摘要：Italian ryegrass is often fertilized with high levels of nitrogen (N) in order to ensure a maximum biomass yield. While overdose of any fertilizer is neither cost-effective nor environmentally sound. In this context, the study was carried out at the agricultural experimental area of Igdir University during 2013, to find out the optimum dose of nitrogenous fertilizers for maximizing the biomass yield as well as nutrients content of Italian ryegrass. Treatments were five levels of nitrogen viz., 0 (N_o), 2 (N_2)，4 (N_4), 6 (N_6) or 8 (N_8) kg da~(-1), respectively. Treatments were arranged in a randomized completed block design with three replications. Data on green herbage and dry biomass yield as well as nutrients content such as Calcium (Ca), Magnesium (Mg), potassium (K), phosphorus (P), Crude protein (CP), Crude ash and Tetany ratio (K/(Ca+Mg)) were examined under the different levels of N. Results of the study showed that increasing rate of N fertilizer increased the green herbage as well as dry biomass yield of Italian ryegrass. The highest green herbage and dry biomass yield were recorded for the 8 kg N da~(-1) (N_8) (1142.7 and 473.7 kg da~(-1)) treated grass followed by those treated with a 6 kg N da~(-1) (N6) (1070.2 and 444.8 kg da~(-1)). Similarly, the maximum seed yield was also recorded in the treatment of 8 kg N da~(-1), followed by the treatment of 6 kg N da~(-1). Considering the nutritional values, the levels of N and K in the ryegrass were decreased from the initial growth stages to seed stages. While, CP, Mg, P and Tetany ratios were decreased as growth stages of plant increased. Therefore, the application of 6 to 8 kg N da~(-1) could be recommended for higher green herbage, dry biomass yield and also improving the nutrients content of Italian ryegrass under the condition of Igdir-Turkey.
关键词：Italian ryegrass;harvest time;biomass yield;nutritive value
