Application of 2-(3, 4-dichlorophenoxy) triethylamine (DCPTA) as a treatment to sugarbeet (Beta vulgaris L. cv. Dihill) seed enhanced leaf and root development and increased taproot sucrose yield, as compared with that of controls. During mid-exponential plant growth, seed treatment with 1ppm DCPTA increased leaf growth and total leaf area development 98% and 75%, respectively, as compared with controls. The increased canopy size of DCPTA-treated plants was caused by delayed senescence of older, mature leaves. After 5 months growth, taproot fresh weight of 10ppm DCPTA-treated plants was increased 28% over that of controls. The sucrose content (%, fresh weight) of these taproots was 15% greater than that of controls, which gave a 47% increase in the sucrose yield per taproot. Taproot in-terring widths between vascular rings two, three, and four of DCPTA-treated plants were generally unchanged relative to controls, suggesting that plant growth regulation by DCPTA does not adversely affect photosynthate partitioning between taproot development and sucrose accumulation. Our results indicate that 10ppm DCPTA seed treatment increased the sucrose yield of ‘Dihill’ sugarbeet.