GENETIC BASE AND COEFFICIENT OF PARENTAGE OF RICE (ORYZA-SATIVA) VARIETIES RELEASED IN KERALA

An examination of the pedigrees of 29 lice (Oryza Sativa L.) varieties of hybrid origin, released in Kerala during 1966-95, revealed a narro w genetic base, as only 37 ancestors were used directly or indirectly in their development. Out of 37 ancestors, 10 ancestors contributed 74 .14% of the genetic base. Similarly, the cytoplasmic diversity was als o limited, as 41.38% varieties could be traced back maternally to the same ancestor 'Ptb 10' ('Thekkancheera') and thus probably carried its cytoplasm. 'Dee Geo Woo Gen' (DGWG) was the most frequently appeared ancestor (96.55%) due to its dwarfing gene (sdl). All the 29 varieties except 'Kayamkulam I' were interrelated with an average coefficient o f parentage of 0.137 for 406 combinations of 29 varieties.