Impact of pre-seed treatments on Gloriosa superba L. seeds

Introduction

Gloriosa superba L., belonging to the Colchicaceae family, is an important medicinal plant widely recognized for its therapeutic properties. Its seeds and tubers serve as the primary economic parts due to their medicinal value. Owing to its extensive medicinal benefits, the plant has been extensively over-exploited from wild populations, raising concerns about its conservation. Propagation of G. superba is primarily achieved through its seeds and tubers, which are critical for cultivation. To satisfy the increasing demand from the pharmaceutical industry, there is a pressing need to produce high-quality planting material and to develop sustainable commercial cultivation methods, ensuring both supply and conservation (Muruganandam et al. 2019). The primary method of propagating this crop has been through tubers. However, the limited availability of tubers presents a significant obstacle in satisfying the current demand for herbs, which has prompted the adoption of seed propagation techniques. Seeds often face poor germination rates due to their impermeable seed coats, making tubers the preferred choice for propagation. These tubers are characterized by their cylindrical, bifurcated shape, resembling an L or V, with two limbs that can be of equal or unequal length and end in pointed tips (Kirtikar and Basu 1975; Farooqui and Sreeramu 2004; Kurian and Sankar 2007). To overcome propagation challenges, various advanced techniques have been employed, including seed treatment, micro-propagation, tissue culture, and somatic embryogenesis, many of which have demonstrated promising results and potential for large-scale production (Ghosh et al. 2006; Kurian and Sankar 2007; Venudevan et al. 2010) [9,6,4,7,5,10] . This study, titled "Impact of Pre-Seed Treatments on Gloriosa superba L. Seeds" was conducted to thoroughly investigate and identify effective pre-sowing seed treatments that can enhance germination rates, promote robust plant growth, and increase tuber yield, recognizing the species ecological and medicinal significance.

Materials and Methods

Site, Layout and Experiment details

The field trial was conducted at the experimental farm of Department of Forest Products, Dr YS Parmar University of Horticulture and Forestry, Solan (Himachal Pradesh). The experiment was conducted under Randomized Block Design (RBD) with 6 treatments and 4 replications in raised nursery beds. The treatment details were as follows: Treatment T 1control (whole seed), Treatment T 2 -Sarcotesta removal and hot water, Treatment T 3 -Arbuscular mycorrhiza, Treatment T 4 -PGPR, Treatment T 5 -N:P:K@120: 40: 60 and Treatment T 6 -N:P:K@120: 60: 60. The seeds of Gloriosa superba have a thick sarcotesta, so to attain the best germination, the sarcotesta is removed, followed by soaking in hot water for 12 hours for all the treatments except treatment T 1 (control). The seeds were treated with Arbuscular mycorrhiza (AM) and Plant Growth Promoting Rhizobacteria (PRPR) before sowing. NPK was applied as a basal dose during nursery bed preparation for the treatments and nitrogen is applied in 3 spit doses. The seeds were treated with arbuscular mycorrhiza after removal of the sarcotesta before sowing. Similarly, the seed were dipped for a short time in plant growth promoting rhizobacteria solution before sowing in nursery beds. The observations for germination parameters, growth parameters, and yield parameters were taken during the experiment and recorded.

Statistical analysis

The Analysis of Variance (ANOVA) under a Randomized Block Design (RBD) was performed using R statistical tool (version 3.3.0) and python (version 3.13).

Results and Discussions:

Seed treatment involves applying chemicals or other suitable substances to seeds to boost germination, overcome dormancy, and enhance nutrient access and plant development. Gloriosa superba L. seeds are covered by an outer sarcotesta and a hard inner part. The sarcotesta acts as a barrier, leading to poor and inconsistent germination (Mahajan et al. 2023). Many studies have examined the effects of various chemicals and hot water treatments on seed germination and dormancy breaking in Gloriosa superba L. as well as other crops (Venudevan et al. 2010; Anandhi and Rajamani 2012) [8,10,1] .

Germination Parameters

Seed germination was initiated earlier (25.67±0.28 days) in seeds after removal of the sarcotesta and hot water treatment, whereas late germination (31.00±0.16 days) was observed in seeds under the NPK@120:60:60 nutrient dosage. The maximum germination period (42.00±0.24 days) was observed in PGPR-treated seeds, and the least (35.00±0.15 days) in treatment T6. Seeds treated with arbuscular mycorrhiza before sowing showed the maximum germination percentage of 77.20±0.96 days, whereas the whole seeds (control) sown showed the least germination percentage (36.40±0.68 days) among all treatments. Similarly, the impact of hot water seed treatment of Gloriosa superba 2023) also reported enhanced seed germination percentage with seed soaking in hot water and removal of sarcotesta afterwards compared to control. The present study revealed that the hot water-treated seeds along with incorporation of AM resulted in maximised germination percentage (77.00%) in Gloriosa superba L [10,2,9,3,8] .

Growth and Yield Parameters

The seedling height was greatest (49.03±0.69 cm) in treatment T 3 compared to the control (20.50±0.06 cm). The highest number of leaves per seedling (35.60±0.30) was observed with NPK@120:40:60, while the control had the fewest (18.03±0.03). Harvested tubers' fresh weight was measured, with the heaviest tubers (15.20±0.37 g) from seeds treated with PGPR, and the lightest (7.13±0.07 g) from seeds sown without treatment (T 1 ). The length and diameter of both arms of L or V shaped tubers were measured using a measuring tape and vernier caliper. Arm 1 length was longest (9.90±0.24 cm) in tubers from PGPR treated seeds, compared to 5.17±0.11 cm in controls. Arm 1 diameter was greatest (11.27±0.07 mm) in T 5 , and smallest (8.10±0.16 mm) in T 1 .

Similarly, arm 2 length was maximum (8.43±0.03 cm) in PGPR-treated tubers versus 4.03±0.06 cm in controls. [11,3,9,10,2] .

Conclusion

The study demonstrates that the removal of sarcotesta and hot water treatment significantly improves the germination and growth of Gloriosa superba seeds. These seed treatments effectively enhance not only germination rates but also subsequent tuber yield. Overall, all tested treatments resulted in better tuber production compared to the control, indicating that adopting such treatments can be beneficial for optimizing cultivation and yield of Gloriosa superba.

Acknowledgement

AcknowledgmentsAll authors express gratitude to Indian Council of Agricultural Research-All India Coordinated Research Project on Medicinal and Aromatic Plants and Betelvine (ICAR-AICRP on MAP&B) and Dr. Yashwant Singh Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India for providing infrastructure and research facility throughout the study. Disclosure statementNo potential conflict of interest was reported by the author(s)

References

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