PG Thesis
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Item Flowering, pollination and fruit set in Brinjal (Solanum melongena L)(Division of Agricultural Botany, Agricultural Botany, Agricultural College & Research Institute, Vellayani, 1965) Leelamma Mathew; Kumara Pillai, PItem 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, TThe 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.Item Inheritance of male sterility and development of new male sterile line in ridge gourd (Luffa acutangula (L.) Roxb.(Department Of Olericulture, College Of Horticulture, Vellanikkara, 2011) Kannan, D; Pradeepkumar, TThe present study entitled “Inheritance of male sterility and development of new male sterile line in ridge gourd Luffa acutangula (L.) Roxb.” was undertaken in the Department of Olericulture, College of Horticulture, Vellanikkara during 2010-11. The objective of the study was to investigate the inheritance of male sterility in ridge gourd and to develop new male sterile line in ridge gourd using back cross generations of sterile hybrids. Study also aims in evaluating the performance of F1 hybrid, MS x Arka Sumeet for horticultural characters. Male sterile line is now maintained under in vitro condition. All the in vitro regenerated plants exhibited stability in the expression of male sterility. F2 seeds resulted from the selfing of F1 hybrid, MS x Arka Sumeet was raised to study the expression of male fertility. Out of 106 plants raised in the F2 generation, 56 plants were male fertile and 50 plants were male sterile. There were observable differences between the male sterile and male fertile plants with respect to male flower production whereas female flowers in both types were similar. Chi square test was employed to test the goodness of fit and the 9:7 (fertile: sterile) complementary gene action ratio was found to be significant. The Chi square test suggested that two dominant genes might have certain interactions with cytoplasmic male sterility (CMS). Two dominant fertility restorer gene viz., Rf1 and Rf2 is now proposed for this model. Assuming that MS line in ridge gourd is having a genotype, S (rf1rf1 rf2rf2) carrying both fertility restorer gene in homozygous recessive state and sterile cytoplasm, S, and Arka Sumeet possess a genotype N (Rf1Rf1 Rf2Rf2) carrying both fertility restorer gene in homozygous dominant state and normal fertile cytoplasm, N, F1 will be male fertile as the genotype of F1 is S (Rf1rf1 Rf2rf2). Here though F1 is inheriting a sterile cytoplasm from male sterile female parent, presence of both dominant fertility restorer gene, viz., Rf1 and Rf2 restores the fertility of F1. In F2, presence of both dominant fertility restorer gene in either homozygous or heterozygous condition ensures male fertility. All three way crosses viz, (MS x Deepthi) x Arka Sumeet, (MS x IC-92685) x Arka Sumeet, (MS x IC-92671) x Arka Sumeet and (MS x CO2) x Arka Sumeet regained fertility indicating the presence of dominant fertility restorer gene in Arka Sumeet. The sterile hybrids on back crossing with respective pollen parents also exhibited male fertility at various stages of crop growth. Restoration of male fertility in BC1 generation indicate the unstable nature of sterile cytoplasm. F2 segregants producing fertile racemes during last stage of crop growth have more potential for evolving stable male sterile lines. Selective mating of these plants with male sterile plants or selfing can be advocated for developing new male sterile lines. The F1 hybrid (MS x Arka Sumeet) exhibited significant heterobeltiosis for days to emergence of first female flower, node to first male flower, node to female flower, number of fruits per plant and yield per plant. High heterosis exhibited by the F1 hybrid (MS x Arka Sumeet) indicates the scope of exploiting the male sterile line in heterosis breeding. This is the first study which attempted to find out the inheritance of male sterility and fertility restoration in ridge gourd and is the first report of presence of cytoplasmic male sterility and dominant fertility restorer gene in cucurbits.