Grain yield and protein concentration of two amaranth species ( Amaranthus spp.) as influenced by the nitrogen fertilization

Abstract

Amaranth, an alternative cereal, is attracting researchers’ attention mainly because of the high nutritional value of its seed, which can be influenced by nitrogen fertilization. The goal of the research carried out on eutric cambisol in Zagreb in the period 2002–2004 was to determine the influence of nitrogen fertilization upon seed yield, seed protein concentration, 1000-seed weight, dry matter content in flowering, plant height and inflorescence length of two grain amaranth varieties belonging to different species: G6 ( Amaranthus cruentus L.) and 1008 ( Amaranthus hypochondriacus L.) grown in the agroecological conditions of north-western Croatia. As nitrogen fertilization is among the most important factors of high yielding of all field crops, knowledge of the grain amaranth nitrogen requirements has an important role for its efficient production. Nitrogen was applied before sowing at the rates of 0, 50 and 100 kg ha −1. Application of 50 and 100 kg N ha −1 led to a significant increase of seed yield and 1000-seed weight compared to the control (without nitrogen fertilization) only in the dry 2003. Seed protein concentration was not affected by nitrogen fertilization. A. hypochondriacus L. gave a higher seed yield while A. cruentus L. had a higher 1000-seed weight. Nitrogen fertilization had no influence on the dry matter content in flowering and plant height. Responses of tested species to weather conditions differed with respect to the said agronomic traits. In the years with higher precipitation A. cruentus L. had a higher dry matter content, while a significantly higher dry matter content in flowering was recorded for A. hypochondriacus L. in the dry 2003. In all the three trial years, A. cruentus L. achieved greater plant height and inflorescence length, but the difference was statistically significant only for plant height in 2002. Positive correlations were recorded between plant height and inflorescence length as well as between inflorescence length and seed yield.