The effect of nitrogen on the yield and quality of vegetable amaranth

Abstract

The effect of nitrogen on the yield and quality of three species of vegetable amaranth, namely; Amannthus hypochondriacus, A.tricolar, and A.hyridus was studied under field conditions for three different planting times during the planting season of 1996/97. ln the first experiment seven different nitrogen levels viz 0. 25, 50, 75, 100, 125, and 150 kg N ha-1 were evaluated and only yield data was taken. The last two experiments saw addition of two more treatments viz. 175and 200 kg N ha-1 bringing the total number of treatments to nine. Data collected in the last experiment consisted of yield data (fresh and dry matter) and quality (nutritional composition and total nitrogen content). Nitrogen fertilizer was found to significantly increase the yield of vegetable amaranth, with all three species showing varietal/genotypic differences in the response to nitrogen fertilizer. The yields declined with delay in planting time and with the last planting lower yields were obtained. Nutritional composition, although not analyzed in its entirety, showed vegetable amaranth to compare favorably with other leafy vegetables. Total nitrogen content increased with levels of nitrogen application. Unlike yields, nitrogen content increased with delay in planting date with the autumn crop having a higher nitrogen content than the spring and summer plantings. Varieta/genotypic difference was also confirmed with A. tricolor accumulating more nitrogen than the other species. Plant age was also found to play an important role with younger plants containing more nitrogen than older ones.