Breeding rice for submergence-prone and aman areas of Bangladesh
2009
Salam, M.A.
Composite cross, backcross, and shuttle-breeding programs have been carried out to improve rice varieties for the submergence-Prone and aman areas of Bangldesh.BRRI dhan33 was released in 1997 and BRRI dhan39 in 1999 as replacements for the early photoperiod-sensitive landraces. BR5226-3-2 , a strongly photoperiod-sensitive line, has been isolated for delayed planting up to 15 September coinciding with the recession of floodwater. Also, BR6110-10-1-2 was found to be adaptable to tidal wetland areas up to 60-cm tidal depth. These two lines are being placed in the variety release pipeline. Under a shuttle-breeding program, IR70175-54-1-1-2-3-HR2 showed an advantage of earliness by 10 days and lodging tolerance over the standard varieties BR11 and BRRI dhan32. Also, slow-elongating IR lines have been evaluated in shallow flooded areas, but they showed poor adaptability. The evaluation of IR lines for flash-flood submergence isolated tolerant genotypes but these were prone to lodging. Moreover, 53 landraces were collected from the submergence-prone areas of the country for characterization and identification of new gene sources for submergence. Several breeding lines have been developed through composite crosses having fine grain, improved plant type, and Insensitivity to photoperiod. Short-duration near-isogenic lines have been developed using the recurrent parents BR11 and Swarna under a backcross-breeding program. Another backcross program has been progressing in applying the Sub1 gene to develop varieties for flash-flood submergence.
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