Inheritance of Resistance to Races of Blast Disease in Rice.
The p r e l im in a r y t e s t s showed re a s o n a b ly good agreem ent w i th th o se r e p o r t e d by p re v io u s w o rk e rs, and the s t r a n 1709 was found to be r e s i s t a n t to r a c e s 6, 8 and 16.
Abstract
S tu d ie s on i n h e r i t a n c e o f r e s i s t a n c e to r a c e 6 o f r i c e b l a s t ( P i r i c u l a r i a o ry zae Cav.) were i n v e s t i g a t e d . M a te r i a l from th e c ro s s in v o lv in g p a r e n t s t r a i n s 1709 and Cl 9418 was t e s t e d f o r r e a c t i o n to r a c e 6 in Fj_, F2 and Fg g e n e r a t i o n s . S e le c te d F^ l i n e s o f known r e a c t i o n to r a c e 6 were a l s o t e s t e d w i th r a c e s 8 and 16. B e fo re t e s t i n g th e h y b r id m a t e r i a l , p r e l im in a r y t e s t s were conducted on 16 v a r i e t i e s and s t r a i n s o f known r e a c t i o n to r a c e s 1 and 6 . The te c h n iq u e s o f i n o c u la t io n o f r i c e s e e d l in g s and e v a lu a  t i o n o f i n f e c t i o n f o r s i x l e s i o n types were s t a n d a r d i z e d . A l l t e s t s were c a r r i e d o u t in th e g reen house , under h ig h h u m id ity chambers d u r in g th e s p r in g and f a l l o f 1962. The p r e l im in a r y t e s t s showed re a s o n a b ly good agreem ent w i th th o se r e p o r t e d by p re v io u s w o rk e rs , i n d i c a t i n g t h a t th e te c h n iq u e s used in th e p r e s e n t s tu d y were r e l i a b l e . The s t r a i n 1709 was found to be r e s i s t a n t to r a c e s 6 , 8 and 16 b u t s u s c e p t i b l e to r a c e 1 , w h i le Cl 9418 was found to be s u s c e p t i b l e to a l l f o u r r a c e s . The r e a c t i o n o f th e fo u r F ̂ p l a n t s to r a c e 6 was s i m i l a r to th e r e s i s t a n t p a r e n t , i n d i c a t i n g t h a t r e s i s t a n c e i s dom inant to su sc e p  t i b i l i t y i n t h i s c r o s s . The b e ^ i o r o f 6 6 F 2 p l a n t s showed a good