1. Evaluation of rice germplasm in the drought prone rainfed environment in northwest Bangladesh
B Karmakar1, MAR Sarkar2, SM Haefele3, TL Aditya1, MA Ali1, MT Islam1 and MR Islam1
1 Bangladesh Rice Research Institute (BRRI), Regional Station, Rajshahi and BRRI, Gazipur, Bangladesh,
2 Professor, Bangladesh Agricultural University, Mymensingh; 3International Rice Research Institute (IRRI), Los Baños, Laguna, Philippines,
INTRODUCTION
Rice is cultivated on m ha in Bangladesh, including about 2 m ha drought-prone rainfed lowland rice (BBS, 2008).
Drought-prone rice is mostly grown in the northwestern part of Bangladesh where the irrigation potential is limited and the rainfall is erratic (annual mean of 1200 mm) (Saleh et al and Mazumder et al. 2006).
Drought occurs in the wet season mainly at the beginning of the cropping season prior to transplanting of rice seedlings and at the reproductive phase (Fig 1).
Genotypes with increased drought tolerance are considered to be the first necessary step to improve the productivity of drought-prone rice-based systems (Bernier et al., 2007).
Picture 3. Performance of IR under drought stress, PVS 2009
Picture 4. Performance of IR under drought stress, PVS 2009
RESULTS AND DISCUSSION (continued)
Harvest index was reduced under drought in all genotypes (Fig 5).
Spikelet sterility was significantly higher in mega/check varieties under drought stress, however, it was similar under control conditions.
In farmers’ preference analysis, IR and IR obtained the highest preference.
IR showed the highest tolerance of drought stress, as evaluated with by the leaf rolling score (Fig 6).
IR under drought stress, PVS 2009
IR under drought stress, PVS 2009
Picture 2. Land remains fallow regularly due to drought stress in rainfed fields, Rajshahi, 2009
Picture 1. Drought- prone rice is mainly located in northwest Bangladesh (red color)
MATERIALS AND METHODS
23 breeding lines were evaluated through Participatory Variety Selection (PVS) trials in farmer’s fields and on-station during the wet season (WS) 2009.
Fertilizer and insecticide were applied uniformly.
Drought sensitivity was monitored through scoring of leaf rolling.
Soil moisture was measured at 20 cm depth twice in a week started from 25 DAT up to ripening stage.
Ground water table was measured twice a week.
Fig 4. Grain yield and growth duration of the promising rice germplasm compared to check varieties, PVS, wet season 2009
CONCLUSIONS
We successfully used Participatory Variety Selection experiments to evaluate and select improved drought tolerant rice germplasm for rainfed lowlands in northwest Bangladesh. In comparison with the mega/check varieties (BRRI dhan49 and Guti Swarna), yield of the selected lines (IR and IR ) was higher under drought stress but at par under control conditions. In addition, farmers like their appearance in the field as indicated by the preference analysis. Thus, the lines IR and IR have considerable potential to improve the livelihood of farmers in drought-prone rainfed environment. The lines were already submitted for the national release procedure.
Fig 1. Rainfall and temperature distribution in 2009, Godagari, Rajshahi, Bangladesh
RESULTS AND DISCUSSION
Soil moisture was low at the flowering stage in October, which can cause spikelet sterility especially in varieties susceptible to drought (Fig 2).
Ground water levels were inaccessible to roots during flowering stage (Fig 5).
Among the 23 entries, the highest grain yield was obtained by IR (4.35 t/ha) and IR (4.29 t/ha) under drought stress conditions (Fig 4).
Yield of the mega/check varieties (farmers’ usual choice) was drastically reduced under drought stress. However, yield of all the genotypes was 1.0 to 2.5 t/ha higher in control conditions without drought stress.
Growth duration of the two high yielding IR lines was much shorter (105 days) than in the existing long duration varieties (140 days). In general, growth duration was reduced 3-6 days under drought stress.
Fig 6. Leaf rolling score and Farmer’s
preference, PVS 2009
Fig 5. Harvest index and sterility, PVS 2009
REFERENCES
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hybrid rice varieties in Barind and highland ecosystems. In: Proceedings of the 20th National Workshop on Rice Research and
Extension organized by BRRI, Gazipur, Bangladesh April 28, p 260.
Saleh AF, Bhuiyan MSI and Kirby C Drought alleviation in rainfed agriculture using on-farm reservoirs. Hydrology in a
challenging environment. Volume III. Proceedings of the British Hydrological Society Intl. Conference, Exeter, UK, July p
Fig 2. Soil moisture status at flowering
PVS 2009, Godagari, Rajshahi
Fig 3. Ground water depth during reproductive phase, PVS 2009, Godagari, Rajshahi
Poster (Abstract sequence # 4143) presented in the 3rd International Rice Congress held at Hanoi, Vietnam on 8-12 Nov 2010