Growth rate, yield and protein content of two leafy vegetables as affected by nitrogen fertilization

The growth rates, yields and protein content of Amaranthus cruentos, L. and Sesamum radiatum, Schum. were studied at different levels of nitrogen application under rainfed conditions in the Guinea savanna ecological zone of Nigeria. Nitrogen application was 0,45,90 and 180 kg N ha⁻¹ for amaranth and 0,30,60 and 90 kg N ha⁻¹ for sesame. The results showed that at the highest level of N application, amaranth (a C4 plant) had a very high growth rate coefficient (0.471 ha⁻¹ day⁻¹) before cutting while the growth rate coefficient of sesame (a C3 plant) was lower (0.221 ha⁻¹ day⁻¹). The growth rate coefficients of both plants were drastically reduced after cutting; the values were 0.21 and 0.07 (ha⁻¹ day for amaranth and sesame, respectively. Total shoot and leaf dry matter yields increased significantly up to 45 and 60 kg N ha⁻¹, for amaranth and sesame, respectively. The crude protein contents of the leaves at first harvest of amaranth and sesame were high and averaged about 30% on a dry weight basis.