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ThesisItem Open Access Genetic variability, path analysis and stability parameters in sesame(Department of Plant Breeding, College of Agriculture, Vellayani, 1985) Sverup, John; KAU; Gopinathan Nair, VBiometric analysis in a varietal collection of sesame was undertaken to study the genetic variability, correlations, path analysis and stability parameters. One hundred sesame types were evaluated in replicated trials at Vellayani in uplands during rabi and at Kayamkulam in rice fallows during summer. Genetic variability and correlations were estimated and path analysis worked out independently as both the locations. Location trials for estimating stability parameters were conducted at three places viz. in uplands during rabi at Pattambi and Vellayani and in rice fallows during summer at Kayamkulam. Large values for genotypic coefficients of variation were obtained for characters such as number of capsules on branches, number of capsules perplant, number of capsules on main stem and number of branches during rabi as well as summer. The lowest genotypic coefficient of variation was obtained for number of days to maturity during both rabi and summer. High values of heritability were recorded by seed protein content , seed oil content, height upto first capsule and weight of 1000 seeds under both conditions.ThesisItem Open Access Genetic divergence, prepotency and inbreeding depression in para rubber (Hevea brasiliensis Muell. Arg.)(Department of Plant Breeding, College of Agriculture, Vellayani, 1992) Kavitha Mydin, K; KAU; Gopinathan Nair, VA study on genetic divergence, prepotency and inbreeding depression in rubber was undertaken in an effort to identify clones for use as components of polyclonal seed gardens. Forty clones of Indian, Indonesian, Malaysian and Sri Lankan origin were evaluated in a replicated trial at the Rubber Research Institute of India. Genetic variability, correlations and the cause and effect relationships of dry rubber yield and its components were worked out. Genetic divergence was estimated employing the Mahalanobis' D2 techinique. The factors of divergence were identified through principal factor analysis. Twenty promising clones from genetically divergent clusters were subjected to seedling progeny analyses for the estimation of propotency based on performance of their open pollinated seedling progenies and inbreeding depression in the first generation of selfing. Significant clonal variation was revealed in respect of all the physiological, morphological and structural attributes studied as mean values for the fourth year of tapping for the stress period and for the peak yield period. High genetic variability for volume of latex under stress, plugging index under stress, annual mean dry rubber yield and dry rubber yield during the stress and peak periods was indicated by the high estimates of genotypic coefficient of variation. Additive gene effects offering scope for improvement through selection was indicated for dry rubber yield, latex flow rate and volume of latex during the three periods, girth increment rate, annual mean plugging index and plugging index under stress, by the moderate to high heritability estimates along with high genetic advance for these traits. Non- additive gene action was indicated by the high heritability and low genetic advance for dry rubber content during the three periods, girth and bark thickness. At both genotypic and phenotypic levels, annual mean dry rubber yield showed moderate to high positive correlations with dry rubber content and latex flow rate during the three periods, girth, girth increment rate, length of the tapping panel and bark thickness and negative correlations with yield depression under stress and plugging index during the three periods. Dry rubber yield under stress emerged as a more important component than peak dry rubber yield by its higher magnitude of positive direct effect on annual mean dry rubber yield. Latex flow rate during the stress and peak periods and annual mean volume of latex exhibited high positive direct effects on annual mean dry rubber yield while plugging index during the peak yield period, volume of latex under stress and girth increment rate had negative direct effects on annual mean dry rubber yield. The magnitude and direction of the effects of the components on dry rubber yield during the three periods varied indicating these relationships to be under different genetic control. Selection for a high dry rubber yield under stress, annual mean volume of latex and latex flow rate during the stress and peak periods and against a high plugging index during the peak period, volume of latex under stress and girth increment rate would help achieve improvement in annual mean dry rubber yield. Considerable genetic diversity was revealed by the wide range of D2 values and intra and inter cluster distances. The forty clones were grouped into eight genetically divergent clusters irrespective of their country of origin indicating the absence of any relationship between geographical diversity and genetic divergence. Volume of latex, plugging index, latex flow rate, dry rubber content and dry rubber yield contributed more towards divergence than the morphological and structural attributes. Supporting evidence was obtained from principal factor analysis which revealed the yield factor to be the main factor of divergence with respect to the clusters studied. Junveile rubber yield on test tapping, number of latex vessel rows and number of leaf flushes in seedling progenies exhibited high heritability and genetic advance indicating scope for their use as early selection parameters, while girth exhibited high heritability and low genetic advance. These three traits showed significant positive correlations with juvenile rubber yield, of which girth exhibited the strongest association. Juvenile rubber yield, number of latex vessel rows, girth and number of leaf flushes were identified as important traits for being accorded simultaneous emphasis in the computation of performance index and index scores for the determination of recovery of superior seedlings as estimates of prepotency. Nine clones were identified as likely preopotents on the basis of seedling progeny analysis at the age of two years. Selfing resulted in a lower fruit set than open pollination in the clones in general. No significant inbreeding depression was recorded for juvenile vegetative traits and rubber yield in seedlings. Clones PB 28/83, PB 215, RRII 105, AVT 73, PB 217, PB 252, Ch 26, PB 242 and PB 5/51 were identified as likely prepotents from three genetically divergent clusters. They recorded superiority for yield and various yield components. These clones exhibited synchrony in flowering and are suggested as components of a nine parent polyclonal seed garden. For a seven parent seed garden the clones suggested to be excluded are PB 5/51 and PB 242. A polyclonal seed garden comprising these nine or seven clones as components could generate good quality polycross seed material. Appropriate seed garden layouts have been suggested.ThesisItem Open Access Genetic analysis of biological nitrogen fixation traits and yield components in cowpea (Vigna unguiculata (Linn). walp)(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1995) Sreekumar, K; KAU; Manikantan Nair, PA study on the parameters of variability, correlations, path-coefficients, combining ability, gene action and heterosis in cowpea was undertaken at the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 1991 to 1993. Fifty three genotypes of cowpea collected from different sources were planted in a field experiment for the estimation of variability, correlation and path coefficient. Eleven biological nitrogen fixation characters, viz., number of days to flower, length of primary root, number of secondary roots, number of nodules in the primary root, number of nodules in the secondary roots, total number of nodules, weight of effective nodules in the primary root, weight of nodules in the secondary roots, total weight of nodules, nitrogen content in the plant at 50 per cent flowering and plant dry weight and six yield characters, viz., grain yield per plant, length of pods, number of pods per plant, number of seeds per pod, weight of 100 seeds and seed protein content were considered for this study. The ten selected varieties/types from the initial evaluation trial were crossed in a line x tester model, keeping the three high nitrogen fixing types and three high yielding types as lines (total six lines) and two low nitrogen fixing and two low yielding types as testers (total four testers). The F1’s along with their parents were compared in a field experiment and combining ability, gene action and heterosis were estimated. The study of combining ability and gene action were confined to six biological nitrogen fixation characters, viz., number of days to 50 per cent flowering, weight of nodules in the primary root, total weight of nodules, weight of effective nodules, dry weight of the plant and nitrogen content per plant and six yield characters, viz., length of pod, number of seeds per pod, number of pods per plant, hundred seed weight, seed protein content and grain yield per plant. The analysis of variance revealed that a considerable amount of variation among the varieties was present with respect to the characters under study. Characters like number of days to flower, total nodule weight, nitrogen content per plant, weight of 100 seeds and seed protein content had recorded narrow relative magnitude of difference of phenotypic and genotypic coefficient of variation along with high heritability estimate. Moderate magnitude of difference of PCV and GCV along with moderate heritability was recorded for the characters viz., number of nodules in the primary root, number of nodules in the secondary roots, total number of nodules, weight of effective nodules in the primary root, weight nodules in the secondary root, length of pods and number of pods per plant. Plant dry weight and grain yield registered a wider difference of PCV and GCV along with low heritability indication the greater influence of environment over these two characters. Genetic advance as percentage of mean was found to be high for the characters like number of nodules in the secondary roots, weight of effective nodules in the primary root, weight of nodules in the secondary roots, total nodule weight, number of pods per plant and 100 seed weight and moderate for number of nodules in the primary root, total number of nodules and grain yield. Low genetic advance was recorded by number of days to flower, plant dry weight, nitrogen content per plant, length of pod and seed protein content. Hence characters such as number and weight of nodules in the primary root, number and weight of nodules in the secondary roots, total number and weight of nodules, number of pods per plant and weight of 100 seeds may be controlled by additive genes whereas days to 50 per cent flowering, nitrogen content in plant, length of pod and seed protein content may be controlled by non-additive genes. Correlation coefficients were workedout at the genotypic and phenotypic levels. Based on the genetic correlation of characters studied, it was understood that high nitrogen fixing genotypes may not be high yielders because of the antagonistic relationship between grain yield and total nitrogen per plant. Weight of nodules in the primary root and total nodule weight were positively correlated with the nitrogen content in plant. Hence genotypes which was able to form effective large nodules on the primary root system seems to be a better nitrogen fixer. Number of days to 50 per cent flowering had negative genotypic correlation with grain yield. Hence an early flowering genotype may be better yielder than a late flowering type. Weight of hundred seeds and seed protein content exhibited very strong negative correlation indicating that small seeded genotypes may be better with respect to protein content. Grain yield recorded positive phenotypic and genotypic correlation with number of pods per plant. Path coefficient analysis at the genotypic level revealed that total number of nodules had the highest positive direct effect on nitrogen content per plant followed by weight of effective nodules in the primary root and weight of effective nodules in the secondary root. Highest positive direct effect was recorded for length of pod with grain yield. The combining ability analysis revealed that both additive and non-additive gene actions were important for all the characters under study. However GCA and SCA variance ratio which was less than unity for all the traits under study indicated the predominance of non-additive gene action in the inheritance of these traits. Considering the combining ability effects, VCP 4 was found to be the best general combiner for most of the biological nitrogen fixing characters and V 322 was the best general combiner for the grain yield. The cross combination of V 27 x C 152 and V 271 x Co Vu 85020 showed the best performance with respect to sea for the character number of days to 50 per cent flowering while VCP 4 x C 152 for weight of nodules in the primary root and nitrogen content in plant. DPLC 210 x PTB 2 recorded high sea for total weight of nodules, weight of effective nodules, dry weight of the plant and number of pods per plant, on the other hand Co Vu 358 x C 190 recorded high sca for length of pod, number of seeds per pod and seed protein content. The cross combination V 322 x C 190 exhibited high sca for hundred seed weight and V 27 X C 152 for grain yield per plant. Marked heterosis was observed in many cross combinations for most of the characters studied and pronounced heterotic expression was obtained for weight of nodules in the primary root, total weight of nodules, weight of effective nodules, dry weight of the plant at 50 per cent flowering, number of pods per plant and grain yield. It was already established that these characters are predominantly governed by the non – additive gene action. Hence the heterotic vigour expressed by the hybrid combination with respect to these characters are justified. Since the biological feasibility for the exploitation of heterosis is not economical as a plant improvement programme in this crop, genetic improvement of these trait can be brought about more effectively through combination breeding involving genetically diverse and high combining parants.ThesisItem Open Access Genetic variability, path analysis and stability parameters in sugarcane(Department of Plant Breeding, College of Agriculture, Vellayani, 1986) Sreekumar, S G; KAU; Gopinathan Nair, VInvestigations on genetic variability, path analysis and stability parameters wore conducted at the Sugarcane Research Station, Thiruvalla, Sugarcane Research Centre, Chittoor and Horticultural Research Station, Ambalavayal. The analysis of data collected from 48 clones evaluated at Thiruvalla revealed that the clones showed significant differences for all the 21 characters except Juiciness at 10th month in the first ratoon crop. The germination count on the 45th day, shoot count on the 180th day, number of late shoots at harvest, number of millable canes per plot, cane yield per plot and sugar yield per plot recorded moderate to high heritabiiity in the broad sense coupled with high genetic advance both in the plant and in the first ratoon crops indicating that selection based on these characters will be effective in improving cane and sugar yields. Correlation studies revealed that cane yield per plot had significant positive genotypic correlations with germination count on the 43th day, shoot count on the 180th day, number of millable canes per plot, cane weight and length of cane both in the plant and the first ratoon crops. Therefore, improvement in any one or more of these characters will result In a simultaneous improvement in the yiold of cane. Tho quality characters such as Juiciness, brix, pol and C.C.S. percentages at 12th month had positive but non-significant correlations with cane yield In ths plant crop and the first ratoon crop, suggesting difficulty in the simultaneous improvement of cane yield and quality characters through direct selection. The number of late shoots at harvest had highly significant positive genotypic and phenotypic correlations with the yield of cane in the first ratoon crop indicating that the number of late shoots at the time of harvest can be considered as a reliable criterion for the selection of clones with good yielding ability in the ratoon crop. Sugar yield recorded significant positive gonotypic correlations with cane yield and tho components of cane yield such as germination count on the 45th day, number of millable canes per plot, cane weight and length of cane. Sugar yiola also had significant positive genotypic correlations with brix, pol and C.C.S,percentages at 12th month, Tho significant positive gonotypic correlations of sugar yield with cane yield and its important components suggests that by increasing the cane yield, sugar yield per plot can be increased.ThesisItem Open Access Genetic variability, path analysis and stability parameters in sesame(Department of Plant Breeding, College of Agriculture, Vellayani, 1985) Sverup John; KAU; Gopinathan Nair, VBiometric analysis in a varietal collection of sesame was undertaken to study the genetic variability, correlations, path analysis and stability parameters. One hundred sesame types were evaluated in replicated trials at Vellayani in uplands during rabi and at Kayamkulam in rice fallows during summer. Genetic variability and correlations were estimated and path analysis worked out independently as both the locations. Location trials for estimating stability parameters were conducted at three places viz. in uplands during rabi at Pattambi and Vellayani and in rice fallows during summer at KayamkulamThesisItem Open Access Genetic resources utilisation and biometric analysis in groundnut (Arachis hypogaea L.)(Department of Plant Breeding, College of Agriculture, Vellayani, 1983) Pushkaran, K; KAU; Gopinathan Nair, VMaximising the production, of vegetable oils in the country is one of the badly felt national needs for which the improvement in the productivity of groundnut, the major oilseed crop of the country, deserves the best attention. As a crop, groundnut has wide adaptability and a number of other favourable attributes. Breeding improved varieties suited to the two major areas of groundnut cultivation viz, the traditional uplands during kharif land the non-traditional, but potential rice fallows during summer is an immediate necessity for popularising the crop in this State. Germplasm collection, evaluation and utilisation constitute the basic approaches in the genetic improvement of any crop. Hence this investigation. Eighty eight divergent varieties of groundnut were collected from different sources and subjected to preliminary evaluation in uplands during kharif. Ninety three varieties were evaluated in rice fallows during summer. These varieties showed wide variability in general performance, yield and other attributes within and between the situations. AH-6915 in uplands and TG-3 in rice fallows were the highest yielders. Several varieties were better in yield than the recommended varieties, viz., TMV-2 and TMV-7. A few varieties such as TG-14 end Spanish Improved were consistently superior at both' the situations.ThesisItem Open Access Induction of genetic recombinations in interspecific crosses of Abelmoschus(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1994) Sheela, M N; KAU; Manikantan, Nair PA study was undertaken at the College of Agriculture, Vellayani during 1990-91 aimed at inducing recombinations of the economic attributes of Bhindi (Abelmoschus esculentus (L.) Moench) and the yellow vein mosaic disease resistance of wild relatives. A preliminary evaluation of 56 accessions revealed good genetic diversity in Bhindi germplasm. The accessions were grouped into four clusters. The characterization of germplasm was done based on IBPGR descriptors. High genotypic coefficients of variation were exhibited by weight of fruits per plant, leaf area, height of plant, number of fruits per plant, single fruit weight and number of branches per plant indicating scope for selection. High heritability along with high genetic advance was recorded for weight of fruits per plant, height of plant, leaf area and number of seeds per fruit. Low heritability coupled with low genetic advance recorded for yellow vein mosaic disease incidence indicated the predominant role of environment in the inheritance of disease resistance.ThesisItem Open Access Genetic variability, path analysis and stability parameters in sugarcane(Department of Plant Breeding, College of Agriculture, Vellayani, 1986) Sreekumar, S G; KAU; Gopinathan, Nair VThe stability analysis done for component characters on cane yield and sugar yield gave an insight in to the characters contributing to yield stability across environments. Among the cane yield and its most important components viz. number of millable canes per plot and girth of cane the absence of G x E interaction itself is an indication that these characters are stable across environments. The other components of cane yield such as cane weight and length of cane had significant linear components of G x E interaction alone suggesting the stability of these characters. In sugar yield and its more important components viz. brix and pol percentage, the pooled deviations were highly significant suggesting the unpredictability and unstable nature of these quality characters across environments. Therefore, for breeding stable varieties across environments due weightage must be given for characters like number of millable canes per plot, cane weight, girth of cane and cane yield per plot.ThesisItem Open Access Genetic analysis of brown planthopper resistance in rice(Department of Plant Breeding, College of Agriculture, Vellayani, 1988) Rema Bai, N; KAU; Gopinathan Nair, VThe Brown planthopper (BPH), Nilaparvata lugens (Stal), has become a serious threat to rice production throughout Asia. Very extensive losses have occurred in India, Indonesia, and the Phylippines. The most severe outbreak in India occurred in Kerala during 1973-74 in ‘Kole’ lands of Trichur district and ‘Kuttanad’ area of Kottayam and Alleppey districts. Although insecticides provide effective control, this approach is expensive and creates problems of environmental pollution. Resistant varieties can provide protection and insurance against this insect pest at no extra cost and with no danger from chemical residues. Very little work has been done in Kerala to identify sources of resistance to the local biotype of BPH and on the genetic basis of BPH resistance. The major objectives of the present investigation were to identify sources of resistance to BPH and to conduct genetic analysis and understand the mode of inheritance of BPH resistance. One hundred and nine rice types were studied for their reaction to BPH through the bulk seedling test at the seedling stage and tiller test and honeydew experiment at the tillering stage. Out of them 41 were found to be resistant, 22 moderately resistant, 13 moderately susceptible and 33 highly susceptible. In the tiller test, 31 out of the 41 resistant varieties were resistant, nine moderately resistant and one moderately susceptible. The thirty one types found resistant under tiller test were subjected to honeydew experiment, out of which 30 were found to be resistant and one was moderately resistant. 2 The inheritance of resistance was studied in eight types selected from among the 30 types proved to be resistant in all the three tests. They were crossed with the susceptible variety TN1 and the F1, F2 and F3 generations were studied by bulk seedling test, tiller test and honeydew experiment. F1 seedlings were also screened by bulk seedling test, tiller test and honeydew experiment. The F2 progenies were screened by the bulk seedling test and tiller test. The F3 seedlings were screened by bulk seedling test only. The F2 and F3 progenies were scored separately as resistant and susceptible types and the observed segregation ratios were tested against the expected by applying the test of goodness of fit. The F1s of all the eight crosses were resistant indicating that resistance in each of the eight types was governed by dominant gene. The F2 populations of all the eight crosses segregated in the ratio of 3 resistant : 1 susceptible indicating that a single dominant gene governed resistance in each of the eight resistant types. F3 breeding behaviour of the nine F2 resistant plants from each of the eight crosses confirmed the monogenic control of resistance over susceptibility. Two dominant genes Bph1 and Bph3 were identified at IRRI (Bph1 in variety Mudgo and Bph3 in RatuHeenati). In the present study, Mudgo containing Bph1 and RatuHeenati with Bph3 gene were not resistant. Hence it is assumed that the dominant resistant gene identified in the present study is neither Bph1 nor Bph3. 3 Diallele crosses were made between six resistant types selected based on diverse origin. The F1 and F2 progenies of the 15 combinations were studied to get information on the allelie relationship between the resistance genes. The F1 progenies of all the crosses were resistant and the F2 progenies were homogeneous for resistance. This lead to the conclusion that all the six types have the same dominant gene for resistance. All the six resistant types were isogenic and hence all of them are expected to carry a dominant gene for BPH resistance other than Bph1 and Bph3. The present study has thus made available several types resistant to the local biotype of BPH and also enabled the location of a new dominant gene conferring resistance to this biotype. These results and the materials made available can form the basis for a more effective breeding approach for BPH resistance in this region.