Study the flag leaf related characteristics of rice (Oryza sativa L.) varieties in response to different levels and application of nitrogen

Flag leaf has the most efficient photosynthetic element among different organs of rice during grain filling. In order to study the effect of nitrogen levels and applications on flag leaf characteristics, three groups of varieties, Tarom, Shafagh, and Bahar l hybrid) were examined at a field in Rice Research Institute. Deputy of Mazandaran (Amol)-in 2005. A split split Plot according to Randomized Complete Block Design with three replications and three factors were used. Nitrogen rates at three levels (including 46, 69 and 92 kg. N ha1 from the urea source), spilt at the three levels (in transplanting, tillering and heading stages) including: S1 (50%, 25% and 25%) S2 (25% , 50% and 25%) and S3 (25%, 25% and 50%) and varieties, amount of nitrogen and application times were considered as the main plot, sub-plot and the sub-sub-plot, respectively. Results showed that, leaf area and chlorophyll content of the flag leaf were affected by nitrogen levels, split application of nitrogen affected varieties. Split application of nitrogen and varieties affected only the dry matter of the flag leaf but nitrogen content of flag leaves were stable. Among the application times, S2 had the highest effect on the most studied traits. Bahar 1 hybrid had the highest values of charachters related to flag leaf, but it had lower yield than Shafagh, due to high nonfilling grain per panicle.