Influence of auxin type and concentration on propagation responses of hardwood cuttings of bougainvillea ‘Partha’

Introduction

Bougainvillea is an important ornamental woody climber valued for its prolonged display of brightly coloured bracts and its adaptability to tropical and subtropical landscapes. Commercial multiplication depends largely on clonal propagation because vegetative methods preserve cultivar identity. Hardwood cuttings are inexpensive and suitable for nursery-scale multiplication, but rooting performance can vary with genotype, physiological condition, rooting environment and auxin treatment. Auxins regulate adventitious root formation through effects on cell division, differentiation and root primordium development. Indole-3-butyric acid (IBA) is widely used for rooting woody cuttings because of its relative stability, while indole-3-acetic acid (IAA) and naphthalene acetic acid (NAA) can also modify sprouting and rooting responses. Earlier work in bougainvillea has shown substantial cultivar-and concentration-dependent responses to auxins. Singh (2012) [1] reported significant effects of IBA concentration and cultivar on sprouting and rooting, and Kumar et al. (2021) [2] observed differential responses of hardwood cuttings to IAA, IBA and NAA. More recent studies likewise demonstrate that rooting response depends on both auxin dose and propagation conditions (Qudoos et al., 2024; Kumar et al., 2026) [3,4] . Information on the response of cultivar 'Partha' to different auxins is limited. The present investigation therefore compared IAA, IBA and NAA at three concentrations for their effects on the timing of bud and root initiation and on subsequent leaf, bud and root development in hardwood cuttings of bougainvillea 'Partha'.

Material and methods

The experiment was conducted at Kolaghat, West Bengal, India, beginning on 22 March 2021. Hardwood cuttings of bougainvillea 'Partha' were used. The experiment comprised 10 treatments in a randomized block design with three replications. Each treatment contained seven cuttings per replication, giving 210 cuttings in total. Plant-to-plant spacing was 10 cm and the recorded plot length was 290 cm. The propagation beds were covered after planting and individual treatment units were tagged.

Results and discussion

Auxin treatments altered both the onset of growth and the magnitude of subsequent shoot and root development (Table 2). First bud initiation ranged from 7 to 15 days. T 3 (IAA 1500 ppm) was earliest at 7 days, followed by T 7 and T 9 at 8 days, whereas the control required 15 days. With a reported CD (5%) of 2.30 days, the 8-day advantage of T 3 over the control was substantial. Root initiation was earliest under T 2 (IAA 1000 ppm; 7 days), followed by T 6 (IBA 1500 ppm; 8 days), compared with 14 days in the control (CD 5% = 2.06 days). These responses indicate that IAA was particularly effective for accelerating the initial developmental events in 'Partha'. Post-initiation growth showed a different pattern. The maximum leaf number was recorded in T 6 (IBA 1500 ppm; 21 leaves per cutting), closely followed by T 4 and T 5 (20 leaves), while the control produced only 9 leaves. The reported CD (5%) was 3.47, indicating a clear improvement of the higher-performing IBA treatments over the control.

Bud number varied from 2.4 in the control to 3.5 under T 5 (IBA 1000 ppm); the difference exceeded the reported CD of 0.29. The superior vegetative growth under IBA may reflect improved root-system development and consequently greater capacity for water and nutrient acquisition. Root-system quality was most strongly enhanced by IBA. T 6 (IBA 1500 ppm) recorded 10.5 roots per cutting and a mean root length of 9.8 cm, compared with 5.6 roots and 1.4 cm in the control. T 4 and T 5 also produced more than 10 roots per cutting with mean root lengths above 9 cm. The reported CD (5%) values were 1.39 roots and 2.44 cm for root length. These findings are consistent with the estab-lished role of IBA in adventitious rooting of bougainvillea. Singh (2012) [1] documented improved rooting responses to IBA in several bougainvillea cultivars, while Kumar et al. (2021) [2] reported strong root growth under IBA in 'Manila Red'. Variation among published optimum concentrations emphasizes that auxin requirement is genotype-and environment-dependent rather than universal.

Conclusion

The study demonstrates distinct auxin-specific responses in hardwood cuttings of bougainvillea 'Partha'. IAA at 1500 ppm accelerated bud initiation and IAA at 1000 ppm accelerated root initiation, whereas IBA at 1500 ppm gave the strongest overall root and leaf development. On the basis of the measured traits, IBA at 1500 ppm is a promising treatment for nursery propagation where a well-developed root system is the principal objective. Future validation should include rooting and survival percentages, shoot length and biomass,

References

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7. How to cite this article: Maiti P, Reja RM, Tirki S, Chowdhuri TK, U H. Influence of auxin type and concentration on propagation responses of hardwood cuttings of bougainvillea 'Partha'. International Journal of Advanced Biochemistry Research. 2026;SP-10(9):2076-2081. doi: https://www.doi.org/10.33545/26 174693.2026.v10.i9Sz.10121