Polyploid Induction in Pear in vitro Treatment With Gamma-rays THE EFFECTS OF 137 Cs GAMMA RAYS IRRADIATION ON UPLAND COTTON POLLEN AND M 1(F 1M 1) GENERATION Autoradiographic Study of Gamma-Ray Induced Unscheduled DNA Synthesis in Bean Root Meristem Cells Mutagenic effects of gamma-rays on Coix lacryma-jobi var.ma-yuen Polyploid Induction in Pear in vitro Treatment With Gamma-rays