Wednesday, 8 January 2014

Progress on the development of drought-tolerant varieties in the rainfed lowland rice ecosystem in Bangladesh

PBGB Division Seminar

Tamal Lata Aditya
Visiting Research Fellow
Drought Group, PBGB, IRRI

2:00pm, Friday, 10 January 2014
Room A, Umali Hall, IRRI

Aditya TL,1 Karmakar B,2 Islam T,2 Pervin S,2 Islam R,2 and Ahmed HU2

1Bangladesh Rice Research Institute, Comilla, Bangladesh
2Bangladesh Rice Research Institute, Gazipur, Bangladesh

In Bangladesh, where rainfall distribution is sporadic and uneven, approximately 4.2 million ha of rainfed rice land are drought-prone. Efforts to breed and select genotypes for drought tolerance for target environments have been minimal. The weak photoperiod-sensitive BR11 and long-duration variety Swarna have replaced the strong photoperiod-sensitive landraces from the drought-prone T. Aman areas because of their high yield potential and maturity in October when seeding is done in early June.

However, these varieties show high yield losses in years with moderate to severe drought. The development of a 120–130-day high-yielding, drought-tolerant variety is a suitable option for T. Aman areas. The second option is to develop 100–105-day short-duration varieties that mature earlier than the presently cultivated BRRI dhan33 and BRRI dhan39. These short-duration varieties are suitable for seeding in early July and to be harvested in late October, thus avoiding the terminal drought. Recently, a large number of advanced breeding lines that IRRI had developed were tested in the High Barind Tracts of Bangladesh under the project supported by the Bill and Melinda Gates Foundation. The breeding lines are evaluated based on grain yield under drought through a standardized field drought-screening protocol and in irrigated non-stress conditions.

A participatory varietal selection (PVS) trial was conducted to identify suitable genotypes through farmers’ preference analysis. Results from the PVS trial indicated that the drought-tolerant breeding lines─IR74371-70-1-1 and the early-maturing, terminal drought-escaping line BR7873-5*(NIL)-51-HR6─were preferred by a majority of the farmers. Considering farmers’ choices and researchers’ points of view, these breeding lines were finally evaluated by the National Seed Board of Bangladesh (NSB) and released as varieties in 2010 for drought-prone areas under the rainfed lowland ecosystem. The former was named BRRI dhan56 and the latter was called BRRI dhan57.

In 2012, NSB evaluated another drought-tolerant line, IR82635-B-B-75-2 (IR08L251), and compared it with BRRI dhan56. Multilocation adaptive trials were also conducted in 2012 using one IR64 near-isogenic line (IR87707-446-B-B-B) and involved drought quantitative trait loci DTY2.2 and DTY4.1, along with three other IRRI lines, IR82589-B-B-84-3, IR83383-B-B-129-4, and IR83373-B-B-27-4.

Drought breeding efforts from 2008 onwards could bring some promising varieties with 110–130 days duration for Bangladesh. Molecular breeding efforts are underway to develop a drought-tolerant version of the submergence-tolerant line BRRI dhan 52.

No comments:

Post a Comment