Six accessions of Pachyrhizus tuberosus (Lam.) Spreng. and one of P. erosus were cultivated in three field trials in 1994, 1995, and 1996 under rain-fed conditions in the Kingdom of Tonga, South Pacific, in order to investigate the impact of reproductive and vegetative pruning on plant production. Trial designs were Split-Plot with treatments as main plots and accessions as sub-plots. Reproductive pruning gave an overall increase in tuber yield of 51.5% in comparison with the control (P. tuberosus: 29.2% and P. erosus: 102.1%). Vegetative pruning had no effect on tuber yield. Significant differences among accessions were found for tuber yield, roundness, dry matter (DM), and soluble solids content of tubers, top yield, DM of top, and the number of tubers developed per plant. Tubers from reproductively-pruned plants had more regularly shaped and smooth tubers than from control plants.