Hasan Haghshenas - Department of Agronomy and Young Research Club, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran.
Abbas Ghanbari Malidarreh - Department of Agronomy, Jouybar Branch, Islamic Azad University, Jouybar, Iran.

This study examined to compare high-yielding cultivars and respond to N fertilization especially yield component and the aim of this development of rice cultivars suitable for low input requirements. An experiment was arranged in a randomized complete block design with a split-plot arrangement of five rice cultivars, three N rates with four replications in ۲۰۱۱ in Iran. N rates including ۰, ۶۹, and ۱۳۸ kg N/ha as (N۰), (N۶۹) and (N۱۳۸) and rice cultivars including Nemat (C۱), Khazar (C۲), Neda (C۳), Shirodi (C۴), and Tarom (C۵). The results indicated that all traits response to cultivar and N rates were detected for the parameters examined. The lowest applied N rate had a lower yield than the other two N rates. Grain yields were ۵۵۵۲ for ۶۹ kg N/ha and ۶۱۲۴ for ۱۳۴ kg N/ha averaged over all cultivars. The grain yield of Khazar and Tarom was independent of the N rate, but the grain yield of Nemat, Neda and Shirodi increased when the N rate was increased from ۶۷ to ۱۳۸ kg/ha. Panicle density responded to an N rate similar to grain yield. Khazar produced more total spikelet number while Neda had a higher Panicle density. Grain yield and yield components of Nemat, Neda, and Shirodi respond to N rates dependently when planted into high nitrogen. Finally, modern rice cultivars were more efficient at recovering N than older cultivars.

rice, nitrogen, Cultivar, Tiller, Panicle