The international Irrigated rice observational nursery (IIRON-Early)‎( IIRON-Early‎).

This study, 38th International rice observational nursery- early, was conducted with 68 genotypes including 64 genotypes from different country, 3 international checks and one national check in Rice Research Institute of Iran-Rasht and Amol in 2012. The experimental design was augmented in randomized complete block design with four replications. Each line was transplanted on 5m‎ أ ‎1.4m plot in Rasht and 2m‎ أ ‎2.5m in Amol with hill spacing of 20cm‎ أ ‎20cm. In this study quantitative traits such as paddy yield, plant height and days to 50% of flowering date were recorded. Analysis of variance in Rasht and Amol showed a highly significant difference among genotypes (checks) and the difference among blocks was not significant for all traits. Mean comparison of the traits for check varieties showed that the best variety for paddy yield was IR72. Mean comparison of non-replicated genotypes with check (IR72) using the least significant differences (LSD) method showed that the genotype No 032 had the highest Paddy yield(7224kg/ha). Genotypes No 058, 039, 051, 041, 047 and 014 were the high yielding rice genotypes with 6053-7143Kg/ha that were significant differences at 5% and 1% probability level with IR72. The earliest genotypes which had significant differences at 1% level with check were 057, 060, 059, 063, 018 and 058 with the less heading date 72, 76, 76, 78, 80 and 81 days to 50% of flowering, respectively. Genotypes No 043 and 051 were also recognized as suitable growth duration genotypes with 94 and 93 days to 50% of flowering, respectively. Consequently genotypes No 058, 051 and 060 with 7143, 6550 and 5527 kg/ha paddy yield, respectively were selected as highest yield and earliest maturity genotypes for advance researches of Rasht. In Amol genotype No 038(IR04A117) was selected as a high yielding and medium maturity line (7050.2 kg/ha). In addition genotypes 048,057,059,060 and 063 were highly significant earlier than local Tarom with 80 days to 50% of flowering. Key words: Rice, early maturity, yield comparison, augmented design, IIRON-Early