Response of Growth Indices of Sunflower (Helianthus annuus L.) To Different Level of Deficit Irrigation and Nitrogen Fertilizer

BACKGROUND: Growth analysis is a suitable method for plant response to the different environmental conditions during crop life. Nitrogen is the most significant nutrient to improve yield and quality of sunflower seeds. It is an essential plant nutrient to stimulate plant growth and development and ultimately yield and quality. OBJECTIVES: This research was conducted to assessment effect of different levels of irrigation regime and nitrogen fertilizer on growth curves traits of sunflower. METHODS: Current study was carried out according split plot experiment based on randomized complete blocks design with four replications. The main factor included irrigation regime and nitrogen fertilizer (N1: 50, N2: 100 and N3: 150 kg.ha-1) belonged to sub factor. RESULT: Evaluation comparison different level of irrigation regime indicated that maximum amount of studied traits (instead net assimilation rate) was noted for I1 treatment and minimum of that belonged to I2 and I3 treatment, respectively. Compare different level of nitrogen revealed the highest amount of total dry weight, leaf area index, crop growth rate was belonged to use 150 kg.ha-1 nitrogen (N3) and the lowest ones was found for 50 kg.ha-1 nitrogen (N1), but net assimilation rate had the reverse trend. CONCLUSION: The results show apply low irrigation should be done in stages that have less impact on the final yield crop needs less water and less sensitivity at that stage, and nitrogen can also play a constructive role, but it is recommended to use less nitrogen under deficit irrigation. Although I1 treatment had the superior amount of growth indices but under water limitation I3 treatment can considered for producers.