Gibberellic acid and calcium chloride: stimulatory effect on seed germination and enhanced seedling vigor of okra (Abelmoschus esculentus (L.) Moench)

ABSTRACT:

Seed priming improves the seed germination in various crops, including okra. In this study, Gibberellic acid (GA₃) (12.50, 25, and 50 ppm), calcium chloride (CaCl₂ at 3000 and 6000 ppm), and hydropriming were applied to okra (cv Smooth Green) by priming the seeds for 3 h. It was conducted to evaluate the stimulation effect of seed priming methods on the seedling vigor of okra. Seeds without priming served as the control. Ambient conditions, with a temperature of 29 ± 5 °C and a relative humidity of 65 ± 5%, were maintained, along with a photoperiod of 10h/14h (light/dark). A Completely Randomized Design with four replications was used in the study. Standard germination, germination index, mean germination time, chlorophyll content, seedling length, fresh and dry weights of seedling, secondary root count per seedling, and seedling vigor were gathered. GA₃ and CaCl₂ improved germination, resulting in more than 85% germination and a faster germination rate compared to unprimed seeds. Moreover, at 21 days after sowing (DAS), GA₃ (25 ppm) and CaCl₂ (3000 and 6000 ppm) produced longer seedlings. However, CaCl₂ outperformed the other priming methods and unprimed seeds in its root count per seedling and seedling fresh weight. GA₃ (50 ppm) and CaCl₂ (3000 ppm) displayed heavier seedling dry weight and vigorous seedlings. CaCl₂ influenced the chlorophyll by obtaining a higher content. Thus, to obtain vigorous seedlings, either GA₃ (50 ppm) or CaCl₂ (3000 ppm) is recommended.

Index terms:
faster germination; low GA₃ concentration; smooth green variety; vigorous seedling

RESUMO:

O condicionamento de sementes melhora a germinação em diversas culturas, incluindo o quiabo. Nesse estudo, ácido giberélico (GA₃) (12,50, 25 e 50 ppm), cloreto de cálcio (CaCl₂ a 3000 e 6000 ppm) e hidrocondicionamento foram aplicados em sementes de quiabo (cv. Smooth Green) por meio de osmocondicionamento durante 3 horas. Foi conduzido para avaliar o efeito estimulante dos métodos de condicionamento de sementes no vigor de plântulas de quiabo. Sementes sem condicionamento serviram como controle. As condições ambientais, com temperatura de 29 ± 5 °C e umidade relativa de 65 ± 5%, foram mantidas, juntamente com um fotoperíodo de 10 h/14 h (claro/escuro). Um delineamento inteiramente casualizado com quatro repetições foi utilizado no estudo. Foram coletados dados sobre germinação, índice de germinação, tempo médio de germinação, teor de clorofila, comprimento da plântula, massa fresca e seca da plântula, número de raízes secundárias de plântulas e vigor de plântulas. GA₃ e CaCl₂ melhoraram a germinação, resultando em mais de 85% de germinação e uma taxa de germinação mais rápida em comparação com sementes não tratadas. Além disso, aos 21 dias após a semeadura (DAS), GA₃ (25 ppm) e CaCl₂ (3000 e 6000 ppm) produziram plântulas mais desenvolvidas. No entanto, o CaCl₂ apresentou melhor desempenho do que os outros métodos de condicionamento e sementes não tratadas em relação ao número de raízes por plântula e à massa fresca de plântulas. O GA₃ (50 ppm) e CaCl₂ (3000 ppm) proporcionaram maior massa seca e plântulas mais vigorosas. O CaCl₂ influenciou o teor de clorofila, resultando em um teor mais elevado. Portanto, para obter plântulas vigorosas, recomenda-se o uso de GA₃ (50 ppm) ou CaCl₂ (3000 ppm).

Termos de indexação:
germinação mais rápida; baixa concentração de GA₃; variedade verde lisa; plântula vigorosa

INTRODUCTION

Seed priming proves that it can enhance the seed germination of various crops with vigorous seedlings. Through this pre-germinative technique by soaking the seeds for a certain period, depending on the crop species and priming duration, without the radicle emergence and until the initial moisture content is set back, it improves seedling vigor. Seedling characteristics of okra (Abelmoschus esculentus (L.) Moench) can be improved through seed priming using agents such as hydropriming, calcium chloride (CaCl₂), and gibberellic acid (GA₃). Improving the seedling performance at the early stage plays a pivotal role in crop production success. Especially, okra is one of the high-value crops and a good source of livelihood for farmers. Moreover, okra pods are good sources of minerals, soluble sugars, organic acids, and tocopherols (Romdhane et al., 2020). Therefore, to provide a sustainable okra pod production, improving the seedling characteristics is needed. Quality planting materials, including seedlings, are the foundation of a good crop production due to its direct influence on the crop health, yield, and income (Park et al., 2022).

Various studies reported the benefits of seed priming (hydropriming, halopriming, and hormonal priming) in crops at the early seedling growth stage. Seed priming improved germination rate, produced normal seedlings, and good crop performance due to the starch metabolism and high α-amylase activity and soluble sugars (Afzal et al., 2005; Silva-Neta et al., 2015; Hossain et al., 2015; Karim et al., 2020; Raga et al., 2024; Khairilanwar et al., 2025). Hydropriming and hormonal priming using GA₃ at 200 ppm produced longer seedlings in okra (Sheferie, 2023), which was concurred by a previous study in okra (Adhikari and Shrestha, 2020). In a separate study, it was reported that hydroprimed okra exhibited longer seedlings (Kaur et al., 2023). Hydropriming shortened the germination time of okra (Adhikari and Shrestha, 2020). This indicates that there are more germinated seeds in a short period.

However, CaCl₂ (30000 ppm) showed a similar germination and height of okra to the unprimed seeds (Mukhtar et al., 2024). But in another study using CaCl₂ at 12 to 30 h of priming produced a higher germination percentage than the unprimed yardlong bean seeds (Karim et al., 2020). However, 12 h of CaCl₂ priming was higher than longer durations. Moreover, at the same duration of CaCl₂ priming, it exhibited higher germination index and vigor index, with faster germination rate, and longer roots, shoots, and seedlings. While GA₃ at 100 ppm enhanced the germination, and root and shoot lengths of okra genotypes (A. manihot and angulosus) using 2 h of priming (Kamboj et al., 2024).

Hydropriming, GA₃, and CaCl₂ proved that germination and seedling characteristics are affected by these priming methods. However, it should be noted that the varieties used in these previous studies were different from those used in the current study. Hence, a study on the evaluation of the impact of these seed priming methods on the seedling vigor of okra using the Smooth Green variety was conducted.

MATERIAL AND METHODS

Acquisition of seeds and preparation of the priming methods

Okra seeds (Smooth Green variety) were purchased from the local farm supply in the City of Batac, Ilocos Norte, Philippines. Prior to priming, including the unprimed seeds, sterilization with 1% sodium hypochlorite for 3 min was done. After sterilization, the seeds were rinsed with distilled water three times. The seeds were primed in distilled water (hydropriming), GA₃, and CaCl₂ for 3 h. The 3 h of priming was based on the previous study (Mukhtar et al., 2024), wherein beyond this period had no further increase in germination; hence, 3 h was used.

CaCl₂ powder at 0.3 and 0.6 g was dissolved in distilled water (100 ml) to produce 3000 and 6000 ppm concentration, respectively. A 1000 ppm GA₃ stock solution was prepared, and it was used to produce 12.50, 25, and 50 ppm. A minor modification was made in the concentration of CaCl₂, which was based on the previous study (Mukhtar et al., 2024). Three concentrations of GA₃ were based on the preliminary test, wherein less than 12.50 ppm showed a lower germination, and there was an increased germination beyond 12.50 ppm.

Growing conditions

Ambient conditions, with a temperature of 29 ± 5 °C and a relative humidity of 65 ± 5%, were used, along with a photoperiod of 10h/14h (light/dark) at the Postharvest and Seed Technology laboratory room of the Department of Agricultural Sciences, College of Agriculture, Food, and Sustainable Development in the Mariano Marcos State University, Philippines. The roll method was used for the standard germination, seedling length, secondary root count per seedling, chlorophyll content, and fresh weight of seedlings. A germination box was used for the germination index and mean germination time.

Standard germination, germination index, and mean germination time

These were measured using the method of ISTA (2008). Standard germination was measured at 4 (initial count) and 21 (final count) days after sowing (DAS). Germination index and mean germination time were measured by counting the germinated seeds for 21 days. A hundred seeds were sown in a germination box and roll method. A formula below was used to measure the germination index and mean germination time (Kulkarni et al., 2007).

$GerminationIndex\left(\%\right)=\sum \frac{numberofgerminatedseeds}{daywhentheseedgerminated}$

$MeanGerminationTime\left(day\right)=\frac{\sum \left(nxd\right)}{N}$

Which means, n = number of germinated seeds on a specific day

d = number of days from the start of the germination test

N = total number germinated seeds by the end of the test

Chlorophyll content

A chlorophyll meter (SPAD-502 Plus, Konica Minolta) was used to measure the chlorophyll content of the leaves of the primed and unprimed seeds.

Seedling characteristics

Shoot, root, and seedling lengths: Twenty sample seedlings were used to measure the shoot and root lengths using a standard ruler and vernier caliper. Shoot and root lengths were measured from the shoot and root tip to the root attachment, respectively. The lengths of the root and shoot were computed for the seedling length (cm).

Secondary root count per seedling and root-to-shoot ratio: At 21 DAS, the secondary root count of 20 sample seedlings was counted manually. Whereas the ratio of the dry weights of root and shoot at 4 and 21 DAS was computed.

Shoot, root, and seedling weight: At 4 and 21 DAS, the fresh and dry weights (g) of root, shoot and seedling were weighed using a digital weighing scale. Samples were oven dried at 60 °C for 48 h (Imran et al., 2018).

Seedling vigor index (SVI)

The product of standard germination (%) and seedling length (cm seedling^-1) to measure the SVI-I, whereas SVI-II was measured by getting the product of standard germination (%) and seedling dry weight (g.seedling^-1).

Statistical analysis

Analysis of variance for the completely randomized design with four replications was used. Statistical Package for the Social Sciences (SPSS) (SPSS for Windows Version 17.0, Released 2008, SPSS Inc., Chicago, IL, USA) program was used to analyze the data. Tukey’s Honestly Significant Difference (HSD) test was used to determine the treatment mean differences.

RESULTS AND DISCUSSION

Seed priming enhanced the standard germination (Figure 1A) and germination index (Figure 1B) of okra. GA₃-primed CaCl₂-primed okra seeds showed more than 95% germination, whereas hydroprimed seeds exhibited more than 85% standard germination. It proves that these seed priming methods displayed promising potential to improve germination, wherein unprimed seeds had less than 80% germination, and it was less than the international standard germination rate of 85%. However, irrespective of GA₃ and CaCl₂ concentrations, they exhibited comparable standard germination and germination index. It was previously reported that the germination of okra (Arka Anamika variety) was increased by hydropriming and GA₃-priming (200ppm) (Lamichhane et al., 2021). They reported that the germination was increased by 36% in hydropriming and 43% in GA₃ as compared to unprimed seeds. However, the germination of okra in the study was higher than in their study. This variation was due to the priming duration (including concentration) and varietal differences. The priming duration of the previous study was 24 h (Lamichhane et al., 2021), whereas 3 h in the study, and Smooth Green variety was used in this study. In another study, hydropriming enhanced the germination of okra using 12 h of priming as compared to unprimed seeds (Kaur et al., 2023). But the germination of the present study (85.75%) and the previous study (83.33%) was almost similar; however, the present study met the international standard. Hydropriming and CaCl₂ (3000 ppm)-priming improved the germination (Alam et al., 2024). But in their study, CaCl₂ had a higher germination than the hydroprimed seeds. Whereas in the study, the germination rates were similar to each other. The difference between these studies was the varietal differences and priming duration used. A previous study reported that CaCl₂ at 30000 ppm showed a similar germination and height of okra to the unprimed seeds (Mukhtar et al., 2024). The difference between the previous and current studies was the variety and the CaCl₂ concentration used, which may have resulted in varying results. Using 2 h GA₃ at 100 ppm enhanced the germination, and root and shoot lengths of okra genotypes (A. manihot and angulosus) (Kamboj et al., 2024). Previous reports that seed priming improved germination rate, produced normal seedlings, and good crop performance due to the starch metabolism and high α-amylase activity and soluble sugars (Hossain et al., 2015; Silva-Neta et al., 2015).

Figure 1
Standard germination (A), germination index (B), and mean germination time (C) of primed and unprimed okra seeds. Bars with different letters in a column are significantly different at P≤0.05 level using a Tukey’s Honest Significant Difference test.

There was a shorter germination time of okra if the seeds were primed as compared to unprimed (Figure 1C). The lower the mean germination time, the faster the seeds germinate in a short period. Hydroprimed, GA₃-primed, and CaCl₂-primed (3000 ppm) seeds had a lower mean germination time than the unprimed seeds, but these priming methods had the same mean germination time. Just like the previous study (Adhikari and Shrestha, 2020), hydropriming shortened the germination time of okra. Results indicate that any of the priming agents (except CaCl₂ at 6000 ppm) can be used to obtain a higher germination rate at a shorter time under similar conditions as the study. However, the present study was almost 10 times lower in mean germination time in hydroprimed seeds as compared to the previous study (Adhikari and Shrestha, 2020). Variations were due to the okra variety and priming duration. A short period of seed germination may have the potential to mitigate the impacts of stress conditions. A further study is suggested by using the same priming methods and the same okra variety to be tested under stress conditions.

Early germination by initiating the metabolic processes is influenced by seed priming, resulting in a higher and uniform germination rate and enhanced seedling vigor (Anghla et al., 2025). GA in GA₃ may act as the main hormonal signal, whereas calcium ions in CaCl₂ act as an essential secondary messenger and cofactor enzyme, and these priming methods may be due to increased gene expression and α-amylase activity that enhanced germination (Sghayar et al., 2023; Padhilha et al., 2024; Siega et al., 2025). Calcium ions may have a direct influence on the modulation of root development with the application of CaCl₂, which acts as the second messenger in auxin-mediated biosynthesis (Zhang et al., 2020). The CaCl₂-primed seeds may have enough amounts of auxin to regulate the secondary root count in okra. It was reported that high amounts of auxin impede root growth and development (Alarcon et al., 2019). The auxin levels in primed and unprimed seeds need further study.

CaCl₂, irrespective of the concentrations, exhibited the highest chlorophyll content as compared to unprimed and primed seeds (Figure 2A). It was reported that CaCl₂ helps to slow down chlorophyllase activity and reduce chlorophyll degradation and serves as a protective agent to mitigate photosynthetic pigment loss (Li et al., 2017). However, unprimed seeds had a lower chlorophyll content than the unprimed seeds. Moreover, it was observed that GA₃-primed seeds exhibited a higher chlorophyll content than the hydroprimed seeds. Among the GA₃ concentrations, increasing the concentration from 12.50 to 50 ppm did not increase the chlorophyll content. It indicates that 12.50 ppm GA₃ is the optimum concentration.

Figure 2
Chlorophyll content (A), shoot length (B), root length (C), and seedling length (D) of primed and unprimed okra seeds. Bars with different letters in a column are significantly different at P≤0.05 level using a Tukey’s Honest Significant Difference test. Bars with and without a thick black outline represent the 4 and 21 days after sowing, respectively.

The shoot and seedling of okra were longer if seed priming was used. It was observed that unprimed seeds produced shorter shoots, roots, and seedlings (Figures 2B-2D). At 4 and 21 DAS, primed seeds with 12.50 ppm GA₃ and hydropriming, and all priming methods displayed longer shoots than the unprimed seeds, respectively. But for the root length, 25ppm GA₃ and 0.3% CaCl₂ exhibited shorter roots than the unprimed seeds; however, these priming agents were comparable to other methods at 4 and 21 DAS. Root and shoot elongation in primed seeds may be due to the influence of priming on the hormonal modulation, which may increase the growth-promoting plant hormones such as gibberellins and auxins with low levels of abscisic acid (ABA) (Hasanovic et al., 2025). It indicates that seed priming enhanced the amounts of auxin and gibberellins (GAs) in primed okra seeds, resulting in longer roots, shoots, and seedlings. A further study is recommended on the plant hormone levels in primed and unprimed seeds using a similar priming method and an okra variety. It was previously reported that auxin promotes shoot elongation and rooting, whereas internodal elongation in GAs (Bora and Sarma, 2006). Seed priming with CaCl₂ impacts the endogenous levels of indole-acetic acid, ABA, and GAs (Hongna et al., 2021; Torun et al., 2022), indicating that these plant hormones have a potential role during the growth of okra. It was reported that early reserve mobilization in the aleurone layer due to the secretion of GAs from the embryo to the endosperm, and aleurone cells promote amylase synthesis that has a direct effect on the germination rate (Rithcie et al., 2000). This report may be the factor that GA₃-primed seeds enhanced germination. But a further study is needed to confirm the GAs and amylase activity in the primed seeds.

On the other hand, longer seedlings were observed in 25 ppm GA₃, and 3000 ppm and 6000 ppm CaCl₂ than in the unprimed seeds (Figure 2D). It indicates that priming stimulated the growth of seedlings. However, further increase of GA₃ concentration did not produce longer seedlings. A similar observation was recorded in the increase of CaCl₂ concentration, which showed a comparable seedling length between 3000 and 6000 ppm. Moreover, it was observed that there may be an inhibitory effect on the seedling length of okra if the GA₃ concentration was beyond 25 ppm.

The inhibitory impact may be due to the physiological plant response to a higher amount of GA levels, a dose-response curve (Kumar et al., 2018). Also, a high concentration of GA3 inhibited the root elongation. Results signify that 25 ppm could be an optimum GA₃ concentration to obtain longer seedlings. A previous study reported that hydroprimed and GA₃-primed (200ppm) okra seeds produced longer seedlings (Sheferie, 2023). This was concurred by a previous study (Adhikari and Shrestha, 2020). Kaur et al. (2023) reported that longer seedlings were achieved by hydropriming as compared to unprimed seeds.

A high secondary root count per seedling was produced by using priming methods (Figure 3A). At 4 DAS, 25 ppm GA₃ and 6000 ppm CaCl₂-primed seeds showed a similarity in root count, but they were higher than the other priming agents. Additionally, the other priming agents produced more root counts as compared to unprimed seeds. On the other hand, at 21 DAS, it was consistently observed that seed priming induced the production of secondary root count. However, 3000 ppm CaCl₂-primed seeds had a higher root count than the other priming agents. Moreover, an increase in the concentration of this priming agent did not increase the root count. Among the GA₃ concentrations, 12.50 ppm is enough because there was no further increase in the root count. These results indicate that an optimum concentration in GA₃ and CaCl₂ is needed to produce more secondary root count. However, concentrations lower than those used in the study must be further studied.

Figure 3
Root count (secondary) (A), root-to-shoot ratio (B), shoot fresh weight (C), root fresh weight (D), and seedling fresh weight (E) of primed and unprimed okra seeds. Bars with different letters in a column are significantly different at P≤0.05 level using a Tukey’s Honest Significant Difference test. Bars with and without a thick black outline represent the 4 and 21 days after sowing, respectively.

At 4 DAS, the root-to-shoot ratio was higher in okra seeds primed with 3000 ppm CaCl₂ than in the other primed and unprimed seeds (Figure 3B). However, at 21 DAS, the root-to-shoot ratio was higher in GA₃-primed (50 ppm) and CaCl₂-primed (3000 ppm) seeds. It was observed that the root-to-shoot ratio was increasing as the GA₃ concentration increased. But this condition was a reverse result with CaCl₂ at a higher concentration, wherein the 6000 ppm had a lower root-to-shoot ratio than 3000 ppm. A high root-to-shoot ratio means that a larger proportion of allocation of its biomass is allocated to roots than to the shoot (Lynch et al., 2012).

A factor due to severe ion toxicity and osmotic stress from 6000 ppm CaCl₂ may inhibit the root growth than the shoot growth resulting in a high accumulation of chloride ions and disrupting the nutrient balance in roots (Kwon et al., 2021). It is recommended that future studies on the quantification of chloride ions must be conducted. Results signify that seed priming through the utilization of GA₃ and CaCl₂ (3000 ppm) contributed to a higher root-to-shoot ratio.

Heavy shoot, root, and seedling fresh weights were obtained by using priming methods in two observation periods (Figures 3C-3E). At 4 DAS, hydropriming, and 12.50 and 50ppm GA₃ had a higher shoot fresh weight than the other priming agents. There was no significant increase in the fresh weight of shoots at 6000 ppm CaCl₂ due to its similarity with the 3000 ppm. However, among the GA₃ concentrations, a decreasing trend of the shoot fresh weight was observed beyond 12.50ppm. But an increase in the fresh weight if the GA₃ concentration was 50 ppm. On the other hand, CaCl₂ exhibited heavier shoot fresh weight than the other priming agents and unprimed seeds (Figure 3C).

At 4 DAS, the root fresh weight of okra was increased by using GA₃ (50ppm) and CaCl₂ (3000 ppm) (Figure 3D). However, at 21 DAS, the root fresh weight was heavier if the priming agents used were CaCl₂ (3000 ppm). Concentrations higher than those of the mentioned priming agents showed no further increase in the root fresh weight.

On the other hand, at 4 DAS, priming using any of the priming agents produced heavy seedling fresh weight, but only GA₃ (12.50 and 50ppm) and CaCl₂ (3000 and 6000 ppm) outperformed the others. But at 21 DAS, CaCl₂ exhibited heavier seedling fresh weight than the other priming agents and unprimed seeds.

At 4 DAS, primed and unprimed seeds displayed a comparable shoot dry weight (Figure 4A). Furthermore, okra seed primed with 3000 ppm CaCl₂ displayed a lower shoot dry weight than hydroprimed and 12.50 ppm GA₃-primed seeds. However, these primed seeds showed a similarity with unprimed seeds and other concentrations. There was no significant variation in shoot dry weight between primed and unprimed seeds at 21 DAS (Figure 4A).

Figure 4
Shoot dry weight (A), root dry weight (B), seedling dry weight (C), seedling vigor index-I (D), and seedling vigor index-II (E) of primed and unprimed okra seeds. Bars with different letters in a column are significantly different at P≤0.05 level using a Tukey’s Honest Significant Difference test. Bars with and without a thick black outline represent the 4 and 21 days after sowing, respectively.

A higher root dry weight was produced by priming the seeds with 50 ppm GA₃ and 3000 ppm CaCl₂ at 4 and 21 DAS (Figure 4B). An increasing trend in the root dry weight of okra was observed as the concentration of GA₃ was increased. Whereas in CaCl₂, a further increase in the concentration showed no significant improvement in the dry weight. This trend was also observed in the seedling dry weight at 21 DAS. Results show that priming using 50 ppm GA₃ and 3000 ppm CaCl₂ can be used to obtain heavier seedling dry weight, signifying a greater biomass in primed seeds than the unprimed seeds (Figure 4C).

Vigorous seedlings were produced from primed seeds, based on the SVI-I at 4 and 21 DAS (Figures 4D and 4E). However, hydroprimed, 25ppm GA₃, 6000 ppm CaCl₂ displayed a comparable SVI-I with unprimed seeds, but they were lower than 12.50 and 50 ppm GA₃, and 3000 ppm CaCl₂. There was no further increase in SVI-I beyond 3000 ppm CaCl₂. However, at 21 DAS, all of the priming agents, except hydropriming, had vigorous seedlings than unprimed seeds. This observation was also evident in the SVI-II of okra at 4 DAS. But at 21 DAS, only 50 ppm GA₃ and 3000 ppm CaCl₂ produce vigorous seedlings as compared with the unprimed and other primed seeds. It was observed that increasing the concentration of CaCl₂ showed no impact on the vigor. Likewise, in GA₃, as the concentration increased, the SVI-II also increased. To produce vigorous seedlings using the two indices, 50 ppm GA₃ and 3000 ppm CaCl₂ are recommended. GA₃-primed okra seeds displayed vigorous seedlings, as previously reported (Sheferie, 2023). Vigorous seedlings can also be achieved using hydropriming rather than the unprimed seeds, which was also observed by the other study (Kaur et al., 2023).

CONCLUSIONS

Seed priming positively stimulated the germination, seedling weight, and enhanced the vigor of okra seeds. Any priming method used in the study can be used to achieve germination rates above 85% with a low mean germination time. But to obtain high seedling fresh and dry weight, use CaCl₂ (3000 ppm), and 50 ppm GA₃ and 3000 ppm CaCl₂, respectively. Likewise, enhanced seedling vigor (SVI-II) was attained using vigorous seedlings using GA₃ (50 ppm) and CaCl₂ (3000 ppm).

ACKNOWLEDGMENTS

The authors are thankful to the Mariano Marcos State University for the support of the study.

REFERENCES

• ADHIKARI, A.; SHRESTHA, A. Effect of primed and un-primed seeds on germination, growth performance and yield in okra [Abelmoschus esculentus (L.) Moench]. Turkish Journal of Agriculture-Food Science and Technology, v.8, p.1686-1691, 2020. https://doi.org/10.24925/turjaf.v8i8.1686-1691.3460
  » https://doi.org/https://doi.org/10.24925/turjaf.v8i8.1686-1691.3460
• AFZAL, I.; BASRA, S.; IQBAL, A. The effects of seed soaking with plant growth regulators on seedling vigor of wheat under salinity stress. Journal of Stress Physiology and Biochemistry, p.6-14, 2005. https://www.researchgate.net/publication/26493348_The_effects_of_seed_soaking_with_plant_growth_regulators_on_seedling_vigor_of_wheat_under_salinity_stress
  » https://www.researchgate.net/publication/26493348_The_effects_of_seed_soaking_with_plant_growth_regulators_on_seedling_vigor_of_wheat_under_salinity_stress
• ALARCON, M.; SALGUERO, J.; LLORET, P. Auxin modulated initiation of lateral roots in linked to pericycle cell length in maize. Frontiers in Plant Science, v.10, p.1-10, 2019. https://doi.org/10.3389/fpls.2019.00011
  » https://doi.org/https://doi.org/10.3389/fpls.2019.00011
• ALAM, M.; KHAN, M.; HOSSAIN, M.; SULTANA, M.; ANJUM. Effects of different priming treatments on the germination and growth of okra (Abelmoschus esculentus) Journal of Tropical Crop Science v.11, p.91-96, 2024. https://doi.org/10.29244/jtcs.11.01.91-96
  » https://doi.org/https://doi.org/10.29244/jtcs.11.01.91-96
• ANGHLA, L.; REHAN; DAS, S.; SHARMA, A.; THAKUR, S.; RANA, N.; SHARMA, S. Assessment of seed priming for mitigating abiotic stress and improving growth of horticultural crops: a review. Discover Applied Sciences, v.7, p1-28, 2025. https://doi.org/10.1007/s42452-025-08054-2
  » https://doi.org/https://doi.org/10.1007/s42452-025-08054-2
• BORA, R.; SARMA, C. Effect of gibberellic acid and cycocel on growth, yield and protein content of pea. Asian Journal of Plant Sciences, v.5, p.324-330, 2006. https://doi.org/10.3923/ajps.2006.324.330
  » https://doi.org/https://doi.org/10.3923/ajps.2006.324.330
• HASANOVIC, M.; DURMIC-PASIC, A.; KARALIJA, E. Seed priming beyond stress adaptation: broadening the agronomic horizon. Agronomy, v.15, p.1-25, 2025. https://doi.org/10.3390/agronomy15081829
  » https://doi.org/https://doi.org/10.3390/agronomy15081829
• HONGNA, C.; LEYUAN, T.; JUNMEL, S.; XIAORI, H.; XIANGUO, C. Exogenous salicylic acid signal reveals an osmotic regulatory role in priming the seed germination of Leymus chinensis under salt-alkali stress. Environmental and Experimental Botany, v.188, 104498, 2021. https://doi.org/10.1016/j.envexpbot.2021.104498
  » https://doi.org/https://doi.org/10.1016/j.envexpbot.2021.104498
• HOSSAIN, M.; BHATTACHARJEE, S.; ARMIN, S.; QIAN, P.; XIN, W.; LI, H.; BURRITT, D.; FUJITA, M.; TRAN, L. Hydrogen peroxide priming modulates abiotic oxidative stress tolerance: insights from ROS detoxification and scavenging. Frontiers in Plant Science , v.6, 420, 2015. https://doi.org/10.3389/fpls.2015.00420
  » https://doi.org/https://doi.org/10.3389/fpls.2015.00420
• IMRAN, M.; BOELT, B.; MUHLING, K. Zinc seed priming improves salt resistance in maize. Journal of Agronomy and Crop Science, v.204, p.390-399. 2018. https://doi.org/10.1111/jac.12272
  » https://doi.org/https://doi.org/10.1111/jac.12272
• ISTA. International Rules for Seed Testing Bassersdorf, The International Seed Testing Association. 2008.
• KHAIRILANWAR, K.; YI, S.; BAKRI, M.; NAWI, I.; AZMI, A.; AIK, C. Eco-friendly nanopriming: zinc oxide nanoparticles derived from banana peel extract for improved germination of chili seeds. Journal of Seed Science, v.47, e202547006, 2025. https://doi.org/10.1590/2317-1545v47290750
  » https://doi.org/https://doi.org/10.1590/2317-1545v47290750
• KAMBOJ, A.; SANGHA, M.; DEVI, V.; KUMAR, P.; PATHAK, M.; SINGLA, D. Enhancing germination and growth in wild okra genotypes through gibberellic acid priming. Scientia Horticulturae, v.334, 113332, 2024. https://doi.org/10.1016/j.scienta.2024.113332
  » https://doi.org/https://doi.org/10.1016/j.scienta.2024.113332
• KARIM, M.; SANI, M.; UDDAIN, J.; AZAD, M.; KABIR, M.; RAHMAN, M.; CHOI, K.; NAZNIN, M. Stimulatory effect of seed priming as pretreatment factors on germination and yield performance of yard long bean (Vigna unguiculata). Horticulturae, v.6, 104, 2020. https://doi.org/10.3390/horticulturae6040104
  » https://doi.org/https://doi.org/10.3390/horticulturae6040104
• KAUR, N.; GANDHI, A.; MAL, D.; GHARDE, S. Impact of seed hydro priming duration on germination and seedling performance of okra (Abelmoschus esculentus L. var. Punjab Suhawani). Ecology, Environment and Conservation, v.29, p.718-725, 2023. http://doi.org/10.53550/EEC.2023.v29i02.028
  » https://doi.org/http://doi.org/10.53550/EEC.2023.v29i02.028
• KWON, K.; CHOI, J.; KIM, S.; JEONG, N.; PARK, B. Growth and physiological responses of three landscape plants to calcium chloride. Sustainability, v.13, 5429, 2021. https://doi.org/10.3390/su13105429
  » https://doi.org/https://doi.org/10.3390/su13105429
• KULKARNI, M.; STREET, R.; STADEN, J. Germination and seedling growth requirements for propagation of Dioscorea dregeana (Kunth) Dur. And Shinz-a tuberous medicinal plant. South African Journal of Botany, v.73, p.131-137, 2007. https://doi.org/10.1016/j.sajb.2006.09.002
  » https://doi.org/https://doi.org/10.1016/j.sajb.2006.09.002
• KUMAR, S.; HOSSAIN, M.; ABDULLAH, M.; SHUKOR, N. Gibberellic acid (GA₃) affects growth and development of some selected kenaf (Hibiscus cannabinus L.) cultivars. Industrial Crops and Products, v.118, p.180-187, 2018. https://doi.org/10.1016/j.indcrop.2018.03.036
  » https://doi.org/https://doi.org/10.1016/j.indcrop.2018.03.036
• LAMICHHANE, A.; MAMATA, K.; SHRESTHA, M.; BARAL, B. Effect of seed priming on germination of okra (Abelmoschus esculentus var. Arka Anamika). Malaysian Journal of Sustainable Agriculture, v.5, p.111-114, 2021. https://doi.org/10.26480/mjsa.02.2021.111.114
  » https://doi.org/https://doi.org/10.26480/mjsa.02.2021.111.114
• LI, Z.; TAN, X.; LU, K.; LIU, Z. WU, L. The effect of CalC₂ on calcium content, photosynthesis, and chlorophyll fluorescence of tung tree seedlings under drought conditions. Photosynthetica, v.55, p.553-560, 2017. https://doi.org/10.1007/s11099-016-0676-x
  » https://doi.org/https://doi.org/10.1007/s11099-016-0676-x
• LYNCH, J.; MARSCHNER, P.; RENGEL, Z. Effect of internal and external factors on root growth and development Marschner’s Mineral Nutrition of Higher Plants. 3^rd ed. Academic Press. p.331-346, 2012. https://doi.org/10.1016/B978-0-12-384905-2.00013-3
  » https://doi.org/https://doi.org/10.1016/B978-0-12-384905-2.00013-3
• MUKHTAR, N.; SHAMSUDIN, N.; MD ZAIN, N.; NAHER, L.; RAHMAN, K.; SIDEK, N. Enhancing okra (Abelmoschus esculentus) growth performance through seed priming. Bio Web of Conferences, v.131, 05010, 2024. https://doi.org/10.1051/bioconf/202413105010
  » https://doi.org/https://doi.org/10.1051/bioconf/202413105010
• PADILHA, M.; COELHO, C.; SIEGA, Y. Phytase and alpha-amylase activity are positively associated with seed vigor in common bean seeds. Revista Ciencia Agronómica, v.55, e20238762, 2024. https://doi.org/10.5935/1806-6690.20240014
  » https://doi.org/https://doi.org/10.5935/1806-6690.20240014
• PARK, Y.; GOMEZ, C.; RUNKLE, E. Indoor production of ornamental seedlings, vegetable transplants, and microgreens In: KOZAI, T.; NIU, G.; MASABNI, J. (Eds.). Plant Factory Basics, Applications and Advances: ACADEMIC PRESS, 2022. p.351-375.
• RAGA, Y.; WIDAJATI, E.; ILYAS, S.; PURWANTO, Y. Enhancing viability and vigor of deteriorated true shallot seeds (Allium cepa var. ascalonicum) through ultra-fine bubble and plasma-activated water priming. Journal of Seed Science , v.46, e202446029, 2024. https://doi.org/10.1590/2317-1545v46286463
  » https://doi.org/https://doi.org/10.1590/2317-1545v46286463
• RITCHIE, S.; SWANSON, S.; GILROY, S. Physiology of the aleurone layer and starchy endosperm during grain development and early seedling growth: new insights from cell and molecular biology. Seed Science Research, v.10, p.193-212, 2000. https://doi.org/10.1016/j.cj.2020.11.006
  » https://doi.org/https://doi.org/10.1016/j.cj.2020.11.006
• ROMDHANE, M.; CHAHDOURA, H.; BARROS, L.; DIAS, M.; CORREA, R.; MORALES, P.; CIUDAD-MULERO, M.; FLAMINI, G.; MAJDOUB, H.; FERREIRA, I. Chemical composition, nutritional value, and biological evaluation of Tunisian okra pods (Abelmoschus esculentus L. Moench). Molecules, v.25, 4739, 2020. https://doi.org/10.3390/molecules25204739
  » https://doi.org/https://doi.org/10.3390/molecules25204739
• SHEFERIE, M. Effect of seed priming methods on seed quality of okra (Abelmoschus esculentus (L.) Moench) genotypes. Advances in Agriculture, v.2023, p.1-9, 2023. https://doi.org/10.1155/2023/3951752
  » https://doi.org/https://doi.org/10.1155/2023/3951752
• SGHAYAR, S.; DEBEZ, A.; LUCCHINI, G.; ABRUZZESE, A.; ZORRIG, W.; NEGRINI, M.; MORGUTTI, S.; ABDELLY, C.; SACCHI, G.; PECCHIONI, N.; VACCINO, P. Seed priming mitigates high salinity impact on germination of bread wheat (Triticum aestivum) by improving carbohydrate and protein mobilization. Plant Direct, v.7, e497, 2023. https://doi.org/10.1002/pld3.497
  » https://doi.org/https://doi.org/10.1002/pld3.497
• SIEGA, Y.; COELHO, C.; PEIXOTO DA SILVA, M.; ALBURQUERQUE, M.; PADILHA, M.; MENDES, G. Impact of gibberellic acid on seedling growth and enzymatic activity in bean cultivars with contrasting seed vigor. Acta Scientiarum, v.47, e72032, 2025. https://doi.org/10.4025/actasciagron.v47i1.72032
  » https://doi.org/https://doi.org/10.4025/actasciagron.v47i1.72032
• SILVA-NETA, I.; PINHO, E.; VEIGA, A.; PINHO, R.; GUIMARAES, R.; CAIXETA, F.; SANTOS H.; MARQUES, T. Expression of genes related to tolerance to low temperature for maize seed germination. Genetics and Molecular Research, v.14, p2674.2690. 2015. https://doi.org/10.4238/2015.march.30.28
  » https://doi.org/https://doi.org/10.4238/2015.march.30.28
• TORUN, H.; NOVAK, O.; MIKULIK, J.; STRNAD, M.; AYAZ, F. The effects of exogenous salicylic acid on endogenous phytohormone status in Hordeum vulgare L. under salt stress. Plants, v.11, 618. 2022. https://doi.org/10.3390/plants11050618
  » https://doi.org/https://doi.org/10.3390/plants11050618
• ZHANG, X.; MA, C.; SUN, L.; HAO, F. Roles and mechanisms of Ca²⁺ in regulating primary root growth of plants. Plant Signaling and Behavior, V.7, 1748283, 2020. https://doi.org/10.1080/15592324.2020.1748283
  » https://doi.org/https://doi.org/10.1080/15592324.2020.1748283

• DATA AVAILABILITY
  Additional data will be made available by the authors upon reasonable request.

Edited by

• Editor:
  Heloisa Oliveira dos Santos

Data availability

Additional data will be made available by the authors upon reasonable request.

Publication Dates

• Publication in this collection
  30 Mar 2026
• Date of issue
  2026

History

• Received
  06 Jan 2026
• Accepted
  23 Feb 2026