For studying study of seedling age on the yield and yield component of rice cultivars. The experimental was applies in education and research farm of Islamic Azad University in Chalous on 2012 of Iran. The primary factor of seedling age (20, 27, 35 days) and the secondary factor of rice cultivar (Tarem Deylamani, Danesh, Nok Siah) were considered. The greatest seed’s yield had been related to the 27 days seedling age among the seedling ages with 5.82 ton per hectare. Among the cultivars of the maximum and minimum yield of the seed was produced in Tarem Deylamani cultivar with 6.47 ton per hectare and Fajr cultivar as well with 4.87 ton per hectare. The greatest yield of the seed was produced under the counter effect of 2 factors for Tarem Deylamani cultivar. The weight of a thousand seed influenced by the cultivar and the counter of seedling age on the cultivar became probably 1%. The maximum weight of a thousand seed influenced by the seedling age was produced for the 27 day age (22.08 gr) and the least was for the 20 day age (20.23). The maximum weight of a thousand seed was produced in the 27 day of seedling age and Tarem cultivar (27 gr) due to the counter effect of seedling age.
