Effects of Plant Growth Regulators on Prickles Density, Growth and Physiological Characteristics of Zanthoxylum bungeanum

To screen for plant growth regulators that inhibit prickle development, four plant growth regulators, namely lovastatin, n-1-naphthylphthalamic acid, salicylic acid, and paclobutrazol, were sprayed separately on the leaves of Zanthoxylum bungeanum seedlings. Spraying the solvent (methanol Silwet l - 77 aqueous solution) was used as the control treatment, with 3 replicates for each treatment. Subsequently, the changes in the density of prickles and the main growth physiological indicators were analyzed. The results showed that all the four plant growth regulators could affect the development of prickles, and were able to change the growth status of the seedlings, photosynthetic physiology, nutrient accumulation capacity, and their distribution patterns. However, there were differences in the effects of different plant growth regulators. Among them, the spraying of lovastatin reduced the density of prickles on the stems and rachis by 12.84% and 34.10% respectively. Moreover, it could promote root development, increase the content of photosynthetic pigments, as well as the nitrogen and potassium contents in the leaves, and the biomass of the seedlings increased by 26.63%. N-1-Naphthylphthalamic Acid reduced the density of prickles on the rachis of Z. bungeanum by 22.16%, and improved the nutrient status and photosynthetic performance of the leaves. Salicylic acid and paclobutrazol reduced the density of prickles on the rachis by 27.19% and 18.70% respectively, but the growth of the seedlings was inhibited. Lovastatin may have a greater potential to induce the prickleless or less-prickle state of Z. bungeanum.