Sources of resistance to brown leaf spot [Drechslera oryzae (Breda de Haan) Subram. and Jain] in some wild Oryza spp.

Abstract

Brown Leaf Spot (BLS) caused by [Drechslera oryzae (Breda de Haan) Subram. and Jain] has been observed frequently in varying severities in almost all the states of India. In Punjab, its incidence and destructive potential on all the modern commercial rice cultivars including PR 103, PR 106, PR 111, PR 114, PR 116, PR 118 and Pusa 44 is increasing [1-2]. Economic losses due to reduced yield (ranging from 30 to 43 %) as well as quality (glume discoloration) are substantial. Various environmental factors along with inherent susceptibility of a rice cultivar are primarily responsible for brown leaf spot epidemics [3]. This disease can be controlled through chemicals but this approach is neither economical nor eco-friendly. Therefore, development of resistant varieties is a better strategy for the management of BLS. Germplasm collections have been evaluated for resistance to BLS but, the sources of resistance are rare in rice particularly in varieties belonging to the cultivated species, Oryza sativa. As the wild rice germplasm is known to be a rich source of disease resistance genes [4], the present investigation was planned to evaluate 200 accessions belonging to 14 wild Oryza species for resistance against Drechslera oryzae under simulated epiphytotic conditions.