Investigation the sink characteristics of contrast rice (Oryza sativa L.) cultivars under different nitrogen applications Poshtmasari Hossein Kazemi1,2, Pirdashti Hemmatollah1,2, Bahmanyar Mohammad Ali1,3, Nasiri Mortaza1,4 1Member of Young Research Club of Islamic Azad University (Rasht Branch), Sari, Iran 2Department of Agronomy and Plant Breeding, Mazandar University, Sari, Iran 3Department of Soil Science, Mazandaran University, Sari, Iran 4Rice Research Institute of Mazandaran (Amol), Amol, Iran Abstract In order to study nitrogen applications and cultivar effects on some traits in relation to sink characteristics in the contrast rice (Oryza sativa L.) cultivars, a field experiment was carried out in the Rice Research Institute of Iran-Deputy of Mazandaran (Amol) - during 2005. A split plot experiment on the basis of randomized complete block design with 3 replications and 3 factors were used. It includes 3 levels of fertilizer rates (100, 150 and 200 kg.ha−1 from urea source) as main plots, and 3 split levels of nitrogen at transplanting S1 (50%, 25% and 25%), tillering S2 (25%, 50% and 25%) and heading stages S3 (25%, 25% and 50%) as sub plots and three cultivars (Tarom, Shafagh and Bahar1 hybrid) were raised in as ultimate plots. Results showed that nitrogen management and cultivar had significant effects on all the traits studied in relation to sink (grain number per panicle, panicle length and panicle number of m2). Shafagh and Bahar1 were found superior than Tarom for all traits except for grain weight. Interaction effects between cultivar and transplanting showed highest paddy yield related to Shafagh cultivar. Among sink characteristics, grain number per panicle had the highest and positive correlation with paddy yield. In general, modern cultivars (Shafagh and Bahar1) had higher sink capacity than Tarom a traditional cultivar (considered as a sink - limiting cultivar). Top Key words Rice, sink, nitrogen fertilizer, split application, contrast cultivars. Top |