Thumbnail Image

Theses

Browse

2001 - 20023
Reset filters
Subject: Genetics and Plant Breeding × End date: 2002 × Start date: 2001 × Type: Thesis × Thesis Type: M.Sc ×
Reset filters

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    ThesisItemOpen Access
    Genetic variability and character associations in Anthurium andreanum Linden
    (Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2002) Asish, K Binodh; KAU; Mayadevi, P
    Genetic variability studies was conducted on fifty different genotypes of Anthurium andreanum Linden, generated from a previous hybridisation programme in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani. The analysis of variance revealed significant variation among the fifty genotypes for all the seventeen quantitative characters studied. This reveals the high genetic potential for the improvement of this crop. Variability studies indicated that high phenotypic and genotypic coefficients of variation for the characters of total anthocyanin content, pollen fertility, inclination of candle to spathe and duration of interphase. Except for leaf area and number of flowers per candle, all the other characters were highly influenced by genotypic variation. High heritability with a good genetic advance was found for all characters except for suckering ability and number of spadices/plant/year which exhibited medium heritability and high genetic advance. These results indicated that selection of plants which were phenotypically superior with respect to fifteen of the characters studied will certainly result in a significant improvement in the next generations. Plant height was found to have significant positive phenotypic correlation with internode length, leaf area and days from emergence to maturity of inflorescence. Candle length showed significant positive correlation with leaf area, number of flowers per candle, life of spadix and duration of female phase. Genotypic correlations were higher and for most of the characters it showed high positive correlations. Most of the estimates of the environmental correlation coefficients for the characters are low and insignificant indicating the least effect of environment in the expression of the characters studied. Pollen fertility ranged from 7.03 per cent in PR X FR(2) to 50.80 per cent in U X MW. The protogynous nature of the flower and low pollen fertility suggests the hybrid nature of the crop. During the months from March to July, the pollen emergence pattern was less where the maximum and minimum temperatures were relatively high. Path coefficient analysis revealed that the characters leaf area and duration of female phase are more associated with number of flowers per candle and 40 per cent variation in flower production was attributed by the environment. High selection index values were recorded by the genotype LR X DT followed by FR X MW(l), PR X LR (3), MW X FRO). If parents are selected based on selection index values, 45 per cent genetic gain can be expected in the next generation.
  • Thumbnail Image
    ThesisItemOpen Access
    Impact of seed deterioration on seedling vigour in mango (Mangifera indica L.)
    (Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2002) Anila, P; KAU; Girija, T
    The present study on 'Impact of seed deterioration on seedling vigour in mango' was undertaken at the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara during 1999-2001 with the objectives of assessing the variability of seedling characters obtained fr0111 a single plant, the effect of seed deterioration on seedling characters and to ascertain the critical moisture content of the varieties. Three varieties of mango were selected for the study. Assessment of variability of seedling characters of these varieties revealed that seedling girth is the most variable character, variability within varieties and between varieties was high for this character. Moreover, the response of girth to variation in seed weight due to loss in moisture content of the seed was also high indicating that this character may be influenced by both genetic factor as well as the physiological condition of the seed. The critical, moisture content was estimated to be 24% for Chandrakkaran, 30% for Moovandan and 28% for Puliyan. Seedling characters like height, girth, internodal length, number of leaves etc. were studied. These characters were found to be highly depended upon the moisture content of seed. There was considerable reduction in these characters with loss of moisture from seed. Polyembryonic nature of these varieties were not affected by seed desiccation. Biochemical characters like chlorophyll content, phenol content and sugar content were found to decrease with seed desiccation. Electrolyte leakage was found to be high with seed desiccation leading to reduction in viability. Seedling vigour was found to be positively correlated with biochemical characters.
  • Thumbnail Image
    ThesisItemOpen Access
    Genetics of bruchid (Callosobruchus sp.) resistance and yield in cowpea
    (Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2001) Jyothi, C; KAU; Kanakamany, M T  
    The present study 'Genetics of bruchid (Callosobruchus sp.) resistance and yield in cowpea' was undertaken in the Department of Plant Breeding and Genetics, College of Horticulture, Kerala Agricultural University, Vellanikkara. The study was carried out to estimate the various genetic parameters of characters, to identify the yield components, to study association of characters related to pulse beetle resistance and to identify superior genotypes and hybrids having high yield and tolerance to pulse beetle. High variability among parents and hybrids was observed for most of the yield and bruchid resistance traits. The characters namely number of eggs laid, number of adult beetles emerged, number of bore holes produced, loss of weight per seed and tannin content exhibited higher values of heritability, genetic advance and genotypic coefficient of variation, indicating the preponderance of additive gene effects. A positive association was found to exist among yield attributes and also with yield in parents and hybrids. Genotypes having a thicker seed coat showed better resistance to pulse beetle attack and this character was found to be independent in gene action. Kanakamoni among the lines and EC 390231 among the testers were found to be the most promising genotypes for hybridization and selection since they recorded high positive gca. For heterosis breeding the crosses Kanakamoni x IC 201092 followed by C 152 x EC 390231 were found to be superior for pod yield. Kanakamoni and C 152 among the lines and EC 390231 and IC 201092 among the testers showed high tolerance to pulse beetle attack and are recommended for evolving resistant varieties using these genotypes through hybridization and selection. For evolving hybrids showing resistance to pulse beetle the crosses, C 152 x EC 367711 and V 240 x IC 201092 were rated supreme.