Marathwada Agricultural University, Parbhani 431402, India
Iron deficiency chlorosis is of common occurrence in rice grown under upland conditions on the black cotton soils (Vertisols) of the Deccan Plateau of India. Prabhavati (PBN 1), an induced semidwarf mutant derived from the tall variety Ambeniohor local, is tolerant of iron chlorosis like the parental variety (Nerkar et al. 1984). Inheritance of iron chlorosis tolerance was studied by crossing the variety Prabhavati with 7 sensitive genotypes, viz., Basmati 370, Pun'ab 1, IET 8573, RPA 5929, Pusa 33, Dee Geo-Woo-Gen and CRM-8-5708-388-712. The parental, F1, F2, and backcross generations were raised under upland conditions.
Table 1. Iron chlorosis reaction and test of significance ________________________________________________________________ Cross No. of plants X2 ____________________ 3:1 for F2 Tolerant Sensitive 1:1 for BC ________________________________________________________________ PBN (0. 1) x F1 35 - Punjab 1 (2.5) F2 279 102 0.36 BC1 42 1 - BC2 24 22 0.20 PBN (0. 1) x F1 38 - IET 8573 (208) F2 223 77 0.07 BC1 41 - BC2 24 24 0.00 PBN (0. 1) x F1 38 - RPA 5929 (2. 1) F2 298 104 0.16 BC1 45 - BC2 25 23 0.08 PBN (0. 1) x F1 35 8 - DGWG (2.8) F2 260 99 1.27 BC1 35 5 - BC2 22 28 0.85 PBN (0. 1) x F1 35 - CRM mutant (3.0) F2 227 73 0.01 BC1 37 1 - BC2 23 23 0.00 PBN (0. 1) x F1 49 - Pusa 33 (2.8) F2 251 78 0.35 BC1 45 - BC2 26 25 0.08 PBN (0. 1) x F1 32 14 - Basmati 370 (2.O) F2 235 79 0.01 BC1 39 2 - BC2 26 27 0.02 ________________________________________________________________ BC1: F1 xP1, BC2: F1xP2. P1: PBN (Prabhavati), tolerant. All chi-square values are insignificant (P=)0.20~1.00)Direct seeding was done in the field by hand drilling. Segregation for iron deficiency reaction was scored 20 and 70 days after seeding. A cotton felt dipped into a freshly prepared ferrous sulphate solution (1%) was rubbed gently on the leaves showing yellowing symptoms. If the treated leaf turned normal green after 1 to 2 days, iron chlorosis was confirmed. Individual plants were scored on the basis of visual symptoms on a 0 to 4 point scale. Scores 0 and 1 were taken as the tolerant class, while 2, 3 and 4 were taken as the sensitive class. The data on segregation pattern in the different crosses are presented in Table 1. The mean iron chlorosis grade of the parents is given in the brackets. From the segregation pattern in the F2 and backcross generations, it is inferred that tolerance of iron chlorosis in Prabhavati is controlled by a single dominant gene Ic, while sensitivity in the sensitive varieties is controlled by its recessive allele ic.
Reference
Nerkar, Y. S., M. B. Misal and R. V. Marekar, 1984. PBN 1, a semidwarf upland rice cultivar tolerant of iron deficiency. Int. Rice Res. Newsl, 9: 15-16.