Effect of mutagens on regeneration and growth of in vitro grown epicotyl segments of rough lemon seedlings (Citrus jambhiri Lush.)

The present study on the effect of mutagens on regeneration and growth of in vitro grown epicotyls segments of rough lemon seedlings (Citrus jambhiri Lush.) was carried out during the years 2009- 2010 and 2010- 2011 in the Tissue Culture Laboratory, Department of Fruit Science, Punjab Agricultural University, Ludhiana. Developmental characteristics of the in vitro grown epicotyls segments on regeneration media were treated employing gamma radiation in Gray(Gy) at 0, 5,10,15, 20,25,30,35,40 and 45 Gy; the alkylating agent ethyl methane sulfonate (EMS) and methyl methane sulfonate (MMS) each at 0, 0.1, 0.2, 0.3, 0.4,0.5 and 0.6% (v/v) were evaluated. Epicotyl segments from one month old in vitro grown seedling were cultured in regeneration medium (MS+BAP 1.0 mglit-1) under controlled laboratory conditions (25±2? C, 16 hr photoperiod, 2000 lux light). LD50, the dose required to kill half of the tested population corresponded to 35Gy for gamma radiation, 0.3% each for EMS and MMS treatments. Number of days taken for regeneration increased with increasing dose of gamma irradiation, EMS and MMS. Percent regeneration, number of buds, number of shoots, shoot length, number of leaves, internodal length, primary root length and number of secondary roots decreased with increasing dose of gamma radiation , EMS and MMS. The study would be beneficial to induce desirable variations in plant growth characteristics of rough lemon by the use of mutagens treatment.