Effect of irrigation and nitrogen level on yield, yield components and some morphological traits of sunflower

To study the effect of water deficit and N fertilizer on some morphological traits, yield and yield components of sunflower cv. Progress, a study was carried out as a split plot experiment based on a Randomized Complete Block Design with three replications in research field of Islamic Azad University, Birjand Branch, Iran in 2009. In this study, the irrigation was the main plot at three levels including supplying 100, 67 and 33% of plant water requirement (PWR) and N fertilizer was the sub-plot at four levels of 0, 60, 90 and 120 kg N/ha. The results of analysis of variance showed that irrigation significantly affected plant height, stem diameter, head diameter, seed number per head, 1000-seed weight and seed yield, and N significantly affected all morphological traits, yield and yield components, but the interactions between irrigation and N level significantly affected none of the studied traits. The treatment of supplying 100% of PWR produced the highest seed number per head (680.43), 1000-seed weight (46.58 g) and seed yield (3567.67 kg/ha) which was superior over the treatments of supplying 67 and 33% of PWR by 24.1 and 67% in the case of seed number and by 27.2 and 57.8% in the case of 1000-seed weight, respectively. The seed yield under the treatment of supplying 100% of PWR was 2.64 times greater than that under the treatment of supplying 33% of PWR and with the decrease in supplying PWR from 100 to 33%, plant height, stem diameter and head diameter decreased by 32, 21.9 and 30.8%, respectively. In addition, with the increase in N fertilizer level from 0 to 120 kg/ha, plant height, stem diameter, leaf number, head diameter, seed number/head, 1000-seed weight and seed yield significantly increased by 15.6, 14.4, 13.2, 17.1, 24.2, 13 and 49.1%, respectively. In total, on the basis of the results, the treatment of optimum irrigation and application of 120 kg N/ha can be recommended for realizing high productivity in sunflower cultivation under the conditions of the current study.