Heterosis studies for fruit yield and it’s component traits through diallel analysis in okra [Abelmoschus esculentus (L.) Moench]

Introduction

Okra (Abelmoschus esculentus (L.) Moench), popularly known as lady's finger, bhendi, or gumbo, is one of the most important vegetable crops cultivated in tropical and subtropical regions of the world. It belongs to the family Malvaceae and is believed to have originated in tropical Africa. The crop is valued for its tender green fruits, which are rich in dietary fiber, vitamins, minerals, antioxidants, and mucilage, making it an important component of human nutrition as well as a valuable source of farm income. India is the largest producer of okra globally, cultivating the crop over approximately 0.531 million hectares, with an annual production of 6.46 million tonnes and an average productivity of 12.17 t ha -1 (Anonymous, 2022a) [1,2] . In Gujarat, okra occupies nearly 0.085 million hectares, producing 1.019 million tonnes with an average productivity of 11.97 t ha - 1 during 2022-23 (Anonymous, 2022b) [1,2] . Despite its economic importance, there remains considerable scope for enhancing fruit yield and productivity through the development of superior hybrids. The exploitation of heterosis has become one of the most successful breeding strategies for improving yield potential, earliness, adaptability, and overall crop performance in crosspollinated and often crosspollinated vegetable crops. The increasing adoption of F₁ hybrids by farmers has created a growing demand for high-yielding hybrids possessing superior agronomic performance and wider adaptability. Successful hybrid breeding largely depends on the identification of genetically diverse parents capable of producing highly heterotic hybrid combinations. Heterosis, expressed as the superior performance of F₁ hybrids over their parents or a standard commercial cultivar, provides valuable information for the identification of promising hybrid combinations and the selection of suitable parental lines. Estimation of heterobeltiosis and standard heterosis for fruit yield and its component traits facilitates the development of commercially exploitable hybrids and improves breeding efficiency. Therefore, the present investigation was undertaken to assess the magnitude of heterosis for fruit yield and associated yield-contributing traits in okra using a 10 × 10 half-diallel mating design, with the objective of identifying superior hybrid combinations for future hybrid breeding programmes.

Materials and Method

The experiment was carried out during kharif (July to October) 2023 at Centre for Vegetable Research, Department of GPB, C. P. college of agriculture, S. D. Agricultural University, Sardarkrushinagar. The basic materials consisted of ten genotypes of okra viz., JOL 20-04, NOL 11-12, JOL 18-07, JOL 18-12, GP2, GP1, GAO 5, GO 6, Pusa Sawani and GAO 8. These varieties were chosen for the current study based on genetic diversity for several agronomic features and maturity parameters. The genotypes are crossed in Half diallel fashion without reciprocals to produce 45 hybrids in summer 2023. These 45 F₁ along with their 10 parents and one standard check (GJOH 4) were evaluated in a randomized complete block design with three replicates during kharif (July to October) 2023. So in this experiment analysis based on fruit yield and it's other traits present in okra. Observations were recorded on Observations were recorded on days to 50% flowering, fruits per plant, fruit length (cm), fruit girth (cm), fruit weight (g), fruit yield per plant (g), plant height (cm) and internodal length (cm). Days to 50% flowering, plant height and internodal length was consider as negative trait in okra so low scoring parent consider as a better parent for estimation of heterobeltiosis. The various observations were recorded on five competitive plants in each plot leaving border ones. Heterosis percentage was worked out as per formula suggested by Fonseca and Patterson (1968) and Meredith and Bridge (1972) [3] . for calculation of heterobeltiosis and standard heterosis, respectively. The observations were recorded on randomly selected three plants per genotype from each replication and mean values were used for the statistical analysis. The per cent heterosis was estimated as increase or decrease in the mean value of F1 hybrid over better parent, i.e., heterobeltiosis (Fonesca and Patterson, 1968) [4] and over standard check (GCU-1), i.e., Standard heterosis (Meredith and Bridge, 1972) [3] for each character. Heterobeltiosis was measured in percentage by using following formula

The standard heterosis was measured in percentage by using following formula

Standard heterosis (%) = F 1 -SC

SC × 100

Where, BP = Mean performance of better parent SC = Mean performance of standard check i.e., GCU-

Results and Discussion

The analysis of variance for fourteen characters is presented in Table 1. The mean squares due to genotypes were further partitioned into parents, hybrids, parents vs hybrids and check vs hybrids. The result revealed that mean square values due to genotypes were found highly significant for all the characters, indicating the presence of sufficient amount of genetic variability in the material under study. The variance due to parents were found significant for the characters like; days to 50% flowering, fruits per plant, fruit length, fruit girth, fruit yield per plant, plant height and internodal length. The mean square due to hybrid indicated significant difference for all the traits under study. The results indicated the existence of sufficient amount of genetic variability among the parents for all the characters except fruit weight and hybrids for all the characters under study. Mean sum of squares due to parents vs hybrids showed significant differences for characters under study viz., fruits per plant, fruit girth, fruit weight, fruit yield per plant, plant height and internodal length which suggested the existence of differences between parents and hybrids leading to manifestation of heterosis. The mean square difference due to check vs hybrid showed significant difference for traits under study viz., fruits per plant, fruit length, fruit girth and fruit yield per plant. The results of mean squares due to check vs hybrids suggesting that hybrids differed statistically from given check for given traits.

Heterosis

The hybrid with high value of heterosis in desired direction can be further exploited. The hybrids are normally assessed in terms of per cent increase better parent and over standard check hybrid. The range of heterosis over better parent and standard check found to be different for all traits under study.

Days to 50% flowering

For days to 50% flowering earliness, heterotic effect in negative direction is desirable. [10] , Patel and Patel (2016) [11] , Gavint et al. (2018) [7] , Chavan et al. (2021) [8] , Sidapara et al.( 2021) [9] and Chaudhary et al. (2023) [12] . (Table 2).

Fruit length

The range of heterobeltiosis for this trait was - [8] . (Table 3). [8] and Sidapara et al. (2021) [9] . Value of standard heterosis for fruit girth. (Table 3)

Fruit weight

The magnitudes of heterobeltiosis ranged from -19.81 (GP1 × Pusa Sawani) to 30.14 (GP2×GAO8) per cent for this trait. The top three crosses for better parent heterosis were GP2 × GAO 8 (30.14%), GAO 5 × GO 6 (25.87%), GP1 × GO 6 (23.44%). Similar results were reported by Budha Ram (2015) [5] . The range of standard heterosis was varied from -15.98 (GP2 × GAO 5) to 35.98 (GP2 × GAO 8) per cent. Among sevnteen, top three crosses viz., GP2 × GAO 8 (35.98%), GP1 × GAO 8 (24.41%) and JOL 18-12 × GP1 (23.39%). Similar result were found by Patel and Patel (2016) [11] , Gavint et al. (2018) [7] and Chaudhary et al. (2023) [12] . (Table 4)

Fruit yield per plant

Fruit yield per plant is very important attribute for okra which the breeder attempt to improve by evolving high yielding hybrids. The perusal of results revealed that heterobeltiosis varied from -38.28 to 42.15 per cent. The cross NOL 11-12 × GP1 (42.15%) was reported highest significant and positive heterobeltiosis followed by GP2 × GP1 (31.14%) and JOL 18-12 × GO 6 (26.97%). The estimate of standard heterosis for this trait was ranged from -26.62 to 47.20 per cent. Top four crosses depicted standard heterosis in desired direction for this trait are GAO 5 × GO 6 (47.20%), GP1 × GAO 8 (41.91%) and JOL 20-04 × GAO 8 (41.76%) as well JOL 20-04 × JOL 18-12 (40.00%) were found to be best hybrids for fruit yield per plant based on the positive standard heterosis. These results Confirmed with findings of Patel and Patel (2016) [11] , Gavint et al. (2018) [7] , Chavan et al. (2021) [8] Sidapara et al. (2021) [9] and Chaudhary et al. (2023) [12] . (Table 4 and Figure 4 & 5)

Plant height

For plant height, heterotic effect in negative direction was considered as desirable. The magnitude of heterobeltiosis range from -7.43% (JOL 18-12 × GP2) to 49.43% (GP1 × GAO 8) for this character. The range of standard heterosis over check GJOH4was-22.22% (NOL 11-12 × GO 6) to 20.97% (GAO 5 × GAO 8). Out of forty five crosses, Sevan crosses manifested significant negative heterosis. The cross NOL 11-12 × GO 6 (-22.22%) had highest significant and negative standard heterosis followed by JOL 20-04 × JOL 18-07 (-17.93%) and NOL 11-12 × JOL 18-12 (-16.16%) for this trait. Similar results were reported by Kumar and Sreeparvathy (2010) [13] , Raghuvanshi et al. (2011), Khatik et al. (2012) [14] , Paul (2013) [15] , Kishor et al. (2013) [16] , Kumar et al. (2013) [17] , Nagesh et al. (2014) [18] , Badiger et al. (2014) [19] and Tiwari et al. (2015) [20] . (Table 5) Sreeparvathy (2010) [13] , Khatik et al. (2012) [14] , Paul (2013) [15] , Kumar et al. (2013) [17] , Nagesh et al. (2014) [18] , Badiger et al. (2014) [19] and Tiwari et al. (2015) [20] . ( The highest yielding cross GAO 5 × GO recorded 47.20% higher fruit yield per plant than standard check variety GJOH 4 and also significant for other trait viz., days to 50% flowering, fruits per plant and fruit weight. This cross had founded 19.83% higher value than its better parent and also significant for other traits as same as standard heterosis in desire direction. (Table 6) The next superior hybrid GP 1 × GAO 8 had standard heterosis for fruit yield per plant (41.91%) with yield attributing characters viz., days to 50% flowering, fruits per plant, fruit length, fruit girth and fruit weight. This cross also exhibited 18.69% heterobeltiosis and also significant for other traits as same as standard heterosis except fruit per plant in desire direction. (Table 6) The third cross, JOL 20-04 × GAO 8 had standard heterosis for fruit yield per plant (41.76%) over standard check variety GJOH 4 for fruit yield per plant also exhibited in desirable direction significant for the characters viz., days to 50% flowering, fruits per plant, fruit length, fruit girth and fruit weight. This cross showed 18.57% heterobeltiosis and also significant for other traits as same as standard heterosis. (Table 6) The cross JOL 20-04 × JOL 18-12 observed significant 40.00% higher than standard check GJOH 4 and also significant for other trait viz., days to 50% flowering, fruits per plant, fruit length, fruit girth and fruit weight. This cross showed 24.48% higher value than its better parent and also significant for related to other traits as same as standard heterosis expect fruit length in desire direction. (Table 6) The cross GAO 5 × GAO 8 observed significant 38.27% higher than standard check GJOH 4 and also significant for other trait viz., days to 50% flowering, fruits per plant, fruit length, fruit girth and fruit weight. This cross had founded 12.56% higher value than its better parent and also significant for other traits as same as standard heterosis in desire direction. (Table 6)

Conclusion

The present investigation demonstrated the considerable potential of heterosis breeding for improving fruit yield and associated agronomic and quality traits in okra. Among the evaluated hybrids, GAO 5 × GO emerged as the most promising cross, exhibiting 47.20% standard heterosis over the commercial check GJOH 4 and 19.83% heterobeltiosis for fruit yield per plant. In addition to superior yield performance, this hybrid showed significant improvement in several important traits, including days to 50% flowering, number of fruits per plant, average fruit weight, plant height, total soluble sugars, protein content, total chlorophyll content, and fruit moisture.

Based on the combined assessment of standard heterosis and heterobeltiosis, the hybrids GAO 5 × GO 6, GP1 × GAO 8, JOL 20-04 × GAO 8, JOL 20-04 × JOL 18-12, GAO 5 × GAO 8, and JOL 18-07 × GAO 5 were identified as the most promising combinations for enhancing fruit yield and desirable quality attributes. These hybrids possess substantial potential for commercial hybrid development and warrant further evaluation across diverse environments to assess their yield stability and adaptability. Furthermore, they may serve as valuable breeding material for exploiting hybrid vigour and for generating superior segregating populations aimed at developing highyielding, quality-rich okra cultivars.

References

1. Meredith WE, Bridge RR. Heterosis and gene action in cotton (Gossypium hirsutum L.). Crop Science. 1972;12:304-310.
2. Fonesca S, Patterson F. Hybrid vigor in a seven parent diallel crosses in common winter wheat (Triticum aestivum L.). Crop Science. 1968;8:85-88.
3. Gavint KN, Vadodariya KV, Bilwal BB. To study the nature and magnitude of heterosis for fruit yield and yield attributes in okra [Abelmoschus esculentus (L.) Moench]. Journal of Pharmacognosy and Phytochemistry. 2018;7(1):2583-2587.
4. Sidapara MP, Gohil DP, Patel PU, Sharma DD. Heterosis studies for yield and yield components in okra [Abelmoschus esculentus (L.) Moench]. Journal of Pharmacognosy and Phytochemistry. 2021;10(1):12681275.
5. Bhatt JP, Patel NA, Acharya RR, Kathiria KB. Heterosis for yield and its related traits in Okra [Abelmoschus esculentus (L.) Moench]. Electronic Journal Plant Breeding. 2015:189-196.https://dx.doi.org/10.5958/0975928X.2016.00026.0
6. Patel R, Chauhan R, Patel J. Heterosis for yield and yield components in sesame (Sesamum indicum L.). Electronic Journal of Plant Breeding. 2016;7(4):1151.https://doi.org/10.5958/0975928x.2016.00160.5
7. Moench]. International Journal of Plant & Soil Science. 2023;35(11):84-98.
8. Kumar PS, Sreeparvathy S. Study of heterosis in okra [Abelmoschus esculentus (L.) Moench]. Electronic Journal of Plant Breeding. 2010;1(6):1431-1433.
9. Khatik KR, Chaudhary R, Khatik CL. Heterosis studies in okra. Annales Horticulture. 2012;5(2):213-218.
10. M. Sc. Thesis, NAU., Navsari; 2013.
11. Kishor DS, Arya K, Duggi S, Magadum S, Raghavendra NR, Venkateshwaralu Challa, Reddy PS. Studies on heterosis for yield and yield contributing traits in okra [Abelmoschus esculentus (L.) Moench]. Molecular Plant Breeding. 2013;4(35):277-284.
12. Kumar A, Baranwal DK, Judy Aparna, Srivastava K. Combining ability and heterosis for yield and its contributing characters in okra [Abelmoschus esculentus (L.) Moench]. Madras Agriculture Journal. 2013;100(13):30-35.
13. Nagesh GC, Mulge R, Rathod V, Basavaraj LB, Mahaveer SM. Heterosis and combining ability studies in okra [Abelmoschus esculentus (L.) Moench] for yield and quality parameters. The Bioscan. 2014;9(4):1717-1723.