Abstract

                                ASD 20, derivative of IR 18348-38-3/IR 25863/IR 58 was released in January 1997 for general cultivation in Tamil Nadu. It recorded a mean yield of 6.7 Uha in 110 days with 6.0 (ASD 16) to 21.2 per cent (IR 50) increased yield in Kar season. During late Pishanam, ASD 20 recorded a mean yield of 5.6 t/ha in 108 days with 12.9 (ASD 16) to 25.4 per cent (ADT 36) increased yield over checks. Its overall mean yield in 320 trials (1988-1996) was 5.7 t/ha with 5.6 (ADT 36) 10 9.6 per cent (IR 50/ASD 18) increased yield over checks, The biological yield of ASD 20 was 18.5 t/ha (6.7 tha of grain; 11.8 t/ha of straw) and its potential grain yield was 9.7 t/ha. It is semidwarf.in stature with long slender white rice. ASD 20 is resistant to stem borer, leaf folder, sheath rot and moderately resistant to blast and RTV. ASD 20 can be sown in April-July, October-November and December-January throughout Tamil Nadu and is the best alternative to IR 50.

Key words : Rice, early duration, high yielding long slender rice