29. Genetic control of iron deficiency chlorosis tolerance in rice

C. D. R. REDDY, Y. S. NERKAR and M. B. MISAL

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.