Thumbnail Image

Thesis

Browse

20233
 Reset filters

Settings

Subject: Plant Breeding ×

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    ThesisItemOpen Access
    Heterotic Grouping of High Altitude Maize (Zea mays L.) Genotypes on the basis of Agro-morphological Traits
    (SKUAST Kashmir, 2023) Mir, Anjuman; Waza, Showkat Ahmad
    Maize (Zea mays L.) is one of the most important cereal crops cultivated throughout the world. The first and foremost step in the success of any crop improvement programme is determined by the amount of genetic diversity existing in that crop. The appropriate exploitation of nature and magnitude of genotypic and phenotypic variability present in the crop species plays a vital role in formulating the successful breeding programmes for the development of superior cultivars. Development of hybrid maize varieties needs selection of appropriate parents (inbred lines) which is the basis for achieving heterosis in maize. Therefore, the knowledge regarding heterotic behavior of inbred lines is important for the development of heterotic hybrids in maize. The present investigation "Heterotic Grouping of High-Altitude Maize (Zea mays L.) Inbreds on the basis of Agro-morphological Traits" was carried out using line x tester mating design involving 118 inbred lines and two testers (SMI-48 and SMI-462). In the present study, the diversity evaluation of inbred lines, mean performance of crosses and their combining ability analysis was carried out for grouping of the inbred lines into different heterotic groups. The study involves the identification of good general combiners among the inbred lines and good specific combiners among the crosses. 236 crosses (118 inbred lines crossed with two testers) along with the three standard checks were evaluated for yield and yield related traits. Analysis of variance revealed significant differences among the genotypes for most of the traits studied. Among the crosses, SMI-43 x SMI-462 (6.98 t ha-1), was found to be the highest yielder. Eighteen lines and both the testers showed high positive GCA value for grain yield, in which the inbred line SMI-83-1 had the highest positive GCA value of 50 for the trait. The estimate of SCA effects revealed that the positive significant SCA effects for grain yield was observed in about 24 crosses, out of which SMI-111 x SMI-462 had highest SCA effect (99.7) followed by the crosses CML-190 x SMI-48 (98.6), SMI-25 x SMI-48 (98.0) and SMI-56 x SMI-48 (97.9). Depending upon the direction of SCA effect towards the grain yield, 61 inbred lines were grouped into heterotic group A, 48 lines were grouped into heterotic group B and the remaining 9 lines were grouped in both A and B (AB). Inbred lines from different heterotic groups can be used for the development of heterotic hybrids and lines within a heterotic group with good GCA value can be used for the development of synthetic varieties. Hybrids with desirable SCA effects and better yield performance can be tested in multi-location trials to identify the best-performing cross combinations for commercial cultivation.
  • Thumbnail Image
    ThesisItemOpen Access
    Study on Genetic Variability and Diversity for Yield and Yield Contributing Traits of Chickpea (Cicer arietinum L.)
    (SKUAST Kashmir, 2023) Arbaz Qayoom; Dar, Sher Ahmad
    The present investigation “Study on Genetic Variability and Diversity for Yield and Yield Contributing Traits of Chickpea (Cicer arietinum L.)” was conducted on 50 genotypes of chickpea procured from ICARDA-BCIP, to know the genetic variability and diversity for yield and yield contributing traits in chickpea and to identify the wilt inciting pathogen via micro and macro conidia, chlamydospores and molecular basis. The treatment differences were statistically highly significant for all the traits along with higher magnitude of genotypic and phenotypic coefficient of variation indicating presence of good amount of variability. The trait, pods per plant exhibited highest range of variability followed by days to maturity, plant height and days to 50% flowering. The estimates of genotypic as well as phenotypic coefficient of variation were highest for seed yield per plant followed by biological yield, pods per plant, and number of primary branches. The highest heritability (broad sense) was observed for biological yield (95%) followed by days to maturity and seed yield per plant (92%), plant height (91%), pods per plant (86%), 100 seed weight (73%), and days to 50% flowering (76%). Biological yield exhibited highest genetic advance as per cent of mean (100.34), followed by the seed yield per plant (98.81), number of pods per plant (88.76). Path coefficient analysis revealed that biological yield has the highest direct effect (0.95) on seed yield per plant followed by days to 50% flowering (0.146), and plant height (0.072.). In the present investigation, D2 values ranged from 415.70 to 545.79 and the genotypes were grouped into three clusters , with cluster I accommodating maximum 22 genotypes followed by cluster III with 16 genotypes and cluster II with 12 genotypes. The cluster mean revealed that clusters I, and III varied considerably for most of the characters from those of other clusters and can be used in future breeding programme for creating maximum spectrum of variability for different yield contributing characters, which would help in developing superior genotypes with high yield and desired traits. The sequence base identification of the wilt pathogen revealed that Fusarium oxysporum f.sp. ciceri was the inciting agent for the wilt disease in chickpea. The morpho-cultural characteristics of the wilt pathogen revealed initially a white aerial growth and later develops into dense fluffy cotton growth with regular margin. The macroconidia were hyaline in color, septate (1-3), fulcate with pointed ends and length ranges from 23.23 to 28.64μm and breadth 2.52to 4.37μm, . The microconidia were also hyaline in colour, ellipsoid to oval in shape with a septation of 0-1. The length of microconidia ranged from 5.38 to 9.25μm and breadth ranged from 1.58 to 2.61μm. The precise identification of the wilt pathogen was made through ITS primer and the ITS sequence displayed a similarity index of 99.07 per cent with reference sequences. The sequence of the pathogen was registered in NCBI Gen Bank as Fusarium oxysporum isolate FT under the accession number of ON703290.1.
  • Thumbnail Image
    ThesisItemOpen Access
    Assesment of Genetic Diversity in Fennl (Foeniculum vulgare Mill.) under temperate ecology of Kashmir valley
    (SKUAST Kashmir, 2023) Andleeb Javaid; Khan, Mudasir Hafiz
    An experiment entitled “Assessment of Genetic Diversity in Fennel (Foeniculum vulgare Mill.) under Temperate Ecology of Kashmir Valley” was carried out during Kharif season, 2021 at Advanced Research Station of Saffron and Seed Spices, SKUAST-K, Pampore, Jammu and Kashmir. The experiment was laid out in randomized complete block design with 35 genotypes in three replications to estimate the extent of genetic variability, heritability, genetic advance, correlation between yield and yield attributing traits and direct and indirect effect of yield attributing traits through path coefficient analysis. Morphological characters of seeds were also recorded. Analysis of variance revealed significant differences for all the characters indicating the presence of inherent genetic variation among the genotypes. Phenotypic coefficient of variation were higher than genotypic coefficient of variances for all the characters studied indicating the role of environmental factors on the expression of characters. High magnitude of phenotypic and genotypic coefficient of variation (PCV and GCV) were observed for essential oil content while, the lowest for days to maturity. High heritability (broad sense) coupled with high genetic advance as percentage of mean was observed for essential oil content and number of primary branches per plant, which revealed that these traits could be utilized for improvement of yield and essential oil content of fennel. Correlation studies revealed that the seed yield per plant was significantly and positively correlated with plant height and number of secondary branches per plant suggesting that these are important yield contributing characters. Path coefficient analysis at both phenotypic and genotypic level revealed that number of secondary branches per plant followed by 100-seed weight exert high positive direct effect on seed yield per plant whereas, number of primary branches per plant exhibited maximum negative direct effect on seed yield per plant in fennel. Thirty-five genotypes got grouped into 10 clusters as per the Mahalanobis D2 analysis employing Tocher’s method. Maximum genotypes were found in cluster I. Cluster mean for cluster II, Cluster V and Cluster VIII surpassed the population mean for most of the yield contributing characters and the maximum intra cluster distance was observed for cluster VI while, maximum and minimum inter-cluster distance was observed between cluster V and VIII and cluster VI and IV, respectively. Seed traits viz., seed colour, seed shape, seed size and seed ridges exhibited good variation and shall provide a reference for characterizing germplasm and identification of superior traits in future studies.