www.iaset.us editor@iaset.us INDUCE MUTATION BREEDING FOR DOWNEY MILDEW TOLERANCE IN ISABGOL (PLANTAGO OVATA FORSK.) Dinesh Kumar Jain 1 & S. K. Jain 2 1 Plant Manager, Rajasthan State Seeds Corporation Ltd, Baran, Rajasthan, India 2 Associate Professor, College of Agriculture, Sri Karan Narendra Agriculture University, Jobner, Rajasthan, India ABSTRACT Twenty four mutagenic progenies of isabgolwere selected from different families of M 2 generation of gamma rays irradiated variety RI 89. These lines were grown in a sick plot along with infector rowsin randomized block design with three replications at the experimental farm of Rajasthan College of Agriculture, Udaipur. The observations were recorded on stage of disease occurrence (crop age), per cent disease index andtotal phenolic compounds in leaves at 55, 75 and 95 DAS. The observations for other quantitative and qualitative characters were also recorded. Out of 24 lines 14 lines showed disease resistance to downy mildew. It was also noted that disease tolerant lines were having a higher concentration of total phenolic compounds in leaves. Further, with increasing severity of disease the depletion of total phenolic compound in leaves was less intolerant lines. In the present study it is clear that total phenolic compounds in leaves play an important role in disease resistance and reducing the downy mildew disease of the host plants. The 4 mutant lines viz., L7, L19, L2 and L15 were having less than 8 percent disease infestation and may be used for developing downy mildew disease tolerant varieties for commercial cultivation. KEWWORDS: Isabgol, Mutation Breeding, Phenolic Compounds, Disease Index Article History Received: 26 Jul 2018| Revised: 30 Jul 2018 | Accepted: 01 Aug 2018 INTRODUCTION Isabgol or Blond Psyllium (PlantagoovataForsk.) is a winter season medicinal plant. It belongs to the family ofPlantaginaceae and genus Plantago.The seeds of psyllium are mainly valued for mucilaginous rosy white husk which have been used in the indigenous medicines for many centuries (Singh and Virmani, 1982 and Lalet al., 1998).In recent years, the demand of isabgol has been increased in the western countries and it is traded in the major medicinal drug market of the world. In India it is cultivated traditionally in north Gujarat and south western Rajasthan. India holds a monopoly in the production and export of isabgol to the world market. The productivity of isabgol is far below the desired level and India is not able to meet the global demand. If India is to retain monopoly in production and export of this important foreign exchange earning commodity, then intensive efforts will have to be made to breed high yielding varieties with good swelling capacity of husk and tolerant to downy mildew disease. Downy mildew of Isabgol is most important and endemic disease in Rajasthan. It is caused by Pseudoperonosporaplantaginisin southern Rajasthan and Peronosporaalta in western Rajasthan. It occurs in all isabgol growing areas and causes considerable loss and an increase International Journal of Applied and Natural Sciences (IJANS) ISSN(P): 2319-4014; ISSN(E): 2319-4022 Vol. 7, Issue 5, Aug - Sep 2018; 33-40 © IASET