Screening of okra (Abelmoschus esculentus (L.) Moench) genotypes for fruit yield and yield-related traits under heat stress for heterosis breeding

Introduction

Abelmoschus esculentus (L.) Moench, better known as okra or lady's finger, is a hardy annual belonging to the Malvaceae family-a group that also includes cotton and hibiscus (Elkhalifa et al., 2021) [6] . Originally from East Africa (specifically Ethiopia, Eritrea, and Sudan), it's now grown across tropical and warm temperate zones for its tender green pods. The crop is selfpollinating, loves heat and drought, but perishes with frost (Westerfield, 2022) [23] . Okra is more than just a vegetable; it's a nutritional powerhouse. Fresh pods are about 90% water but pack vitamins C and K, plus moderate minerals like magnesium and folate (Dantas et al., 2021) [4] . The seeds are especially valuable, containing 18-20% oil rich in linoleic acid. Beyond nutrition, the mucilage in the pods has shown real promise in managing blood sugar and reducing inflammation, with recent reviews confirming its cardiometabolic benefits (Thakur & Sharma, 2026; Worthington & Lee, 2025) [19,24] . In 2025, the world produced roughly 12.1 million tonnes of okra from 1.25 million hectares (FAO, 2025; Arif & Khan, 2026) [2,7] . India still dominates, accounting for nearly 70% of global output with 8.5 million tonnes, followed by Nigeria and Mali (Tridge, 2025). Pakistan cultivates about 16,200 hectares, yielding around 122,500 tons, while the U.S. continues to rely on imports, which reached $68.4 million in 2024-25 due to steady consumer demand (APEDA, 2025). Despite its importance for food security, okra yields vary widely depending on genotype and environment (Kumar, 2019; Patel & Gupta, 2025) [8,10,14] . This inconsistency makes it critical to screen germplasm carefully and breed for resilience. That's exactly what this study aims to do: screen genotypes and analyze key yield traits to identify lines that are both high-yielding and stress-tolerant (Srivastava & Verma, 2026) [18] . and identify lines suitable to heterosis breeding.

Materials and Methods

In Zaid 2024, we evaluated a total of 17 genotypes under heat stress conditions at the field experimentation center of the Department of Genetics and Plant Breeding. The experiment followed a Randomized Block Design (RBCD) with three replications and a spacing of 30 cm × 45 cm. We recorded 14 key observations: days to 50% flowering (DF50), days to first picking (DFP), branches per plant (NBPP), plant height (PH, cm), number of internodes (IL), fruit length (FL, cm), seed index (SI), fruits per plant (NFPP), seeds per pod (NSPP), average fruit weight (AFW, g), days to last picking (DLP), nodes to first pod (NDP), fruits per first node (FFN), and fruit yield per plant (FYPP, g).

Results and Discussions ANOVA and Variability Parameters

The analysis of variance showed clear differences among the okra genotypes for several important traits. Genotypic effects were highly significant for days to 50% flowering, days to first picking, number of branches per plant, fruit length, days to last picking, number of days to picking, and first fruiting node, which indicates that the material had enough genetic diversity for these characters and that they can be useful in selection and breeding work. (Table .1) The variation observed for days to 50% flowering and days to first picking shows that the genotypes differed in earliness. In okra, early flowering and early harvesting are desirable because they allow earlier market returns and better crop planning. Similar variation in flowering and picking traits has been reported by Kumar et al. (2019) and Singh et al. (2014) [10, 16] , who also found substantial genetic differences for earliness-related and yield-related traits in okra. The significant differences in days to last picking and number of days to picking also suggest variation in crop duration and harvesting span among the genotypes. Number of branches per plant and first fruiting node also showed highly significant variation, reflecting differences in plant architecture and fruiting behaviour. These characters are important because branching pattern and fruiting position can influence productivity as well as ease of harvest. Fruit length also varied significantly among the genotypes, showing that there is scope to select lines with better pod size and market preference. Similar findings were reported by Patel et al. (2025) [14] , who noted that genotype-byenvironment interaction can strongly affect the expression of yield-related characters in okra. In contrast, plant height, inter-node length, average fruit weight, number of fruits per plant, number of seeds per pod, seed index, and fruit yield per plant did not show significant differences among the genotypes. This may be due to limited genetic variation in the tested material or stronger environmental influence on these traits. Fruit yield per plant is a complex trait and is usually controlled by several component characters together, so it often shows less clear variation in early screening studies. Similar observations were also made by Alam et al. (2024) and Patel et al. (2025) [2, 14] , who suggested that complex yield traits are often more affected by environmental conditions than by direct genotype effects. The variability estimates showed that phenotypic variation was higher than genotypic variation for all traits, which means that environmental factors had some effect on trait expression. The traits with the highest GCV and PCV were first fruiting node (GCV 8.974, PCV 13.487), number of nodes per plant (GCV 6.904, PCV 9.388), days to first picking (GCV 5.447, PCV 6.432), and days to 50% flowering (GCV 5.359, PCV 6.231). This indicates a wider range of variation and better scope for improvement through selection. Kumar et al. (2019) [10] also reported similar variability for earliness and related traits in okra. On the other hand, average fruit weight (GCV 1.074, PCV 8.024), seed index (GCV 1.364, PCV 9.741), and fruit yield per plant (GCV 0.846, PCV 5.947) showed low values, suggesting limited variability for these traits. (Table . 3) Heritability values also varied across the traits. High heritability was observed for days to 50% flowering (73.964), days to first picking (71.706), days to last picking (59.782), number of branches per plant (53.986), number of nodes per plant (54.082), and fruit length (44.998), indicating that these traits are mainly controlled by genetic factors and may respond well to selection. Comparable results were reported by Verma et al. (2024) [22] , who found that flowering and structural traits in okra were more heritable and therefore more useful in breeding work. In contrast, average fruit weight (1.791), seed index (1.960), and fruit yield per plant (2.022) showed very low heritability, which suggests that environmental effects were stronger for these characters. Genetic advance was also higher for first fruiting node (0.651), number of nodes per plant (0.865), days to first picking (3.854), and days to 50% flowering (3.779), with corresponding GAM values of 12.302, 10.459, 9.501, and 9.494, respectively. High heritability combined with good genetic advance usually indicates additive gene action, which means selection is likely to be effective. This makes these traits especially valuable for breeding programmes. Similar conclusions were drawn by Srivastava et al. (2026) [18] , who emphasized the importance of such traits in climate-resilient okra improvement. The low genetic advance for fruit yield per plant (0.559, GAM 0.248), seed index (0.019, GAM 0.393), and average fruit weight (0.014, GAM 0.296) suggests that direct selection for these traits may not be very effective, and improvement may be better achieved through selection of their component characters. (Table .3) Overall, the study shows that the okra genotypes possessed useful variation mainly for earliness, branching, fruiting habit, and node-related traits. These characters can be used as reliable selection criteria in future breeding efforts. The findings are also in agreement with the broader work of [4,6,15,19,24] , who highlighted the nutritional, medicinal, and breeding potential of okra. Since fruit yield per plant showed low heritability and low genetic advance, it would be more effective to improve yield indirectly by selecting for its contributing traits rather than relying on yield alone.

Correlation Analysis

The correlation study showed that most of the important traits in okra were positively associated with one another, indicating that improvement in one character may also improve other related traits. At the phenotypic level, days to 50% flowering showed a significant positive association with days to first picking (0.47**), number of branches per plant (0.48**), plant height (0.52**), fruit length (0.35*), number of fruit per plant (0.32*), number of seeds per pod (0.57**), days to last picking (0.40**), number of nodes per plant (0.55**), first fruiting node (0.57**), and fruit yield per plant (0.32*) ( [10,16] . Days to first picking also had significant positive correlations with number of branches per plant (0.42**), plant height (0.45**), number of fruit per plant (0.43**), days to last picking (0.54**), number of nodes per plant (0.60**), and first fruiting node (0.49**). This shows that earliness is related to overall plant vigour and harvesting duration. Similar findings were reported by Patel et al. (2025) [14] , who observed that flowering and picking traits are strongly influenced by genotype and environment. (Table .5) Number of branches per plant showed positive and significant correlations with plant height (0.34*), number of fruit per plant (0.30*), number of seeds per pod (0.44**), days to last picking (0.50**), number of nodes per plant (0.35*), first fruiting node (0.43**), and fruit yield per plant (0.28*). This indicates that branching is an important trait for plant type and productivity. Similar results were reported by Kumar et al. (2019) and Verma et al. (2024) [10,22] . Plant height was also positively and significantly associated with fruit length (0.37**), number of fruit per plant (0.32*), number of seeds per pod (0.42**), days to last picking (0.48**), number of nodes per plant (0.48**), and first fruiting node (0.37**). This points to a strong link between vegetative growth and reproductive performance. [16,18] . Fruit length showed positive associations with days to last picking (0.66**) and number of nodes per plant (0.48**) at the phenotypic level. At the genotypic level, it was also strongly associated with plant height (0.64**), days to last picking (0.81**), number of nodes per plant (0.63**), and first fruiting node (0.49*). This suggests that longer pods were generally found in better-growing genotypes with a more favorable fruiting pattern. Similar conclusions were drawn by Alam et al. (2024) and Patel et al. (2025) [1,14] . Number of fruit per plant emerged as one of the most important traits in the study. It showed a highly significant positive correlation with days to last picking (0.66**), number of nodes per plant (0.60**), first fruiting node (0.62**), and fruit yield per plant (0.63**) at the genotypic level. At the phenotypic level, it was also positively associated with days to 50% flowering (0.32*), days to first picking (0.43**), number of branches per plant (0.30*), plant height (0.32*), days to last picking (0.66**), number of nodes per plant (0.40**), first fruiting node (0.43**), and fruit yield per plant (0.63**). These findings clearly show that fruit number is a major contributor to final yield, as also reported by Kumar et al. (2019) and Patel et al. (2025) [10,14] . Number of seeds per pod was positively associated with days to 50% flowering (0.57**), plant height (0.42**), days to last picking (0.42**), number of nodes per plant (0.67**), and first fruiting node (0.51**) at the phenotypic level. At the genotypic level, it was also significantly related to plant height (0.74**) and average fruit weight (0.58*). This suggests that stronger plants with better fruiting positions tend to produce better-filled pods. Similar relationships were reported by Verma et al. (2024) and Srivastava et al. (2026) [18, 22] . Days to last picking, number of nodes per plant, and first fruiting node were also closely associated with several growth and yield traits. Seed index showed negative and significant correlations with days to first picking (-0.30*) and first fruiting node (-0.28*) phenotypically, while genotypically it was negatively related to days to first picking (-0.52*), average fruit weight (-0.52*), days to last picking (-0.55*), and number of branches per plant (-0.40). These negative associations suggest that seed index may behave independently from the main yield traits. Similar trends were noted by Patel et al. (2025) and Verma et al. (2024) [14,22] . Fruit yield per plant had positive and significant associations with number of branches per plant (0.28*), days to first picking (0.29*), and number of fruit per plant (0.63**) phenotypically, while genotypically it was positively correlated with number of branches per plant (0.51*). This indicates that yield improvement may be more effective through selection of component traits rather than direct selection for yield alone. Overall, genotypic correlations were stronger than phenotypic correlations, showing that these relationships are mainly genetic and therefore useful for selection across generations. Selection for number of fruit per plant, number of branches per plant, plant height, days to last picking, and first fruiting node may help improve yield indirectly in okra.

Conclusion

The present study clearly demonstrated that the okra genotypes possessed useful genetic variability for a number of important quantitative traits The highest fruit yield per plant was recorded in Pusa5 (239.67 g), followed by VRO-492-9-1 (236.67 g), IC-913995 (233.33 g). The analysis of variance confirmed significant differences among genotypes and Variability estimates further indicated that several traits had high heritability and favorable genetic advance, suggesting the predominance of additive gene action and good scope for genetic improvement. Correlation indicates yield in okra is mainly controlled by component traits. Number of branches, number of fruits per plant, plant height, days to last picking, and first fruiting node showed positive associations with yield, so indirect selection for these traits would be more effective than selecting yield alone. Overall, the study suggests These traits provide a strong foundation for developing early, high-yielding, and superior okra varieties with better agronomic performance and farmer acceptance

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