Determination of Mutagenic Sensitivity (LD50) of Acid Lime [Citrus aurantifolia (Christm.) Swingle] cv. PKM-1 to Physical and Chemical Mutagens

In mutation breeding programme, determination of LD50 dose is very important to as it indicates the response of different explants to a particular mutagen which ultimately helps to fix optimal mutagenic dose for maximum recovery of mutants with minimum loss of explants. For this, in vitro raised shoot tip of acid lime cv. PKM-1 were treated with various concentration of gamma ray (GR) (10-40 Gy) and ethyl methane sulphonate (EMS) (10-50 mM) followed by cultured them under in vitro condition. The survival rate of the explant was reduced gradually with the increasing concentration of GR and EMS. Shoot length, leaf number per explant and root length were also reduced significantly with increasing GR and EMS concentration. Further, no survival of the explant was observed when they were treated with GR dose beyond 35 Gy and EMS dose beyond 45 mM. Probit curve developed based on survival rate as well as further growth of experimental explants under in vitro condition revealed that LD50 dose for treatment of acid lime shoot tip with GR and EMS to be 20-25 Gy and 20-25 mM, respectively.