Effect of IBA, NAA and types of cutting on rooting in Chinese tallow tree [Triadica sebifera (L.) Roxb.]

Introduction

The Chinese Tallow Tree (Triadica sebifera L. Roxb), a member of the Euphorbiaceae family, is widely recognized for its ornamental value. The tree's common name, "Chinese tallow," is derived from its historical use as a seed oil crop in Asia for over 1,500 years, while "popcorn tree" refers to its distinctive, persistent white fruit. The species "sebifera" aptly describes its wax-bearing characteristics (Bruce et al., 1997) [1] . Chinese tallow trees are frequently found in moist or periodically inundated environments, conditions that likely contribute to their invasive potential, as they exhibit exceptional tolerance to flooding and anaerobic soil conditions. Although the seeds do not germinate in waterlogged or saturated soils, the seedlings, once established, develop substantial flood tolerance within two months (Gabler and Siemann, 2013). The success of propagating woody plants through cuttings varies depending on the plant's nature and physiological behaviour. Rooting hormones, particularly auxins, play a critical role in the development of adventitious roots (Wiesman et al., 1988) [2] . These hormones are synthesized in the apical meristem and young leaves of aboveground plant parts and are subsequently transported to their site of action (Ljung et al., 2001) [3] . The concentration of endogenous auxin correlates with different stages of rooting (Heloir et al., 1996) [4] . High levels of auxin are associated with rapid rooting at the initial stage (Blazkova et al. 1997). When exogenous auxin is applied to cuttings, the concentration of endogenous auxin peaks after wounding, coinciding with root initiation (Gaspar et al., 1996) [5] . Auxins effectively induce adventitious roots in various woody species (Klerk et al. 1999) [6] . Root formation in some species from cuttings can be challenging, but this issue can be addressed using synthetic auxins, such as IBA and NAA, which are commonly employed in commercial settings to enhance the rooting process. In addition to rooting hormones, several factors influence rooting success, including the cultivar and age of the source tree, the timing of cutting collection, the length and diameter of cuttings, the degree of hardening, injuries to the cutting, heat treatments, hormone concentration, planting time, the maturity of the stock plant and the propagation environment (Hartmann et al. 2001). Properly applying growth regulators, manipulating stock plants, selecting appropriate rooting media and timing the cutting process can significantly improve the development of adventitious roots (Harbage et al. 1994). However, no research has been conducted in Kashmir on propagating Chinese tallow trees through cuttings during different seasons with rooting hormone application. This study was proposed to fill this gap, providing a foundation for future research and establishing protocols for the mass multiplication of this tree.

Material and Methods

The study on the rhizogenesis of the Chinese Tallow Tree (Triadica sebifera L. Roxb.) was designed to evaluate the effects of different rooting hormones and cutting types under a propagation chamber at SKUAST-Kashmir, utilizing 18 treatment combinations. These combinations included softwood (S 1 ) and semi-hardwood cuttings (S 2 ) treated with varying concentrations of Indole 3-butyric acid (IBA) and Naphthalene Acetic Acid (NAA), specifically: T 1 (Control + S 1 ), T 2 (IBA 500 ppm + S 1 ), T 3 (IBA 1000 ppm + S 1 ), T 4 (IBA 1500 ppm + S 1 ), T 5 (IBA 2000 ppm + S 1 ), T 6 (NAA 500 ppm + S 1 ), T 7 (NAA 1000 ppm + S 1 ), T 8 (NAA 1500 ppm + S 1 ), T 9 (NAA 2000 ppm + S 1 ), T 10 (Control + S 2 ), T 11 (IBA 500 ppm + S 2 ), T 12 (IBA 1000 ppm + S 2 ), T 13 (IBA 1500 ppm + S 2 ), T 14 (IBA 2000 ppm + S 2 ), T 15 (NAA 500 ppm + S 2 ), T 16 (NAA 1000 ppm + S 2 ), T 17 (NAA 1500 ppm + S 2 ) and T 18 (NAA 2000 ppm + S 2 ). The experiment, replicated three times with 20 cuttings per treatment, assessed various parameters such as the number and length of primary roots and number of secondary roots, days taken to rooting, rooting percentage, survival percentage of rooted cutting, root fresh mass and root dry mass.

Methodology for measurement of parameters Average Number of Primary Roots

After root initiation, each cutting was carefully uprooted and washed under tap water. The count of major primary roots originating from the basal region was recorded manually for each cutting.

Average number of secondary roots

All secondary (lateral) roots emerging from primary roots were counted using a magnifying lens. The average per cutting was calculated for each treatment.

The longest primary root of each cutting was measured using a digital scale. Length was recorded in centimetres and the mean was computed for each treatment

Days taken for root emergence

Cuttings were inspected daily. The number of days from planting until first visible root emergence was recorded for each treatment and averaged

Root systems were washed gently and blotted with tissue paper. Fresh weight was recorded using a precision digital balance with 0.001 g accuracy.

The same roots were placed in labelled butter-paper bags and dried in a hot-air oven at 65 °C until constant weight was achieved. Dry weight was recorded using the same precision balance.

Results and Discussion

The primary objective of this research was to evaluate the effects of different rooting hormones viz., Indole-3-butyric acid (IBA) and Naphthalene Acetic Acid (NAA) and types of cuttings viz., softwood (S 1 ) and semi-hardwood (S 2 ), on the rhizogenesis of the Chinese Tallow Tree (Triadica sebifera L. Roxb.). The study aimed to optimize propagation techniques for T. sebifera in the temperate climate of the Kashmir region.

Average number of primary roots:

The study revealed significant variations in the number of primary roots across different treatments, highlighting the importance of exogenous rooting hormones in promoting rhizogenesis. The control treatment (T 1 ) exhibited a low mean number of primary roots at 1.89, with softwood cuttings (S 1 ) averaging 2.11 roots and semi-hardwood cuttings 1.67 roots as shown in Table 1. In contrast, treatments with IBA showed a marked increase in root formation, with T 2 (IBA 500 ppm) resulting in a mean of 2.83 roots, T 3 (IBA 1000 ppm) at 3.50 roots, T 4 (IBA 1500 ppm) at 3.94 roots and T 5 (IBA 2000 ppm) achieving the highest mean of 4.50 roots. NAA treatments also demonstrated enhanced root production, with T 6 (NAA 500 ppm) showing the highest mean of 4.67 roots, followed by T 9 (NAA 2000 ppm) at 4.06 roots, T 8 (NAA 1500 ppm) at 3.72 roots and T 7 (NAA 1000 ppm) at 3.33 roots. Softwood cuttings consistently produced more roots than semi-hardwood cuttings across all treatments. Statistical analysis via ANOVA confirmed that both hormone type and concentration, as well as cutting type, significantly influenced the number of primary roots (p < 0.05), with a significant interaction between hormone type and cutting type, indicating differential responses based on cutting type. This may be due to the appropriate plant growth regulator and its concentration, which increase the cell division, cell elongation and early differentiation of callus tissue towards the root formation resulted number of roots in cutting will increased. This is followed by root formation, which early absorb nutrients and water there by encourage sprouting in cutting. The results are in conformity with the findings of Netam et al. (2018) [7] in jasmine cuttings and Parmar et al. (2010) [8] in bougainvillea cuttings.

Average number of secondary roots:

The treatments significantly impacted the number of secondary roots, which are vital for plant robustness and nutrient uptake. The control group (T 1 ) recorded an average of 8.77 secondary roots, with softwood cuttings producing 9.56 roots and semi-hardwood cuttings 7.98 roots. IBA treatments showed a marked enhancement in secondary root formation, with T 2 (IBA 500 ppm) achieving a mean of 21.61 roots, T 3 (IBA 1000 ppm) increasing to 24.09 roots, T 4 (IBA 1500 ppm) reaching 26.89 roots and T 5 (IBA 2000 ppm) recording the highest mean of 29.67 roots. In contrast, NAA treatments also promoted secondary root growth, with T 6 (NAA 500 ppm) producing 18.56 roots, T 7 (NAA 1000 ppm) increasing to 20.56 roots, T 8 (NAA 1500 ppm) further rising to 22.22 roots and T 9 (NAA 2000 ppm) showing a significant increase to 27.08 roots. Across all treatments, softwood cuttings consistently generated more secondary roots than semi-hardwood cuttings. This might be due to its high concentration which would have stimulated the emergence of sprouts in the root zone of cutting. Similar findings were reported by Parmar et al. (2010) [8] in bougainvillea. Masoodi et al. (1994) [9] reported that 4000 mg l -1 IBA proved the best for the number of roots per cutting in Bougainvillea peruviana cv. Tourch Glory and in case of Glycyrrhiza glabra Linn. Deshmukh et al. (2006) [10] reported that IBA at 6000 ppm was found significantly superior for increasing the number of roots of Bougainvillea buttiana cv. Mahara. Root length of primary roots (cm): Root elongation, crucial for plant establishment and stability, showed significant variation across treatments. The control (T 1 ) had an average root length of 4.75 cm, with softwood cuttings at 4.91 cm and semi-hardwood cuttings at 4.60 cm. Treatments with IBA demonstrated progressive increases in root length: T 2 (500 ppm) at 5.95 cm, T 3 (1000 ppm) at 6.99 cm, T 4 (1500 ppm) at 8.86 cm and T 5 (2000 ppm) with the highest at 10.12 cm. NAA treatments also showed an increase: T 6 (500 ppm) at 5.50 cm, T 7 (1000 ppm) at 6.20 cm, T 8 (1500 ppm) at 7.15 cm and T 9 (2000 ppm) at 8.00 cm (Fig. 1). Both hormone type and concentration, as well as cutting type, significantly affected root length (p < 0.05), with interactions between hormone type and cutting type highlighting differential responses to the treatments. The result indicated that root length was significantly affected by IBA concentrations. This might be due to auxins plays main role in the process of root formation. For successful rooting induction, plants should be contained a certain quantity of IBA. Auxins can control cell enlargement, bud formation and root initiation and promote the production of other hormones (Kumari et al., 2013) [11] . Days taken to root emergence: The effect of different concentrations of IBA and NAA on the days taken for root emergence in 'Triadica sebifera' was evaluated using two types of cuttings: softwood and semi-hardwood. The results indicated that both the hormone type and concentration significantly influenced the time to root emergence. Cuttings treated with distilled water T 1 (control) took the longest time to initiate roots, with softwood cuttings averaging 42.68 days and semi-hardwood cuttings 44.00 days, resulting in a mean of 43.34 days. The application of IBA significantly reduced the days to root emergence in both cutting types. At 500 ppm, softwood cuttings rooted in 36.45 days and semi-hardwood in 38.82 days. Increasing IBA concentration further decreased rooting time, with the shortest time observed at 2000 ppm (30.00 days for softwood and 32.64 days for semi-hardwood, mean of 31.32 days). NAA also reduced the days to rooting, but less effectively than IBA at similar concentrations. NAA at 2000 ppm resulted in root emergence at 31.33 days for softwood and 33.64 days for semi-hardwood cuttings, with a mean of 32.49 days. Overall, softwood cuttings rooted faster than semi-hardwood cuttings across all treatments and higher concentrations of both IBA and NAA significantly accelerated root emergence.

Percentage of cutting rooted:

The percentage of rooted cuttings varied significantly across different treatments and hormone concentrations. The control treatment (T 1 ) had the lowest rooting percentage at 45%. Application of IBA (Indole-3-butyric acid) showed a positive correlation between concentration and rooting success. T 2 (IBA 500 ppm) improved the rooting percentage to 60%, T 3 (IBA 1000 ppm) to 70%, T 4 (IBA 1500 ppm) to 80% and T 5 (IBA 2000 ppm) achieved the highest rooting percentage of 90%. Similarly, treatments with NAA also demonstrated a concentration-dependent increase in rooting percentage. T 6 (NAA 500 ppm) resulted in 65% rooting, T 7 (NAA 1000 ppm) increased to 75%, T 8 (NAA 1500 ppm) to 85% and T 9 (NAA 2000 ppm) achieved the highest rooting percentage of 95%. Overall, the use of higher concentrations of both IBA and NAA significantly enhanced the rooting percentage, with NAA 2000 ppm (T 9 ) yielding the best results. IBA and NAA to enhance rooting in cuttings. They promote root initiation by stimulating cell differentiation in the cambium and formation of root primordia, mimicking natural auxins to enhance rooting efficiency (Haissig, 1974) [12] . These hormones also promote cell division and elongation, which are crucial for robust root development (De Klerk et al., 2011) [13] . Due to their stability and slow metabolism, IBA and NAA sustain their action longer than natural auxins, effectively inducing adventitious roots (Hartmann et al. 2011). They also reduce oxidative stress by increasing antioxidant enzyme activities, mitigating cellular damage during rooting (Da Costa et al., 2013) [14] . Additionally, IBA and NAA regulate gene expression involved in cell cycle and root meristem formation, further enhancing root development (Lavenus et al., 2013) [15] . Survivability of rooted cutting: The survival rates of the cuttings followed a pattern similar to that of the rooting percentage, demonstrating the influence of hormone treatment and concentration on cutting survival. For the control treatment (T 1 ), the survival rates were 40% for softwood cuttings and 35% for semi-hardwood cuttings. The use of IBA improved survival rates significantly: T 2 (IBA 500 ppm) resulted in 55% survival for softwood and 50% for semi-hardwood; T 3 (IBA 1000 ppm) improved to 65% and 60%, respectively; T 4 (IBA 1500 ppm) showed further improvement to 75% and 70% and T 5 (IBA 2000 ppm) had the highest survival rates at 85% for softwood and 80% for semi-hardwood. NAA treatments also increased survival rates in a concentration-dependent manner. T 6 (NAA 500 ppm) resulted in survival rates of 60% for softwood and 55% for semi-hardwood; T 7 (NAA 1000 ppm) improved to 70% and 65%, respectively; T 8 (NAA 1500 ppm) to 80% and 75% and T 9 (NAA 2000 ppm) had the highest survival rates of 90% for softwood and 85% for semihardwood. The data indicate that higher concentrations of both IBA and NAA significantly improve the survival rates of cuttings, with NAA 2000 ppm (T 9 ) again showing the best performance. The increased survival rates of cuttings treated with IBA and NAA are due to their roles in promoting root formation and enhancing stress tolerance. These synthetic auxins improve rooting success, which directly enhances water and nutrient uptake, critical for cutting survival (De Klerk et al., 2011) [13] . IBA and NAA also increase antioxidant enzyme activity in plant tissues, reducing oxidative stress and protecting cells from damage during the rooting process (Da Costa et al., 2013) [14] . Additionally, auxins enhance the synthesis of proteins involved in stress responses and cell repair, supporting survival under suboptimal conditions (Lavenus et al., 2013) [15] . Research has shown that IBA and NAA treatments increase endogenous auxin levels, promote cell division and improve physiological resilience, which collectively boost the survival rate of rooted cuttings (Aminah et al., 1995) [16] . By promoting root initiation and improving root systems, these treatments enhance overall plant health, leading to higher survival rates.

The root fresh mass is a critical indicator of the overall vitality and health of the root system, reflecting the plant's ability to absorb water and nutrients. The control treatment (T 1 ) showed a relatively low average root fresh mass of 2.5 g, with softwood cuttings at 2.8 g and semi-hardwood cuttings at 2.2 g, highlighting the limited effectiveness of natural rooting without hormone intervention. IBA treatments demonstrated a progressive increase in root fresh mass with increasing hormone concentrations. T 2 (IBA 500 ppm) resulted in an average fresh mass of 3.0 g, with softwood cuttings at 3.2 g and semi-hardwood at 2.8 g. T 3 (IBA 1000 ppm) saw a further rise to 3.5 g, with softwood cuttings at 3.8 g and semi-hardwood at 3.2 g. The most significant increases were observed in T 4 (IBA 1500 ppm) and T 5 (IBA 2000 ppm), with fresh masses of 4.0 g and 4.5 g, respectively, showing the highest fresh mass recorded at 4.8 g in softwood cuttings under T 5 . Similarly, NAA treatments followed a comparable trend, with T 9 (NAA 2000 ppm) achieving the highest root fresh mass of 4.8 g, emphasizing the efficacy of NAA in promoting root development, especially in softwood cuttings. The increase in root fresh mass (g) with the application of IBA and NAA can be attributed to their role as auxins, which are essential plant hormones that regulate root development. IBA and NAA promote cell elongation and division at the root meristem, leading to the formation of more root cells, which contributes to a greater overall mass (Blakesley et al., 1991) [17] . These synthetic auxins mimic natural auxins like indole-3-acetic acid (IAA), enhancing the initiation of adventitious roots and stimulating vascular differentiation, which is crucial for water and nutrient uptake, thereby increasing root fresh mass (De Klerk et al., 1999) [6] . Additionally, the presence of auxins at the root initiation site enhances the expression of genes involved in root development, further contributing to increased biomass accumulation in the roots (Gaspar et al., 1996) [5] . This auxin-induced root proliferation explains the observed increase in root fresh mass with higher concentrations of IBA and NAA (Hartmann et al. 2002). Root Dry Mass (g): Root dry mass serves as an essential measure of the root system's structural integrity and the plant's long-term ability to sustain itself, reflecting the accumulation of biomass. The control treatment (T 1 ) yielded an average root dry mass of 0.8 g, with softwood cuttings slightly higher at 0.9 g compared to 0.7 g in semi-hardwood cuttings. This baseline indicates the minimal biomass formation without hormone application. IBA treatments significantly enhanced the root dry mass, with T 2 (IBA 500 ppm) increasing to 1.0 g, T 3 (IBA 1000 ppm) to 1.2 g and T 4 (IBA 1500 ppm) to 1.5 g. The high est dry mass was observed in T 5 (IBA 2000 ppm), where the root dry mass reached 1.8 g, with softwood cuttings at 1.9 g and semi-hardwood at 1.6 g. NAA treatments also produced substantial gains in root dry mass, with T 6 (NAA 500 ppm) at 1.1 g, rising to 1.6 g in T 8 (NAA 1500 ppm) and peaking at 1.9 g in T 9 (NAA 2000 ppm). The data consistently showed that higher concentrations of both IBA and NAA resulted in greater root dry mass, particularly in softwood cuttings, underscoring the importance of exogenous hormone application for robust root development. The increase in root dry mass with the application of IBA and NAA is primarily due to their role in enhancing root development and secondary growth (De Klerk et al., 1999) [6] . IBA and NAA promote the formation of more root cells by stimulating cell division and elongation, which leads to greater root biomass (Hartmann et al. 2002). These auxins also encourage the differentiation of vascular tissues, particularly the xylem, which is essential for efficient water and nutrient transport, contributing to increased root thickness and mass (Gaspar et al., 1996) [5] . The higher root dry mass observed with these treatments reflects not only an increase in root volume but also the accumulation of structural carbohydrates and proteins, which are critical for the plant's overall stability and nutrient storage (Hartmann et al. 2002). As these roots develop, they become more lignified and robust, leading to an increase in dry mass, which is indicative of a more mature and functional root system (De Klerk et al., 1999) [6] . Fig. 2

Conclusion

The study demonstrated that rooting hormone concentration and cutting type significantly influenced rhizogenesis in Triadica sebifera (L.) Roxb. Softwood cuttings exhibited superior rooting performance compared with semi-hardwood cuttings. Overall, IBA at 2000 ppm was highly effective in promoting root development, particularly in terms of primary and secondary root growth, earlier root emergence and root biomass. NAA at 2000 ppm, however, recorded the highest rooting and survival percentage of rooted cuttings, while also producing comparable root biomass. Thus, the application of higher concentrations of IBA and NAA, particularly on softwood cuttings can be effectively utilized to improve vegetative propagation and facilitate the multiplication of T. sebifera under the temperate conditions of Kashmir.

Acknowledgement

AcknowledgementThe authors sincerely acknowledge the support and facilities provided by the Division of Floriculture and Landscape Architecture and the Division of Basic Sciences, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir (SKUAST-K), for their valuable assistance and cooperation in conducting this research.

References

1. Bruce KA, Cameron GN, Harcombe PA, Jubinsky G. Introduction, impact on native habitats and management of a woody invader, the Chinese tallow tree, Sapium sebiferum (L.) Roxb. Natural Areas Journal. 1997;17(3):255-260.
2. Wiesman Z, Riov J, Epstein E. Comparison of movement and metabolism of indole-3-acetic acid and indole-3-butyric acid in Mung bean cuttings. Physiologia Plantarum. 1988;74(3):556-560.
3. Ljung K, Bhalerao RP, Sandberg G. Sites and homeostatic control of auxin biosynthesis in Arabidopsis during vegetative growth. The Plant Journal. 2001;28(4):465-474.
4. Heloir MC, Kevers C, Hausman JF, Gaspar T. Changes in the concentrations of auxins and polyamines during rooting in-vitropropagated walnut shoots. Tree Physiology. 1996;16(5):515-519.
5. Gaspar T, Kevers C, Penel C, Greppin H, Reid D, Thorpe T. Plant hormones and plant growth regulators in plant tissue culture. In Vitro Cellular and Developmental Biology Plant. 1996;32(4):272289.
6. De Klerk GJ, Krieken VDW, De Jong JC. The formation of adventitious roots: new concepts, new possibilities. In Vitro Cellular & Developmental Biology-Plant. 1999;35(3):189-199.
7. Netam N, Neeraj S, Gaurav S, Jitendra KS. Effect of Different IBA concentration on survivability and rooting of Jasmine (Jasminum sambac (L.) Aiton) stem cuttings. Journal of Pharmacognosy and Phytochemistry. 2018;1:614-617.
8. Parmar BR, Patel VB, Bhalerao PP, Tank RV. Effect of different plant growth regulators on vegetative propagation of Bougainvillea peruviana cv. 'Torch Glory' through hardwood cutting. Asian Journal of Horticulture. 2010;5(1):222-224.
9. Masoodi NA, Shrivastava LJ, Mir NA. Studies on the effect of growth regulators on initiation of rooting in cuttings of Gylcyrrhiza glaba Linn. Indian Journal of Plant Physiology. 1994;1:28-29.
10. Deshmukh KK, Barad AV. Effect of growth regulators on rooting of stem cutting in Bougainvillea buttiana var. 'Mahara'. Crop research. 2006;32(3):391-393.
11. Kumari A, Arya MC, Joshi PK, Ahmed Z. Response of auxin on semi hardwood cuttings of Jatropha curcas under Central Western Himalayas, India. Agricultural Science Digest-A Research Journal. 2013;33(2):123-126.
12. Haissig BE. Influences of auxins and auxin synergists on adventitious root primordium initiation and development. New Zealand Journal of Forestry Science. 1974;4(31):317-323.
13. De Klerk GJ, Guan H, Huisman P, Marinova S. Effects of phenolic compounds on adventitious root formation and oxidative decarboxylation of applied indole-acetic acid in Malus 'Jork 9'. Plant Growth Regulation. 2011;63:175-185.
14. Da Costa CT, de Almeida MR, Ruedell CM, Schwambach J, Maraschin FS, Fett-Neto AG. When stress and development go hand in hand: main hormonal controls of adventitious rooting in cuttings. Frontiers in Plant Science. 2013;4:133.
15. Lavenus J, Goh T, Roberts I, Guyomarc'h S, Lucas M, De Smet I, Fukaki H, Beeckman T, Bennett M, Laplaze L. Lateral root development in Arabidopsis: fifty shades of auxin. Trends in plant science. 2013;18(8):450-458.
16. Aminah H, Dick JMCP, Grace J. Rooting of juvenile and mature Shorea leprosula cuttings: Effects of IBA and NAA. Forest Ecology and Management. 1995;73(1-3):117-126.
17. Blakesley D, Weston GD, Elliott MC. Endogenous levels of indole-3-acetic acid in relation to rooting in cuttings of several tree species. Journal of Plant Growth Regulation. 1991;10(1-4):163169.
18. Anderson RG, Woods TA. An economic evaluation of single stem cut rose production. Acta Horticulture. 1999;481:629-634.
19. Duke JA. Sapium sebiferum (L.) Roxb. Handbook of energy crops. In: New Crops: New crop resource online. West Lafayette, In Purdue University, Department of Horticulture and Landscape Architecture, Centre for New Crops & Plant Products; 1983.
20. Duncan WH, Duncan MB. Trees of the south-eastern United States. Athens: The University of Georgia Press; 2000. 18:322.
21. Gaspar T, Kevers C, Penel C, Greppin H, Reid DM, Thorpe TA. Plant hormones and plant growth regulators in plant tissue culture. In Vitro Cellular & Developmental Biology-Plant. 1996;32(4):272-289.
22. Godfrey RK. Trees, shrubs and woody vines of northern Florida and adjacent Georgia and Alabama. University of Georgia Press; 1988.
23. Hartmann HT, Kester DE, Davies FT, Geneve RL. Plant Propagation Principles and Practices (8th Edn.). New Delhi: Prentice Hall of India Private Limited; 2015. p. 36.
24. Hartmann HT, Kester DE, Davies FT, Geneve RL. Plant Propagation Principles and Practices (6th Edn.). New Delhi: Prentice Hall of India Private Limited; 2002.
25. Hartmann HT, Kester DE, Davies FT, Geneve RL. Plant Propagation: Principles and Practices. Prentice Hall; 2002.
26. Hartmann HT, Kester DE, Davies FT, Geneve RL. Plant Propagation: The Feasibility of Utilizing Tobacco Greenhouses as Propagation Facilities for Ornamental Plants. In Combined Proceedings International Plant Propagators' Society. 2002;52:440.
27. Hilbert DR, Roman LA, Koeser AK, Vogt J, van Doorn NS. Urban tree mortality: A literature review. Arboriculture & Urban Forestry. 2019;45(5):167-200.
28. Jaryan V, Uniyal SK, Gupta RC, Singh RD. Phenological documentation of an invasive species, Sapium sebiferum (L.) Roxb. Environmental Monitoring and Assessment. 2014;186:44234429.
29. Lieux, Meredith Hoag. Dominant pollen types recovered from commercial Louisiana honey. Economic Botany. 1975;29:87-96.
30. Roxb.]. International Journal of Advanced Biochemistry Research. 2026;SP-10(9):2136-2142. doi: https://www.doi.org/1