37. High recovery of useful hybrid mutants in a lowland variety of rice

R. C. CHAUDHARY, D. P. MISHRA and V. N. SAHAI

Rajendra Agricultural University, Agric. Research Institute, Bihar, Mithapur, Patna, Bihar, 800001 India

A well adapted lowland rainfed variety of rice called Janki was treated with 0.4% EMS during rabi 1979-80. In M\1\ generation 28 mature plants were obtained from a total of 1000 treated seeds. In M\2\ generation very high spikelet sterility was observed and 1212 plants were harvested in bulk. In M\3\ & M\4\ the population was promoted by bulk method except that the plants looking like janki were rejected. In the M\4\ population, observations were recorded on 3120 plants. Tremendous genetic variability was observed with unusual combination of the mutant characters (Table 1).

Table 1. Hybrid-mutants of Janki with red and white rice in various plant height classes in M4 generation

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                                    No. with
    Plant height class
    (cm)                      Red kernel  White kernel
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1.  up to 90                      75            10
2.  91-106                       155            14
3.  107-122                      456            26
4.  123-138                      439            22
5.  139-154                       87             5
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Total No. of plants             1212            77
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In this method of breeding, it was expected that the sterility in M\2\ Would promote high rate of outcrossing. Mutants and the normal plants were expected to cross pollinate each other. This situation has led to the recovery of very high number of hybrid-mutants. It may be noted that Janki is a released and adopted variety for a water regime of about 1 metre depth in the state of it Bihar in India. It has also done exceedingly well in several Eastern States of India and countries like Vietnam. The variety has excellent submergence tolerance, kneeing ability and resistance to rice tungro virus and problem soils, but has coarse grains and red kernels. Several mutants have white kernel and fine grains in the background of semi-dwarf to semi-tall plant height and varying degrees of photoperiod sensitivity. These mutants are of great practical value. The breeding method followed is cost efficient and involves very little time and funds.