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ThesisItem Open Access Genetic analysis of segregating generations of irradiated interspecific hybrids in okra (Abelmoschus spp.)(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1997) Sophia John; KAU; Manju, PA study* was. conducted in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during l996-'97 to estimate the extent of variability generated in the f 2M? and F3M3 generations as a result of hybridisation and hybrid irradiation of the interspecific hybrids between A. s esculenins and A. manihot and also to isolate high yielding yellow vein mosaic disease resistant lines from among the segregating generations In the l-^M-, generation, the irradiated treatments were found to be late flowering and had more number of leaves per plant, flowers per plant and fruits per plant Irradiation was found to increase pollen sterility and was maximum in 10 kR However seed set was lower for the irradiated treatments. Average fruit weight and weight of fruits per plant was maximum in plants belonging to the treatment 20 kR. Fruit length and girth were found to increase with increasing radiation doses. Number of ridges per fruit, fruiting phase and plant duration were higher in the irradiated treatments when compared to 0 kR and was maximum in 40 kR Plant height was highest in the treatment 30 kR Irradiation was found to increase YVM disease incidence and fruit and shoot borer incidence and it was maximum in 30 kR among the irradiated treatments. However a few high yielding YVM disease resistant plants resembling the cultivated parent were also observed in 30 kR ■Genotypic coefficient of variation, heritability and genetic advance were high for number of branches per plant and number of seeds per fruit in all the irradiated treatments in F2M2. High heritability with high genetic advance were observed for leaf number, number of flowers per plant, Iruits • ' per plant and pollen sterility in 20 kR and 30 kR. Significant positive * . correlation of number of leaves per plant, flowers per plant and fruits per plant with weight of fruits per plant and also among themselves was observed in all the irradiated treatments in F2M0. Average fruit weight and fruit yield A* • 0 per plant were positively correlated in treatments 0 kR, 10 kR, 40 kR, P, and P2. % In F3M3 the irradiated treatments were found to be late flowering and had more number of leaves, branches, flowers and fruits per plant. Pollen sterility was lower for the irradiated treatments, when compared to the unirradiated treatment and was lowest in 30 kR. However the number of seeds per fruit was more in 30 kR compared to the other treatments excluding parental treatments. Irradiation was found to decrease average fruit weight but fruit yield per plant was more for the irradiated treatments due to the larger number of fruits and was maximum in 40 kR. Length of fruit increased with increasing radiation doses. Significant differences among the irradiated treatments were not observed with respect to number of ridges per fruit. Irradiation was found to increase the fruiting phase as well as plant duration. Plant height was maximum in 10 kR when compared to all the other treatments. Yellow vein mosaic disease incidence was high in the cultivated parent and the higher dose radiation treatments viz , 30 kR and 40 kR. From the present study *a few recombinants which resembled the cultivated parent, with high yield and YVM disease resistance could be isolated from 30 kR, which suggested that 30 kR could be ideal radiation dose for evolving high yielding YVM disease resistant lines in okra. Fruit and shoot borer incidence was highest in the cultivated parent and was also high in 30 kR. High to moderately high genotypic coefficient of variation was observed.lor number of branches per plant, leaves per plant, flowers per plant, fruits per plant, weight of fruits per plant and number of seeds per fruit in all irradiated treatments in F3M3. High heritability and genetic advance were observed lor number of fruits per plant, weight of fruits per plant, flowers per plant and pollen sterility in all the irradiated treatments. Number of leaves per plant, flowers per plant and fruits per plant were positively correlated with fruit yield per plant in all the treatments while average fruit weight had significant positive correlation with fruit yield per plant in 0 kR, P, and P2 in the F3M3 generation. As a future line of work, high yielding, YVM disease resistant plants assembling the cultivated parent which have been isolated from the treatment 30 kR will be further evaluated for a few more generations and if found superior and YVM disease resistant it will finally be developed into a YVM disease resistant variety.ThesisItem Open Access Genetic variability in fodder bajra(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1997) Suresh, S; KAU; Sumabai, D IA research programme was carried out at the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during May to August 1995, with the objective of assessing the genetic variability and the scope of selection for forage yield and quality in bajra. Twenty varieties were evaluated adopting a randomised block design with three replications. Data on twelve characters were collected and subjected to statistical analysis. Analysis of variance revealed significant difference among the varieties for all the characters studied. Genotypic and phenotypic coefficients of variation were high for leaf weight per plant, green fodder yield, dry matter yield, leaf- stem ratio and crude protein content. High heritability coupled with relatively high genetic advance was recorded for leaf weight per plant and internodal length suggesting the reliability of these characters during selection programme. High positive genotypic correlation of dry matter yield, plant stand after germination, leaf number per plant, leaf weight per plant and leaf area index with green fodder yield had indicated that selection based on the above components results in the improvement of green fodder yield. Path analysis revealed that leaf number per plant and leaf area index were the most important characters influencing green fodder yield and dry matter yield. Selection index based on yield contributing characters had enabled to select four high yielding fodder bajra genotypes namely HTGPK – 1993, SSG – 59 - 3, IP – 5714 and LSGP – 1995.ThesisItem Open Access Combining ability for drought tolerance and yield in blackgram(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1997) Roy Isaac Varghese; KAU; Abdul Khader, K MA research programme consisting of five drought tolerant lines, three high yielding testers and their fifteen hybrids was carried out at the Department of Plant Breeding, College of Agriculture, Vellayani, during 1996-97, to evaluate the combining ability and gene action for drought tolerance, yield and related characters in blackgram. The lines and testers were selected based on previous performance and crossed and subjected to line x tester analysis and data recorded on both yield and drought related characters. Significant difference among the treatments was observed for all characters. Differences among parents were observed for all characters except number of branches per plant and number of pods per plant. Crosses were significantly different for all the characters. Therefore combining ability analysis was carried out for all characters. Specific combining ability variance was significant for all traits except number of branches per plant indicating the importance of non additive gene action. Both additive and non additive gene action were found to be involved for duration of the crop, number of pods per plant and grain yield per plant. However in all cases non additive gene action was predominant. Among lines, T 9 emerged as the best general combiner for various yield and drought related characters. The line, CoBG 302 was also found to be a better general combiner for various characters. Among testers, WBG 67 proved to be the best general combiner followed by VB 11. No specific cross combination was found to be significantly different for all the traits together. However the cross PDU 101 x WBG 67, CoBG 302 x CoBG 303 and T 9 x VB 11 were found to be the better specific combiner, when all the characters are considered. In short on the basis of combining ability estimated the lines T 9 and CoBG 302? the testers WBG 67 and VB 11 and the hybrids PDU 101 x WBG67, CoBG 302 x CoBG 303 and T 9 x VB 11 were suggested for further utilization for improvement.ThesisItem Open Access Seedling Progeny analysis in selected clones of Guinea grass (Panicum maximum Jacq.)(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1997) Babu, R; KAU; Suma Bai, D IA study was carried out at the Department of Plant Breeding and Genetics, College of Agriculture. Vellayani during July 1996 to May 1997 with the objective of ascertaining the seedling progeny behaviour in selected clones of guinea grass. A field experiment was conducted utilizing ten guinea grass clones available with All India Co- ordinated Research Project on Forage Crops to assess variability and identify three superior clones. Analysis of variance revealed significant difference for seven out of the eleven characters studied. The estimates of genotypic and phenotypic coefficient of variation were in general low for all the characters. Leaf area index recorded high heritability coupled with low genetic gain indicating non additive gene action. Correlation values of green fodder yield with all other characters were positive both at genotypic and phenotypic level. A selection index was formulated and three high yielding clones viz JHGG 96-3. JHGG 96-4 and Riversdale were selected and then subjected to progeny mean analysis along with two high yielding mutant clones viz Haritha and Marathakom in a compact family block design using seeds and slips. Marathakom recorded insignificant difference in variability with respect to two types of planting materials for ten out of the eleven characters studied, thus confirming the predominance of apomictic mode of reproduction and suitability to large scale seed production. Significant difference in variability was discernible in the remaining clones for more than one character indicating prevalence of sexual reproduction in these clones. Further studies on inheritance of percentage sexual reproduction in these clones would be desirable before embarking on large scale seed production.