The Influence of Nitrogen Fertilizer Application on Yields and Nitrogen Use Efficiencies of <i>Solanum macrocarpon</i> and <i>Solanum scabrum</i> in Southwest Nigeria

Abstract

Solanum macrocarpon and Solanum scabrum are good sources of vitamin, minerals, protein, anti-oxidants and fiber in southwest Nigeria. The study examined the effects of nitrogen fertilizer application on yields and nitrogen use efficiencies of Solanum macrocarpon and Solanum scabrum in Iwaro-Oka, Ondo State in southwest Nigeria in 2014 and 2015. The experiment was a 4 × 4 factorial arranged into a randomized complete block design with four rates of urea-N drilled at 0, 40, 80 and 160 kg/ha and replicated four times. Each plot was 3 m × 2 m with space of 1 m between plots. Vegetable seeds were planted by drilling. Fresh shoot and dry matter yields were determined. Nitrogen content and uptake were determined, and nitrogen use efficiency estimated. The result showed that average dry matter weight for S. macrocarpon was 228 kg/ha and S. scabrum was 6116 kg/ha. Average nitrogen uptake was 5.90 kg/h and 158.60 kg/ha for S. macrocarpon and S. scabrum , respectively. Nitrogen use efficiencies were 6.48 kg/ha, 0.15 kg/ha and 0.1 kg/ha for S. macrocarpon and 87.33 kg/ha, 26.14 kg/ha and 24.35 kg/ha for S. scabrum at 40, 80 and 160 kg N/ha, respectively. Negative values were obtained for N-recovery for S. macrocarpon while S. scabrum gave 5.85%, 2.10% and 1.44% at 40, 80 and 160 kg N/ha, respectively. The study concluded that S. scabrum had higher nitrogen use efficiency in the soil than S. macrocarpon and that highest NUE and N recovery were obtained at 40 kg N/ha.