Abstract

Most fertilizer studies on yam are concerned with its effect on tuber yields. In this study yam tuber moisture, starch, ash and dry matter contents of three hybrid yams Dioscoreae rotundata (TDr 89/02677, TDr 89/02565 and TDr 89/02665) grown with nine combinations of N, P and K fertilizers (F₀, F₁, F₂, F₃, F_4, F_5, F₆, F₇, and F₈) on a Typic Paleudult in southeastern Nigeria were evaluated after harvest. The soil was characterized. Results showed that the soil was acidic with a pH (H₂0) of 4.96 and deficient in total N (0.11%) and exchangeable K (0.06 cmol/kg). The quality parameters were not significantly influenced by hybrid yams. Fertilizer rates increased dry matter and starch contents of yam tubers except at 90 kg N, 8 kg P and 25 kg K/ha which had 0.83 and 0.56% depressant effects on starch and dry matter, respectively. Highest significant improvement (9.5%) in starch content was achieved at a fertilizer rate of 60 kg N, 8 kg P and 50 kg K/ha, indicating the potentials of fertilizer in improving qualities of yam tubers on acid soils of soils of southeastern Nigeria.

Key words:  Fertilizer, hybrid yam, starch, dry matter, Typic Paleudult.