Abstract:
Rice, the staple food of Bangladesh is grown in about 10 million hectares covering about 80 percent of the arable land and accounting for94 percent food grain projection of the country. The total rice production in the country has increased considerably with the area expansion under modern varieties but the productivity in general has been plateaued. Rice is grown in four distinct rice-growing seasons such as Aus ( Broadcast and Transplanted), Transplanted Aman Broadcast Aman and Boro. These seasons in general corroborate to the internationally classified rice ecosystems like Upland, Rain fed lowland, Deepwater and Irrigated. Rice improvement in the then Bengal started in 1910 following mostly pure-line selection and their classification on the basis of their morphological characters and collection of germplasm of both endemic and exotic sources to identify varieties which were more adaptable to different seasons. Minor attempts have been made to improve varieties through hybridization and other plant breeding techniques. With the establishment of BRRI in 1970 rice breeding programme at the beginning was operated into two directions i) short term programme emphasizing introduction of IRRI progeny lines and subsequent selection of genotypes with superior performance under local condition and ii) a long term programme with a view to developing high yielding varieties for favorable environment having shorter growth duration and resistance to major pests and diseases. BRRI has so far released 38 modern varieties most of which have been performing well under favorable environments of Aus, Boro and T-Aman seasons. Specific programme to release varieties for unfavorable environment was started in early 1980s and BR17, 18 and 19 were resealed for submergence prone haor areas for Boro season and BR20 and BR 21 for upland conditions.
