Influence of nitrogen fertilisation on yield of Amaranthus species

One of the essential elements for normal plant growth is nitrogen. Leaf vegetables have a great nitrogen demand because of high vegetative volume. The objective of the study was to determine the growth and yield responses of two Amaranthus species (A. hybridus and A. hypochondriacus) to nitrogen fertilisation. Although many other leaf vegetables had been evaluated for their responses to fertiliser application; the amaranth crop was chosen for its nutritional importance in the diet of many communities in Africa as substantial amount of protein, minerals and vitamins could be obtained from the crop. A field study was conducted to evaluate the effect of nitrogen fertiliser on growth and yield of the crop. Four rates of nitrogen fertiliser (0, 50, 100, and 200 kg/ha) were applied. Results showed that plant height, number of leaves produced, fresh and dry weights of plant parts increased with increased rate of nitrogen fertiliser. Application of fertiliser at the rate of 200kg N/ha increased leaf production by 75% and 60% in A. hybridus and A. hypochondriacus respectively compared to the control. While 120% and 114% yield increases in edible portion at the vegetative stage were observed in A. hybridus and A. hypochondriacus treated with 200kg N/ha respectively. The unfertilized plants also had yellowish green coloration compared to the brighter green color observed in fertilized plants. Furthermore, A. hybridus produced higher fresh matter yield than A. hypochondriacus, while the latter had higher seed yield. Nitrogen fertilization at the rate of 100kg N/ha appeared to be optimum for A. hybridus.