摘要：Nitrogen (N) is considered as one of the most essential nutrients that influences the leaf growth, herbage yield and protein content of oat as a forage crop. The majority of N absorption by plants are occurred almost immediately before the stem elongation stage for rapid growth, whereas the demand of N is maximum at early to maximum vegetative stage. However, to obtain maximum herbage and grain yield and also to increase N use efficiency, it is important to apply N when crop is physiologically prepared to generate tillers and also crop is at a favourable environmental conditions. In the context, the current research was undertaken to describe the effects of different levels of N on herbage, seed yield and nutrients content of oat at the Agricultural Research Station of Iğdir, Turkey during the year 2014. Treatments were four levels of N with a control treatment: 0, 30, 60, 90 and 120 kg N ha~(-1). After experimentation, it was observed that increasing levels of N improved the plant length, green herbage and seed yield. The herbage yield of oat was increased from 16.0 to 31.1 t ha~(-1) due to the increase of N levels. Similarly, the crude protein (CP%) was increased from 7.57 to 10.0 % by increasing N levels upto 120 kg ha~(-1). Although, no significant difference in CP % was observed among the levels of N, but numerically the maximum CP % was recorded from the maximum level of N (120 kg ha~(-1)), followed by 60 and 90 kg N ha~(-1). The neutral detergent fiber (NDF) and acid detergent fiber (ADF %) did not differ significantly among treatments. Numerically, the highest NDF % and the lowest ADF % were recorded from 120 kg N ha~(-1) treatment. But, dry matter digestibility (DMD), digestible energy (DE) and metabolisable energy (ME) of Oat herbage were influenced significantly by different levels of N. The maximum DMD, DE and ME were recorded from the maximum levels of N (120 kg N ha~(-1)), followed by 60 kg N ha~(-1). In case of grain yield (GY) and yield attributes, the maximum values were also recorded from 120 kg N ha~(-1), followed by 90 kg N ha~(-1) and the lowest values for all parameters and harvest index were recorded from control plot. In conclusion, application of N fertilizers to wild oat at a rate up to 120 kg N ha~(-1) can improve the yield and nutrient composition of oat herbage with more favorable nutritional facts for livestock.
