Sensitivity of Peach Seedling Vegetative Growth to Paclobutrazol

Abstract

Abstract ‘Nemaguard’ peach seedlings [Prunus persica (L.) Batsch] were grown for 21 days in nutrient solution cultures containing a range (0 to 3.4 μM) of paclobutrazol concentrations. Shoot growth rate and total extension growth were reduced by all paclobutrazol treatments. Within 2 days of treatment, paclobutrazol at 3.4 μM significantly reduced the growth rate, as did the 3.4 × 10 −2 μM concentrations after 5 days. Increases in paclobutrazol concentrations decreased leaf area and leaf, stem, and shoot weights. However, specific leaf weight increased as paclobutrazol concentration increased. Leaf expansion was more sensitive to paclobutrazol treatments than stem elongation. As paclobutrazol concentration increased, root extension growth was reduced, but roots were thicker and produced more laterals near the tip. Compared with the control, paclobutrazol at 3.4 × 10 −1 and 3.4 × 10 −2 μM significantly increased the root: shoot ratio. Chemical name used: β-[(4-chIorophenyl)methyl]-α-(1,1-dimethylethyl)-1 H- 1,2,4-triazole-1-ethanol (paclobutrazol).