The effect of nitrogen and phosphorous application on growth, yield and nutritional quality of vegetable amaranth (amaranthus hybridus)
Two field studies and laboratory experiments were carried out at Kabete Campus, University of Nairobi, between November 1994 and October 1995. The aim of the study was to find out the effect of nitrogen and phosphorous applications on growth, leaf yield and nutritional quality of vegetable amaranth. There were four levels of each treatments and it was conducted on a split plot design with three replications. Growth parameters evaluated included plant height, number of leaves, leaf area index and stem diameter. Fresh weight and dry weight were taken to determine yields. Nutritional quality of leaves was evaluated by analysing for crude fibre, crude protein, dry matter, beta carotene, calcium, iron, phosphorous as well as oxalates and nitrate contents. It was observed that applying seventy five kilogrammes of nitrogen in one hectare gave a .maximum height of thirty three centimetres. A height of thirty two point six centimetres was achieved with the application of sixty kilogrammes of phosphorous n one hectare. Nitrogen application gave a significant effect on stem diameter. Phosphorous application gave a significant effect on leaf area index. Both fresh weights and dry weight were significantly increased with increased application of nitrogen and phosphorous. The nutritional quality of leaves were modified by the application of nitrogen and phosphorous. Crude protein and beta carotene contents increased with the application of nitrogen. The mineral contents of calcium, iron and phosphorous tended to increase with the application of nitrogen and phosphorous. However, the levels of crude fibre and oxalates were significantly reduced with the application of nitrogen and phosphorous.