Assessment of genetic variability and mean performance for pod yield and quality traits in dolichos bean (Lablab purpureus L.)

Introduction

Dolichos bean (Lablab purpureus L.), commonly known as Indian bean or hyacinth bean, is an important traditional legume vegetable cultivated widely in India. Archaeobotanical evidence suggests its origin in the Indian subcontinent, indicating its long history of domestication (Fuller, 2003) [8] . The crop is valued for its adaptability to semi-arid conditions, nitrogen-fixing ability and multiple uses as a vegetable, pulse, fodder and green manure. The pods are nutritionally rich, containing appreciable amounts of proteins, carbohydrates, minerals and vitamins (Naeem et al., 2009) [14] . Despite its economic and nutritional importance, dolichos bean remains underutilized due to low yield potential, photosensitivity, long duration, and indeterminate growth habit. In regions like Telangana, cultivation is largely confined to local landraces and farmer selections, resulting in wide variability in growth, yield and pod characteristics. Improvement in pod yield is challenging because it is a complex trait governed by several yieldcontributing characters and influenced by environmental factors. Genetic variability and diversity within germplasm are essential for effective crop improvement. The success of any breeding programme depends on the extent of genetic divergence among genotypes, as diverse parents are more likely to produce superior recombinants (Parmar et al., 2013) [15] . Mahalanobis D² analysis is a useful tool to assess genetic divergence and classify genotypes into distinct clusters, aiding in the selection of suitable parents for hybridization (Ismunadji and Arsyad, 1990) [11] . Correlation and path coefficient analyses provide insight into the association and direct contribution of yield-related traits towards pod yield. While correlation indicates the relationship among traits, path analysis helps in identifying traits with true direct effects on yield, thereby improving selection efficiency (Al-Jibouri et al., 1958) [1] . Estimates of heritability and genetic advance further assist in understanding the inheritance pattern of traits and predicting response to selection (Burton et al., 1953) [2] .

Materials and Methods

The present investigation was conducted during Rabi 2021-2022 at the PG Research Block, College of Horticulture, Mojerla, Wanaparthy, Telangana to study genetic variability, genetic divergence, correlation and path coefficient analysis for pod yield and yield attributes in dolichos bean (Lablab purpureus L.). The experimental material consisted of forty-five dolichos bean genotypes, including the standard check Arka Adarsh, obtained from the National Bureau of Plant Genetic Resources (NBPGR), Regional Station, Hyderabad and IIHR, Bengaluru. The experiment was laid out in a Randomized Block Design (RBD) with two replications. Each genotype was represented by eight plants per replication, planted at a spacing of 2.0 m × 0.5 m and the crop was trained on a pandal system following recommended agronomic practices. Observations were recorded on sixteen quantitative characters related to growth, yield, yield attributes and quality parameters. The recorded traits included vine length, number of primary branches per plant, days to 50 per cent flowering, days to first harvest, pod length, pod width, number of pods per plant, number of seeds per pod, seed length, seed width, 100-seed fresh weight, 100-seed dry weight, pod yield per plant, protein content, reducing sugars and total sugars. The collected data were subjected to analysis of variance (ANOVA) to test the significance of differences among genotypes as per standard statistical procedures. The mean performance of genotypes for all the studied characters was computed replication-wise and expressed as treatment means. Genotypes were compared based on their mean values to identify superior performers for pod yield and important yield-attributing traits

Results and Discussion

Analysis of variance

Analysis of variance revealed significant differences among the genotypes for all the characters studied at one percent and five percent level of significance. Highly significant differences among the genotypes were observed which indicates the presence of sufficient amount of variability among all the genotypes studied. The analysis of variance for yield and yield attributes under study are presented in Table 1. The mean sum of squares for genotypes was found to be significant for all the characters viz., vine length (cm), number of primary branches per plant, number of pods per plant, pod yield per plant (g), number of seeds per pod, 100-seed fresh weight (g), 100seed dry weight (g), pod length (cm), pod width (cm), seed length (cm), seed width (cm), days to 50% flowering, days to first harvest, protein content (%), reducing sugars (%) and total sugars (%).

Mean performance of genotypes

The average performance of the genotypes for each specific character serves as a crucial criterion for eliminating the unwanted genotypes in any selection method. This suggests that studies of germplasm could serve as a possible source and provide opportunities for choosing genotypes with high yields and favourable horticultural characteristics. The mean performance of 45 genotypes of dolichos bean in respect of various pod yield and yield attributes are described character wise below. Mean performances of the genotypes for the thirteen biometric and three qualitative characters are furnished in the Table 2.

Vine length of genotypes ranged from 217.50 cm to 429.35 cm with a mean of 366.55 cm. The genotype IC-427456 recorded the maximum vine length (429.35 cm), while IC-412977 recorded the minimum (217.50 cm). Three genotypes, IC-427456 (429.35 cm), IC-598467 (421.56 cm) and IC-426983 (416.56 cm), showed higher vine length compared to the check Arka Adarsh (412.50 cm). These results are in agreement with the findings of Chaitanya et al. (2014) [3] and Reddy et al. (2018) [19] in dolichos bean.

Number of primary branches per plant

The number of primary branches per plant ranged from 2.88 to 4.77 with a mean of 3.64. The genotype IC-598467 recorded the highest number of primary branches (4.77), while IC-446587 recorded the lowest (2.88). Several genotypes, namely IC-598467 (4.77), IC-372119 (4.68), IC-412977 (4.65), IC-427423 (4.38), IC-261005 (4.35), IC-446575 (4.25), IC-384066 (4.23), IC-427425 (4.18), IC-546387 (4.16) and IC-426694 (4.15), recorded a higher number of primary branches compared to the check Arka Adarsh (4.11). These findings are in agreement with the results reported by Mohan et al. (2014) [13] and Reddy et al. (2018) [19] in dolichos bean.

Days to 50 per cent flowering

Days to 50% flowering ranged from 51.06 to 102.50 days. The minimum days to 50% flowering were recorded in IC-261004 (51.06 days), while the maximum was observed in IC-598467 (102.50 days). The genotypes IC-261004 (51.06), IC-384066 (53.00), IC-382830 (55.31), IC-446571 (57.91) and IC-446568 (58.85) flowered earlier than the check Arka Adarsh (60.00 days). These results are in accordance with the findings of Singh et al. (2015) [24] and Ganapathi et al. (2020) [9] in dolichos bean.

Days to first harvest

Days to first harvest ranged from 82.96 to 135.92 days with a mean of 101.53 days. The minimum days to first harvest were recorded in IC-261004 (82.96 days), while the maximum was observed in IC-598467 (135.92 days). The genotypes IC-261004 (82.96), IC-446566 (85.80), IC-446568 (86.64), IC-446573 (87.07) and IC-261311 (88.26) recorded earlier first harvest compared to the check Arka Adarsh (89.20 days). These findings are in agreement with the reports of Singh et al. (2015) [24] and Ganapathi et al. (2020) [9] in dolichos bean.

Number of pods per plant

The number of pods per plant ranged from 43.00 to 149.50 with a mean of 65.64. The genotype IC-598467 recorded the maximum number of pods per plant (149.50), while the minimum was observed in IC-426632 (43.00). The genotype IC-598467 (149.50) also recorded a higher number of pods per plant compared to the check Arka Adarsh (128.45). These results are in conformity with the findings of Chattopadhyay and Dutta (2010) [5] and Chaitanya et al. (2014) [3] in dolichos bean.

Pod length ranged from 4.86 to 13.47 cm with a mean of 9.55 cm. The genotype IC-427423 recorded the maximum pod length (13.47 cm), while the minimum was observed in IC-426632 (4.86 cm). Several genotypes, namely IC-427423 (13.47 cm), IC-446574 (12.82 cm), IC-261010 (12.51 cm), IC-427462 (12.47 cm), IC-427414 (12.36 cm), IC-446573 (11.99 cm), IC-426987 (11.95 cm), IC-427456 (11.91 cm), IC-427436 (11.71 cm), IC-427424 (11.59 cm), IC-427417 (10.99 cm), IC-446575 (10.90 cm) and IC-426991 (10.88 cm) recorded higher pod length compared to the check Arka Adarsh (10.88 cm). These findings are in agreement with Singh et al. (2015) [24] in dolichos bean.

Pod width at marketable maturity ranged from 0.79 to 4.74 cm with a mean of 1.81 cm. The genotype IC-382830 recorded the maximum pod width (4.74 cm), while the minimum was observed in IC-446561 (0.79 cm). The genotypes IC-382830 (4.74 cm), IC-426987 (2.41 cm), IC-427429 (2.40 cm) and IC-427424 (2.30 cm) recorded greater pod width compared to the check Arka Adarsh (2.23 cm). These results are in agreement with the findings of Reddy et al. (2018) [19] in dolichos bean.

Number of seeds per pod

The number of seeds per pod ranged from 3.20 to 5.70 with a mean of 4.56. The genotype IC-598467 recorded the maximum number of seeds per pod (5.70), while the minimum was observed in IC-426694 (3.20). Two genotypes, IC-546387 (5.40) and IC-446575 (5.40), recorded values equal to the check Arka Adarsh (5.40). These results are in agreement with the findings of Reddy et al. (2018) [19] and Ganapathi et al. (2020) [9] in dolichos bean.

Seed length at marketable maturity ranged from 0.62 to 1.15 cm with a mean of 0.89 cm. The maximum seed length was recorded in IC-384066 (1.15 cm), while the minimum was observed in IC-598467 (0.62 cm). Several genotypes, including IC-384066 (1.15 cm), IC-372119 (1.12 cm), IC-427436 (1.06 cm), IC-426983 (1.04 cm), IC-427414 (1.03 cm), IC-427462 (1.03 cm), IC-426987 (1.00 cm) and many others, recorded higher seed length compared to the check Arka Adarsh (0.79 cm). These results are in agreement with the findings of Reddy et al. (2018) [19] in dolichos bean.

Seed width ranged from 0.63 to 1.12 cm with a mean of 0.87 cm. The maximum seed width was recorded in IC-384066 (1.12 cm), while the minimum was observed in IC-446575 (0.63 cm). Several genotypes, including IC-384066 (1.12 cm), IC-372119 (1.09 cm), IC-427436 (1.04 cm), IC-427414 (1.03 cm), IC-426957 (1.00 cm), IC-427462 (0.99 cm), IC-426987 (0.99 cm), IC-427424 (0.98 cm) and others, recorded higher seed width compared to the check Arka Adarsh (0.81 cm). These results are in accordance with Reddy et al. (2018) [19] in dolichos bean.

The 100-seed fresh weight ranged from 34.10 to 85.25 g with a mean of 61.30 g. The highest 100-seed fresh weight was recorded in IC-384066 (85.25 g), while the lowest was observed in IC-427428 (34.10 g). Several genotypes, namely IC-384066 (85.25 g), IC-546387 (83.95 g), IC-426966 (81.00 g), IC-372119 (80.30 g), IC-427414 (79.80 g), IC-426957 (77.40 g), IC-427417 (77.00 g), IC-426694 (75.90 g), IC-426970 (74.65 g), IC-427436 (70.50 g), IC-598467 (70.15 g), IC-446574 (67.90 g), IC-446561 (67.10 g), IC-446585 (66.35 g), IC-413709 (65.70 g), IC-446571 (65.20 g), IC-413710 (64.90 g) and IC-446575 (64.55 g) recorded higher 100-seed fresh weight compared to the check Arka Adarsh (64.35 g). These findings are in agreement with Sankaran et al. (2008) [21] and Reddy et al. (2018) [19] in dolichos bean.

The 100-seed dry weight ranged from 22.93 to 34.35 g with a mean of 29.31 g. The genotype IC-598467 recorded the highest 100-seed dry weight (34.35 g), while the lowest was observed in IC-446566 (22.93 g). The genotypes IC-598467 (34.35 g) and IC-427414 (33.50 g) recorded higher 100-seed dry weight compared to the check Arka Adarsh (33.50 g). These results are in agreement with the findings of Reddy et al. (2018) [19] in dolichos bean.

Pod yield per plant ranged from 189.45 to 702.67 g with a mean of 343.98 g. The genotype IC-598467 recorded the highest pod yield per plant (702.67 g), while the lowest was observed in IC-261010 (189.45 g). Two genotypes, IC-598467 (702.67 g) and IC-261004 (648.45 g), recorded higher pod yield per plant compared to the check Arka Adarsh (633.50 g). These findings are in agreement with the reports of Chaitanya et al. (2014) [3] , Sharma et al. (2014) [22] and Reddy et al. (2018) [19] in dolichos bean.

Protein content ranged from 14.54% to 20.29% with a mean of 17.62%. The genotype IC-261004 recorded the highest protein content (20.29%), while the lowest was observed in IC-427436 (14.54%). Several genotypes, namely IC-261004 (20.29%), IC-446585 (19.67%), IC-427429 (19.59%), IC-427424 (19.34%), IC-446583 (19.26%), IC-446566 (19.06%), IC-261311 (18.96%), IC-427423 (18.74%), IC-427456 (18.55%), IC-446573 (18.52%), IC-446584 (18.44%), IC-413709 (18.41%), IC-426957 (18.34%), IC-598467 (18.10%) and IC-546387 (18.71%) recorded higher protein content compared to the check Arka Adarsh (18.03%). These results are in agreement with Reddy et al. (2018) [19] in dolichos bean.

Reducing sugars ranged from 0.41% to 1.26% with a mean of 0.82%. The genotype IC-426988 recorded the highest reducing sugar content (1.26%), while the lowest was observed in IC-426694 (0.41%). Several genotypes, including IC-426988 (1.26%), IC-427436 (1.14%), IC-446571 (1.06%), IC-426966 (1.05%), IC-426632 (1.03%), IC-261010 (1.01%), IC-446566 (1.00%), IC-412977 (0.99%), IC-427456 (0.99%), IC-446561 (0.98%), IC-413709 (0.98%), IC-446574 (0.95%), IC-413710 (0.95%), IC-427428 (0.92%), IC-598467 (0.92%), IC-426970 (0.90%), IC-446581 (0.90%) and IC-261004 (0.88%) recorded higher reducing sugar content compared to the check Arka Adarsh (0.88%). These results are in agreement with the findings of Mahesh et al. (2019) [12] in dolichos bean.

Total sugar content ranged from 0.71% to 1.50% with a mean of 1.06%. The genotype IC-546387 recorded the highest total sugars (1.50%), while the lowest was observed in IC-426694 (0.71%). Several genotypes, including IC-546387 (1.50%), IC-427436 (1.36%), IC-427424 (1.33%), IC-426966 (1.32%), IC-446561 (1.29%), IC-427428 (1.26%), IC-426988 (1.25%), IC-446566 (1.23%), IC-261010 (1.21%) and many others, recorded higher total sugar content compared to the check Arka Adarsh (1.02%). These results are in agreement with the findings of Mahesh et al. (2019) [12] in dolichos bean.

Conclusion

The present study revealed substantial genetic variability among dolichos bean genotypes for growth, yield, yieldattributing and quality traits, indicating wide scope for selection and crop improvement. Significant differences were observed for all the characters studied, with pod yield per plant showing a wide range, highlighting the differential yield potential of the genotypes. The genotype IC-598467 emerged as the most promising for pod yield and major yield-contributing traits, particularly number of pods per plant and branching habit, while IC-261004 was superior for protein content. The identification of early flowering and early harvesting genotypes further suggests the possibility of developing early-maturing, high-yielding varieties. Overall, the superior genotypes identified in the present investigation can be effectively utilized as parents in future breeding programmes aimed at improving yield and nutritional quality in dolichos bean and their performance should be further validated through multi-location trials.

References

1. Al-Jibouri HA, Miller PA, Robinson HF. Genotypic and environmental variances and covariances in an upland cotton cross of interspecific origin. Agron J. 1958;50(10):633-636.
2. Burton GW, DeVane EH. Estimating heritability in tall fescue (Festuca arundinacea) from replicated clonal material. Agron J. 1953;45:478-481.
3. Chaitanya V, Reddy RVSK, Reddy KHP. Genetic variability and character association studies in dolichos bean (Lablab purpureus L.). Legume Res. 2014;37(5):450-455.
4. Chandran K, Venkatesan K, Thangamani C. Variability, heritability and genetic advance in dolichos bean (Lablab purpureus L.). Electron J Plant Breed. 2015;6(2):512-517.
5. Chattopadhyay A, Dutta S. Genetic variability and character association in dolichos bean (Lablab purpureus L.). J Crop Weed. 2010;6(2):78-82.
6. Choudhary R, Patel JB, Patel MP. Genetic variability and association studies in dolichos bean (Lablab purpureus L.). Green Farming. 2016;7(1):120-124.
7. Das S, Das SS, Ghosh G. Variability and correlation studies in dolichos bean (Lablab purpureus L.). J Appl Nat Sci. 2015;7(2):1014-1018.
8. Fuller DQ. African crops in prehistoric South Asia: a critical review. Afr Archaeol Rev. 2003;20(1):1-28.
9. Ganapathi M, Reddy RVSK, Reddy KHP. Genetic divergence and character association studies in dolichos bean (Lablab purpureus L.). Legume Res. 2020;43(4):520-526.
10. Gupta AJ, Patel BN, Patel JB. Genetic variability and character association in dolichos bean (Lablab purpureus L.). Int J Agric Sci. 2017;9(16):4113-4116.
11. Ismunadji M, Arsyad DM. Genetic diversity and breeding strategies in food legumes. Indones Agric Res Dev J. 1990;12:1-10.
12. Mahesh M, Reddy RVSK, Reddy KHP. Studies on quality traits and genetic divergence in dolichos bean (Lablab purpureus L.). Int J Chem Stud. 2019;7(5):1621-1625.
13. Mohan N, Reddy KR, Reddy RVSK. Genetic variability and character association in dolichos bean (Lablab purpureus L.). Plant Arch. 2014;14(2):873877.
14. Naeem M, Khan MMA, Moinuddin. Nutritional composition of legumes. J Food Sci Nutr. 2009;46:122128.
15. Parmar AM, Patel JB, Patel JR. Genetic divergence in dolichos bean (Lablab purpureus L.). Bioscan. 2013;8(3):831-834.
16. Peer SA, Sofi PA, Wani SH. Genetic variability and correlation studies in dolichos bean (Lablab purpureus L.). Int J Curr Microbiol Appl Sci. 2018;7(6):18081814.
17. Rai M, Singh SP, Verma A. Quality traits and genetic variability in dolichos bean (Lablab purpureus L.). Veg Sci. 2014;41(2):185-189.
18. Rai M, Yadav DS, Singh SP. Genetic variability and quality traits in dolichos bean (Lablab purpureus L.). Indian J Hortic. 2009;66(1):96-100.
19. Reddy RVSK, Reddy KHP, Ganapathi M. Genetic variability, heritability and genetic advance in dolichos bean (Lablab purpureus L.). Int J Curr Microbiol Appl 2018;7(3):2052-2060.
20. Sahu P, Bahadur V. Genetic variability and correlation studies in dolichos bean (Lablab purpureus L.). J Pharmacogn Phytochem. 2018;7(5):2915-2919.
21. Sankaran M, Venkatesan K, Thangamani C. Studies on yield attributes in dolichos bean (Lablab purpureus L.). Madras Agric J. 2008;95(7-12):257-260.
22. Singh B, Singh AK, Singh R. Variability and correlation studies in dolichos bean (Lablab purpureus L.). J Food Legumes. 2011;24(3):213-216.
23. Singh P, Singh DK, Verma A. Genetic variability and yield performance in dolichos bean (Lablab purpureus L.). Veg Sci. 2015;42(1):52-56.