Influence of supplemental foliar application of nitrogen and potassium on the grain yield, concentration and efficiency of nitrogen in rice (Oryza sativa L.)

A randomized complete block design with three replications was performed in Rice Research Institute of Iran, Rasht in 2008, to find the effect of supplement foliar application of nitrogen and potassium on Bahar-1 hybrid rice’s grain yield, concentration and efficiency of nitrogen. Foliar application of 20 kg nitrogen (5 % N) and 15 kg potassium (3 % K2O) in different pre-anthesis stages (maximum tillering, booting, and both stages) was considered as treatments. Foliar application of distilled water was considered as control. Results revealed that the grain yield and grain protein yield were increased in treatments which nitrogen and potassium was applied in pre-anthesis stages compared to control treatment. Foliar fertilization in booting stage resulted to the highest amount of grain and straw nitrogen. No significant effect of foliar fertilization was seen on potassium amount of grains. Foliar nitrogen application had no significant effect on agronomic and physiological efficiency and apparent recovery of nitrogen. However, nitrogen uptake efficiency increased by 14.8 % compared to control treatment in maximum tillering stage. The highest amount of grain protein (11.6 %) was related to foliar application of nitrogen in both maximum tillering and booting stages compared to control. Overall, it could be concluded that maximum tillering and booting stages are the best pre-anthesis time for foliar application of nitrogen and potassium on cv. Bahar-1 hybrid rice.