INTRODUCTION Okra (Abelmoschus esculentus L. (Moench) is an economically important vegetable crop grown in the tropical and sub-tropical parts of the world. which have chromosome number 2n=2x=130 (Patil et al., 2015). It is native of Tropical Africa (Yawalkar, 1980 and Benchasri, 2012). The immature green seed pods are the edible part of this plant which are consumed as cooked vegetable, mostly fresh but sometimes sun-dried (Liu et al., 2021). Okra is gaining importance with regard to its nutritional, medicinal and industrial value. Apart from nutritional and health importance, okra plays an important role in income generation and subsistence among rural farmers in developing countries like India. Okra is commercially grown in the Indian states of Andhra Pradesh, Gujarat, Maharashtra, Karnataka and Tamil Nadu (Raikar et al., 2020). It represents 13% of the total fresh vegetable exports and having potential to earn foreign currency. Commercial exploitation of hybrid vigour in okra is simple due to its ease emasculation; high fruit set rate and huge amount of seeds per fruit (Varmu et al., 2011). Being an often cross-pollinated crop, out crossing to an extent of 5 to 9% by insects is reported which renders considerable genetic diversity (Duggi et al., 2013). Hence, the first step in okra improvement should involved evaluation of the germplasm for genetic variability. As a second step, it is required to generate crosses employing a suitable mating design to know the extent of heterosis for various economic traits and inheritance pattern of desired characters, which in turn, would help in deciding the breeding strategies as well as identifying potential parents and crosses for further use in breeding programme (Singh and Singh 2012). Combining ability helps to assess the genetic value, selection of suitable parents for hybridization and identification of good hybrid cross combinations that can be utilized for commercial exploitation of heterosis (Das et al., 2020). The prominent position of okra among Indian vegetables can be due to its easy cultivation, dependable and regular yield, wider adaptability and year round cultivation. In spite of its importance, no major breakthrough has been made in this crop and the farmers are still growing their own local varieties or open pollinated varieties. Hence, there is a need for restructuring this vegetable crop for increasing the productivity. Therefore, the present investigation was undertaken to obtain the information on combining ability and mode of gene action in okra genotypes for yield and quality parameters. MATERIAL AND METHODS The present investigation on combining ability studies in okra was carried out at the Vegetable Research Farm, Department of Vegetable Science, Banda University of Agriculture and Technology, Banda, Uttar Pradesh during rabi season by providing good agronomic practices to keep the crop in good condition. The material for experimentation comprised of 10 distinct genotypes [Arka Anamika (P1), Kashi Pragati (P2), Hisar Naveen (P3), Hisar Unnat (P4), Punjab-8 (P5), Pusa A-4 (P6), Varsha Uphar (P7), Akola Bahar (P8), Phule Vimukta (P9) and Punjab Suhavani (P10)] collected from different research Institutes & SAUs and maintained in department of vegetable science. These 10 lines were crossed in all the possible combination in diallel technique, excluding reciprocals crosses to derive all possible 45 F1 hybrids and seeds were collected under study purpose. The parents were also maintained through selfing. All the 45 F1s seeds along with 10 parents were sown in randomized block design (RBD) with three replications during kharif season. Each treatment or a genotype in each replication was represented by one row each accommodating 10 plants at a row to row spacing of 60cm and 30cm from plant to plant. The observations were recorded on randomly selected five plants in each replication of F1s and their parents. The selected plants were tagged and properly labeled before flowering for taking observations, viz. Days to first flowering, Days to 50% flowering, Plant height (cm), Number of branches per plant, Node at which first flower Appear, Internodal length (cm), Number of nodes per plant, Number of fruits per plant, Fruit yield per plant (g), Fruit yield (q ha-1), Fruit length (cm), Fruit diameter (cm), Fruit weight (g), Days to edible fruit maturity, Number of seeds per fruit, Seed weight per fruit, 100-Seed weight and Seed yield per plant. The combining ability analysis was carried out by the procedure suggested by Griffing (1956a&b) and Robinson (1996) was taken up for the material under study. RESULTS AND DISCUSSIONS General Combining Ability (GCA). During experimentation, variance due to general combining ability (GCA) and specific combining ability (SCA) are presented in (Table 1). It is evident from the table that mean squares due to GCA were highly significant for all the characters except days to edible fruit maturity and fruit diameter (cm). Were SCA had also highly significant for all the eighteen characters studied. The estimation of GCA effects of the parents for all the eighteen characters are presented in (Table 1). For days to first flowering, number of seed per fruit and other maturity traits general combiners with negative values are desirable. The general combiners with negative value are usually desirable for the character days taken to first flowering. Out of ten parental lines, one parent namely P7 (-0.817) showed significant and negative GCA estimates and they were classified as good general combiners (Table 2). Out of ten parental lines, one lines viz., P6 (-0.828) showed significant and negative GCA effect in desirable direction for days to 50 % flowering (Table 2). During study, node at which first flower appears, general combiners with negative values are usually desirable. Out of ten parental lines two expressed the negative significant GCA effects. The most desirable parental lines was P2 (-0.177) and P10 (-0.153) both are valuable because this showed highly negative significant GCA effects (Table 2). Earliness for days to edible fruit maturity is most important character in okra. None of the parents showed significant GCA effects in desirable direction (Table 2). Two parental lines viz., P7 (1.230) and P5 (0.733) showed positive significant GCA effect for number of node per plant. However, 2 lines were poor general combiners in which P1 exhibited significant GCA effects with a higher value (-0.932) followed by P4 (-0.677) (Table 2). For Internodal length, estimates of negative GCA effects values are considered desirable. Two potential lines P2 (-0.524) and P1 (-0.434) expressed this trends and were classified as the good general combiners (Table 2). Three parental line viz., P3 (0.220) followed by P10 (0.205) and P1 (0.092) were best general combiner as they showed significant GCA effect in desirable direction for this trait. On the other hand, parent P7 (-0.289), P2 (-0.181) and P5 (-0.107) exhibited significant and negative GCA effect was considered as poor general combiner for this trait. Rest of the parents were considered as average as average combiners due to non-significant GCA effects. In order to merit, five parents lines were found to be positively significant GCA effects, in which P10 (5.183) followed by P9 (5.148) and P5 (4.534) were identified as good combiners for plant height which is desirable in okra. On the other hand, four parents were found to be negatively significant GCA effects, in which P2 (-7.392) followed by P8 (-4.859) and P1 (-4.738) were proved to be poor general combiners since they exhibited significant and negative GCA effects. The rests of the parents were average combiner for this trait as they showed non-significant GCA effects. A critical examination of (Table 2) reveled that only two parents viz., P7 (1.614) and P8 (0.881) exhibited significant and positive GCA effect and hence, it was depicted as good general combiner for this trait. On the other hand, two parent viz., P1 (-1.593) and P4 (-1.053) exhibited significant and negative GCA effects and were considered as poor general combiner due to non-significant GCA effects. Significant and positive GCA effects for 10-fruits weight were observed in three parents viz., P10 (0.900) followed by P8 (0.704) and P2 (0.630). Thus, they were registered as good general combiners for fruit weight (gm). On other hand, three parents viz., P1 (-1.752) followed by P3 (-0.937) and P9¬ (-0.643) exhibited significant and negative GCA effects, hence they were proved as poor general combiner for this trait. The rest of the parents were average combiner for this trait as they showed non-significant GCA effects. Estimates of GCA effects revealed that one parent viz., P7 (0.559) was considered as good combiner for fruit length as it had exerted significant and positive GCA effect, on other hand, one parents viz., P2 (-0.353) exhibited significant and negative GCA effects. While rest of the parents were average combiner for this trait as they showed non-significant GCA effects. A critical examination of Table 3 revealed that only one parent i.e. P2 (0.062) showed good combiners as they had significant effect in desirable direction for fruit diameter. On the other hand no any parents exhibited significant and negative GCA effects and were considered as poor general combiners for this trait. Rests of the parents were considered as negative combiners due to non- significant GCA effects. In order of merit, P4 (-1.803) followed by P1 (-1.701), P3 (-1.322) and P9 (-1.106) exhibited significant and negative GCA effects which is desirable in okra hence, expressed as good combiners for number of seeds per fruit. On the other hand, parent P10 (2.259) and P5 (1.162) was proved to be poor general combiner since it exhibited significant and positive GCA effect for this trait, while rest of the parents were average combiner for this traits as they showed non-significant GCA effects. In seed weight per fruit, two parental lines viz., P6 (0.340) and P1¬ (0.251) shows valuable positive significant GCA effects and found to be good combiners for this trait. On the other hand, three parents viz., P4 (-0.253), P7 (-0.179) and P8 (-0.139) exhibited significant and negative GCA effects and were considered as poor general combiners for this trait. The rests of the parents were considered as average combiners due to non-significant GCA effects. In 100-seed weight only three parents viz., P6 (0.459) followed by P3 (0.194) and P7 (0.163) were considered as good combiners for 100-Seed weight as they had exerted significant positive GCA effects. On other hand, parent P2 (-0.289), P4 (-0.226) and P1 (-0.166) exhibited significant and negative GCA effects suggested that poor general combiners for this trait (Table 3). The rests of the parents were considered as average combiners due to non-significant GCA effects. In seed yield per plant, only one parent line i.e. P¬6 (4.056) were found for positive significant GCA effects, this is desirable for okra. On the other hand, two parents viz., P¬8 (-3.862) and P10 (-3.291) exhibited significant and negative GCA effects and were poor general combiner for this trait. The rests of the parents were considered as average combiners due to non- significant GCA effects. For fruit yield per plant two parents P¬8 (30.719) and P¬3 (29.156) showed significant positive GCA effects whereas, five parental lines were poor general combiner, with negative GCA effects (Table 3). Parents P8 the best general combiner for fruit yield per plant was also found as the best general combiner for fruit yield per plant. Estimates of GCA effects reveled that two parents viz., P8 (17.066) and P3 (16.198) were considered as good general combiners for fruit yield q/ha-1 as they had exerted significant and positive GCA effects which is considered as desirable traits in okra. On the other hand, parent P10 (-10.554) followed by P5 (-9.737) and P4 (-5.921) exhibited significant and negative GCA effect suggested that poor general combiner for this trait. Remaining parents were considered as average combiners due to non-significant GCA effects. Similar result were found by Similar correspondence between these parameters was observed by Gill and Kumar (1988) in water melon, Musmade and Kale (1986) in cucumber, Jindal and ghai (2005); Rai et al. (2011); Singh et al. (2012); Vachhani et al. (2012); Nimbalkar (2017); Ivin et al. (2022) in okra. Specific Combining Ability (SCA). The estimates of SCA effects (Sij) of 45 F1s crosses and their standard errors of different comparisons were studied for eighteen metric traits and the results have been presented in (Table 4). The SCA effects in negative directions was considered desirable for maturity traits viz., days to first flowering, days to 50 per cent flowering and days to edible fruit maturity. Out of 45 F¬1 hybrids, three showed significant and negative SCA effects in desirable direction for days to first flowering. The highest, significant and negative SCA effect was observed in cross P5 × P¬6 (-4.328) followed by P2 × P¬10 (-3.578) and P4 × P7 (-3.578). Five crosses had found significant and positive SCA effects for late flowering (Table 4). Estimates of specific combining ability for earliness in respect of days to 50 % flowering were significantly negative and desirable in five hybrids. The crosses P5 × P¬7 (-3.854) followed by P2 × P¬10 (-3.659) and P3 × P5 (-2.826) were found as the best three specific combiners (Table 4). Eight crosses had found significant and positive SCA effects for late flowering. The significant negative SCA effects for earliness for node at which first flower appear were observed in 9 hybrids. The best three promising crosses in order of performance for earliness were P1 × P¬10 (-1.014) exhibits maximum negative SCA effects followed by P1 × P¬5 (-0.983) and P1 × P4 (-0.911) were identified as good specific combiner for this trait (Table 4). On the other hand, 13 crosses showed positively significant which is not desirable for this trait (Table 4). The magnitude of SCA effects in hybrids varied from -4.337 (P¬¬5 × P7) to 9.671 (P7 × P9). Out of 45 crosses, one cross combinations showed significant and negative SCA effects for days to edible fruit maturity. The highest SCA effect was exhibited by the cross P¬¬5 × P7 (-4.337) (Table 4). The spectrum of variation for SCA effects in hybrids was from -5.786 (P¬¬5 × P6) to 3.461 (P3 × P10) (Table 4). Out of 45 crosses, eight are showed significant and positive SCA effects for number of node per plant. The highest, significant and positive SCA effect was observed in cross P3 × P10 (3.461) followed by P6 × P8 (3.302) and P2 × P6 (3.288) which is desirable good specific combiners for this trait. Out of 45 crosses, eight crosses exhibits significant and negative SCA effects for less Internodal length which is desirable trait. The highest, significant and negative SCA effect was observed in cross P2 × P5 (-1.575) followed by P1 × P9 (-1.224) and P8 × P9 (-1.001) (Table 4). Ten crosses had found significant and positive SCA effects for more Internodal length. The significant variation of specific combining ability effects in hybrids ranged from -0.663 (P¬¬1 × P4) to 0.702 (P1 × P8) (Table 4). Out of 45 crosses, thirteen hybrids showed significant and positive SCA effects, therefore, they were considered as good specific combinations for more number of branches per plant. While twelve crosses noted as poor specific cross combinations as they noted significant and negative SCA effects. The magnitude of SCA effects in hybrids varied from -30.123 (P¬¬3 × P4) to 32.350 (P2 × P8) (Table 4). Out of 45 crosses, fourteen hybrids exhibited significant and positive SCA effects for this trait. The crosses P¬¬2 × P8 (32.350) rank first trailed by P¬¬1 × P6 (21.947) and P3 × P5 (20.551) (Table 4) for this trait. Among the 45 crosses producing significant SCA effects, twelve crosses were in desired direction. The cross P¬¬6 × P8 (5.794) ranked first followed by P¬¬5 × P6 (5.417) and P2 x P5 (5.227) (Table 4). While nine hybrids depicted as the poor specific cross combinations for this trait. The magnitude of SCA effects for fruit weight in hybrids varied from -6.327 (P¬¬5 × P6) to 8.918 (P5 × P7) (Table 5). Out of 45 crosses, Seventeen hybrids exhibited significant and desirable (positive) SCA effects for this trait. The cross P¬¬5 × P7 (8.918) rank first trailed by P¬¬2 × P9 (7.077) and P2 x P6 (6.638) (Table 5) for this trait. The spectrum of variation for SCA effects in hybrids was ranged from -1.031 (P¬¬2 × P5) to 1.817 (P4 × P6) (Table 5). Out of 45 crosses, three crosses showed significant and positive SCA effects for fruit length. The maximum fruit length was observed in cross P¬¬4 × P6 (1.817) followed by P¬¬3 × P7 (1.153) and P2 × P10 (1.097) (Table 5) which is positively significant and considered for good specific combiners for fruit length. The ranged of SCA effects in hybrids varied from -0.299 (P¬¬7 × P9) to 0.274 (P3 × P10) (Table 5). Out of 45 crosses, Four hybrids cross combinations showed significant and positive SCA effects for high fruit diameter with highest SCA effects in P¬¬3 × P10 (0.274) followed by P¬¬2 × P5 (0.201) and P1 × P3 (0.186) (Table 4.7). On the other hand, P¬¬7 × P9 (-0.299), P8 × P10 (-0.229), P¬¬3 × P4 (-0.219) and P5 × P7 (-0.216) occupied the poor specific cross combinations for fruit diameter. In case of crosses only seven were showed positive significant SCA effects. The most promising three crosses were P¬¬3 × P9 (8.105) followed by P¬¬2 × P9 (7.673) and P6 × P9 (6.048) (Table 5) displayed highest positive significant SCA effects. Whereas P¬¬5 × P9 (-10.479) followed by P¬¬1 × P9 (-10.219) and P2 × P3 (-9.788) (Table 5) expressed high negative significant SCA effects. The combined result showed that P¬¬3 × P9 (8.105) and P¬¬2 × P9 (7.673) were the good specific combinations. Among 45 crosses, only eight were expressed valuable positive significant SCA effects. The most promising three cross were P¬¬2 × P7 (1.283), P¬¬6 × P10 (0.827) and P7 × P8 (0.703) (Table 5) showed positively significant effects. Whereas P¬¬2 × P4 (-1.019) showed highest negative significant SCA effect followed by P¬¬2 × P10 (-0.991) and P4 × P8 (-0.995) (Table 5). While the cross considering the Estimates of SCA effects and per se performance of the crosses P¬¬2 x P7 Was good cross combinations for this trait. In respect of crosses seventeen were expressed positive significant SCA effects. The most promising three crosses were P¬¬2 × P7 (1.801) showed positive significant SCA effects followed by P¬¬3 × P6 (1.249) and P¬¬4 × P10 (1.095) (Table 5). While the crosses P¬¬2 × P4 (-1.497), P¬¬2 × P10 (-1.482) and P¬¬5 × P5 (-1.317) showed negative significant SCA effects. Considering the estimates of SCA effects and per se performance of the crosses P¬¬2 × P7 and P¬¬3 × P6 were good cross combination for this trait. Among 45 cross combinations, the SCA effects revealed that only five crosses displayed positive significant effects. Best three cross combinations, P¬¬4 x P10 (11.778), P¬¬4 × P7 (10.625) and P¬¬4 × P5 (10.084) (Table 5) were most promising specific combiners. Highest negative SCA estimates were observed in cross P¬¬2 × P4 (-24.964), P¬¬9 × P10 (-16.634) and P¬¬7 × P9 (-14.687) (Table 5). Considering the estimates of SCA effects and per se Performance of the crosses, P¬¬4 × P10 was best combiners for this trait. Twelve cross combinations showed significant and positive SCA effect for higher fruit yield per plant with highest SCA effects in P¬¬4 × P6 (56.651) followed by P¬¬2 ×P8 (56.530), P6 × P7 (55.878) and P¬¬5 × P8 (53.988) (Table 5). While seventeen cross combinations showed significant and negative SCA effects for fruit yield per plant. Out of 45 F1 hybrids, twelve displayed positive significant SCA effects. Crosses P¬¬4 × P6 (31.473) followed by P¬¬2 × P8 (31.405), P6 × P7 (31.043) and P¬¬5 × P8 (29.993) were the most promising combinations for fruit yield per plant (Table 5). On the other hand, seventeen crosses showed negative estimates of SCA effect with significant values. The seventeen highest negative estimates of SCA effects was observed in cross P3 × P8 (-42.177). Similar results have also been reported by Shwetha et al. (2018); Tiwari et al. (2016); Nagesh et al. (2014).