59-05-032 Proceeding

97 Proceedings of the Princess Maha Chakri Sirindhorn Congress based biomassmaterial lies in its photosynthetic ability [7]. As biofuels are produced frombiomass of crop plants, they offer enormous opportunities to improve the income levels of smallholder farmers in developing countries [8] . Mutation breeding is an important tool to create variability for quantitatively inherited traits in different plants and is considered as an alternative method to increase genetic variability in plant breeding [9]. Among various physical mutagens such as x-rays, fast neutrons, thermal neutrons, ultraviolet and beta radiation, Gamma rays in particular are well known with their effect on the plant growth and development by inducing cytological, physiological and morphological changes in cell and tissues [10]. In the present study, an attempt has been made for improvement of locally cultivar of sorghum (Shweni -15) by using gamma radiation. II. Materials and Methods Seeds of Sorghum(Shweni-15) were obtained fromtheDepartment of Agriculture Research (DAR), Yezin. Dry seeds were irradiated with (0 Gy - 800 Gy) doses of Gamma radiation from 60Co source. The lethal dose 50% (LD-50) value for sorghum was 830 Gy. The gamma radiation was carried out at the Department of Atomic Energy (DAE), Ministry of Science and Technology, Yangon. Each treatment was carried out for more than 250 seeds. All treated along with control were sown in the field at a spacing of 15 cm within plants and 45 cm between plants to raise the M1 generation during the growing season in 2013. All M1 plants were used bulk harvesting method to raise M2 generation. Screening and evaluation of M2 generation was performed during the 2014 growing season, using a randomized complete block design (RCBD) with 3 replications. In this generation, the treated and controlled populationwere carefully screened for viablemutation and spectrumofmutation inM2 generation. Frequency of viablemutations was calculated in percentage on the basic of number of mutant plants identified versus the plant population of each treatment. Some quantitative traits among selected in M2 mutant plants of Sorghum viz, plant height, stem width, stalk weight juice volume, brix%, number of seeds per plant, 100 grain weight, grain yield and days to maturity were observed in M2 generation. Brix% was measured by hand refractometer. III. Results and Discussions A. Frequency and Spectrum of viable mutation Frequency and spectrumof viablemutations observed in theM2 generation of Sorghum was indicated in (Table 1). Mutation affecting many morphological changes such as plant habit and high brixmutant (Figure 1), leaf morphology (Figure 2), earlymutant and seeds type variation (Figure 3) and seeds color variation (Figure 4) was observed inM2 generation.The total frequency of viable mutation ranged from 0.96 to 6.44. A largest frequency and spectrum of viable mutation was found in 400 Gy. On the other hand, the least frequency and spectrum of viable mutation was