Effect of progressive bi-monthly weeding on the yield of yam (dioscorea Esculenta) at Saramandi, East Sepik Province.

Abstract

Lesser yam (Dioscorea esculenta var Mangilmu) was planted in a weeding trial in which weeding duration was 0, 2, 4, 6, 8 and 10 months after planting (MAP), allowing weed competition in five out of six treatments. Total yield increased from 4.2 t/ha with no weeding to 7.7 t/ha with weeding for four MAR It then slightly decreased between weeding for four and eight MAP to 6.4 t/ha and yielded the highest at 9.3 t/ha under weeding for 10 MAP. Total yields with weeding for zero and two MAP were significantly (P<0.05) lower than with 10 MAP, and yield with weeding for four MAP was also significantly higher than with no weeding. Total tuber number only for 0 weeding (11470/ha) was significantly lower than 15760/ha from weeding for 10 MAP. Tuber number and yield proportion of large tubers increased with increased duration of weeding. Weeding for four and two MAP gave the highest estimated net incomes per hectare of K13, 457 and K12.518 after subtracting the weeding cost.