PG Thesis

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Subject: search.filters.subject.Variability

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    Estimation of genetic parameters in green gram (Phaseolus aureus Roxb.)
    (Department of Agricultural Botany, College of Agriculture, Vellayani, 1980) Presanna Kumari, K T; Mary K George
    Biometric studies on fifteen divergent green gram varieties (Phaseolus aurreus Roxb. syn. Vigna radiata (L.) wilzeck.) was conducted at the College of Agriculture , Vellayani , during November- January, 1979-80, to estimate the important genetic parameters like mean, range, genotypic and phenotypic coefficientsof variation , heritability, genetic advance and genetic gain and to find out the direct and indirect contributions of various component characters on yield by path coefficient analysis. There were significant differences among the varieties for all characters studied. Genotypic coefficient of variation was maximum for number of branches per plant followed by 100 seed weight and minimum for days to 50 per cent flowering . High heritability estimates were observed for pod length , 100 seed weight, plant height, number of seeds per pod days to 50 per cent flowering and number of pods per plant. Genetic gain was maximum for number of branches per plant followedby 100 seed weight and minimum for days to 50 per cent flowering. The number of branches per plant 100 seed weight, number of pods per plant and pod length had high heritability and genetic gain indicating the presence of additive gene action and hence they can be relied upon in selection programmes.
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    Variability and hetrosis in green fruited brinjal
    (Department of Olericulture, College of horticulture, Vellanikkara, 1995) Sathya Varma, P C; Nirmala Devi,S
    The present investigation on “Variability and heterosis in green fruited brinjal (Solanum melongena L.)”was conducted at the Vegetable Research Farm, College of Horticulture, Thrissur during 1992 – 94. Twenty three genotypes of brinjal collected from different parts of the country were grown in a randomised block design with two replications to assess the extent of genetic variability for fifteen characters viz., plant height, plant spread, number of primary branches per plant, days to first flowering, number of flowers per cluster, days to first fruit set, days to first harvest, average fruit weight, total fruits per plant, percentage of productive flowers, fruiting period and fruit yield per plant. The genotypic and phenotypic coefficients of variation, heritability, genetic advance and genetic gain were estimated. Correlation studies and path coefficient analysis were conducted to study the association among yield and its component characters and to estimate the direct and indirect effects of component characters on yield. Based on genetic divergence the 23 genotypes were grouped into five clusters. Seven superior genotypes were selected from these clusters based on their field performance and bacterial wilt resistance. The seven genotypes were crossed in a 7 x 7 diallel pattern to get 21 F1 hybrides. These F1 hybrids were evaluated along with their parents to derive information on general and specific combining ability and heterosis. Significant variation was observed among the genotypes for all the 12 characters studied, indicating scope for improvement. High heritability along with high genetic advance was observed for the characters fruit yield per plant, total fruits per plant, average fruit weight and percentage of productive flowers, indicating the action of additive genes. From the correlation studies, it was observed that yield had positive significant correlation with total fruits per plant, fruiting period, average fruit weight and number of flowers per cluster and negative significant correlation with days to first flowering, fruit set and harvest. Path coefficient analysis revealed that the character total fruits per plant had the maximum direct effect on yield. From the combining ability analysis it was noticed that the parental lines SM 247, SM 246 and SM 6 – 6 were good combiners for yield. The best combination for yield was SM 246 x SM 262 and that for earliness was SM 6 – 6 x SM 141. Significant heterosis was observed in many of the hybrids for most of the characters. SM 141 x SM 262 was the hybrid showing significant positive heterosis for plant height, plant spread, number of primary branches, average fruit weight and fruit yield per plant. Similarly SM 6 – 6 x SM 141 was the earliest hybrid to flower, set fruits and be harvested. This also showed the lowest percentage of bacterial wilt incidence. Another hybrid which showed significant heterosis for total fruits per plant, fruit yield and percentage of wilt incidence was SM 6 – 6 x SM 197. The study of heterosis thus revealed that the three hybrids viz., SM 141 x SM 262, SM 6 – 6 x SM 141 and SM 6 – 6 x SM 197 are promising combinations showing superiority in most of the economic characters considered for the study.
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    Male sterility and its utilization for crop improvement in ridge gourd Luffa acutangula (L.)Roxb.
    (Department of Olericulture, College of horticulture, Vellanikkara, 2009) Vijeeth C Hegade; Predeepkumar, T
    The present investigation on male sterility and its utilization for crop improvement in ridge gourd is undertaken with the objective of investigating the stability of male sterility in ridge gourd Luffa acutangula (L.) Roxb. and expression of male sterility on combinations with different pollen parents of diverse groups. Micropropagation was effective in maintaining the male sterile line. Standardized protocol was followed for in vitro maintenance of male sterile line. In vitro regenerated plants exhibited stable male sterility all round the flowering season. Pollen fertility found to be zero in all the male sterile plants. Cytological analysis of pollen mother cells revealed normal meiosis in form of tetrad formation and pollen degradation found to be in post meiotic stage. Fourteen ridge gourd genotypes were collected from different parts of the country and evaluated for variability with respect fourteen traits. The genotypes exhibited significant variability for the characters studied. Genotypes were grouped into five clusters based on Mahalanobis’s D2 statistics. Five pollen parents from diverse groups were selected for hybridization with the male sterile female parent. Heterosis values were estimated over mid, better and standard parents. Out of five hybrids, four were male sterile and one was partially fertile. Inheritance of male sterility and restoration of fertility is a complex mechanism and the available information on male sterility is not sufficient to explain this unique mechanism. Available result points towards the presence of partial dominant gene action in controlling male sterility. The pattern of inheritance of male sterility and restoration of fertility can only be explained by studying the F2 and back cross generations and the three way cross involving male sterile hybrids and the pollen parent which restores the fertility.