Effect of nitrogen splitting and supplemental irrigation on yield, yield components, and oil percentage of sunflower

In order to study the effect of nitrogen splitting and supplemental irrigation on yield, yield components and oil percentage of sunflower a factorial experiment was conducted based on randomized complete block design on farm research of Gonbad University with three replications during crop year of 2019.

Treatments in this experiment included nitrogen splitting (none consumption of nitrogen (as control), 25% of nitrogen at planting time and 75% before flowering, 50% of nitrogen at planting time and 50% before flowering and 75% of nitrogen at planting and 25% before flowering and supplemental irrigation (none irrigation ((as control)), supplementary irrigation at flowering stage, supplemental irrigation at grain filling stage, supplemental irrigation at flowering stage and grain filling stages) in four levels.

The results showed that consumption of 25% nitrogen at planting time and 75% before flowering led to the highest increase in number of grains per row, number of grains per head, one thousand-grain weight, grain yield (4318 kg.ha-1) and harvest index. Consumption of 75% nitrogen at planting time and 25% before flowering increased the number of rows per capita. None consumption of nitrogen increased oil percent though oil yield decreased. Irrigation at flowering and grain filling stages increased the number of grain per capita, grain weight, and grain yield (4427 kg.ha-1).

According to the results, irrigation at flowering and grain filling stages as well as application of 25% nitrogen at planting time and 75% before flowering is suitable to achieve optimum sunflower yield.