Dry matter remobilization and yield of durum wheat in Ardabil, Iran as affected by plant density and N fertilization level

In order to study the effect of different N fertilization levels on dry matter remobilization of durum wheat cv. Seymareh at different planting densities, a study was conducted at Agriculture Research Station of Islamic Azad University, Ardabil Branch, Ardabil, Iran in 2009 as a split plot experiment based on a Randomized Complete Block Design with three replications. The main plot included plant densities at three levels of 300, 350 and 400 seeds.m-2 and the sub-plot included N fertilization at four levels of 0, 70, 140 and 210 kg.ha-1. Results revealed that as N fertilization level was increased, straw dry weight and biological yield were increased whereas dry matter remobilization rate from whole plant and stem to grain and contribution of dry matter remobilization and stem reserves to grain yield were decreased. Also, the application of 140 kg N.ha-1 gave rise to the highest grain yield, the highest number of spikes, 1000-grain weight and harvest index and further increase in N fertilization level resulted in loss of grain yield and other traits. As plant density per unit area was increased, all studied traits were increased except 1000-grain weight and harvest index. Therefore, in order to increase the contribution of dry matter remobilization and grain yield, to avoid environmental contamination and to decrease (excessive) fertilization application which increases production costs, it is recommended to use N fertilization level of 140 kg.ha-1 and the density of 400 plants.m-2 under the conditions of the current study.