Agronomic and yield responses of selected improved sweet potato cultivars to different rates of organic fertilizer in the Niger Delta region, Nigeria

Abstract

The increased demand for sweet potato has led to increased cultivated acreage, with heterogeneous soil nutrient levels, resulting in increased use of inorganic fertilizer with residual effects in the environment. This study thus evaluated the response of selected improved sweet potato varieties to different application rates of organic fertilizer. Seven improved cultivars of sweet potato (UMOSPO 1, UMOSPO 3, UMOSPO 4, KWARA (Local cultivar 1), TIS/087, BUTTER MILK, and NWAOYIRIMA (Local cultivar 2)) were planted in plots fertilized with four rates (0, 15, 30, and 45 ml) per plant of liquid organic fertilizer in the 2020 and 2021 planting seasons. The experiment was a 7 (cultivars) by 4 (nutrient rate (NR)) factorial arranged in a randomized complete block design with three replicates. The vine length (VL), leaf area (LA), and fresh tuber weight (FTW) were collected and analyzed using ANOVA, and means were separated using least significant differences at 5% level of significance. Application of organic fertilizer significantly increased vine length, leaf area, and fresh tuber weight. The highest vegetative growth was recorded at a fertilizer rate of 45 mL. At the same time, cultivar TIS/087 produced the highest tuber yield with VL, LA, and FTW of 143.57±6.07 cm and 82.76±5.23 cm2, and 0.62±0.09, respectively, while cultivar TIS/087 produced the highest tuber yield.