Virus-vector and host relationship of rice tungro disease in promising rice genotypes

Thirty rice genotypes (30 Nos) collected from different places viz., India (9 Nos), Indonesia (6Nos), Srilanka (1No), IRRI, Philippines (12 Nos) and Bangladesh (2 Nos) were tested under glasshouse conditions. The results revealed that all rice genotypes expressed typical tungro symptoms except in five rice genotypes viz., Palisithari 601, Utri Merah, Utri Rajapan, ARC 11554 and IR 81366-124-1-2-2 which were found free of foliar symptoms except mild stunting. The initial symptoms in all rice genotypes expressed were stunting followed by interveinal chlorosis and initiation of leaf discolouration and twisting of discoloured leaves. Three rice genotypes showing moderately resistant reaction obtained from IRRI (IR 73546-20-2-2-2, IR 77298-5-6 and IR 81336-39-3-3-3) expressed resistant reaction with (score 3) with varied levels of resistance to the green leafhoppers. Resistant rice genotypes expressed high level of tungro resistance with a score of 1 or 3. The per cent tungro infection (6.6) was recorded in rice cultivars, Palisithari 601, Utri Merah and IR 81366-124-1-2-2. Rice cultivars, Palisithari 601 and ARC 11554 recorded (1 score) for both tungro and as well as green leafhoppers and rice genotypes Tjempo Kijik, Utri Merah an Utri Rajapan recorded (1 score) for tungro resistance and recorded (7 Score) total susceptibility to the leafhoppers. Key words: Rice tungro, leaf hopper vector, rice, virus-vector relationship.