Overview of Common Rooting Powder Formulations
1. Indole-3-Acetic Acid (IAA) and Naphthylacetic Acid (NAA) Rooting Powder
The most widely used rooting powder on the market is a 50% mixture of Indole-3-Acetic Acid (IAA) and Naphthylacetic Acid (NAA) (comprising 30% IAA and 20% NAA). IAA is an endogenous plant hormone naturally present in plants; it induces the formation of adventitious roots and promotes the proliferation of lateral roots. Upon entering the plant, NAA induces ethylene production; at low concentrations, endogenous ethylene also promotes rooting. Application method: For peanuts and wheat, treat seeds with a concentration of 20–30 mg/kg; this accelerates seed germination and the rate of root formation.
2. Indole-3-Butyric Acid (IBA) and Naphthylacetic Acid (NAA) Rooting Powder
Another common rooting powder on the market is a 50% mixture of Indole-3-Butyric Acid (IBA) and NAA (comprising 40% IBA and 1% NAA). This type of rooting powder appears as a white to pale red powder; it is readily soluble in organic solvents, slightly soluble in warm water, and insoluble in cold water. This formulation is frequently used to promote rooting in cuttings of trees and ornamental flowers. Application methods include: the rapid soaking method (concentration of 500–1000 mg/L, soaking the lower 3–4 cm of the cutting for 10–15 seconds) and the slow soaking method (concentration of 10–100 mg/L, soaking the lower 3–4 cm of the cutting for 12–24 hours). Lower concentrations and shorter durations are used for plants that root easily, while higher concentrations and longer durations are used for plants that are difficult to root.
3. Indole-3-acetic acid (IAA) and catechol rooting powder
When English ivy cuttings (20–25 cm in length) were treated at the basal cut with IAA at a concentration of 10 mg/kg, the average number of roots per cutting was 1.3. However, when a mixture of IAA (10 mg/kg) and catechol (5 × 10⁻⁵ mol/L) was applied to the basal cut, the average number of roots per cutting rose to 9.4, demonstrating a significant synergistic effect. Research indicates that catechol effectively inhibits the biological activity of IAA oxidase within the cuttings, thereby allowing the exogenously applied IAA to fully exert its root-inducing function and resulting in superior rooting performance; conversely, in the absence of catechol, IAA entering the plant tissue is rapidly oxidized and inactivated by IAA oxidase, leading to poor rooting results.
4. Indole-3-acetic acid (IAA) and saccharin
Using kidney bean seedlings (2 cm tall) as test material, the plants were soaked for 16 hours in solutions of either 0.02% indole-3-acetic acid (IAA) or 0.0019% saccharin (sulfobenzoic acid) before being transplanted to a greenhouse for hydroponic growth. After 12 days of treatment, the number of lateral roots was assessed; treatment with 0.02% IAA alone resulted in 42 roots per plant, while treatment with 0.0019% saccharin alone did not increase the number of lateral roots. However, the combined application of IAA and saccharin (0.02% + 0.0019%) resulted in as many as 96 lateral roots per plant, demonstrating a clear synergistic effect. Similarly, applying the mixture of IAA and saccharin to rose seedlings significantly promoted lateral root formation. Subsequent research revealed that this mixture promotes lateral root formation in seedlings of various agricultural and horticultural plants, often exhibiting a synergistic effect.
5. Abscisic acid (ABA) and IAA rooting powder
Abscisic acid (ABA) inhibits gibberellin biosynthesis and thus promotes rooting in cuttings. Using cowpea hypocotyls as cutting material, treating the base of the cuttings with ABA (S-ABA) alone at concentrations of 1–5 mg/kg promoted rooting, as did soaking the base in IAA (5 mg/kg) alone. However, the combined application of ABA and IAA (1–5 mg/kg ABA + 5 mg/kg IAA) demonstrated a synergistic effect in promoting rooting in cowpea hypocotyl cuttings. When ABA (1.25–15 mg/kg) was combined with potassium indole-3-butyrate (K-IBA) or IAA (5–25 mg/kg) to promote rooting or stimulate root growth in plants such as peas, tomatoes, grapes, and poplars, additive effects were observed in most cases, with synergistic effects appearing under certain conditions; however, excessively high concentrations of ABA inhibited rooting. 6. Combined use of fulvic acid and potassium indole-butyrate
In an experiment involving one-year-old apple cuttings, soaking the cuttings for 12–24 hours in a 500-fold dilution of fulvic acid alone promoted rooting, as the absorbed fulvic acid stimulates the activity of certain invertases. Soaking for 12–24 hours in potassium indole-butyrate (20 mg/kg) alone also promoted rooting. However, the combined use of fulvic acid and indole-butyrate (500-fold dilution plus 20 mg/kg) increased the number of roots formed.
The most widely used rooting powder on the market is a 50% mixture of Indole-3-Acetic Acid (IAA) and Naphthylacetic Acid (NAA) (comprising 30% IAA and 20% NAA). IAA is an endogenous plant hormone naturally present in plants; it induces the formation of adventitious roots and promotes the proliferation of lateral roots. Upon entering the plant, NAA induces ethylene production; at low concentrations, endogenous ethylene also promotes rooting. Application method: For peanuts and wheat, treat seeds with a concentration of 20–30 mg/kg; this accelerates seed germination and the rate of root formation.
2. Indole-3-Butyric Acid (IBA) and Naphthylacetic Acid (NAA) Rooting Powder
Another common rooting powder on the market is a 50% mixture of Indole-3-Butyric Acid (IBA) and NAA (comprising 40% IBA and 1% NAA). This type of rooting powder appears as a white to pale red powder; it is readily soluble in organic solvents, slightly soluble in warm water, and insoluble in cold water. This formulation is frequently used to promote rooting in cuttings of trees and ornamental flowers. Application methods include: the rapid soaking method (concentration of 500–1000 mg/L, soaking the lower 3–4 cm of the cutting for 10–15 seconds) and the slow soaking method (concentration of 10–100 mg/L, soaking the lower 3–4 cm of the cutting for 12–24 hours). Lower concentrations and shorter durations are used for plants that root easily, while higher concentrations and longer durations are used for plants that are difficult to root.
3. Indole-3-acetic acid (IAA) and catechol rooting powder
When English ivy cuttings (20–25 cm in length) were treated at the basal cut with IAA at a concentration of 10 mg/kg, the average number of roots per cutting was 1.3. However, when a mixture of IAA (10 mg/kg) and catechol (5 × 10⁻⁵ mol/L) was applied to the basal cut, the average number of roots per cutting rose to 9.4, demonstrating a significant synergistic effect. Research indicates that catechol effectively inhibits the biological activity of IAA oxidase within the cuttings, thereby allowing the exogenously applied IAA to fully exert its root-inducing function and resulting in superior rooting performance; conversely, in the absence of catechol, IAA entering the plant tissue is rapidly oxidized and inactivated by IAA oxidase, leading to poor rooting results.
4. Indole-3-acetic acid (IAA) and saccharin
Using kidney bean seedlings (2 cm tall) as test material, the plants were soaked for 16 hours in solutions of either 0.02% indole-3-acetic acid (IAA) or 0.0019% saccharin (sulfobenzoic acid) before being transplanted to a greenhouse for hydroponic growth. After 12 days of treatment, the number of lateral roots was assessed; treatment with 0.02% IAA alone resulted in 42 roots per plant, while treatment with 0.0019% saccharin alone did not increase the number of lateral roots. However, the combined application of IAA and saccharin (0.02% + 0.0019%) resulted in as many as 96 lateral roots per plant, demonstrating a clear synergistic effect. Similarly, applying the mixture of IAA and saccharin to rose seedlings significantly promoted lateral root formation. Subsequent research revealed that this mixture promotes lateral root formation in seedlings of various agricultural and horticultural plants, often exhibiting a synergistic effect.
5. Abscisic acid (ABA) and IAA rooting powder
Abscisic acid (ABA) inhibits gibberellin biosynthesis and thus promotes rooting in cuttings. Using cowpea hypocotyls as cutting material, treating the base of the cuttings with ABA (S-ABA) alone at concentrations of 1–5 mg/kg promoted rooting, as did soaking the base in IAA (5 mg/kg) alone. However, the combined application of ABA and IAA (1–5 mg/kg ABA + 5 mg/kg IAA) demonstrated a synergistic effect in promoting rooting in cowpea hypocotyl cuttings. When ABA (1.25–15 mg/kg) was combined with potassium indole-3-butyrate (K-IBA) or IAA (5–25 mg/kg) to promote rooting or stimulate root growth in plants such as peas, tomatoes, grapes, and poplars, additive effects were observed in most cases, with synergistic effects appearing under certain conditions; however, excessively high concentrations of ABA inhibited rooting. 6. Combined use of fulvic acid and potassium indole-butyrate
In an experiment involving one-year-old apple cuttings, soaking the cuttings for 12–24 hours in a 500-fold dilution of fulvic acid alone promoted rooting, as the absorbed fulvic acid stimulates the activity of certain invertases. Soaking for 12–24 hours in potassium indole-butyrate (20 mg/kg) alone also promoted rooting. However, the combined use of fulvic acid and indole-butyrate (500-fold dilution plus 20 mg/kg) increased the number of roots formed.
