اثر رقابت نوري و كود نيتروژن بر ساختار كانوپي گندم و يولاف وحشي

Effect of light competition and Nitrogen fertilizer on canopy structure of wheat and wild oat

The effect of light competition and nitrogen fertilizer on canopy structure of wheat and wild oat was studied by two experiments. The 1st experiment which carried out at the field research station was an addetive experiment using a split plot experiment, based on a randomized complete block design, with 4 replications. Amounts of nitrogen topdressing (25, 50, 75 and 100 kg N ha-1) were assigned to the main plots and wild oat plant densities (0, 30, 50 and 80 plant m-2) were assigned to the subplots. The population of wheat was 400 plant m-2. The 2ʹd experiment which was conducted at the greenhouse was a replacement series experiment using a factorial experiment, based on a randomized complete block design, with 4 replications. Amounts of nitrogen topdressing were 0, 0.5, 1, 1.5 and 2 grams per pot, and relative densities of wheat and wild oat were 100:0, 75:25, 50:50, 25:75 and 0:100. The results of the addetive experiment indicated that, by increasing wild oat plant density, the proportion of upper layer of wild oat canopy from shoot dry matter and leaf area index was increased. In pure stand of wheat light absorption was more than mixed canopy and light was extended at upper height of canopy. Vertical distribution of shoot dry matter in both species was not affected by nitrogen amounts. In the replacement series experiment leaf nitrogen content at all laters of wheat pure stand canopy was less than mixed canopy, wheares wild oat pure stand had more leaf nitrogen content at all its layers.