Journal of Science, Technology, Mathematics and Education (JOSTMED), 12(2), August, 2016 2 MUTAGENIC EFFECTS OF UREA AND COLCHICINE ON TWO RICE LANDRACES (FARRAR JOLLOF AND YAR ZAMFARA) AT M 1 GENERATION. ALIYU, R. E., BAYERO, U, ADEBOLA, M. I., AMINU, A., & ADAMU, A. K 1 Department of Biological Sciences, Faculty of Science, Ahmadu Bello University, Zaria, Nigeria. Email: s.ramatu@gmail.com , enehezeyi@abu.edu.ng Phone No: +234-803-366-8634 Abstract This research was aimed at determining the effective dose and efficiency of urea and colchicine to induce morphological variants on the growth and development of Farrar jollof and Yar Zamfara rice at M 1 generation. Morphological variants were induced with varying concentrations of colchicine (0.00, 0.0125, 0.1, 0.125, 0.5 and 1.0mM) and nitrosomethyl urea (0.00, 0.125, 0.5 and 1.0mM). The effects of the mutagens on the landraces were concentration dependent following a non- progressive model. Emergence rate of the seedlings were 75% and 42% for urea and colchicine application respectively. The mutation frequencies induced by nitrosomethyl urea on Farrar jollof and Yar Zamfara was 13.89% and 18.06% respectively. Similarly, colchicine induced a mutation frequency of 43.89% on Farrar jollof and 23.89% on Yar Zamfara. The mean efficiency of urea and colchicine were 64.98% and 58.75% respectively. Highly significant (p< 0.01) effects of mutagens on most morphological traits evaluated were observed. Effective dose of nitrosomethyl urea and colchicine on Farfar jallof was 0.5mM and 0.0125mM respectively. Additionally, the effective dose of urea and colchicine on Yar Zamfara was 0.125mM and 0.1Mm respectively. Chlorophyll deficient mutants were induced by nitrosomethyl urea (6.25%- albina, chlorine and virescent) in Yar Zamfara (6.94%) and Farrar jallof (5.56%). However, the mutagens failed to exert significant improvements on the yields of the cultivars. Conclusively, colchicine and nitrosomethyl urea induced morphological mutants in Yar Zamfara and Farrar jallof however their effect did not culminate to improved yield at M 1 generation. Keywords: chemical mutagenesis, colchicine, nitrosomethyl Urea, polyploidy, Rice Introduction International development agencies believe that breeding new crops is important for ensuring food security by developing new varieties that are higher yielding, drought tolerant or regionally adapted to environment and growing conditions (Costa-Font and Mossialos, 2007). The role of mutation breeding in increasing the genetic variability for desired traits in various crop plants have been proved beyond doubt by a number of scientists (Kozgar et al., 2011). Mutation have played a great role in increasing food security, since new food crop varieties embedded with various induced mutations have contributed to the significant increase of crop production (Novak and Brunner, 1992). Mutation induction offers significant increase in crop production (Kharkwal and Shu, 2009) and the possibility of inducing desired attributes that either cannot be found in nature or have been lost during evaluation. The prime strategy in mutation breeding has been to upgrade the well- adapted plant varieties by altering one or two major agronomic metrical traits which limit their productivity or enhance their quality (Roychowdhury & Tah, 2011). Mutations can be chemically induced using colchicine and urea (Koornneff & Stam, 2001). Chemical mutagenesis is regarded as an effective and important tool in improving the yield and quality characters of crop plants. They have enhanced agronomic traits of crop plants and increasd the genetic variability for quantitative traits (Adamu & Aliyu, 2007; Mostafa, 2011). Nitrosomethyl Urea increases the spectrum of variability in morphological characters (Menssah et al., 2003). Induced mutation is an important tool in rice breeding worldwide (Maluszynski et al., 1998) and has been applied for inducing genetic variation in rice (Oka et al., 1958). Mutation breeding has been a good