number of flowers per cluster, number of fruits per cluster. The residual effect indicated that 78 per cent of total variability in yield was contributed by the eighteen characters under study and still some of the characters were there which had least direct and indirect effects on yield which were not considered and may be included for further study to give higher amount of variation in yield. The genetic divergence analysis revealed that lowest D2 value between 11/TOBW-3 and BT-433-1-2 and highest between BT-12-3-2 and BT-22-4-1. According to Tocher’s method of classification 40 genotypes were grouped into 7 clusters, of which Cluster I contains 15 genotypes, cluster II contains 16, cluster III contains 4, cluster IV contains 2 and cluster V, VI, VII contain one genotype in each. From the inter-cluster distance, it was observed that clusters VI and II were most divergent, while clusters IV and VII were least divergent. The characters like fruit yield/plant, plant height and relative growth rate contributed more towards total divergence. From the molecular diversity analysis, it was found that among the 18 SSR primers 6 were informative and TG-06 was the most effective one. In the present study 46 amplified fragments were produced and all bands were polymorphic in nature. Primer TG-06 was found to be most effective primer. Molecular dendrogram grouped 40 genotypes into five clusters at 0.75 coefficient level. Cluster I contains 18 genotypes, cluster II contains 2, cluster III contains 15, cluster IV contains 3, Cluster V contains 2 genotypes. According to Eberhart and Russel model (1966), five genotypes viz. BT-3, BT-18, BT-106, BT-428-3 and BT-429-1-1 were having average stability and said to be suitable for all tested environments. Based on AMMI stability model, the genotypes viz. BT-18, BT-106, BT-12-2 and BT-433-1-2 were stable genotypes in all three environments for fruit yield of tomato. Hence from both the stability analyses, the two common genotypes (BT-18 and BT-106) were identified as stable in the three tested environments and could be utilized in future crop improvement programme.
