Potato (Solanum tuberosum L.) Tuber Yield and Yield Components as Influenced by Different Levels of Nitrogen, Phosphorus and Potassium in Rwanda

Abstract

Despite potato yield potential, its intensification level remains low in Rwanda, translating into low yield occasioned mainly by the decline in soil fertility. Field experiments were conducted in Birunga, Mudende [L1]) and Buberuka, Rwerere [L2] highlands Agro-ecological zones (AEZs), during September to December 2016 and March to June 2017 crop growing seasons to determine the effects of varying rates of N, P and K on potato tuber yield and yield components. The experiments were laid out using a randomized complete block design with a factorial arrangement, with four replicates. Factors were N rates (NX) i.e N1-0 kg ha-1, N2 – 50 kg ha-1, N3 – 100 kg ha-1 ; P2O5 rates (PX) i.e P1-0 kg ha-1, P2 – 50 kg ha-1, P3 – 100 kg ha-1and K2O rates (Kx) i.e K1- 0 kg ha1and K2- 50 kg ha-1. Number of tubers per plant, fresh tuber weight, small tuber yield, medium tuber yield, large tuber yield, and total tuber yield were measured. Analysis of variance, performed using SAS-version 9.2, revealed that interaction effects of N×P×K were very highly significant on all parameters. Generally, N3P3K2 performed better than other treatments and recorded highest tuber yields in all situations: (32.73 ± 0.43) t ha-1[L1] and (29.36 ± 0.41) t ha-1 [L2] and (31.05 ± 0.52) t ha-1for pooled analysis of variance (ANOVA). Contrarily to what happened at L2, N3P3K2 and N2P3K2 were not significantly different at L1. N2P3 K2 is recommended to L1 whereas N3P3K2 is recommended to L2. Key words: Potato, N-P-K nutrients, location-specific fertilizer recommendation, Rwanda.