Thailand is among the world’s biggest rice producers and exporters. Around 13% of its GDP comprises agriculture, and the sector alone employs 40.7% of the country’s labor force. Aside from being the most important export crop, rice is both a staple in the diet and an important part of the culture of the Thai people.
More than one-half of Thailand’s rice area can be found in its northeast region but it accounts for only 37% of the total rice production. The average rice farm size here is smaller than in other regions, and soil erosion and drought during the dry season are acute problems.
A total of 397,830 hectares of rice are affected by drought in Thailand.
Drought-affected areas in Thailand
Up to 31% of the total production comes from the central region, where about one-fifth of Thailand’s total cultivated rice land is located. An intensively cultivated alluvial area, the average farm size here is large. Most farms also have irrigation facilities, which allow farmers to plant two rice crops per year. Almost 75% of the dry-season rice grown under irrigated conditions is also located in this region. Farm operations are almost entirely mechanized and farmers use the direct-seeding method of crop establishment to save labor.
A third of Thailand’s land area is in the northern region, where upland rice is grown in the lower altitudes of high hills and in upland areas and lowland rice in lower valleys and on some terraced fields where water is available. Thailand’s northern region accounts for 28% of its total rice production.
The map below shows the salt-affected areas in Thailand.
Salt-affected areas in Thailand
Thailand’s total rice crop area affected by submergence is estimated at 489,840 hectares.
Flood-prone areas in Thailand
- Nakhon Ratchasima Rice Research Center (NRRC)
- Prachinburi Rice Research Center (PRRC)
- Ubon Ratchathani Rice Research Center (URRC)
- Dr. Jirapong Jairin, URRC (new site coordinator)
- Dr. Varapong Chamarerk (former site coordinator)
- Dr. Duangjai Suriya-Arunroj, NRRC
- Mr. Sommai Lertna, NRRC
- Ms. Udompan Promnart, PRRC
- Ms. Waraporn Wongboon, URRC
Drought. Participatory varietal selection (PVS). Working Group 1 implemented PVS for drought-tolerant lines in northeast Thailand. A total of 16 drought-tolerant lines from IRRI were evaluated under favorable and drought conditions in Khong and Phimai districts in Nakhon Ratchasima.
Under favorable conditions, from the 16 lines that were evaluated, IR83388-B-B-8-3 had the highest yield (4.41 t/ha). Under drought conditions, IR82589-B-B-2-2 had the highest yield (2.70 t/ha).
Preference analysis. For preference analysis on agronomic characters under favorable conditions, 22 farmers (18 males and 4 females) liked both IR83376-B-B-130-2 and IR83377-B-B-93-3 because of their sturdy stem, large and compact panicles, and straw-color grains with slender shape.
Submergence. In 2010, 129 local landraces and breeding lines were evaluated by NARES partner-researchers and they found PCR07064 (Bang Taen/IR64Sub1A) having tolerance of submergence, similar to that of FR13A (95% survival and 97% recovery).
FR13A was found to be more tolerant of submergence than Swarna-Sub1 and IR64-Sub1. The tolerance of the new line (PCR07064) needs to be confirmed in more experiments.
Anaerobic germination. For tolerance of anaerobic germination, a total of 109 lines were tested. Varieties Khao Hlan On and Khaiyan, received from IRRI as tolerant checks, showed 48% and 43% survival rates, respectively. Four genotypes—SPR1, RD31, PRE92039-3-1-2-1, and SPR02001-8-1-1-3—showed survival of 30–35%. Other lines showed less than 20% survival. These findings still need to be confirmed in succeeding experiments.
Stagnant flooding. A total of 75 accessions, local varieties, and promising lines received from IRRI were screened for tolerance of stagnant flooding. Traits such as growth duration, yield, plant height, panicle number per hill, and percent seed set were the most affected by stagnant flooding. RD23, RD31, SPR2, and CNT1 exhibited good performance and had a small reduction in yield when affected by stagnant flooding. Three promising lines were tested in semi-deepwater conditions.
The following screening activities for stagnant flooding will continue in subsequent years to identify breeding lines and landraces with greater tolerance of these conditions:
Salinity. Partners in Vietnam generated 100 crosses and 5 backcrosses by using salt-tolerant donors, and 1,911 selections from different generations. They also evaluated 40 breeding lines in OT and RYT in Soc Trang and Dong Xuan, and selected 18 genotypes based on salinity tolerance, growth duration, yield, and homogeneity of morpho-agronomic traits.
- Screening for submergence tolerance
- Screening for tolerance for anaerobic germination
- Screening for stagnant flooding
Overall, partners conducted nine participatory varietal selection trials and evaluated the performance of 1,154 varieties and 605 lines.