Response of Some Bread Wheat (Triticum aestivum L.) Cultivars to Nitrogen Levels

A factorial experiment was conducted at the research field of College of Agriculture, University of Duhok, Summel, Kurdistan region/Iraq, during the season 2014 – 2015. The study aimed to investigate the response of growth and yield of five bread wheat cultivars namely: SHIF-7, NS733, QAF2AH- 31, ALFAJER-1 and TAMUS to different nitrogen levels (0, 100, 120, 140 kg N ha-1). Using randomized complete block design (RCBD) with three replications. The results showed significant differences among the tested wheat varieties for plant height, No. of days to %50 flowering, biological yield, 1000 - grain weight, grain yield Index, total chlorophyll and protein content. The majority of studied traits were maximum with wheat varieties SHIF-7 and ALFAJER-1. Nitrogen levels were also exhibited the significant effect on all studied traits except in few cases. It was found that the application of N up to 120 Kg N ha-1 significantly increased plant height, biological yield, no. of grain spike-1, grain yield, harvest index, total chlorophyll and protein content. The greatest grain yield 433g 1.2m-2 (≃ 3608.3 Kg ha-1) was obtained with interaction between SHIF-7 × 120 Kg Nha-1. However, according to these study, it might be suggested that, rate of 120 Kg N ha-1 with varieties SHIF-7 and ALFAJER-1 could be recommended for appropriate wheat production under local environmental condition.