~ 1025 ~ Journal of Pharmacognosy and Phytochemistry 2017; 6(5): 1025-1027 E-ISSN: 2278-4136 P-ISSN: 2349-8234 JPP 2017; 6(5): 1025-1027 Received: 24-07-2017 Accepted: 26-08-2017 Sheetal Dogra Assistant Professor, Division of Vegetable Science and Floriculture, SKUAST- Jammu and Kashmir, India SR Dhiman Professor, Department of Floriculture and Landscaping, Dr YS Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India Correspondence Sheetal Dogra Assistant Professor, Division of Vegetable Science and Floriculture, SKUAST- Jammu and Kashmir, India Effect of gamma rays on per cent survival of calli in carnation cultivars ‘Tempo’ and ‘Raggio-de Sole’ Sheetal Dogra and SR Dhiman Abstract The present study was conducted at Department of Floriculture and Landscaping, Dr Y S Parmar University of Horticulture and Forestry, Nauni, Solan (H.P.) to analyse radiosensivity in calli of carnation for the development mutants. Calli of carnation culivars ‘Tempo’ and ‘Raggio de Sole’ were exposed to different doses of gamma rays (10 Gy, 20 Gy, 30 Gy, 40 Gy and 50 Gy). Lowest survival rate (53.42 per cent) was obtained at the highest dose of gamma irradiation (50 Gy). Survival rate of callus was more in cultivar ‘Tempo’ over ‘Raggio- de- Sole’. Among interactions, lowest survival rate of callus was observed in cultivar ‘Tempo’ at 50 Gy gamma rays. Keywords: carnation, tissue culture, gamma irradiation, mutation Introduction During the last two decades, a lot of interest has been generated in cell mutagenesis (Gavazzi et al., 1987; Crino et al., 1990) [6, 2] . The major advantage of in vitro mutagenesis is that much higher number of mutants could be recovered by treating large number of population in a small in vitro space than in vivo mutagenesis. Furthermore, optimal conditions for survival and propagation after irradiation are controlled. Therefore, the breeding programme is shortened which is of outstanding economical importance (Walther and Sauer, 1985) [16] . Induction of variation depends upon the kind and dose of mutagenic treatment. Chemicals as well as radiations have been utilized for mutation induction. However, radiation is the preferred method to make genetic changes and the problem of handling and disposing of chemicals (Ahloowalia, 1998) [1] . In the mutation studies in vegetatively reproducing plants, LD50 values were accepted as an upper limit to prevent the unwanted mutations (Sananda and Amano, 1998) [8] . Determination of survival of explants after irradiation is an essential step to find out LD50. Thus the present investigation was conducted to study the effect of different doses of gamma rays on per cent survival of calli in carnation cultivars ‘Tempo’ and ‘Raggio de Sole’. Material and methods To study the effect of different doses of gamma rays on per cent survival of callus and callus type in carnation, the in vitro multiplied calli of cultivars ‘Tempo’ and ‘Raggio-de-Sole’ grown on standardized callus multiplication medium was cut into uniform size pieces (80 mg) under aseptic conditions in a laminar flow cabinet and put into polypropylene tissue culture bottles (3 calli pieces/culture bottle). The culture bottles were then closed with plastic caps followed by sealing with parafilm. These culture bottles were exposed to gamma rays. The gamma ray treatment was performed in the Radiation Therapy Department of Post Graduate Institution of Medical Education and Research (PGI), Chandigarh, using Theatron 750C in which cobalt 60 was used as the source of irradiation. The source to subject distance chosen was 80 cm while the field of view was 25x25 cm 2 . The irradiation was done at the rate of 77.28 rads/minute. Hence, the treatments of 10, 20, 30, 40 and 50 Gy were of 13, 26, 39, 52 and 65 minutes, respectively. After irradiation, the culture bottles were maintained as such in the tissue culture laboratory of the department upto 21 days. The surviving calli after 21 days were transferred on callus multiplication medium. Result Per cent survival of calli Per cent survival of calli was observed after 21 days of irradiation. Data on per cent survival presented in Table 1. Indicates that increase in the doses of gamma rays resulted in significant decreased per cent survival of calli which was minimum at 50 Gy (54.32 %). Even the lowest dose of 10 Gy (98.41%) resulted in significant decrease in per cent survival over control where