Interaction Of Compound Fertilizer Rate And Plant Spacing On Vine And Root Yeild Of Sweetpotato (Ipomoea batatas (L.) Lam) In Degrated Ultisol

ABSTRACT

A two year field experiment was conducted during the growing seasons of 2015 and 2016 at National Root Crops Research Institute, (NRCRI) Umudike, South eastern Nigeria to evaluate the response of sweetpotato variety (UMUSPO 1kj) to four rates (0 ,200, 400 and 600kgha^-1) of NPK 15:15:15 fertilizer and four levels of plant spacing (15,20,25 and 30cm). The experiment was laid out as a factorial in randomized complete block design (RCBD) with three replications. Result showed that fertilizer significantly (P < 0.05) increased vine length at 4 and 16 weeks after planting in 2015 when 400kgha^-1 of fertilizer was applied with the longest vine length observed at 30cm plant spacing at 8 and 12 WAP in 2015 while in 2016, it ranged from 43.6 to 59.2 respectively with 15cm that gave the longest vine length. Fertilizer had no significant (P>0.05) effect on yield of sweetpotato in both years but the yield obtained in wet season was higher than that of dry season when 400kgha^-1 of fertilizer was applied across the both years.