Balancing dormancy break and storability: Polyphenols, leaching duration and storage behaviour in coriander seeds

Introduction

Coriandrum sativum L., an annual herb belonging to the Apiaceae family, serves as a cornerstone of the global spice trade, valued for its dual utility as a fresh condiment and a primary source of bioactive secondary metabolites for the pharmaceutical and nutraceutical sectors [1] . As of 2024, the global market for anise, badian, fennel, and coriander reached 2.8 million tons with a valuation of $6.8 billion, with India dominating approximately 66% of global production and 56% of total consumption [2] . Within the Indian national agricultural framework, the spice sector contributes significantly to the Gross Value Added (GVA), which was estimated at 17.7% for the 2023-24 fiscal year [3] . Despite this economic prowess, coriander cultivation is frequently disrupted by inherent physiological constraints, specifically low and non-uniform seed germination rates that hinder predictable field establishment and yield [4] . The failure of coriander seeds-technically dry schizocarps comprising two mericarps-to germinate uniformly is largely attributed to a state of physiological dormancy [5] . This dormancy is regulated by a complex matrix of endogenous chemical inhibitors present within the pericarp and seed coat [4] . These inhibitors, particularly 2-methoxy-4-vinylphenol (MVP), have been documented to suppress the activity of alpha-amylase, the critical enzyme required for starch mobilization during the early stages of germination [6] . In high-yielding varieties of coriander (Coriandrum sativum L.), total phenolic content has been reported in the range of approximately 12-16 mg GAE g -1 , which may act as a biochemical barrier to moisture imbibition and metabolic activation during seed germination [7] To overcome these constraints, seed leaching has emerged as a fundamental pre-sowing intervention to wash off water-soluble inhibitors from the seed coat.

However, the standardization of leaching duration is a critical technological requirement; insufficient leaching fails to disrupt the dormancy cycle, while excessive hydration can trigger cellular injury or the premature depletion of essential stimulatory metabolites. Recent studies have identified a 24-hour leaching duration as the optimal standard for maximizing germination and seedling vigor in coriander [4] . Furthermore, while coriander seeds are classified as "orthodox" (desiccation-tolerant), they remain highly susceptible to biochemical deterioration during ambient storage, particularly in tropical regions characterized by high temperatures and relative humidity [8] . The deterioration process, or seed aging, is characterized by a loss of membrane integrity due to lipid peroxidation, the accumulation of reactive oxygen species (ROS), and a concomitant decline in the activity of vital enzymes such as dehydrogenase and catalase [9] . While the removal of inhibitors through leaching improves initial germination, the reduction in the "antioxidant reserve"-composed largely of the same polyphenols that inhibit germination-may accelerate the rate of physiological decline during storage [10, 11] . Considering these multifaceted challenges, the present study was undertaken to provide a comprehensive framework for optimizing coriander seed quality. The investigation followed three primary experimental objectives: The assessment of physical, physiological, and biochemical changes in control and leached seeds over a 12-month ambient storage period.

Materials and Methods

Seeds of coriander variety CO 5 was obtained from the Department of Spices and Plantation Crops, Horticultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore and used as base materials for the study during January 2025 to December 2025.

Seed Leaching

To establish a standard leaching protocol, fresh coriander seeds (mericarp CO 5) were placed in cloth bags and submerged in water at a 1:10 seed-to-solution ratio for intervals of 6, 12, 18, 24, and 30 hours. Every 6 hours, the water was drained and replaced with fresh water. Following the treatment, the seeds were shade-dried for 24 hours until they returned to their original moisture levels.

Assessment of physical, physiological and biochemical changes in control and leached seeds of coriander during storage

To evaluate the preservation quality of coriander seeds, fresh CO 5 variety seeds (serving as a control group) along with seeds subjected to various leaching intervals were stored in cloth bags under ambient environmental conditions. At the beginning of the storage period, both control and leached seeds underwent initial testing for physiological and biochemical parameters. Subsequently, seed samples were collected from every treatment group at monthly intervals throughout the storage duration to monitor changes in these specific physiological and biochemical characteristics.

Germination test

Germination trials were carried out in a controlled setting at 25±1 ºC with 95±2% relative humidity. Using 400 mericarp seeds placed in roll towels, the study followed International Seed Testing Association protocols [12] , which mandate a 21day period for coriander before assessing physiological metrics.

Germination percentage

Germination % of coriander seeds were calculated using the formula: Germination% = (Number of normal seedlings/Total number of seeds sown) × 100

Root length and Shoot length

In each replication, ten normal seedlings were chosen at random to determine root and shoot lengths. Root length was measured from the hypocotyl base to the primary root tip using a scale, with the average recorded in centimeters. Subsequently, the same seedlings were measured from the hypocotyl base to the tip of the primary leaves to calculate the mean shoot length in centimeters.

Dry matter

After the seedlings were measured, 10 representative samples were placed in a hot air oven at 80 °C for 24 hours to calculate their dry weight.

Vigour index

Following the procedure described by Abdul-Baki and Anderson [13] , the seedling vigour index was calculated as follows:

Vigour index I = Germination percentage × Total seedling length (cm)

Determination of dehydrogenase activity

Mericarp coriander seeds were preconditioned by soaking in water for 6 h. Seeds were bisected longitudinally to expose the embryo. These sections were then immersed in a 0.1% solution of 2, 3, 5-triphenyl tetrazolium chloride and incubated in the dark at 40 °C for six hours for staining. Once stained, the seeds were rinsed with distilled water and placed into 10 mL of 2-methoxy ethanol within an airtight 25 mL conical flask, which was kept in an incubator overnight in total darkness to extract the red formazan. The coloured solution was decanted and the color intensity was measured in an ELICO UV-VIS spectrophotometer (Model SL-159) at 470 nm, with methyl cellosolve serving as the blank. The measured optical density was then recorded as the level of dehydrogenase activity [14] .

Determination of total phenols

Coriander seeds were grinded using a pestle and mortar with a tenfold volume of 80% ethanol. Following homogenization, the mixture was centrifuged at 3000 rpm for 10 minutes to collect the supernatant. A 1 mL aliquot of this supernatant was diluted to 3 mL with distilled water, then combined with 0.5 mL of Folin-Ciocalteu reagent. After a 3-minute incubation, 2 mL of 20% Na2CO3 solution was incorporated and thoroughly mixed. The resulting sample was heated in a boiling water bath for 1 minute, allowed to cool, and its absorbance was measured at 650 nm using a UV-VIS spectrophotometer. Total phenol concentration was subsequently determined via a standard curve, with results reported as the mean value in mg GAE/g [15] .

Statistical analysis

The laboratory study was organized using a Completely Randomized Design (CRD), with results presented as the mean from four replicates. Statistical analysis was performed using AGRES software, employing an analysis of variance (ANOVA) at a P<0.05 significance level. To distinguish between treatment means, Duncan's Multiple Range Test (DMRT) was applied.

Results and Discussion

The 12-month storage study under ambient conditions showed a clear balance between short-term improvement and long-term storage life. At the initial evaluation (P 0 ), seeds leached for 24 h (T 5 ) were clearly best treatment: germination was 79% (Table 2), speed of germination of 13.475 (Table 1), dry matter of 0.0587g (Table 6), and vigour index of 1876 (Table 7). These data confirm that removing inhibitory compounds is very effective when seeds are used soon after treatment. However, this advantage reduced more quickly over time in leached seeds than in the control. By 12 months (P 12 ), T 5 germination had fallen to about 65%, while the control (T1) increased from 63% at P 0 to 68% at P 12 (Table 2), creating a "leaching-longevity paradox" where the best lot at sowing did not have the best final survival. The behaviour of the control is consistent with after-ripening, in which natural inhibitors slowly break down during dry storage, allowing dormant seeds to gradually become able to germinate [16,17] . In contrast, leached seeds can be seen as "biochemically exposed": removing much of the phenolic antioxidant layer and subjecting seeds to a hydration-drying cycle likely made them more vulnerable to reactive oxygen species (ROS), lipid peroxidation and membrane injury during storage [8,18] . This view agrees with seed-ageing models that point to antioxidant loss and ROS build-up as major causes of declining vigour [19,20] . Measurements of electrical conductivity (EC), dehydrogenase activity and TPC during storage helped to explain these patterns. EC, which reflects leakage of electrolytes from damaged cell membranes, increased with both longer leaching and longer storage: the 30-h treatment (T 6 ) showed the highest mean EC (0.80 dS m -1 ), while the control remained lowest (0.52 dS m -1 ), indicating more severe membrane damage in heavily leached seeds. Within T 5 , EC increased from 0.623 dS m -1 at P 0 to much higher values at P 12 (Table 5), while dehydrogenase activity dropped from 0.412 to 0.315 OD; the control changed more slowly, from 0.314 to 0.340 OD over the same period (Table 6). TPC showed a similar trend: in T 5 seeds it decreased from 4.53 mg GAE g -1 at P 0 to about 3.00 mg GAE g -1 at P 12 , while in the control it fell only from 8.24 to about 6.70 mg GAE g -1 (Table 7). This gradual loss of phenolic compounds supports their role in neutralizing ROS and protecting membranes during storage [21,22] . Taken together, the rise in EC, the fall in dehydrogenase and α-amylase activities, and the steady decrease in TPC form a consistent biochemical picture of faster ageing in leached seeds, especially when leaching is too long. Seed health observations showed disease incidence increased with time. By P 12 , disease incidence was about 15.9% in the 24-h leached seeds (T 5 ) compared with 14.3% in the control (Table 8), suggesting that partial removal of antimicrobial volatiles such as linalool and some phenolic defences during leaching may slightly lower resistance to seed-borne fungi during long storage [1,23] . When all storage times are averaged, 24-h leached seeds (T 5 ) still show the best overall performance, with the highest mean speed of germination (12.74) (Table 1), germination (72.5%) (Table 2), vigour index [1676] (Table 4), dehydrogenase activity (0.37 OD) (Table 6). At the same time, the slightly higher final germination of the control at P 12 highlights the value of the intact, phenolic-rich seed coat for long-term survival, even though it causes lower initial field emergence. Overall, these results show that polyphenols in coriander seeds have two roles: at high levels they maintain dormancy and restrict α-amylase, but at moderate levels they act as important antioxidants that slow ageing and disease development during storage. For practical seed handling, leaching for 24 h is the best pre-sowing treatment for coriander cv. CO 5 when seeds will be planted soon and rapid, uniform emergence is the main goal, whereas un-leached mericarps are better for storage periods longer than about 9-12 months, when maintaining viability is more important than maximum initial vigour [1,4,24] . 0.427 0.427 0.435 0.445 0.460 0.480 0.500 0.525 0.550 0.575 0.600 0.630 0.660 0.517 T2-Seed leaching in standing water for 6 hours 0.475 0.475 0.480 0.490 0.505 0.520 0.540 0.565 0.590 0.615 0.640 0.665 0.690 0.558 T3-Seed leaching in standing water for 12 hours 0.526 0.526 0.530 0.540 0.555 0.570 0.590 0.615 0.640 0.665 0.690 0.715 0.740 0.608 T4-Seed leaching in standing water for 18 hours 0.575 0.575 0.580 0.590 0.605 0.620 0.640 0.665 0.690 0.715 0.740 0.765 0.790 0.658 T5-Seed leaching in standing water for 24 hours 0.623 0.623 0.630 0.640 0.655 0.670 0.690 0.715 0.740 0.765 0.790 0.815 0.840 0.707 T6-Seed leaching in standing water for 30 hours 0.698 0.698 0.705 0.720 0.740 0.760 0.785 0.810 0.835 0.860 0.885 0.910 0.

Conclusion

The present study shows that coriander seeds (cv. CO 5) contain both germination-promoting and inhibitory compounds, with high polyphenol levels playing a key role in dormancy and storage behaviour. Leaching in water for 24 hours lowered polyphenol content, increased dehydrogenase and α-amylase activity, and gave maximum germination, seedling growth and vigour, making this the best pre-sowing treatment for immediate planting. Over 12 months of ambient storage, all seed lots deteriorated, but leached seeds-especially those leached for 24-30 hoursaged faster than the control, as shown by higher electrical conductivity, reduced enzyme activity and greater polyphenol loss. Although more dormant at first, untreated mericarps after-ripened and kept better germination at the end of storage, confirming that polyphenols both delay germination at high levels and protect viability at moderate levels; therefore, 24-hour leaching suits short-term use, while un-leached seeds are preferable for long-term storage.

References

1. Scandar S, Zadra C, Marcotullio MC. Coriander (Coriandrum sativum) polyphenols and their nutraceutical value against obesity and metabolic syndrome. Molecules. 2023;28(10):4187.
2. IndexBox. World anise, badian, fennel and coriander market overview 2024 [Internet]. 2024 [cited 2026 Jun 4]. Available from: https://www.indexbox.io/search/anise-badian-fenneland-coriander-market/
3. NSO. Provisional estimates of national income 202324. New Delhi: Government of India; 2024.
4. Palani-Vasantha S, Shanmugam K, Ranganathan U, Venkatachalam R, Doraiswamy U, Kulandaivel M, et al. A new dawn for coriander seeds: overcoming dormancy through innovative and comprehensive enhancement techniques. 2024.
5. Yeung EC, Bowra S. Embryo and endosperm development in coriander (Coriandrum sativum). Botany. 2011;89(4):263-273.
6. MVP), in wheat seeds to evaluate its mode of action. Z Naturforsch C. 2007;62(9-10):694-700.
7. Msaada K, Jemia MB, Salem N, Bachrouch O, Sriti J, Tammar S, et al. Antioxidant activity of methanolic extracts from three coriander (Coriandrum sativum L.) fruit varieties. Arab J Chem. 2017;10:S3176-S3183.
8. Nadarajan J, Walters C, Pritchard HW, Ballesteros D, Colville L. Seed longevity-The evolution of knowledge and a conceptual framework. Plants. 2023;12(3):471.
9. Chhabra R, Singh T. Seed aging, storage and deterioration: an irresistible physiological phenomenon. Agric Rev. 2019;40(3):199-207.
10. Stegner M, Wagner J, Roach T. Antioxidant depletion during seed storage under ambient conditions. Seed Sci Res. 2022;32(3):150-156.
11. Gaonkar SS, Sincinelli F, Balestrazzi A, Pagano A. Quercetin and rutin as tools to enhance antioxidant profiles and post-priming seed storability in Medicago truncatula. Agriculture. 2024;14(5):738.
12. International Seed Testing Association (ISTA). International rules for seed testing. Bassersdorf, Switzerland: ISTA; 2023.
13. Abdul-Baki AA, Anderson JD. Vigor determination in soybean seed by multiple criteria. Crop Sci. 1973;13(6):630-633.
14. Kittock DL, Law AG. Relationship of seedling vigor to respiration and tetrazolium chloride reduction by germinating wheat seeds. Agron J. 1968;60(3):286-288.
15. Singleton VL, Orthofer R, Lamuela-Raventós RM. Analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent. Methods Enzymol. 1999;299:152-178.
16. Bewley JD. Seed germination and dormancy. Plant Cell. 1997;9(7):1055-1066.
17. Chandel NS, Tripathi V, Singh HB, Vaishnav A. Breaking seed dormancy for sustainable food production: revisiting seed priming techniques and prospects. Biocatal Agric Biotechnol. 2024;55:102976.
18. Pop OL, Suharoschi R, Socaci SA, Berger Ceresino E, Weber A, Gruber-Traub C, et al. Polyphenols-ensured accessibility from food to the human metabolism by chemical and biotechnological treatments. Antioxidants. 2023;12(4):865.
19. Agrawal P, Sinha S. Response of okra seeds (Abelmoschus esculentus L.) of different chronological ages during accelerated aging and storage. Seed Res. 1981;9(1):29-34.
20. Bhanuprakash K, Yogeesha HS, Naik LB, Arun MN. Studies on physiological and biochemical changes in relation to seed viability in aged onion seeds. J Hortic Sci. 2006;1(1):15-18.
21. Corso M, Perreau F, Mouille G, Lepiniec L. Specialized phenolic compounds in seeds: structures, functions, and regulations. Plant Sci. 2020;296:110471.
22. Wangensteen H, Samuelsen AB, Malterud KE. Antioxidant activity in extracts from coriander. Food Chem. 2004;88(2):293-297.
23. Nouioura G, El Fadili M, El Hachlafi N, Maache S, Mssillou I, Abuelizz HA, et al. Coriandrum sativum L. essential oil as a promising source of bioactive compounds with GC/MS, antioxidant, antimicrobial activities: in vitro and in silico predictions. Front Chem. 2024;12:1369745.
24. Tang EL, Rajarajeswaran J, Fung SY, Kanthimathi M. Antioxidant activity of Coriandrum sativum and protection against DNA damage and cancer cell migration. BMC Complement Altern Med. 2013;13(1):347.