Effect of indole-3-butyric acid concentrations on root and shoot morphogenesis and nursery establishment of dragon fruit (Hylocereus undatus (Haw.) Britton & Rose) stem cuttings

The rapid expansion of commercial dragon fruit (Hylocereus undatus (Haw.) Britton & Rose) cultivation necessitates the standardisation of reliable vegetative propagation protocols for producing high-quality planting material. A 2-year field investigation (2023–24 and 2024–25) was conducted at the Central Nursery, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani, Maharashtra, India (19.26° N, 76.78° E, 409 m above mean sea level), to evaluate the effects of different indole-3-butyric acid (IBA) concentrations (I1 = 5000 ppm, I2 = 6000 ppm and I3 = 7000 ppm; quick dip for 10–15 sec) on adventitious rooting, shoot morphogenesis, sapling survival and economic returns. Exogenous IBA treatments induced significant (P < 0.05) variation in all evaluated parameters. Application of IBA at 6000 ppm (I2) consistently gave superior performance in both seasons and in the pooled analysis. The minimum number of days to shoot initiation was recorded under I2 (34.34 days) and this treatment also gave the greatest shoot length at 120 days after sprouting (DASp) (38.13 cm), absolute growth rate (0.25 cm day-1), relative growth rate (0.019 cm cm-1 day-1), shoot fresh weight (130.63 g) and shoot dry weight (26.10 g). For rhizogenesis, IBA at 6000 ppm produced the highest number of primary roots per cutting (18.20 at 120 DASp), maximum root length (25.20 cm), root density (0.112 mg cm-3, equivalent to 1.84 mg in-3), root fresh weight (15.20 g) and root dry weight (5.28 g). The same treatment optimised nursery establishment, with a peak survival of 83.07 %, lowest mortality of 16.93 % and a balanced root-to-shoot length ratio of 0.80. Increasing the concentration to 7000 ppm (I3) produced supra-optimal auxin inhibition, delaying sprouting (36.96 days), reducing primary root number (16.70) and root density (0.094 mg cm-3) and raising mortality to 32.77 %. Economic evaluation, recomputed treatment-wise, established IBA at 6000 ppm as the most profitable treatment (gross B:C ratio 2.33; net B:C ratio 1.33). A quick-dip treatment of IBA at 6000 ppm is therefore recommended for efficient, high-quality and commercially viable nursery production of dragon fruit saplings.