Effect of plant growth regulators on growth and yield of bhendi (Abelmoschus esculentus)

Introduction

According to Kumar and Yadav (2016) [1] , bhendi (Abelmoschus esculentus L. Moench), commonly known as okra or Ladies finger, which is an important warm-season vegetable crop cultivated extensively in tropical and subtropical regions. It is rich in vitamins A, B, and C, calcium, potassium, iodine and dietary fiber, and its mucilage is valued for both medicinal and industrial uses (Nath et al., 2021) [2] . The productivity of bhendi is often constrained by poor fruit set, flower drop, and low yield, which are mainly caused by environmental stress and hormonal imbalances, as reported by Das et al., (2016) [3] . Choudhary et al., (2018) [4] described plant growth regulators (PGRs) as organic substances, other than nutrients, that influence physiological processes at very low concentrations. These regulators play a vital role in manipulating growth, enhancing flowering, and increasing yield in vegetable crops. According to Patel et al., (2017) [4] gibberellic acid (GA3) promotes cell elongation, shoot growth, and early flowering, resulting in increased plant height and biomass. Naphthalene acetic acid (NAA), a synthetic auxin, is effective in improving fruit set, reducing premature fruit drop, and enhancing pod yield in okra. The efficiency of PGRs depends on crop variety, concentration, timing, and local agro-climatic conditions, as emphasized by Raut et al., (2021) [31] . Bhowmick and Banerjee (2021) [6] found that the combined application of GA3 and NAA is more effective than individual treatments in improving both vegetative and reproductive parameters of okra. Such combinations increase plant height, leaf number, branching, fruit length, fruit weight, and total yield while promoting early maturity and synchronized flowering (Lakshmi et al., 2018) [7] . According to Kale et al. (2020) [8] , repeated foliar sprays of PGRs enhance pod length and reduce the time to first harvest, making the crop more profitable. Therefore, the present investigation was undertaken to evaluate the effect of different concentrations and combinations of GA3 and NAA on the growth and yield performance of bhendi under the field conditions of Erode district, Tamil Nadu.

Materials and Methods

The study was laid out in a randomized block design with three replications, whereas each treatment plot measured 3m x 2m with spacing of 45 cm between rows and 30 cm between plants (Gomez & Gomez, 1984) [10] . The okra variety used was (Abelmoschus esculentus L. cv.) with healthy seeds sown directly in the field (Gopalakrishnan, 2007) [11] . The experiment consisted of a series of foliar spray treatments using various Plant Growth Regulators (PGRs) at different concentrations, applied at 30, 45, and 60 days after sowing. All recommended agronomic practices like land preparation, irrigation, weeding, and pest control were followed uniformly (Gopalakrishnan, 2007) [11] . The following growth and yield parameters were recorded from three randomly selected plants in each plot (Reddy, 2012) [12] . The following growth and yield parameters were recorded from three randomly selected plants in each plot: Mean Plant Height (cm) was the average vertical length of the plant, measured from the soil surface to the tip of the main shoot (Panse & Sukhatme, 1985) [13] . The total count of lateral branches emerging from the main stem was recorded as the Number of Branches per Plant (Thamburaj& Singh, 2004) [14] , while the total number of fully expanded leaves on a single plant was counted for the Number of Leaves per Plant (Singh & Singh, 2015) [15] . The Node to First Flowering, which indicates the early onset of reproductive growth, was the node where the first flower appeared (Hartmann et al., 2011) [16] . The Days to First Flowering was the number of days from sowing to the appearance of the first flower (Kumar & Singh, 2012) [17] , and the Days to First Harvest was the number of days from sowing until the first marketable pod was harvested (Chadha, 2001) [18] . According to Singh (2014) [19] , the Percentage of Fruit Set (%) was the proportion of flowers that successfully developed into fruits. The number of days for all plants in a plot to reach full bloom was recorded as Days to 100% Flowering (Rai & Yadav, 2005) [20] , and the time taken for all flowers to convert into fruits across all plants was the Days to 100% Fruit Set (Sharma, 2009) [21] . For fruit observations, the Number of Fruits per Plant was the total number of marketable okra pods harvested from a single plant (Gopinath et al., 2012) [22] . The Average Fruit Length (cm) was the mean length of individual pods (Kumar & Singh, 2017) [9] , and the Average Fruit Weight (g) was the average weight of individual fruits (Gopinath et al., 2012) [22] . Fruit Diameter (cm) was the average thickness or girth of the fruit (Hazra & Som, 1999) [23] . Fruit Weight per Plant was the total weight of all fruits harvested from a single plant (Singh & Yadav, 2013) [24] , and the Fruit Weight per Plot was the cumulative weight of fruits harvested from all plants in a treatment plot (Kumar & Gopalan, 2000) [25] .

Treatments

Results and Discussion

Results of the field experiment entitled "Effect of Plant Growth regulators on growth and yield of Bhendi (Abelmoschus esculentus)" conducted during May-August, 2025 at Kumaraguru Institute of Agriculture, Erode with statistical inferences are presented.

Growth Parameter At 30 DAS

At 30 days after sowing (DAS), the vegetative growth of okra showed significant variation among treatments. Plant height ranged from 14.08 cm in T6 to 28.17 cm in T10. The tallest plants were recorded in T10 (28.17 cm), followed by T4 (26.67 cm), both statistically superior to all other treatments. The shortest plants were found in T6 (14.08 cm), significantly lower than all others. The superior height in T10 and T4 suggests optimal conditions for cell elongation and biomass accumulation, likely due to enhanced nutrient uptake and photosynthetic efficiency during early growth stages. Similar observations were reported by Sarkar and Pal (2016) [26] , who noted that optimal nutrient and growth regulator combinations significantly increase okra height in the vegetative phase. The number of leaves per plant varied between 5.33 in T8 and 9.33 in T9. T9 produced the maximum number of leaves, significantly higher than all other treatment indicating more active leaf initiation and expansion. Treatments T1, T4, and T13 recorded 7.67, 7.67, and 7.50 leaves respectively, forming the next superior group. Higher leaf count in T9 would contribute to greater photosynthetic surface area and better carbohydrate assimilation, which can enhance yield potential. Kumar et al., (2017) [9] linked such increases in leaf production to higher nitrogen availability and favourable soil moisture conditions supporting canopy development. Leaf diameter ranged from 7.42 cm in T8 to 10.92 cm in T1. T1 recorded the widest leaves, significantly superior to all other treatments, followed by T9 (9.92 cm) and T6/T7. Wider leaves enhance light interception, boosting photosynthetic activity and vegetative vigour. This finding aligns with Patel et al., (2018) [4] , who reported that improved water and nutrient uptake in okra promotes leaf blade expansion. Overall, T10 was superior in plant height, T9 in leaf number, and T1 in leaf diameter, indicating that no single treatment dominated all vegetative traits. A combination of the beneficial factors from these treatments could potentially maximize overall vegetative growth and yield in okra cultivation.

At 45 th DAS At 45 days after sowing (DAS), okra growth and yield parameters exhibited highly significant variation among the treatments. Plant height ranged from 90.33 cm in T5 to 157.50 cm in T4, with T4 being statistically superior to all other treatments. This pronounced vertical growth in T4 suggests optimal nutrient and growth regulator synergy, as also noted by Sarkar and Pal (2016) [26] . In contrast, the reduced height in T5 may be attributed to nutrient limitations or growth restrictions. Branch number per plant varied significantly, with T13 (3.33) producing the highest, followed by T6 (2.83) and T9 (2.50). The lowest was in T11 (1.00). The prolific branching in T13 may be due to hormonal stimulation of auxillary bud outgrowth, supported by Kumar et al., (2017) [9] , who linked higher nitrogen and potassium levels to increased branching. Leaf diameter differed significantly, with T4 (15.75 cm) achieving the largest leaves. This may indicate enhanced mesophyll expansion and turgidity, improving light interception, consistent with Patel et al., (2018) [4] . The smallest leaves occurred in T1 (12.17 cm).

The number of leaves per plant was highest in T4, T8, and T10 (28.67), all of which were significantly superior to T1 (24.33) and T11 (23.83).

Higher leaf counts generally indicate sustained leaf initiation and retention, which contribute to a greater photosynthetic surface area and enhanced assimilate production, ultimately improving plant vigour and yield potential. Similar trends have been reported by Ayyub et al., (2013) [24] , who found that foliar application of GA3 markedly increased leaf number in okra compared to untreated controls, and by Rajput et al., (2018) [27] , who observed that GA3 at 200 ppm significantly improved leaf production alongside other vegetative parameters. These findings confirm that PGR application. The highest fruit count was recorded in T6 and T13 (5.17), both significantly exceeding T5 (2.50). This indicates improved flowering and fruit set efficiency under these treatments. Similar results were reported by Thirupathi et al., (2012) [28] and Meitei et al., (2014) [30] ,

where PGR application enhanced fruit retention and increased the number of fruits per plant.Fruit length showed significant variation among treatments, with the maximum recorded in T9 (14.30 cm) and the minimum in T5 (7.50 cm). Fruit breadth also differed significantly, being highest in T8 (5.90 cm) and lowest in T1 (3.37 cm). Such differences in fruit size are attributed to variations in assimilate partitioning and source-sink dynamics. Similar results were reported by Thirupathi et al., (2012) [28] and Meitei et al., (2014) [30] , who found that application of PGRs such as GA3 and NAA in okra enhanced fruit length and breadth by promoting efficient translocation of photosynthates to developing fruits. Fruit weight varied significantly, with T4 (434.67 g) being the highest and T8 (124.67 g) the lowest. T4's superiority in height, leaf area, and fruit weight indicates efficient assimilate production and partitioning, aligning with findings by Thirupathi et al., (2012) [28] and Meitei et al., (2014) [30] . Overall, T4 demonstrated exceptional performance in both vegetative and reproductive traits, suggesting its suitability for maximizing okra yield. While T13 and T6 excelled in branching and fruit number, and T9 and T8 in fruit size, T4 combined advantages position it as the most effective treatment for enhancing growth and productivity.

Yield Parameter

At 60 th day DAS At 60 days after sowing (DAS), significant differences were observed among treatments for all measured growth and yield parameters. Plant height varied from 62.00 cm in T5 to 150.33 cm in T4, with T4 being significantly superior to all other treatments, followed by T10 (110.92 cm) and T8 (99.97 cm). The pronounced height in T4 suggests sustained vegetative vigour due to enhanced nutrient uptake and prolonged cell elongation, consistent with Sarkar and Pal (2016) [26] . The minimal height in T5 likely reflects suboptimal nutrient or moisture availability. Number of branches per plant showed highly significant variation T13 (3.33) produced the highest number, followed by T10 (3.00), both significantly higher than T2 (1.33). This enhanced branching may be due to improved auxillary bud activation under favourable nutrient regimes, as reported by Kumar et al., (2017) [9] . Leaf diameter differed significantly, with T4 (22.90 cm) recording the largest leaves and T11 (14.62 cm) the smallest. Broad leaves in T4 likely enhanced light interception and photosynthetic efficiency, thereby increasing assimilate production for fruit development. Similar observations were reported by Ayyub et al., (2013) [24] and Rajput et al., (2018) [27] , who found that treatments promoting larger leaf area in okra improved photosynthate accumulation, resulting in better growth and yield performance. The number of leaves per plant was highest in T4 (35.67) and T6 (35.00), both significantly exceeding T11 (15.50) and T13 (20.83). Increased leaf production in these treatments suggests prolonged vegetative activity and greater photosynthetic capacity during fruiting. Similar findings were reported by Ayyub et al., (2013) [24] and Rajput et al., (2018) [27] , who observed that treatments enhancing leaf number in okra improved assimilate production, thereby supporting higher yield potential. Number of fruits per plant peaked in T6 (4.67), followed by T10 (3.83), while the lowest was in T7 (1.33). This suggests more efficient reproductive development in T6, aligning with Patel et al., (2018) [4] , who noted that optimal nutrient allocation improves fruit retention. Fruit length was highest in T6 (14.00 cm), followed by T10 (12.33 cm) and T8 (12.00 cm). Fruit breadth was widest in T10 (5.83 cm), significantly exceeding T7 (3.35 cm) and T1 (3.37 cm). These differences indicate that T6 was most effective in promoting longitudinal fruit growth, whereas T10 favoured lateral expansion. Similar trends were noted by Thirupathi et al., (2012) [28] and Meitei et al., (2014) [30] , who reported that PGR application. Overall, T4 consistently dominated vegetative traits (plant height, leaf size, leaf number), T6 excelled in reproductive output (fruit number and length), and T10 achieved superiority in fruit breadth. This indicates that different treatments optimized distinct aspects of growth and yield, suggesting that integrating the beneficial elements of these treatments could maximize both yield quantity and quality in okra production.

At 75 th day DAS Plant height varied significantly among treatments, ranging from 91.83 cm in T13 to 162.67 cm in T4. T4 was significantly superior, followed by T12 (143.00 cm) and T2 (141.17 cm). The taller stature in T4 suggests enhanced nutrient assimilation and vigorous stem elongation, aligning with reports by Ayyub et al., (2013) [24] and Rajput et al., (2018) [27] . Leaf diameter varied significantly, with maximum values in T1 and T11 (17.17 cm) and minimum in T4 (14.50 cm) and T7 (14.00 cm). Wider leaves, as observed by Ayyub et al., (2013) [24] and Rajput et al., (2018), enhance light interception, while narrower leaves may indicate greater resource allocation to stem or fruit growth. Highly significant differences were observed, with T8 (79.67) recording the highest leaf number, followed by T10 (35.50) and T6 (34.00). The lowest counts were in T11 (23.17) and T3 (24.00). The exceptional leaf production in T8 suggests a greater photosynthetic surface area, potentially enhancing assimilate supply for reproductive growth, while low leaf counts in T11 and T3 could limit carbohydrate production and yield potential. Similar findings were reported by Alam et al., and Sadiq et al., (2017) [29] , who noted that higher leaf. Fruit count varied significantly, with T6 (6.17) producing the highest, followed by T7 (5.83) and T5 (5.50). The lowest counts were recorded in T3 (3.83) and T4/T12 (4.00 each). Higher fruit set in T6 indicates favourable reproductive conditions, while lower counts in T3 and T4 may be due to competition between vegetative and reproductive growth. Similar trends were reported by Islam et al., and Meitei et al., (2014) [30] , who found that optimal nutrient balance and hormonal regulation enhance fruit set in okra. Significant variation was observed, with the longest fruits in T5 (17.87 cm), followed by T6 (17.23 cm) and T8 (16.42 cm). The shortest were in T12 and T11 (12.31 cm each). Longer fruits in T5 may be attributed to enhanced cell elongation, while shorter fruits in T12 and T11 could be due to limited assimilate availability. Similar results were reported by Prakash et al., (2017) and Singh et al., (2020) [8] , who noted that adequate nutrient supply and hormonal activity promote longitudinal fruit growth in okra. Significant differences were recorded, with T5 (1.92 cm) producing the widest fruits, followed by T13 (1.85 cm) and T2 (1.77 cm). The narrowest fruits were in T12 (1.46 cm) and T7/T8 (1.58 cm each). Wider fruits in T5 suggest enhanced radial cell expansion, whereas narrower fruits may indicate reduced sink strength. Similar observations were made by Patel et al, (2018) [4] and Kumar et al., who reported that fruit girth in okra is influenced by assimilate distribution and varietal sink capacity.Highly significant differences were observed among treatments.

The maximum fruit weight was recorded in T4 (434.67 g), which was statistically superior to T13 (162.67 g) and T5 (160.00 g). The minimum fruit weight was observed in T8 (124.67 g) and T10 (134.00 g). The higher fruit weight in T4 may be attributed to its greater plant height and enhanced assimilate production and translocation efficiency. Similar findings were reported by Singh et al., (2017) [9] and Meena et al., who noted that vigorous vegetative growth and efficient source-sink dynamics significantly increase fruit weight in okra. Significant variation was observed among treatments. The maximum number of branches was recorded in T5 (3.17), followed by T2 and T8 (3.00 each), while the minimum was in T11 (1.67) and T3 (1.83).

Increased branching in T5 and T2 enhances the number of potential flowering and fruiting sites, contributing to higher yield potential. These results are in agreement with Kumar et al., and Patel et al., (2018) [4] , who reported that higher branch numbers in okra correlate positively with fruit yield due to increased reproductive sites. Overall, T4 excelled in plant height and fruit weight, indicating strong vegetative growth and resource allocation to fruit development. T8 stood out for leaf production, potentially boosting photosynthetic capacity. T6 was superior in fruit number, while T5 produced the longest and widest fruits. These results suggest that different treatments favoured distinct growth and yield parameters, highlighting the potential of integrating the most effective traits to maximize both yield quantity and quality in okra cultivation.

Growth Parameters

Conclusion

The study showes that plant growth regulators have a significant impact on bhendi growth and yield. Among the treatments, T4 (GA3 200ppm) emerged as the best performer, showing strong vegetative growth and heavier fruits. T6 (NAA 100ppm) followed next, excelling in fruit number and length, while T13 (Control) was the least effective, showing lower performance across most traits. These results suggest that selecting the right growth regulator, especially T4 (GA3 200ppm) or T6 (NAA 100ppm), can greatly improve both yield and fruit quality, whereas T13 (Control) may not be ideal for maximizing productivity.

Acknowledgement

AcknowledgementsWe thank Kumaraguru Institute of Agriculture, Erode, Tamil Nadu for provision of required place and financial support for successful conduction of this research.

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