Effect Of Ionizing Radiation On Some Characteristics Of Seeds Of Wheat

Seed irradiation during pre-sowing processes is one of the most effective methods to improve the plant production. This investigation was carried out to determine the effects of ionizing radiation on germination and physiological characteristics of wheat seedlings. Therefore two separate experiments were, therefore, conducted 1. Using the filter paper method to assess the germination and rate and the initial seedling vigour indices I and II in the laboratory conditions. 2. Following a randomized complete block design with three replications in the field of the Nuclear Research Laboratory, IARI, New Delhi. Seeds of Wheat plant were irradiated with gamma rays at Control (0), 0.1, 0.15, 0.155, 0.16, 0.165, 0.17, 0.175, 0.18, 0.19, 0.20, 0.25 kGy on the Cobalt-60 Gamma irradiation chamber (GC-5000, dose rate 2.18 kGy/h) at the Laboratory. Irradiation doses depend on many conditions that involve exposure to the rays (type, quantity and radiation time) and behaviour of the irradiated environment (absorption capacity, physical, chemical and biological modifications, and secondary reactions) (Evangelista, 2000). The parameters studied were percent germination, plant biomass including root and shoot mass and plant height. To determine these effects, seeds were exposed to radiation with time period of 165, 247, 255, 264, 272, 280, 288, 296, 313, 330 and 412 seconds for the irradiated treatment as given above respectively. A dose-dependent increase in percentage emergence in radiated plants up to 0.17 kGy. At higher dose of 190 Gy, there was a drastic reduction in physiological characteristics of seedling of wheat. Shakoor et al., (1978) and Khalil et al., (1986) attributed decreased shoot lengths at higher doses of gamma rays to reduced mitotic activity in meristematic tissues and reduced moisture contents in seeds respectively. The study concludes that gamma radiation at a low dose stimulates, while a high dose (0.18 kGy and above) inhibits plant growth and development of wheat.