Impact of Gamma Radiation on Rice Against Infestation of Rice Hispa Dicladispa Armigera (Olivier)

An experiment was carried out under field and controlled condition at Assam Agricultural University, Jorhat during (kharif) sali 2018 and sali (kharif) 2019 to screen the most efficient doses of gamma irradiation showing resistance against rice hispa, Dicladispa armigera (Olivier) (Coleoptera: Chrysomelidae) infestation. However morphological and biochemical characteristics of paddy plants imparting resistance against rice hispa infestation was also studied. Seeds of popular paddy variety Ranjit Sub-1 were subjected to five different doses of gamma radiation viz. 100Gy, 150Gy, 200Gy, 250Gy and 300Gy along with an unirradiated control and a check variety (Jaya) was taken as treatments and was replicated four times. Among the gamma irradiated doses, 200Gy showed minimum infestation of rice hispa followed by 150 and 100Gy. Infestation was lowest at 200Gy (14.93± 1.05%) and highest at 300Gy (25.81± 1.18%). Biochemical characteristics of the paddy plants like nitrogen, potassium and phenol and morphological characters like total leaves, total tillers and leaf width were found to have significant effect in insect infestation. The scale of infestation of rice hispa was evaluated as per Standard Evaluation System (SES), IRRI, and according the scale the doses 100Gy, 150Gy and 200Gy were considered as Moderately Resistant, 250Gy and 300Gy as Less Susceptible category against rice hispa infestation.