Abstract:
A controlled experiment was conducted in the CIP field, located in Nwalate, in Boane district, between October 2015 to March 2016 in order to evaluate the effect of potassium fertilizer on yield and quality of varieties of Orange-Fleshed Sweet Potato (OFSP) (Ipomoea batatas (L.) Lam). The experimental design was in Completely Randomized Blocks (DBCC) in an arrangement of split plots with four (4) replicates, consisting of five (5) varieties of OFSP (Delvia Erica, Lourdes, Irene and Gloria) allocated in the main plots and four (4) potassium levels (0, 50, 100 and 150 kg ha -1 ) allocated in the sub-main plots. Statistical analyses were performed using the Sisvar and Sigmaplot where were analyzed yield, average number of roots per plant (NMRP), average weight of roots (PMR), contents of β-carotene content, dry matter (MS), starch, reducing sugars and protein. The analysis of variance showed that there was a joint variation between the potassium level and variety factors, indicating dependence between the variables potassium level and varieties on the commercial and total average productivity of the roots. As for the root quality parameters analyzed, ANOVA showed that there was a joint variation between the variety and potassium level factors on the all quality parameters of sweet potatoes, with the exception of reducing sugars, indicating that there is a dependence of the potassium level on the production of dry matter, β-carotene, protein and starch. The variation in the production of reducing sugars was due to the variety factor. The level 50 kg.ha -1 of potassium applied generated high average commercial yields for the Delvia, Irene and Gloria varieties (24,82; 20,07 and 14,06 ton.ha -1 , respectively) and the level 100 kg.ha -1 generated high average commercial yields for the Erica and Lourdes varieties (41,18 and 40,36 ton.ha -1 , respectively). The economic viability analysis indicated results positive gross margins in all K 2 O applied levels for Erica and Lourdes varieties
