Variation in Blister Blight Disease Resistance among TRI 5000 Series Tea Accessions and some Underlying Biochemical Factors

Blister blight disease is a serious economical concern to tea production in Sri Lanka which causes direct crop loss and demand high management cost. Breeding for disease resistance is the economically viable and environmentally friendly long-term strategy. Newly bred TRI 5000 accessions for upcountry region were screened for blister blight resistance under field conditions during 2013-2014. Disease severity was estimated in terms of Area Under the Disease Progress Curve (AUDPC) using a disease assessment key. Accessions 15, 89, 582 and 272 were identified as resistant, 497 and 101 as moderately resistant and 210 as susceptible based on susceptible scale. Biochemical parameters; caffeine, carotenoids, total catechins (catechin (C), epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC) and epigallocatechin gallate (EGCG)) and total polyphenols were analyzed using standard protocols. EC showed strong negative correlation (r2=0.72) while EGCG had strong positive correlation with AUDPC. Principal component analysis with total polyphenol, carotenoids, caffeine, EC, EGCG and total catechins differentiated resistant accession from others. Possibility of using EC and EGCG as candidate biochemical markers for early screening for Blister blight resistance is discussed.