Productivity of lesser yam (Dioscorea esculenta) in PNG as influenced by sett weight and staking.

Abstract

Field experiments were conducted to determine the effects of sett weight and staking on the productivity of the lesser yam, (Dioscorea esculenta. (Lour.) Burk). Setts weighing 100 g, 200 g, 300 g, or 400 g were grown with or without staking. Increasing sett weight resulted in significant increases in total tuber yield (from 38 to 75 tonnes ha'), net tuber yield (harvest yield less the weight of planting material) (from 36 to 67 tonnes ha1), yield of marketable tubers (>100 g) (from 35 to 71 tonnes ha1), number of marketable tubers (from 5.0 to 6.5 plant1), and mean weight per marketable tuber (from 340 to 539g tuber'). Staking also significantly increased each of these yield variables, as well as total tuber number per plant. The total tuber yield increased from 44 to 70 tonnes hanet tuber yield increased from 39 to 66 tonnes ha1, yield of marketable tubers (>100 g) increased from 41 to 66 tonnes ha1, total number of tubers increased from 10 to 12 plant', number of marketable tubers increased from 5.1 to 6.1 plant', and mean weight per marketable tuber increased from 468 to 611g tuber1 with staking The multiplication ratio (tuber weight produced Auber weight that was planted) declined as sett weight increased show that without staking small planting setts (100g) produced a mean yield of marketable tubers of 27 tonnes ha Although this was significantly less than the 91 tonnes ha marketable yield from the staked plants grown from larger setts (400g) it is suggested that a producer after considering the economic and environmental savings due to not staking and the a higher multiplication ratio from the smaller setts may be willing to tolerate a reduced yield.