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Open Access
Combining ability in vegetable cowpea
(Department of Plant Breeding, College of Agriculture, Vellayani, 1992) Rejatha, V; KAU; Ramachandra Nair, N
A 6 x 6 diallel analysis was conducted at the Department of Plant Breeding, College of Agriculture, Vellayani, during 1990, aimed at analysing the combining ability, gene action and heterosis of six vegetable cowpea (Vigna unguiculata var-sesquipedalis) lines collected from the germplasm maintained in this department. The experiment I consisted of crossing the six parental lines in all possible combinations, without reciprocals. The material for experiment II consisted of the six parental lines and fifteen hybrids. They were grown in a Randomised Block Design with three replications.The combining ability analysis was carried out based on method 2 under model I as suggested by Griffing (1956). The treatments showed significant differences in most of characters except number of pods/plant and fruit yield/plant. The variance due to general combining ability was significant and higher in magnitude than specific combining ability for the characters days to flowering, mean weight of pod, mean length of pod, number of seeds/pod, length of internode and seed/pod ratio. It was found that the parent selection 104 and selection 145 were the best general combiners for most of the characters studied. The parent selection 129 was the best general combiner for earliness. The hybrids selection 145 x selection 129 was the best specific combiner for mean weight of pod and number of seeds/pod. The hybrid selection 145 x kurutholapayar was the best specific combiner for earliness. The significance of g.c.a. and s.c.a. variances for most of characters indicate the importance of additive and non-additive gene action in controlling the inheritance of these characters. But additive gene action played a major role suggesting that improvement could be made through selection. Heterosis was calculated over mid and better parental values. Maximum positive heterosis was found for the character fruit yield/plant. Since considerable heterosis was evident in most of the characters, heterosis breeding can be attempted in cowpea
Open Access
Induction of polyploidy in kacholam
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 1996) Ajithmohan, N K; KAU; Pushkaran, K
A trial on induction of polyploidy in Kaempferia galanga L. was undertaken at the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, during the period 1994-'95. A local selection Vellanikkara collected from the genetic stock maintained at AICRP on M & AP was used for the study. The objective was to create variability in kacholam by developing polyploids. The rhizomes of the crop were treated with colchicine for inducing polyploidy. Five concentration of colchicine viz., 0.05, 0.15, 0.25, 0.35 and 0.45 per cent (C2 to C6, C1 being control i.e., 0%) was tried for two time durations viz., four hours and six hours (T1 and T2), the same treatment being repeated on two consecutive days. Two methods of treatment were tried the first (M1) being chemical application in a hole drilled close to the sprouting bud and the second (M2) being the ordinary cotton swab method. Rhizomes with two different stages of bud sprouting were used: (1) with just emerging buds (S1) and (2) buds at an advanced stage of sprouting (S2). The treated rhizomes were planted in the field and their growth was examined. In the end of the crop season, 18 variant plants were identified and they were put to detailed morphological and cytological study in the next growing season. Mitotic study of the parent material confirmed that the chromosome number of kacholam is 55. Of the 18 variants identified one was found to contain 110 chromosomes in the somatic cells. As kacholam is proposed to be a pentaploid the induced polyploid must be a decaploid. The polyploid was obtained from the treatment combination S1M1T1C6. It was characterised by small plant size and reduced vigour. The leaves were thick with reduced size. Stomatal size increased conspicuously with their numbers reduced. The rhizome development was found retarded and the per plant yield was also less. The rhizome morphology was on par with the normal plants. The plant flowered neither in the first season nor in the second. In addition to the polyploid, there other stable variants were obtained from the experiment. They were also characterised by reduced vigour and yield.
Open Access
Combining ability for yield and drought tolerance in cowpea
(Department of Plant Breeding, College of Agriculture,Vellayani, 1993) Anilkumar, S G; KAU; Sreekumar S G, S G
A research programme was carried out at the Department of Plant Breeding, College of Agriculture, Vellayani during 1991 to 92 with five lines, three testers and their fifteen F1s'. The data on sixteen characters were collected and subjected to line x tester analysis for estimating combining ability and gene action in the inheritance of drought tolerance, yield and related characters. Analysis showed that the line DPLC-198 had a positive and significant gca for leaf area index, grain filling period, number of pods per plant, hundred seed weight, grian yield per plant and biological yield. The line IC-38956 showed negative and significant gca for duration upto first flowering and duration upto maturity. The line DPLC-216 had positive and significant gca for grain filling period and hundred seed weight. The line V-240 for number of seeds per pod and VCM-8 for duration upto maturity showed significant gca. The tester C-152 showed significant positive gca for number of seeds per pod, grain yield per plant and biological yield and showed significant gca for duration upto maturity. The tester Chharodi-1 showed significant negative gca for duration upto first flowering and duration upto maturity. The tester Kanakamany showed significant positive gca for grain filling period, hundred seed weight and biological yield. DPLC-198 x chharodi-1 and IC-38956 x C-152 showed significant and negative sca for duration upto first flowering while DPLC-198 x Kanakamany, IC-38356 x Chharodi-1 and VCM-8 x Kanakamany showed significant negative sca for duration upto maturity. Significant negative sca for proline content was recorded by IC-38956 x C-152, V-240 x Chharodi-1 and DPLC-216 x Kanakamany. DPLC-216 x C-152 and DPLC-216 x Kanakamany recorded significant positive sca for filling period. A significant positive sca for number of pods per plant, grain yield per plant and biological yield was recorded by DPLC-198 x C-152. Leaf area index, number of seeds per pod and hundred seed weight which had additive gene action can be improved by selection. Number of pods per plant and proline content had non-additive gene action.Presence of additive and non- additive gene action with preponderance of non-additive gene action was noticed for duration upto first flowering, duration upto maturity, grain yield per plant and biological yield while preponderance of additive gene action was noticed for grain filling period. The characters that are controlled by non-additive genes or predominantly under the control of non-additive gene can be improved by recurrent selection and recombination breeding. Based on the gca estimates the lines DPLC-198 and IC-38956 and the testers C-152 and Chharodi-1 and the hybrids such as DPLC-198 x C-152, DPLC-198 x Chharodi-1, IC-38956 x C-152 and IC-38956 x Chharodi-1 were recommended for further utilization. Exploitation of heterosis normally is not a viable proposition in cowpea in the absence of easy methods of large scale production of hybrid seeds.
Open Access
Morphological Effect of Gamma Rays and EMS on Winged Bean [Psophocarpus tetragonolobus (L.)]
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1993) Reeja Dharan, S; KAU; Kamalam, N
Seeds of winged bean [Psophocarpus tetragonolobus (L.)] variety PT-62 were subjected to induced mutagenesis using six doses of gamma rays (100 to 500 Gy) and six doses of EMS (40 to 200 mM) to obtain information on the extent of genetic variability that can be induced in the M1 generation. The germination percentage was observed to be decreased by both the mutagens, however the effect was more severe with gamma rays in the field study. But gamma rays caused a stimulation of germination and an earlier germination, at all the doses in the laboratory trials. Number of days taken to complete germination was not much affected by either of the mutagens in the field. The growth of root and shoot were reduced by gamma rays linearly with increase of dose and by EMS drastically at its highest dose, however gamma rays showed greater inhibition of shoot growth and EMS caused greater inhibition of root growth. Survival percentage was observed to be reduced by both mutagens, but EMS was of not much effect. Gamma rays caused a stimulatory effect at its lowest dose. Plant height was beneficially affected by gamma rays at the lowest dose and drastically reduced at higher doses. EMS caused not much variation in plant height. Chlorophyll chimeras and morphological variations were mostly observed in gamma rays treated populations. Morphological variations mostly included alteration in number, size and shape of leaves and size and colour of seeds. Earlier flowering was observed in lower doses of gamma rays, but higher doses caused delayed flowering. Days taken to first flowering was not affected by EMS treatments. Both mutagens exhibited not much effect on the number of days to last flowering. However gamma rays treated populations were in reproductive phase for longer period than EMS treated populations. Number of pods per plant and fruit yield per plant were not affected by EMS treatment. But lower dose of gamma rays caused a stimulatory effect, and thereafter a gradual reduction with increase in dose. Weight and length of pod were slightly increased by EMS treatment, and decreased linearly with increase in dose of gamma rays treatment. EMS caused no significant effect on number of seeds per pod, whereas gamma rays showed an inverse relationship with dose. Both the mutagens showed not much variation in hundred seed weight. Greater pollen sterility was induced by gamma rays treatments, but the effect of EMS was not pronounced. An insignificant increase in seed sterility was exhibited by both the mutagens. In the present investigation greater variability for morphological characters was produced by gamma rays than EMS in the M1 generation of winged bean.
Open Access
Reproductive biology and enzyme studies in ocimum
(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 1997) Fancy, Parameswaran; KAU; Presannakumari, K T
The present study on "Reproductive biology and enzyme studies in Ocimum spp." was undertaken at the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara during the period 1994-1996 with a view to make a comparative evaluation of the reproductive biology and phosphorylase enzyme activity of different species of Ocimum. The four species of Ocimum viz. O. tenuiflorum, o. gratissimum, o. canum and o. basilicum collected and maintained in the Department were used for the study. The different species of Ocimum varied significantly in the time taken for inflorescence development, completion of anthesis in an inflorescence, number of flowers per inflorescence and distance between verticils. Species level variations were also observed in seed moisture content, seed density, l000-seed weight and seed dormancy period. Flowers of the four selected species were identical in basic structure although there existed variation in size, colour, hairyness and shape of floral parts. Anthesis occurred earlier in o. canum than the other three species. Pollen grains of Ocimum were hexacolpate and reticulate. However, species level difference existed in the size, shape and fertility of pollen grains. No self incompatibility mechanism existed in the four species studied. The floral morphology and protandrous nature makes the species adapted to cross pollination. Insects and ants are the main agents of pollination. Comparison of Sanctum and Basilicum groups revealed that Sanctum group which includes o. tenuiflorum and O. gratissimum required longer time for inflorescence development than Basilicum group which includes o. canum and O. basilicum. Verticils were closer in the inflorescence of Sanctum group than Basilicum group. Sanctum group produced less conspicous flowers with sessile bracts and yellow pollen grains. In this group anther dehiscence occurred in bud stage. Basilicum group produced conspicous flowers with pedicellate bracts and white pollen grains. Anther dehiscence was after flower opening in this group. Dormancy break was sudden in Sanctum group and gradual in Basilicum group. Moisture content of Ocimum seeds was positively related to phosphorylase enzyme activity. Phenol content was negatively related to both moisture content and phosphorylase enzyme activity of the seeds.
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, V
A 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.
Open Access
Combining ability studies in tomato (lycopersicon esculentum mill)
(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 1995) Seeja, G; KAU; Chandramony, D
An experiment in tomato (Lycopersicon esculentum Mill.) was carried out at the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 1993-94, 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 line x tester model, using three bacterial wilt resistant varieties as lines and five popular varieties as testers. The three bacterial wilt resistant varieties (lines) were Arka Abha, Arka Alok and Sakthi. The five popular varieties (testers) were LE 312, LE 370, LE 373, RFH-1 and PKM-1. These eight parental varieties and 15 hybrids were planted in the field in RBD, with three replications. Observations recorded were plant height, number of branches/plant, growth habit, spread of the plant, period of harvest, individual fruit weight, number of fruits/plant, fruit yield/plant, number of leaves/plant, pericarp thickness, locules/fruit, size of fruit and pest and disease incidence. Analysis of variance revealed highly significant differences among the genotypes for all the characters. Gca alone was significant for number of branches/ plant while sca alone was significant for spread of the plant and pericarp thickness. Both gca and sca were significant for the remaining characters such as plant height, period of harvest, individual fruit weight, fruits/ plant, fruit yield/plant, leaves/plant, locules/fruit and size of fruit. The additive to dominance variance ratio indicated a preponderance for non additive gene action in the above characters. Combining ability analysis showed that all the three lines viz., Arka Abha, Arka Alok and Sakthi were good general combiners with respect to fruit yield and other yield attributes whereas the testers were good general combiners, for the different vegetative characters such as plant height, branches and leaves/plant. Among the 15 hybrids combinations, significant sca and heterosis were observed in the hybrids such as Arka Abha x LE 370, Arka Alok x PKM-1, Arka Alok x LE 312, Arka Abha x RFH-1 and Sakthi x RHF-1. Among these hybrids, Arka Abha x LE 370 showed significance for fruit yield, individual fruit weight, size of fruit, plant height, leaves/plant, branches/plant and also showed resistance to mosaic, leaf cur1 and fruit borer. This hybrid exhibited indeterminate growth habit. The hybrid Arka Alok x PKM-1 showed significance for fruits/plant, fruit yield/plant, plant height and leaves/plant. The combinations Arka Alok x LE 312 and Arka Alok x RFH-1 showed high sca and heterosis for individual fruit weight, fruit size and pericarp thickness, and also high heterosis for fruit yield/plant. Among these, Arka Aloka 312 showed indeterminated growth and Arka Alok x RFH-1 showed semi determinate growth habit. Sakthi x RFH-1 exhibited high sca for fruit yield/plant and heterosis for fruit number and individual fruit weight. This hybrid also showed resistance to leaf curl and mosaic. This hybrid showed determinate growth habit. Therefore these hybrids can be utilized for further crop improvement programme.
Open Access
Genetics divergence in bhindi (abelmoschus esculentus (L.) moench)
(Department of Plant Breeding, College of Agriculture, Vellayani, 1993) Bindu, K K; KAU; Manju, P
A study was conducted in the Department of Plant Breeding, College of Agriculture, Vellayani during the period 1991-93. The main aim was to estimate the magnitude of genetic divergence in a collection of bhindi varieties to select suitable ones for use as parents for developing commercial hybrid varieties. The estimation of genetic parameters of important economic characters, the association among these characters, direct and indirect effects and D2 values were undertaken. Seventy genotypes of bhindi were evaluated in a RBD with three replications. The genotypes showed significant differences in most of the characters studied except fruiting phase and leaf axil bearing the first flower. Genotypic coefficient of variation was maximum for weight of fruits per plant and minimum for days to first flowering. Heritability estimate was maximum for length of fruit while it was minimum for leaf axil bearing the first flower. Genetic advance as percentage of mean was maximum for weight of fruits per plant. High hertibility coupled with high genetic advance was recorded for length of fruit, leaf area, weight of single fruit, height of the plant and weight of the fruits per plant. At genotypic level yield per plant showed positive correlation with all the characters studied. Path coefficient analysis at genotypic level revealed that the number of fruits per plant, weight of single fruit and number of branches exhibited high direct influence on yield. The study indicated that the model for selection of high yielding varieties of bhindi should be based on the number of fruits per plant, weight of single fruit and number of branches. D2 analysis revealed that the 70 genotypes were grouped into six clusters. Cluster I, II, III, IV, V and VI contained fifty seven, four, three, two, three and one genotypes respectively. The maximum divergence was obtained between clusters II and VI and the minimum between clusters I and IV. The intra cluster distance was maximum in cluster III and minimum in cluster IV. In future breeding programme for the development of heterotic hybrids parent may be selected from cluster II and VI for hybridization.
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, P
A 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.

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