9. Genetic variability in Okra

HortFlora Research Spectrum, 1(2): 139-144 (2012) ISSN : 2250-2823 GENETIC VARIABILITY, HERITABILITY, GENETIC ADVANCE, CORRELATION AND PATH ANALYSIS IN OKRA Sanjay Kumar, Annapurna1, Yogesh Chandra Yadav1 and Raghvendra Singh Department of Horticulture, Institute of Agricultural Sciences, Banaras Hindu Univ., Varanasi 1 DAPS (Hort.), B.B.A. Univ., Lucknow ABSTRACT : A field experiment was conducted with twenty diverse genotypes of Okra (Pusa Makhamali, VRO-6, VRO-5, Selection-10, IIVR-10, HRB-10, IIVR-11, Perkins Long Green,VRO-4, HRB-9-2, Parbhani Kranti, RS-410, Punjab-7, DOV-91-4, D-1-87-1, EMS-8-1,Bhindi Vaphy, 315, and BO-2) in randomized block design with three replications. Analysed data revealed that among all the genotypes, Pusa Makhamali, Perkins Long Green, Parbhani Kranti, VRO-6, VRO-5 and Selection-10 gave promising results. Keywords: Okra, genetic variability, heritability, genetic advance, path analysis. relative contribution of various yield related traits. Okra [Abelmoschus esculentus (L.) Moench] Genotypic and phenotypic coefficients of variance belongs to family Malvaceae with 2n =130 suck out the association between yield and yield chromosomes. It is one of the most important contributing traits in okra. If the association is vegetable crops, which is grown throughout the positive and significant, simultaneous important tropical and subtropical parts of the world. Being a and association is possible and significant. As the day neutral plant, it is cultivated in every season in correlation measures the mutual relationship one or other parts of the country. Being a between different traits of a plant, it helps to multipurpose, okra is valued for its tender delicious determine the best yield contributing traits. Path fruits. Its dry seed are a rich source of iodine, analysis deals with a close system of variables that carbohydrate, protein, oil and vegetable curd. Seeds are linearly related. It specifies the causes and are also used as coffee additive or substitute. Its dry generally measures their relative importance. Path seeds contain 13-22% edible and 20-24% crude analysis split the correlation coefficient in to the protein (Thamburaj and Singh, 9), foliage can be measures of direct and indirect effect and used for biomass and dried stem as the source of determines direct and indirect contribution of paper pulp or fuel. Its roots are used to clean various characters towards the yield. sugarcane juice to make jaggery. Okra is praised for its medicinal values, as its fruits are useful in genito-urinary disorders, spermatorrhoea and chronic dysentery. Okra is often cross-pollinated where the natural cross-pollination occurs from 8.75 to 9.61%. Okra is highly susceptible to frost and requires warm climate for fruit production. The improvement in genetic make up i.e., growing habit of the plant increases the harvest index and improvement in resistance to insect-pest and diseases ultimately increase the yield. There are great prospects and possibilities for the further increase in productivity and production of okra. Increase in genetic yield potential gives a boost to okra production. Some biometrical techniques like variability, correlation and path analysis provide Received : 23.12.2011 Revised : 18.2.2012 Accepted : 20.3.2012 MATERIALS AND METHODS The experimental material included 20 diverse genotypes viz. (Pusa Makhamali, VRO-6, VRO-5, Selection-10, IIVR-10, HRB-10, IIVR-11, Perkins Long Green, VRO-4, HRB-9-2, Parbhani Kranti, RS-410, Punjab-7, DOV-91-4, D-1-87-1, EMS-8-1, Bhindi Vaphy, 315, and BO-2) and were sown during rainy season of the year 2005-06 in randomized block design with there replications at Vegetable Research Farm, Institute of Agricultural Sciences, BHU, Varanasi (U.P.). Row -to -row and plant-to-plant spacings were maintained 60 cm and 30 cm, respectively. All the agronomic packages of practices were adopted to grow a healthy crop in each replication. Randomly 5 plants in each 140 Kumar et al. genotype were marked for observation. Observations were recorded in 12 characters viz, plant height (cm), no. of branches /plant, no. of flowers/ plant, no. of fruits/ plant, no. of fruits/ branch, length of fruit (cm), weight of fruit/ plant(g), diameter of fruit (cm) and yield/plant. The recorded data were analyzed as suggested by Panse and Sukhatme (8) for analysis of variance. The genotypic and phenotypic coefficient of variance was calculated as per the formula suggested by Burton (3). Johnson and Comstock (5) for heritability and genetic advance, Al – Jibouri et al., (1) for correlation coefficient and Deway and Lu (4) for path coefficient. RESULTS AND DISCUSSION The mean sum of square was highly significant for all traits, indicating the presence of wide variability in the present genotypes of okra (Table 1). Yield /plant (g) showed a widest range (307.41 – 702.67), the minimum and maximum yield /plant at edible stage was recorded in genotypes Bhindi Vaphy and Pusa Makhamali, respectively with a mean value 401.48. Maximum plant height (cm) was recorded in Pusa Makhamali, (114.71) while minimum in Punjab selection (72.17), with a mean value 90.15. Days to flower appearance ranged from 45.32 to 65.32 (Parbhani Kranti and IIVR-10). Number of leaves/ plant and no. of flowers/plant also registered considerable variability, which ranged from 40.39 to (BO-2 ) to 77.55 (Pusa Makhamali) and 29.90 (BO-2) to 77.67 (Pusa Makhamali) maximum no. of fruits/plant was recorded in VRO-6 and minimum in EMS-8-1, maximum diameter of fruits was recorded in Pusa Makhamali (10.53) and minimum in BO-2 with a mean 8.60. Maximum length of fruits was recorded in Pusa Makhamali (9.60 cm), while minimum in BO-2 (6.19 cm) with a mean value 8.25. The maximum no. of fruits/ branch (9.10) was recorded in VRO-6 and minimum in Larm (5.93). The maximum no. of branches/plant was recorded in VRO-6 and minimum in Perkins Long Green, respectively. The maximum weight of fruit was recorded in Pusa Makhamali and minimum in Bhindi Vaphy. In general, the phenotypic variance and phenotypic coefficient of variance were higher than their respective genotypic variance and genotypic coefficient of variance for all the traits (Table 2), indicating considerable effects of environment on their expression. In the present investigation, genotypes were found to possess a high to moderate phenotypic variance for various characters as revealed by PCV. Phenotypic coefficient of variance varied from 7.53 (weight of fruits) to 25.63 (no. of fruits/plant). The PCV expressed in form of percentage were high for no. of fruits/plant followed by yield/plant, no. of flowers/plant, no. of branches/plant, no. of leaves/plant, length of fruit, no. of fruits/branch, diameter of fruit (mm) and plant height (cm). As the estimate of phenotypic variability cannot differentiate between the effect of genetic and environmental effects, so the study of genetic variability is effective in partioning out the real genetical differences. Higher the GCV, more the chances of improvement in that characters. In the present experiment, GCV were comparatively high for no. of fruits/ plant followed by yield/ plant, no. of flowers/plant, no. of leaves/plant, no. of branches/plant, plant height and stem diameter. The GCV was less than the corresponding PCV, indicating the role in the expression of the traits under the observation. The difference between GCV and PCV was more in case of no. of branches/plant followed by no. of days to flower and length of fruits. The large difference between GCV and PCV indicated that environment affects to a large extent influence the traits having high GCV possessed better potential for further gain and improvement. Burton (3) has suggested that GCV together with heritability estimates would give the best option expected for the selection. Heritability estimates were high (>90%) for plant height, no. of leaves/ plant, no. of flowers/plant, no. of fruits/plant and yield/plant. Moderate heritability (70-90%) for no. of days to flower, diameter of stem , no. of fruits/branch and Genertic variability, heritability, genetic advance, correlation and path analysis in Okra 141 Table 1: Estimates of range, general mean, standard error of mean, PCV, GCV and C.D. value for 12 characters in Okra. S. No. Characters Min. PCV (%) GCV (%) C.D. (P=0.05) 2.102 14.45 14.16 4.248 1.046 1.634 0.125 1.753 23.15 11.41 11.92 19.64 14.83 10.79 13.93 19.28 2.113 3.302 0.252 5.542 1.867 23.51 23.15 3.773 0.431 1.995 1.094 0.433 0.105 16.18 25.63 17.71 15.74 7.53 14.55 25.22 7.12 11.15 5.73 0.871 4.032 2.210 0.875 0.101 11.349 25.52 25.18 2.726 Max. 1. Plant height (cm) 72.17(PB-7) 2. 3. 4. 5. No. of branches/plant No. of days to flower Diameter of stem No. of leaves of/plant 3.99(BO-2) 45.32(P.Kranti) 1.63(PLG) 40.39(BO-2) 6. No. of flower/plant 25.90(BO-2) 7. 8. 9. 10. 11. No. of fruits/branch No. of fruits/plant Length of fruit (cm) Diameter of fruit (cm) Weright of fruits (g) 5.93(Larm-1) 22.92(Ems-8-1) 6.19(BO-2) 6.96 (BO-2) 1.27 (Bhindi vaphy) 307.41 (Bhindi Vaphy) 12. Yield/plant (g) Means Standard error of mean Range 114.77(Pusa 90.15 Makhamali) 9.72(VRO-5) 7.21 65.32(IIVR-10) 53.83 2.84(VK-06) 1.989 77.55(Pusa 57.56 (Makhamali) 77.67(Pusa 56.18 Makhamali) 9.10(VRO-6) 74.56 75.93(VRO-6) 53.96 9.60 (P. Makhamali) 8.265 10.53(P. Makhamali) 8.601 1.64 1.479 (Bhindi Vaphy) 481.48 702.67(Pusa (Makhamali Table 2: Estimate of phenotypic variation and genotypic variation, heritability and genetic advance for 12 characters of Okra. Characters S. No. Phenotypic variation Genotypic variation Heritability (%) Genetic advance Genetic advance of mean 1. Plant height (cm) 1.3 88 1.328 0.961 25.79 1226.92 2. No. of branches /plant 0.945 0.373 0.411 1.41 134.79 3. No. of days to flower 0.263 0.229 0.894 11.31 692.16 4. Diameter of stem 0.440 0.408 0.766 0.50 399.68 5. No. of leaves / plant 94.316 93.18 0.964 22.45 1280.66 6. No. of flowers /plant 0.255 0.078 0.970 26.39 1413.49 7. No. of fruits /branch 8.065 7.987 0.808 2.01 466.35 8. No. of fruits /plant 1.385 0.866 0.969 27.60 1383.45 9. Length of fruit (cm) 0.482 0.296 0.462 0.49 44.78 10. Diameter of fruit (cm) 0.405 0.396 0.766 1.73 399.44 11. Weight of fruits (g) 0.917 0.737 0.578 0.13 260.00 12. Yield / plant (g) 227.29 226.40 0.973 246.43 2171.38 142 Table 3 : Estimates of phenotypic (P) and genotypic (G) correlation coefficient for different characters in Okra. Characters Plant height (cm) No. of branches/plant No. of days to flower Diameter of stem No. of flowers/plant No. of fruits/branch No. of fruits/plant Length of fruit (cm) Diameter of fruit (cm) Weight of fruit (g) No. of flowers/ plant No. of fruits/ branch No. of fruits/ plant Weight Length Diaof fruit meter of of fruits (g) (c m) fruit (c m) Yield/ plant P 0.097 -0.068 -0.005 0.180 0.614** 0.510** 0.775** 0.316 0.246 0.592** 0.347 G 0.064 -0.059 0.008 0.174 0.402* 0.069 0.159 0.164 0.496* 0.006 0.141 P 0.060 -0.321 0.045 0.061 -0.183 -0.118 0.272 0.349 0.404* 0.276 G 0.692** 0.162 0.003 0.525** 0.639** 0.484* 0.464* 0.326 0.508** 0.507** P 0.008 -0.054 0.624** 0.441** 0.435* 0.445* 0.525** 0.418* 0.0515* G 0.024 0.657** 0.0456* 0.595** 0.514** 0.439* 0.431* 0.643** 0.591** P 0.133 0.462* 0.499* -0.047 -0.089 0.161 0.045 0.389 G 0.423* 0.419* 0.658** 0.427* 0.420* 0.220 0.520** 0.636** P 0.645** 0.103 -0.198 0.454* 0.212 0.453* 0.465* G 0.632** 0.468* 0.382 0.111 0.448* 0.446* 0.665** P 0.155 0.450* 0.567** 0.493* 0.595** 0.793** G 0.007 0.616** 0.673** 0.263 0.456* 0.687** P 0.541** -0.191 0.571** 0.470* 0.661** G 0.584** 0.423* 0.330 0.545** 0.511** P 0.151 0.438* 0.588** 0.627** G 0.534** -0.300 0.484* 0.610** P 0.525** 0.478* 0.519** G 0.301 -0.066 0.601** P 0.448* 0.523** G 0.335 0.347 P 0.614** G 0.650** Kumar et al. No. of leaves/plant Plant No. of No. of DiaNo. of height branches days to meter of leaves/ (c m) /plant flower stem plant Table 4 : Direct (diagonal) and indirect effects of different traits contributing to yield in Okra (phenotypic level) No. of Length of Diameter Weight Genotypic Correlafruits/ fruit (cm) of fruit of tion plant (c m) fruits Coefficient (g) of Yield Plant height (c m) No. of branches/p lant No. of days to flower Diameter of stem (c m) No. of leaves/ plant No. of flower/ plant No. of fruits/ branch Plant height (cm) 0.295 -0.019 0.017 -0.002 0.051 0.090 0.020 -0.047 -0.048 0.146 0.019 0.141 No. of branches/ plant -0.005 -0.077 0.007 0.012 0.000 0.002 -0.011 0.006 0.013 0.025 -0.016 0.507 No. of days to flower -0.007 0.011 0.117 0.003 0.007 -0.012 0.011 -0.013 0.016 0.015 -0.005 0.591 Diameter of stem (cm) 0.003 -0.062 0.009 0.074 0.042 0.157 0.137 -0.010 0.008 0.034 0.008 0.336 No. of plant leaves/ -0.037 0.001 0.012 -0.026 0.055 0.133 -0.014 0.038 0.023 0.094 0.073 0.165 No. of plant flower/ 0.023 -0.052 0.008 0.030 0.047 -0.328 0.000 0.150 -0.005 -0.019 -0.012 0.687 No. of branch fruits/ 0.004 -0.008 -0.005 0.200 0.004 0.000 0.210 0.270 0.007 -0.018 -0.019 0.511 No. of fruits/plant 0.115 0.061 -0.083 -0.019 0.132 0.012 -0.351 0.726 -0.025 0.218 0.133 0.610 Length of fruit (cm) -0.035 0.035 0.029 0.004 0.024 0.016 0.026 0.007 -0.212 0.264 0.014 0.601 Diameter of fruit (cm) 0.094 0.062 0.025 0.190 0.085 0.050 0.063 0.057 0.057 0.190 -0.063 0.347 Weight of fruit (g) 0.005 -0.017 0.004 0.002 0.029 0.013 0.029 -0.015 -0.006 -0.028 0.083 0.650 Genertic variability, heritability, genetic advance, correlation and path analysis in Okra Character 143 144 Kumar et al. diameter of fruit suggested that the environmental effects constitute a major portion of the total phenotypic variation and hence direct selection for these characters will be less effective. High heritability for the characters controlled by polygene might be useful to plant breeder for making effective selection. Johnson et al. (5) reported that the heritability estimates along with genetic advance is more useful than the resultant effect for selecting best genotypes, as it suggests the presence of additive gene effects. High estimates of genetic advance were recorded for yield/plant followed by no. of fruits/plant, no. of flowers/plant, plant height and no. of leaves/plant. The information on heritability alone may be misleading but when used in combination with genetic advance, the utility of heritability estimates increases. In the present investigation, high genetic advance alongwith high heritability was observed for yield/plant followed by no. of flowers/ plant, no. of fruits /plant, no. of leaves/plant, plant height and no. of days to flower. It indicated that additive gene effects were more important than these characters, so the improvement in these traits would be more efficiently done through selection in the present materials. Depending upon the variability, heritability and genetic advance estimates, it could be predicted that improvement by direct selection was possible in okra for traits like no. of flowers/plant, length of fruit, no. of branches/plant, plant height and no. of fruits/plant. Results are in consonance with Yadav et al. (10). Fruit yield/plant in okra is the result of the interaction of no. of inter – related characters . Therefore, selection should be based on these components characters after assessing their relation with fruit yield/plant. In the present experiment, the values of correlation at genotypic level were high than the phenotypic correlation, indicating that there is a strong inherent association between the various characters studied. 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