GENETIC VARIABILITY AND ASSOCIATION STUDIES FOR YIELD ATTRIBUTES IN MUNGBEAN (VIGNA RADIATA L. WILCZEK) *Narasimhulu R., Naidu N.V., Shanthi Priya M., Rajarajeswari V. and Reddy K.H.P. Department of Genetics and Plant Breeding, S.V. Agricultural College, Tirupati 517502, A P *Author for Correspondence ABSTRACT Genetic variability and character association were studied in forty mungbean genotypes for different quantitative characters during rabi, 2012. Highest GCV and PCV were observed for number of branches per plant, pods per plant, biological yield per plant and harvest index, respectively. High estimates of genetic advance as percent of mean were observed for 100 seed weight and harvest index. High heritability coupled with high genetic advance as per cent of mean was observed for plant height, pods per plant, pods per cluster, biological yield per plant, harvest index and seed yield per plant suggesting that these traits were controlled by additive gene action. Hence, direct selection may be exercised for improvement of these traits. Eestimates of correlations revealed that seed yield had positive and significant correlation with number of pods per plant, clusters per plant, number of pods per cluster and biological yield per plant. All these traits had significant and positive association with branches per plant might play a vital role in indirect selection for yield. Key Words: Mungbean, Variability, Heritability, Genetic Advance and Correlation INTRODUCTION Mungbean is one of the important pulses in India and is suitable for cultivation under different farming situations. Generally mungbean seeds contain 2228% protein, 6065% carbohydrates, 11.5 % fat and 3.54.5% fibres. However, productivity in the country is still low and there is a need for improvement. Yield is a complex character and is associated with various contributing characters which in turn are interrelated among them. In order to improve yield through breeding techniques, a thorough understanding of variability is prerequisite for a plant breeder. Correlation analysis provides the information of interrelationship among important plant characters which leads to direct and/or indirect improvement in grain yield. Hence, the present investigation was undertaken to study the magnitude of genetic variability for various yield parameters and the extent to which the desirable characters are heritable and interrelated among themselves. MATERIALS AND METHODS The present study was carried out at S.V.Agricultural College, Tirupati during rabi, 2012 in Randomized Block Design replicated twice with spacing of 30cm between rows and 15cm between plants. The recommended agronomic and plant protection practices were followed to maintain healthy stand of the plants. Data were recorded on five randomly selected plants in each genotype for the characters viz., plant height (cm), number of branches per plant, number of clusters per plant, number of pods per cluster, number of pods per plant, number of seeds per pod, 100 seed weight (g), harvest index (%) and single plant yield (g). Genetic parameters like variance, genotypic and phenotypic 82
coefficient of variation, heritability and genetic advance as per cent mean and character association were calculated as per the standard procedure. RESULTS AND DISCUSSION Analysis of variance revealed highly significant differences for all characters under study among the genotypes, indicating the presence of sufficient amount of variability in the varieties. Thus, there is ample scope for selection of different quantitative characters for crop improvement.the mean, range, coefficient of variation, heritability and genetic advance as per cent mean of ten quantitative characters are given in Table 1. The highest range of variation was recorded for plant height, number of pods per plant, harvest index and seed yield per plant indicating maximum scope for the selection of these characters for effective improvement. Primary branches per plant and pods per cluster have not shown significant differences among the genotypes. The PCV value was found higher than the GCV for all the characters and the differences between them were very less indicating less environmental influence on those characters except for number of branches per plant and number of clusters per plant where significant role of environment was observed. Similar results were earlier reported by Rahim et al., (2010) and Mallikarjuna Rao et al., (2006) for seed yield per plant and Veeramani et al., (2005) for number of branches per plant and number of pods per plant. Genotypic coefficient of variation measures the amount of variation present in a particular character. However, it does not determine the proportion of heritable variation present in the total variation. Therefore, heritable variation existing in the character can be find out with greater degree of accuracy when heritability in combination with genetic advance (Dudley and Moll, 1969). High heritability and genetic advance expressed as percentage of mean was high for plant height, number of pods per plant, number of pods per cluster, harvest index and single plant yield confirming the additive gene action and hence, simple selection would be effective in improvement of these traits whereas high heritability along with moderate GAM and low GCV was observed for number of seeds per pod and 100 seed weight indicating the role of nonfixable genetic variance. Genotypic and phenotypic correlations between all pairs of characters were presented in Table 2. Information regarding the nature and extent of association of morphological characters would be helpful in developing imitable plant type, in addition to the improvement of yield a complex character for which, direct selection is not effective. It was observed that genotypic correlations were greater than phenotypic correlations in all most all the cases demonstrating that the environmental influences were not marked enough to alter the degree of association among the characters. Seed yield per plant possessed highly significant positive correlation with number of pods per plant, clusters per plant, number of pods per cluster and biological yield of the plant. These findings are also similar to Haritha and Reddy Sekhar (2002) findings. In addition, selection for pods per plant has frequently been regarded as important for seed yield improvement of mungbean by various authors (Gul et al., 2008; Hakim, 2008; Tabasum et al., 2010). The 83
nonsignificant associations between seed yield and 100 seed weight were also recently reported by Gul et al., (2008) and Tabasum et al., (2010). Hundred seed weight was significantly correlated with seven characters, six of which were negative ( pant height, branches per plant, pods per plant, clusters per plant, seeds per plant and biological yield of plant) while the other one was positive (harvest index). These results are in accordance with those reported by Biradar (2007) who found a negative association between 100 seed weight and clusters per plant, branches per plant. Plant height was significantly and positively associated with branches per plant, seeds per pod, while it was negatively correlated with 100 seed weight and harvest index. Similar results have been reported by Razina et al., (2008). Number of clusters per plant was significantly and positively associated with branches per plant, pods per plant and pods per cluster. This is not surprising since the pods are produced by the clusters, which are in turn produced by the branches. Similar findings were also reported by Chaudhary (1992) and Zhang (1995) who found positive correlations between clusters per plant and pods per plant. Zubair and Srinives (1986) also found associations between clusters per plant and branches per plant as well as pods per plant. By contrast, negative associations were found between clusters per plant and 100 seed weight in agreement with Biradar (2007). Moreover, significantly negative correlation was found between pods per plant and 100 seed weight. Similar findings were reported by Hakim (2008). Table 1: Genetic variability parameters for yield components and seed yield in mungbean CHARACTERS MEAN RANGE GCV PCV H (%) GAM Plant height (cm) 46.16 28.55 57.65 14.06 15.74 79.82 25.87 No. of branches/ plant 1.76 1.00 3.40 21.06 33.16 40.33 27.55 No. of pods/ plant 20.64 8.78 34.30 24.89 26.94 85.39 47.38 No. of clusters/ plant 7.09 4.10 10.46 15.06 19.80 57.90 23.61 No. of pods/ cluster 2.89 1.98 3.80 14.56 17.54 68.98 24.92 No. of seeds/ pod 10.42 8.00 12.40 9.28 10.60 76.64 16.74 100 seed weight (g) 4.11 3.37 5.44 9.44 11.44 68.05 16.04 Biological Yield/plant (g) 12.52 6.60 18.60 22.54 24.62 83.76 42.49 Harvest index (%) 49.24 31.49 70.07 21.72 22.38 94.21 43.43 Seed Yield / plant (g) 5.94 4.07 8.95 17.43 19.73 78.03 31.71 GCV Genotypic Coefficient of Variation; PCV Phenotypic Coefficient of Variation; H (%) Estimate of broad sense heritability; GAM Genetic advance as percent of mean 84
Table 2: Association of yield components between seed yield in mungbean Charact ers PH NB PP CP PC SP TW BY HI SY 0.468* * 0.283 0.386* PH 1 0.323* 0.087 0.325* 0.209 0.348* * 0.006 0.556 NB ** 1 0.269 0.367* 0.048 0.138 0.249 0.350* 0.286* 0.117 0.504* 0.772* 0.619 0.407* 0.568 PP 0.008 * 1 * ** 0.201 0.235 * 0.033 ** 0.618* 0.825* 0.443 CP 0.28 * * 1 0.050 0.093 0.287 0.284 0.021 ** 0.755* 0.332 PC 0.301 0.147 * 0.245 1 0.219 0.001 0.197 0.085 * SP 0.414 ** 0.236 0.207 0.033 0.637 0.508* 0.323* ** * * 0.321 * 1 0.417* * 0.05 0.340* 0.295 0.516* * 1 0.292 0.350* * 0.004 0.405* TW * 0.057 0.553* 0.423* 0.678* 0.474 BY 0.271 * * 0.308* 0.297 0.301* 0.388* 1 * ** 0.463 0.498* 0.432* 0.488* 0.718* HI ** * 0.015 0.026 0.089 * * * 1 0.275 0.581* 0.415* 0.412 0.446* SY 0.105 0.046 * * ** 0.08 0.082 * 0.288 1 Below diagonal Genotypic correlation, Above diagonal Phenotypic correlation *, ** indicate the significance of 5% and 1% level of probability, respectively PH Plant height (cm); NB No. of branches/ plant; PP No. of pods/ plant; CP No. of clusters/ plant; PC No. of pods/ cluster; SP No. of seeds/ pod; TW 100 seed weight (g); BY Biological Yield/plant (g); HI Harvest index (%); SY Seed Yield / plant (g) REFERENCES Biradar K (2007). Genetic studies in greengram and associationanalysis. Karnataka Journal Agricultural Science 20(4) 843844. Chaudhary MS (1992). Path analysis and correlation in high yielding mungbean varieties. In: ARC Training Report 1992. Asian Vegetable Research and Development Center, Shanhua, Tainan, Taiwan 1 5. Dudley JW and Moll RH (1969). Interpretation and uses of estimates of heritability and genetic variance in plant breeding. Crop Science 9 257262. Gul R, Khan H, Mairaj G, Ali S, Farhatullah and Ikramullah (2008). Correlation study on morphological and yield parameters of mungbean (Vigna radiata). Sarhad Journal of Agriculture 24(1) 3742. Hakim L (2008). Variability and correlation of agronomic characters of mungbean germplasm and their utilization for variety improvement program. Indonesian Journal of Agricultural Science 9(1) 2428. 85
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