assessment of terminal heat stress and nitrogen on grain yield and yield com-ponents of canola.

in order to study the effects of terminal heat stress and nitrogen on morphophysiological characteristics, anue (agronomical nitrogen use efficiency) and yield of canola, an experiment was conducted at research farm of ramin agricultural sciences and natural resources university. the experiment was arranged in split plots based on randomized complete block design with four replications. main plots included three n fertilizer levels consisted of 90, 180, and 270 kg.ha-1 nitrogen and control. sub plots were considered as two sowing dates, nov.11 (optimum condition) and jan.26 (terminal heat stress condition). results showed that terminal heat stress and nitrogen had significantly effect on all measured parameters while effect of nitrogen on anue was not significant. the two levels of 180 and 270 kg.ha-1 nitrogen had no significantly different effects on plant height, leaf number, sub branch number, lai and anue. in addition, interaction effects between terminal heat stress and nitrogen was significant on some parameters. in both of optimum and terminal heat stress conditions, increase in used nitrogen led to significantly more yield. nitrogen had no significant effect on anue. decrease in nitrogen levels caused decrease of final grain yield. also, terminal heat stress decreased grain yield about 59 percent. our result suggested that increased nitrogen could have a positive effect on terminal heat stress tolerance of canola.