Browsing by Author "Siby Varghese"

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Genetic analysis in ivygourd (Coccinia grandis (L) viogt)
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2003) Siby Varghese; Chandramony, D
The present investigation entitled "Genetic Analysis in Ivygourd (Coccinia grandis (L) Voigt.) was conducted at the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 1999-2001. Objective of the study was to estimate the genetic basis of different characters, genetic divergence in the germplasm and to formulate a selection index for identifying superior types. The material for the experiment was 90 different local cultivars collected from different agroclimatic regions. The data for the investigation were collected from two field experiments, each laid out in Randornised Block Design with three replications. In Experiment I a collection of 50 genotypes of ivygourd was grouped into 11 clusters using Mahalanobis D2 statistic and based on eight morphological characters. Five genotypes Kuriyabandar local I, Kuriyabandar local Ill, Pilangatta local 11 & III and Kudlu local I, could not be grouped with others and so are kept as independent clusters. The cluster C IX was found to have maximum intercluster distance with seven of the eleven clusters formed. This was followed by C 11 which showed maximum divergence with four out of the eleven clusters. The results suggest that selection of parents from these divergent clusters will be effective in future hybridisation programme. The three superior crosses identified were Balthangadi local I x Pilangatta local 11, Bandargrarn local I x Pilangatta local 11 and Seetharnbeta local I x Pilangatta local II. Number of flowers per plant and number of leaves per plant were found to be the two characters that contributed maximum for the divergence of the genotypes. So both at phenotypic and cluster levels, these two characters can be considered as potential contributors of differentiation in Jvygourd. In Experiment II the data collected from 40 genotypes of ivygourd were subjected to analysis of variance and the genetic parameters like variability, heritability; genetic advance, correlation coefficients and path coefficients were estimated. Based on the above observation, a selection index was also formulated. Significant genotypic differences were observed among the 40 genotypes for all of the sixteen characters studied. High genetic variability was expressed by the characters fruit yield per plant, number of fruits per plant and number of flowers per plant. High heritability along with a good genetic advance was found for all the characters studied, except for number of days for first flower opening which exhibited high heritability and low genetic advance. These results indicate that the selection of plants which are phenotypically superior with respect to fifteen of the characters studied will certainly result in a significant improvement in the next generation. The genotypic correlation coefficients were higher than the corresponding phenotypic and environmental correlation coefficients revealing the fact that phenotypic expression of these correlations are reduced due to the influence of the environment. Yield per plant exhibited positive association with all the characters except number of days for flowering, which had significant negative correlation with yield. Number of fruits per plant and single fruit weight were the characters with high direct and indirect effects. Based on the above results, a selection index was formulated and local cultivars of Alappuzha, Kanjangad, Thirunelli, Mancheswararn and Nangikadapurarn were identified as the five top ranking genetically superior ivygourd genotypes. To sum up, the results of the present study indicates that being strictly a cross pollinated crop with possibility for vegetative propagation, methods of breeding which can. be successfully followed are individual plant selection, mass selection to improve varieties, pedigree method and heterosis breeding and vegetative propagation of the heterotic combinations. Considerable variability of the crop has been observed in Kamataka, Andhra Pradesh, Tarnil Nadu and northern parts of Kerala. There is considerable scope for survey, collection and maintenance of germplasm. The study highlights the feasibility of producing commercially viable indigenous selections and hybrids which are early, producing more number of bold and tender fruits with good storability and resistance to pest and diseases.
Genetic make up of yield and yield attributes in a six parent dialiel cross of tomato
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1998) Siby Varghese; Chadramony, D
An experiment in tomato (Lycopersicon esculentum Mill.) was carried out at the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 1995-96, with the objective of estimating the combining ability of parents, and gene action involved in the inheritance of different yield attributes. The study was conducted in a diallel model, using three bacterial wilt resistant varieties and three popular varieties. The three bacterial wilt resistant varieties were Sakthi, Arka Alok and Arka Abha. The three popular varieties were LE 79-5, LE 373 and PKM 1. These six parental varieties and fifteen hybrids were planted in the field in Randomised Block Design., with three replications. Observations recorded were plant height, number of branches per plant, spread of the plant, number of leaves per plant, number of days taken for first flowering, number of days taken for first harvest, duration of harvest, single fruit weight, fruit size, number of fruits per plant, fruit yield per plant, pericarp thickness, locules per fruit, number of seeds per fruit, reaction to pests and diseases, colour at collar of fruits and fruit cracking. Analysis of variance revealed highly significant differences among the genotypes for all the characters except for number of locules per fruit. Both g.c.a. and s.c.a. were significant for all these characters. The additive to \1 \3«;6 • dominance variance ratio indicated a preponderance for non-additive gene action in the characters such as spread of the plant, number of days for first flowering, number of days for first harvest and duration of harvest, and a preponderance for additive gene action in the remaining characters. Combining analysis showed that Sakthi and PKM 1 were good general combiners with respect to fruit yield and other yield attributes whereas LE 79-5 and LE 373 ",!ere good general combiners for the different vegetative characters such as plant height, branches and leaves per plant. Among the fifteen hybrid combinations, significant S.C.a. and heterosis were observed in the hybrids such as Arka Alok x PKM 1, Arka Abha x PKM 1, Sakthi x Arka Alok, Sakthi x Arka Abha and LE 79-5 x LE 373. Among these hybrids Arka Alok x PKM 1 showed significance for fruit yield, individual fruit weight, size of fruit, plant height, leaves per plant spread of the plant and also showed resistance to mosaic, fruit rot and fruit borer. The hybrid Arka Abha x PKM 1 showed significance for fruits per plant, fruit yield per plant, plant height, leaves per plant and spread of the plant. The combinations Sakthi x Arka Alok and Sakthi x Arka Abha showed high s.c.a. and heterosis for fruit weight, fruits per plant and fruit size and also high heterosis for fruit yield per plant. LE 79-5 x LE 373 exhibited high s.c.a. for fruit yield per plant and heterosis for fruit number and fruit yield. Therefore, these hybrids can be utilized for further crop improvement programme.