Seed germination studies in Amaltas

Introduction

Ornamental trees are primarily cultivated for their aesthetic value, enhancing landscapes with their flowers, foliage, form, bark, and fragrance. In addition to beautifying surroundings, they contribute to environmental improvement by absorbing pollutants and releasing oxygen. With growing interest in urban landscaping, ornamental horticulture has become a vital economic sector. Among ornamental species, Cassia fistula (golden shower tree or Amaltas) is notable for its vibrant yellow blooms, drought tolerance, and low maintenance needs (Arora, 1988) [4] . Native to the Indian subcontinent, it is widely distributed across tropical Asia, Africa, South America, and Australia. Beyond its ornamental appeal, C. fistula holds therapeutic value in traditional medicine systems such as Ayurveda, Unani, and Siddha. Various plant parts exhibit antibacterial, antifungal, antioxidant, antitumor, and hypolipidemic properties. Its pulp acts as a natural laxative, and leaf extracts possess mosquito larvicidal activity (Mehdi et al., 2011) [13] , making it suitable for roadside and institutional plantations. However, seed dormancy due to a hard, impermeable seed coat hampers germination (Cavanagh, 1980) [8] . Pre-sowing treatments with concentrated HCl, H₂SO₄, and HNO₃ have shown efficacy in breaking dormancy and enhancing seed performance. This study evaluates the effects of such treatments on germination and seedling growth in C. fistula, aiming to improve propagation of this ecologically and medicinally valuable species, while addressing practical challenges in nursery practices and seed handling.

Material and Methods

The experiment was conducted during autumn of 2024 to study the effect of different seed treatments in germination of Amaltas. The experiment was laid out in a Completely Randomized Design (CRD) with ten treatments and three replications, using crates as experimental units. Fifty seeds of Cassia fistula were sown per crate, total 30 crates. Treatments included control (T1-water soaking for 24 hours), seed treatment conc. HCl for 2.5 min (T2), conc. HCl for 5 min (T3), conc. HCl for 7.5 min (T4), conc. H2SO4 for 2.5 min (T5), conc. H2SO4 for 5 min (T6), conc. H2SO4 for 7.5 min (T7), conc. HNO3 for 2.5 min (T8), conc. HNO3 for 5 min (T9), conc. HNO3 for 7.5 min (T10). After seed treatment the seeds were washed with cold tap water for several times to remove the residual of acids. Seeds were collected from healthy mature trees within the college premises in June-July 2024 and sown in September 2024 in a soil: sand: FYM (2:1:1) medium. Crates were irrigated daily until germination, followed by twice-weekly irrigation and regular weeding. Meteorological data was recorded from the Department of Agronomy, Nagpur. Observations were recorded from five randomly selected seedlings per treatment for germination (days to germination, percentage), growth (height, shoot length, stem girth, leaf number, leaf length, leaf area, fresh and dry weight and survival percentage. Germination percentage was calculated using: (Germinated seeds/Total seeds sown) × 100. Leaf area was measured using a digital leaf area meter. Dry weight was taken after oven-drying at 60 °C for 24 hours. Survival percentage was computed as: (Alive seedlings/Germinated seedlings) × 100. Statistical analysis was done as per Panse and Sukhatme (1967) [16] with SE(m)±and CD at 5% significance, and appropriate graphical representations were used for clarity.

Results and Discussion

Germination parameters

The data in respect of the germination parameters of Amaltas as influenced by different seed treatment was presented in Table 1.

The treatment T7-conc. H2SO4 for 7.5 minutes recorded significantly minimum days to germination (2.00 days) as compared o other treatments, and it was followed by the treatment T6-conc. H2SO4 for 5 minutes (3.16 days) and T5conc. H2SO4 for 2.5 minutes (4.14 days). Whereas, maximum days to germination (24.33 days) was recorded in control (T1). In hard-coated seeds, acid scarification efficiently breaks dormancy by removing physical barriers. Similar results had been reported by Babalola et al. (2014) [5] in Cassia fistula and Negi et al. (2015) [14] in Ribes alpestre.

The treatment T7-conc. H2SO4 for 7.5 minutes had the highest germination percentage (98.67%) which was significantly superior over all the treatments under study. Whereas, T1-control treatment recorded minimum germination percentage (4.67%). Sulfuric acid breaks physical dormancy, leading to more uniform and higher germination. These results are in agreement with findings by Gupta et al. (1997) [10] in Glycyrrhiza glabra and Bhuse et al. (2001) [6] in Cassia angustifolia.

Growth parameter

The data in respect of the growth parameters of Amaltas as influenced by different seed treatment was presented in Table 2.

At the stage of 90 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum plant height (19.98 cm) which was found at par with the treatment T6-conc. H2SO4 for 5 minutes (18.99 cm) and it was followed by the treatment T5-conc. H2SO4 for 2.5 minutes (17.89 cm). Whereas, minimum plant height (9.42 cm) was recorded under T1-control treatment. At the stage of 120 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum plant height (25.38 cm) which was found at par with the treatment T6-conc. H2SO4 for 5 minutes (23.96 cm) and it was followed by the treatment T5-conc. H2SO4 for 2.5 minutes (22.28 cm). Whereas, minimum plant height (10.46 cm) was recorded under T1-control treatment. Improved physiological activity and longer growing duration contribute to increased height. Similar observations were by Bichi et al. (2012) [7] in Delonix regia and Agbogid et al. (2007) [1] in Dacryodes edulis.

At the stage of 90 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum shoot length (15.87 cm) which was found at par with the treatment T6-conc. H2SO4 for 5 minutes (15.17 cm). Whereas minimum shoot length (7.96 cm) was recorded under T1-control treatment. At the stage of 120 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum shoot length (18.68 cm) which was found at par with the treatment T6-conc. H2SO4 for 5 minutes (17.84 cm). Whereas minimum shoot length (8.73 cm) was recorded under T1-control treatment. Acid scarification helps in establishing a stronger shoot-root axis. The present results are in agreement with the findings of Al Menaie et al. (2010) [2] in Cassia fistula and Cassia nodosa, Tadros et al. (2011) [17] in Leucaena leucocephala.

At the stage of 120 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum stem girth (0.36 cm) which was followed by the treatment T6-conc. H2SO4 for 5 minutes (0.34 cm) and T5-conc. H2 SO4 for 2.5 minutes (0.32 cm). Whereas minimum stem girth (0.11 cm) was recorded under T1-control treatment. Sulfuric acid (H₂SO₄) seed treatment increases stem girth in plants by enhancing early germination, improving nutrient uptake, and stimulating hormonal activity that promotes cell division and thickening. Olatunji et al. (2012) [15] reported the similar results in respect of stem diameter in Acacia auriculiformis.

Number of leaves per seedling

At the stage of 90 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum number of leaves (18.12) which was followed by the treatment T6-conc. H2SO4 for 5 minutes (16.88) and T5conc. H2SO4 for 2.5 minutes (16.15). Whereas, minimum number of leaves (8.62) was recorded under T1-control treatment. At the stage of 120 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum number of leaves (23.88) which was followed by the treatment T6-conc. H2SO4 for 5 minutes (21.77) and T5conc. H2SO4 for 2.5 minutes (20.34). Whereas, minimum number of leaves (10.13) was recorded under T1-control treatment. The increase in leaf production can be linked to the accelerated shoot growth and better nutrient uptake facilitated by a strong root system in sulfuric acid-treated seeds. Similar increases in leaf number were observed by Mabundza et al. (2010) [12] in Tamarindus indica.

At the stage of 120 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum length of leaf (10.98 cm) which was followed by the treatment T6-conc. H2SO4 for 5 minutes (10.23 cm) and T5conc. H2SO4 for 2.5 minutes (9.97 cm). Whereas minimum length of leaf (3.65 cm) was recorded under T1-control treatment. Acid scarification boosts early root activity, enhancing the uptake of water and nutrients necessary for leaf expansion. The result gotten in this study is similar to the findings of Usman and Asan (2017) [18] in A. digitata.

At the stage of 120 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum leaf area (22.03 cm 2 ) which was found statistically at par with the treatment T6-conc. H2SO4 for 5 minutes (21.92 cm 2 ) and T5-conc. H2SO4 for 2.5 minutes (21.45 cm 2 ). Whereas minimum leaf area (10.03 cm 2 ) was recorded under T1-control treatment. This increased leaf area might due to the cumulative effect of improved leaf number and length, which results from better root-shoot coordination in acidtreated seedlings. Similar findings were reported by Amira et al. (2013) [3] in Cassia fistula.

At the stage of 120 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum fresh weight of seedling (8.33 g) which was found statistically at par with the treatment T6-conc. H2SO4 for 5 minutes (7.96 g) and it was followed by the treatment T5conc. H2SO4 for 2.5 minutes (7.24 g). Whereas minimum fresh weight of seedling (3.73 g) was recorded under T1control treatment. This might be explained by the better water absorption and storage capacity of vigorously growing seedlings derived from acid-scarified seeds. Similar increases in fresh weight were observed by Fallah et al. (2014) [9] in Canna indica.

At the stage of 120 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum dry weight of seedling (3.45 g) which was followed by the treatment T6-conc. H2SO4 for 5 minutes (3.22 g) and T5conc. H2SO4 for 2.5 minutes (2.93 g). Whereas minimum dry weight of seedling (0.62 g) was recorded under T1control treatment. This could be attributed to the efficient utilization of photosynthates and nutrient reserves in seedlings with better shoot and root systems from H₂SO₄treated seeds. A higher dry weight reflects structural tissue buildup and metabolic maturity. Similar results were found by Muhammad et al. (2017) in date palm.

At the stage of 120 days after sowing, the treatment T7-conc. H2SO4 for 7.5 minutes had recorded significantly maximum survival percentage (89.96%) which was found statistically at par with the treatment T6-conc. H2SO4 for 5 minutes (87.45%). Whereas minimum survival percentage (44.44%) was recorded under T1-control treatment. This phenomenon could be linked to improved structural strength and physiological balance in sulfuric acid-treated seedlings, enabling better post-transplant survival. These findings are in agreement with Karaguzel et al. (2004) [11] in Lupinus varius.

Conclusion

From the above investigation, it is concluded that seed treatment with concentrated sulfuric acid (H₂SO₄) for 7.5 minutes (T7) proved to be the most effective among all treatments. This treatment resulted in significantly earlier germination and the highest germination percentage. It also exhibited superior performance in various growth parameters, including plant height, shoot length, stem girth, number of leaves per seedling, leaf length, leaf area, fresh and dry weight of seedlings, and survival percentage. Therefore, concentrated H₂SO₄ treatment for 7.5 minutes (T7) can be recommended as the optimum seed pretreatment for enhancing seed germination and seedling growth in Amaltas (Cassia fistula).

References

1. H.J.). International Journal of Agricultural Research. 2007;2(11):952-958.
2. Al Menaie A, Al-Shammary MA, Al-Dosari M. Effect of pre-treatment methods on seed germination and seedling growth of Cassia fistula L. and Cassia nodosa L. Journal of Horticultural Science and Biotechnology. 2010;85(3):231-236.
3. Amira SH, Soliman, Abbas MS. Effect of sulfuric acid and hot water treatments on seed germination and seedlings growth of Cassia fistula. Research Studies, Journal of Cairo University. 2013;12613:1-5.
4. Arora RK. The Indian gene centre. Priorities and prospects for collection. In: Plant Genetic Resources: Indian Perspective. New Delhi: NBPGR Publication; 1988. p. 66-75.
5. Babalola SE, Shonubi O, Okunsanya OT. Seed dormancy in Cassia fistula Linn. population from Nigeria. Journal of American Science. 2014;10:85-93.
6. Bhuse VH, Ghule ST. Effect of various seed treatments for enhancement of seed germination and seedling vigour in Senna. Research on Crops. 2001;2:359-363.
7. Bichi AM. Different pre-germination treatments and Delonix regia seeds. Journal of Research in National Development (Jorind). 2012;10:24-29.
8. Tran VN, Cavanagh AK. Taxonomic implications of fracture load and deformation histograms and the effects of treatments on the impermeable seed coat of Acacia species. Australian Journal of Botany. 1980;28(1):39-51.
9. Fallah Imani A, Salehi Sardoei A, Shahdadneghad M. Effect of H₂SO₄ on seed germination and viability of Canna indica L. ornamental plant. International Journal of Advanced Biological and Biomedical Research. 2014;2(1):223-229.
10. Gupta V, Anjali K, Singh BB. Studies on seed germination and seedling vigour in liquorices (Glycyrrhiza glabra). Journal of Medicinal and Aromatic Plant Sciences. 1997;19(2):412-413.
11. Karaguzel O, Yilmaz M, Isik N. Effect of seed treatments on germination and seedling growth of Lupinus varius L. Turkish Journal of Agriculture and Forestry. 2004;28(5):365-371.
12. Mabundza M, Nsimba A, Mumba M. Effect of seed treatments on germination and seedling growth of Tamarindus indica L. African Journal of Plant Science. 2010;4(5):237-242.
13. Mehdi SH, Qamar A, Khan I, Tayyaba PI. Studies on larvicidal and IGR properties of leaf extract of Cassia fistula and Saraca indica (family: Leguminosae). Journal of Herbal Medicine and Toxicology. 2011;5(1):79-86.
14. Negi PS, Kapoor KS. Studies on the effect of presowing treatments on germination behavior of Ribes alpestre Wall. Ex Decne seeds. Indian Forester. 2015;141(7):726-760.
15. Olatunji D, Maku JO, Odumefun OP. The effect of pretreatments on the germination and early seedlings growth of Acacia auriculiformis Cunn. Ex. Benth. African Journal of Plant Science. 2013;7(8):325-330.
16. Panse VG, Sukhatme PV. Statistical Methods for Agricultural Workers. New Delhi: Indian Council of Agricultural Research; 1967. p. 1-369.
17. Tadrose AA. Effect of different seed treatments on germination and seedling growth of Leucaena leucocephala. Journal of Tropical Forestry. 2011;27(3):187-192.
18. Usman IA, Asan TV. Influence of different pretreatment on seed germination and growth rate of Adansonia digitata seedlings. Journal of Research in Forestry, Wildlife and Environment. 2017;9(2):8-14.