Research Notes 59 17. Inheritance of flag leaf width in rice (Oryza sativa). C. BHARADWAJ 2*, R. MISHRA 1 , C. TARA SATYAVATHI 3 , S.K. RAO 1 , D. K. MISHRA 1 , UPENDRA KUMAR 1 , SUMAN JHA 1 and M. P. JANORIA 1 . 1) Department of Plant Breeding and Genetics, College of Agriculture, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Adhartal , Jabalpur, Madhya Pradesh, India. 2) Scientist, National Research Centre for Soybean (ICAR), Khandwa Road, Indore 452 017. 3) Senior Scientist (Breeding), Division of Genetics, Indian Agricultural Research Institute, Pusa, New Delhi 110012, India. The importance of flag leaf in providing photosynthates to the filling grain has been well worked out. However the nature of gene control for this character remains yet to be worked out. Mori et al, (1973), Iwata and Omura (1984) reported curly leaf mutant to be a pleitropic gene, which is recessive and reduces the width of leaf lamina while Murata et al. (2000) reported narrow leaf mutant to be recessive. Studies on the genetics of flag leaf width recently taken up by Kobayashi et al. (2003) and Mei et al. (2003), reported several dominant QTL’s. We report here, the width of flag leaf to be governed by a dominant gene and propose FLAG LEAF WIDTH 1 [FLW1] and FLAG LEAF WIDTH 2 [FLW2] responsible for wide flag leaf in JNPT 89 and JNPT 63-01 respectively to be dominant over narrow flag leaf. Genetic segregation patterns were studied in the three crosses viz., JNPT 89 x IR 36; JNPT 89 x Pusa Basmati 1 and JNPT 63-01 x Pusa Basmati 1. The Jawahar New Plant Type (JNPT) parents were derived from japonica (group 6). The studies in flag leaf width had taken into consideration the following points in order to classify the flag leaf measurements into discrete classes. All the measurements in the range of + 0.20 cm of the parental class have been included in the respective parental class. The average flag leaf width of NPT 89 was observed to be 2.08cm, of NPT 63-01 was 2.00cm, of IR 36 was 1.04cm and of Pusa Basmati 1 was 1.06cm. In the cross NPT 89 x IR 36 all the flag leaf widths in the range of 2.08 + 0.20 cm were classified as wide and those in the range of 1.04 + 0.20cm were classified as narrow. In the cross NPT 89 x Pusa Basmati 1 all the flag leaf widths in the range of 2.08 + 0.20 cm were classified as wide and those in the range of 1.06 + 0.20cm were classified as narrow. In the cross NPT 63-01 x Pusa Basmati 1 all the flag leaf widths in the range of 2.00 + 0.20 cm were classified as wide and those in the range of 1.06 + 0.20 cm were classified as narrow. 740: 260 in NPT 89 x IR 36; 756: 244 in NPT 89 x Pusa Basmati 1 and 746: 254 in NPT 63-01 x Pusa Basmati 1 were obtained for Wide: Narrow leaf classes perfectly fitting into monogenic ratio of 3:1 with χ 2