Response of sensitive to lodging rice cultivar to nitrogen levels in heading stage and phosphorus rates at the north of Iran

This experiment was done as factorial in randomized complete block design with three replications. Nitrogen levels in heading stage chosen as (0, 50 and 100 kg ha-1 as P2O5) and phosphorus rates as (0, 75, 150 and 225 kg ha-1 as Urea) were treatment. Results showed that stem length, fourth inter-node bending moment, total tiller number per hill, fertile tiller per hill, grain yield and straw yield had significant in nitrogen levels at 1 % and plant height and panicle length had significant in nitrogen levels at 5 % level probability. The highest grain yield (590.1 g m2) was produced for 100 kg N ha-1. Maximum straw yield was produced in 100 kg N ha-1, and minimum of that had observed for control and 50 kg N ha-1. The most plant height, flag leaf length, total tiller number and fertile tiller number were obtained for 50 and 100 kg N ha-1, but the highest forth inter-node bending moment was observed in control and 50 kg N ha-1. Plant height, stem length, flag leaf length, and fourth inter-node bending moment increased 11.54, 11.99, 13.48, 6.78 % by phosphorus application. Lowest fourth inter-node bending moment had observed at interaction of 100 kg N ha-1 × control. The highest grain yield was produced at interaction of 100 kg N ha-1 × control. Therefore, application of 100 kg N in heading stage due to highest grain yield and rice plant was the best treatment, because of deficit phosphorus in soil, showed the best response to 225 kg P ha-1.

Lodging, Nitrogen, Phosphorus, Rice, Yield.