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Experiments was carried out with Blackgram urd bean Variety TNAU Co 6 to Study the Effects of gamma rays and EMS on seeed germination and survival, pollen and seed fertility, plant height, no of primary branch no of cluster per plant,no of pod per plant ,pod length, no of seed per plan, hunder seed weight, and yield per plant in M1generation and progressive reduction in germination and survival percentage, pollen and seed fertility and yield related triats were observed in the mutagenic treatments and the effects were more pronounced in higher doses indicating almost a linear relation ship.the LD 50 Value was observed in
20 mM of EMS and 250 Gy of Gamma rays.The increating dose of gramma rays and EMS decreased in phenotypic and yield related parameters.The reduction in quantitative and yield traits have been attributed to the physiological distribance or chromosomal damage caused to the cells of the plant by the mutagen
Keywords: Vigna mungo, Variety TNAU Co (Bg) 6, gamma rays, Ethyl Methane Sulphonate (EMS),
Blackgram (Vigna mungo (L.) Hepper) is a rich source of protein (20.8 to 30.5 per cent) with total carbohydrates ranging from 56.5 to 63.7 per cent. It is also a good source of phosphoric acid and calcium. It contains a wide variety of nutrients and is popular for its fermenting action and thus it is largely used in making fermented foods. It is an important pulse crop occupying unique position in Indian agriculture. It covering an area of about 3.24 milllion hectares and producing 1.46 million tonnes. Productivity is only 526 Kg/ha. In Tamil Nadu, blackgram covers an area of about 3.41 lakh hectares with production of 1.21 lakh tones and productivity of 355 kg/ha Jayamani et al.(2012) and Project Co-ordinatorâ€™s Report. (2011). about the 70 percent of the total area is in central and southern parts of the country, which contributes about more than 77 per cent of the total production. However the national productivity of black gram is around 500 kg per / ha due to restricted cultivation in the marginal lands, lack of genetic variability, absence of suitable ideotypes for different cropping systems, poor harvest index and susceptibility to pests and diseases pawar.(2001) and Rizwana banu(2005). Research on this species is lagging behind than that of cereals and other legumes.
In order to improve yield and other polygenic characters mutation breeding can be effectively utilized Deepalakshmi and annadakumar.(2004). Mutation induction has become an establishment tool in plant breeding to enhancement existing germplasm and to improve cultivars in certain specific traits kurobane et al.(1979). Induced mutations represent the same kind of changes as occur from natural causes Govindan.(2000). Mutagenesis has been widely used as a potent method of enhancing variability for crop improvement Singh and Singh. (2001). Induced mutation using physical and chemical mutagen is one way to generate genetic variation resulting to new varieties with better characteristic Wongpiyasatid.(2000). Gamma rays are the most energetic form of electromagnetic radiation, possesses the energy level from 10 keV to several hundred kilo electron volts, and they are considered as the most penetrating in comparison to other radiation Kovacs et al .(2002).So an attempt has been made to study the effects in this direction.
MATERIALS AND METHODS
Seeds of black gram variety TNAU Co(Bg) 6 dry healthy and uniform size were treated with gamma rays at 150,200,250,300,350Gy doses and EMS 10,15,20, 25,30 mM concentrations. Five hundred seeds were pre-soaked for six hours in water initially Malarkodi(2008). Then the seeds were immersed for six hours in the requisite concentration of mutagen EMS with intermittent shaking. To ensure uniform absorption of the mutagen, the volume of mutagen solution was maintained at proportion of ten times to that of the seed volume. The whole treatment was carried out at a room temperature of 28Â±1Â°C for four hours after washed in running water, untreated seeds were used as control. The treated seeds of gamma rays, EMS and control seeds were immediately sown in the field in a randomized block design (RBD) with three replications. Each treatment consists of three rows of 5m length/ replication, in which 50 seeds per row were sown with 10Ã- 30 cm distance between plants and rows respectively. Data were recorded on eleven quantitative characters and further statistically analyzed. Mean values for eleven quantitative traits in different treatments and percentage over control are presented.
RESULTS AND DISCUSSION
Germination percentage was significantly reduced in all the gamma ray and EMS treatments. The 50% reduction of germination was recorded at 250 Gy of gamma rays (43.50 %) and 20 mM of EMS (41.30%). it indicated that germination percentage was reduced under the influence of mutagenic treatment with increasing dose/ concentrations. Similar results were reported in red gram Jayanthi.(1986), in winged beanVeereshet al .(1995) and in blackgram Thilagavathi and Mullainathan(2011). Significant survival reduction was observed in the higher dose/concentration of gamma rays 350 Gy (20.00), EMS and 30 mM (7.00). This might have been due to the effect of mutagens on meristematic tissues of the seed. Morphological variations, especially leaf abnormalities are the indicators of effective mutagen treatment. In different treatments morphological variations like trifoliate, tetrafoliate, pentafoliate, hexafoliata and fused leafs were observed in the present investigation. Plant height was also found to be significantly reduced in higher doses of physical and chemical mutagenic treatments. The maximum plant height reduction was observed in 350 Gy of gamma rays (11.20 cm) and 30 mM (9.90 cm). The number of cluster/ plant was also significantly affected in these (3.00) in 350Gy of gamma rays, 30 mM of EMS (2.00) treatments. Similar results were reported the quantitative parameter such as number of primary branches per plant, number of cluster per plant, number of pods per plant, pod length, number of seeds per pod and single plant yield were decreased in gamma rays and EMS treatment than control in M1 generation of Vigna mungo Thilagavathi and Mullainathan (2011) and in Vigna unguiculata Rizwana Banu.(2005) .However, seed weight per plant in different treatments indicated significant reduction in the higher doses of physical and chemical treatment. Percentage reduction in seed weight was maximum (5.00 g) in 150 Gy of gamma rays and (6.00 g) 10 mM EMS treatment. Plant yield for each treatment was recorded in grams and was converted to kg/ ha. Maximum seed yield of 600.50 kg/ ha was recorded in control. There was significant reduction in pollen fertility, seed fertility, hundred seed weight and seed yield was non significant in all the treatments. In the present study, reduction in seed germination and germination percentage was concentration/ dose dependent and linear. Reduction germination in mutagenic treatments has been explained due to delay or inhibition of physiological and biological processes necessary for seed germination which include enzyme activity Kurobane et al.(2002). The treatments showing maximum variation in quantitative characters may show the stable gene mutations in subsequent generation.
All the quantitative and yield traits were proportionately decreased with raise dose/ concentrations of gamma rays and EMS. The decrease in quantitative characters has been attributed to the physiological disturbance or chromosomal damage caused to the cells of the plant by the mutagen. Gamma rays belong to ionizing radiation and interact on atoms or molecules to produce free radicals in cells. These radicals can damage or modify important components of plant cells and have been reported to affect differentially the morphology, anatomy, biochemistry and physiology of plants depending on the irradiation level. Chemical mutagens usually cause point mutation, but loss of a chromosome segment or deletion can also occur. Studies suggested that the most important parameters for inducing physical and chemical mutagen growth and yield characters were reduced consider based on the dose / concentration and duration of treatment. In the present study, it was observed that the gamma ray irradiation and Ethyl Methane Sulphonate effects on Urd bean we observed morphological changes such as, stunted plants, reduction of the plant height and yield parameters.