Strategy of F1 Hybrid Rice Seed Production through CMS Breeding Technology

The production of F1 hybrid rice seeds through CMS breeding technology has been introduced since a couple of decades in India by the technical collaboration of the scientist of the International Rice Research Institute , Manilla, Phillippines. It is a major problem of emerging the inflorescence from the first leaf of this crop which is managed by spraying GA3 plant hormone in different concentrations. GA3 is a costly chemical which is a matter of problem to afford by the middle class farmers as well as margin farmers. It would be helpful to the rice breeders as well as scientific community if we could explore the alternative low cost chemicals instead of GA3 to fulfill the purpose of this breeding technology. Keeping all these views in mind we have undertaken a venture of searching such an alternative chemicals which is low cost i.e., affordable by all classes of farmers. IR58025A as A-line, and KMR-3 as R-line were procured from the State Rice Research Station, Chinsurah, Hooghly which are grown in the research plot in the Crop Research Farm under the Department of Botany of the University of Burdwan following the norms of CMS breeding layout design. Hybrid rice is the commercial rice crop from F1 seeds of cross between two genetically dissimilar parents. Good rice hybrids have potential of yielding 15-20% more than the best inbred variety grown under similar conditions. At present there are three types of hybrid seed production system based on the number of parental lines involved viz. A-line (CMS-line), B-line (Maintainer line) and R-line (Restorer line). After independence we had to face severe famine in the country in 1940s’. The quantity of food production which we had achieved from green revolution of the sixties could have met up the present food scarcity of increasing by growing population of our country. Cereal crop yield could reach 3-6 times more yield by introducing new high yielding photo insensitive cultivars (especially in case of rice). Gradually the green revolution has converted as ‘green’ to ‘greed’ by sacrificing some traditional valuable indica rice cultivars. Seed to seed duration of indica rice cultivars has reduced in 115-120 days from its long duration i.e. 160-170 days. ‘Taichung’ Native-1 rice variety was introduced in India first in 1965 but it could not survive in this country in any agroclimatic zone out of 6 zones in our country. Simultaneously the scientists of International Rice Research Institute discovered the most high yielding rice cultivar IR-8 for maximum yield in tropical country like India. The seed to seed duration of IR-8 was 130-135 days. It was a matter of water stress for the cultivation of IR-8 in winter- summerboro season in artificial irrigation. Indeed, we had no sufficient arrangement of artificial irrigation for boro cultivation of rice cultivars at that time. In course of time a few rice cultivars were evolved which were 110-115 days of seed duration and replace the IR-8 rice cultivars. The cultivation of high yielding rice varieties became saturated in 1984-1985 in our country. Thereafter, the enhanced production of rice became deteriorated due to genetic erosion, technological shortfalls and agronomical practices. Within this seed production system, the out-crossing potential of the seed parent is assessed and the easy of production of particular hybrid combinations determined. The quality of output of the various seed production steps are determined through grow outs conducted after each season (Toldeo et al., 1996). Different doses of chemical viz. GA3, penicillin, Sulfonamide, and gentamicin were applied as foliar spay during flowering times in three phases. This practice for producing F1 seeds from the A-line and R-line were done in both the seasons i.e. (i) winter-summer-boro and (ii) kharif seasons. The produced F1 seeds as well as R-line seeds were measured in various agronomic parameters for assessing the seasonal variations over the same location. Metrical characters viz. 1. Plant height (cm), 2. Tiller/plant ,3. Leaves/plant, 4. panicle length (cm) /treatment, 5. Number of rachilla / panicle, 6. Number of grain/panicle, 7.No. of fertile grain/panicle 8. Grain yield ( g.) /plant, 9. Total yield/ hectare, 10. 1000 Grain wt. /treatment, 11. Length of grain (mm.) /treatment, 12. Breadth of grain (mm) /treatment, 13. Length of awn (mm.) /treatment 14. Straw wt. (kg.)/treatment were observed and recorded properly for biometrical calculations. Correlation matrix model (Singh and Chaudhary, 1985) was followed for determining the metrical traits of cultivars studied. The main aims and objectives of this experiment were to assess the effectiveness of different chemicals for emerging out the inflorescence of ‘A’ line parent cultivar of the experiment.