Effects of different plant growth regulators on rooting of Pinus yunnanensis

To investigate the effects of plant growth regulators on the rooting of Pinus yunnanensis cuttings, this study used lateral branches of two-year-old P. yunnanensis seedlings as cutting materials. The cuttings were treated with different concentrations of IAA, NAA, and ABT1. After 40 days, the cuttings were observed and surveyed to statistically evaluate the rooting rate, average number of roots, average root length, maximum root length for each treatment and replicate, and to calculate the root system effectiveness coefficient. The differences in rooting growth and the effects of hormone type and concentration on root system development were analyzed. Results showed that treatment ABT1 200 g/cm³ had the best performance in rooting rate, average number of roots, and root system effectiveness coefficient across all treatments, with all indicators significantly higher than those of other treatment groups (P<0.05), indicating a strong promoting effect on P. yunnanensis cuttings. Treatment NAA 500 g/cm³showed significantly higher average and maximum root lengths compared to other treatment groups (P<0.05). Analysis of the variation coefficient of root system indicators indicated that plant growth regulators and their concentrations effectively reduced the variation coefficient of root system indicators to 2.44%–51.67%, significantly affecting the stability of root system indicators. Correlation analysis revealed a significant positive correlation between plant growth regulators and P. yunnanensis cutting rooting indicators. Plasticity analysis showed that except for the average number of roots, all other indicators had plasticity greater than 0.5, suggesting that P. yunnanensis cuttings respond to different hormones and concentrations mainly through changes in rooting rate, average root length, maximum root length, and root system effectiveness coefficient to promote rooting. Comprehensive analysis indicated that plant growth regulators at certain concentrations all promoted P. yunnanensis cutting rooting, with ABT1 significantly improving root system quality. The best treatment was ABT1 200 g/cm³, while the NAA 500 g/cm³ treatment is more suitable for situations aiming at root elongation.