Short growing seasons and late season heavy rains are the main challenge of rice cultivation in ‎North of Iran. Thus, the isolation of novel mutants with higher yield, a shorter growing period ‎‎(earlier maturity date), and high grain quality is necessary. Chemical agents can be beneficial ‎since they provide high mutation rates to produce variants for tolerance to biotic/abiotic stress ‎conditions (Jain, 2010). The dose assessment for chemicals is characterized by altering the ‎duration and concentration of treatment, the solvent used (e.g. dimethyl sulfoxide), or the pH of ‎the solution (Jain, 2005). Gohar is a high yielding variety with slender grains and good cooking ‎quality. The variety is late in maturing, requiring a growing period of 135 to 140 days (seed to ‎seed) under local conditions. Therefore, it is of particular importance to improve the variety in ‎order to thus havinge early maturing varieties with a growing period of less than 115 days (seed to ‎seed). The aim of this work has been to select new lines of rice (Gohar variety) that are high ‎yielding, early maturing, and with good grain cooking quality.‎