Dynamics of rainfed lowland rice varieties in Northeast Thailand

Transcription

1 1 Dynamics of rainfed lowland rice varieties in Northeast Thailand Miyagawa Shuichi (Faculty of Agriculture, Gifu University) 1. Northeast Thailand as marginal land for rice cultivation 2. Ecology of rice varieties 3. RD6 and Khao Dok Mali (KDML) 4. Adoption process 5. Impact on agro-ecosystem

2 2 Marginal land ; natural setting The Korat Plateau of m above sea level, undulating topography. Surface has been heavily weathered and nutrition washed out. Paddy fields cover a land area of 600 million ha. Source of irrigation is very limited.

3 Marginal land; 32.0 Rainfall Temperature rain shadow Monsoon area 22.0 rain shadow 20.0 Days of dry spell Temperature ( ) JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Khon Kaen ( ) The amount of rainfall is insufficient for rice cultivation. Year -to-year fluctuation is large. 0.0 Rainfall (mm)

4 Rice and rain 4 It is not possible to plant rice in every paddy plot The rice is suffered by drought and/or floods Good yield Poor yield No yield Unplanted 60.0 Area (%) Rice crops in Don Daeng village ( )

5 Drought, salinity, flood 5

6 6 Production Average yield of Northeast is 1.6t/ha of major rice for Rice is consumed in the village generally and seldom sold.

7 7 Ecology of rice varieties in early 1980s Don Daeng, which is located in the central part of Northeast Thailand 30 varieties were usually planted Glutinous rice and nonglutinous rice

8 8 Maturity of varieties Early, medium, late and extremely late. The mediummaturing variety was the most in terms of the number of cultivars The area covered by the latematuring variety was the largest. Khao Iluangtong Khao Khao Chaomali, Chaodaeng Khao Hommali, Khao Dokmali Others Khao Do-plasiu Khao Makok Khao Doyuan Others Khao Khao Kam Bakmuaihin RD6 Khao Khaoklang Khao Ilongma Khao Maephung Khao Sanpathong Khao Maemim Khao Ithod Khao Hangnak Khao Dokchan Khao Kasetklang Khao Chaoloi Khao Iheng Others Plural groups, upland rice Khao Udomyai Khao Khaoyai Khao Yai Others Khao Kasetyai,Khao Kamphai Planted area of varieties (DD,1983)

9 nong 9 The shallow saucer shaped topography. About 20 nongs around village compounds. Topo-sequence Lower paddy field Middle paddy field Upper paddy field

10 Water dynamics of paddy field The water in the upper 40 paddy field vanishes sooner but that in the 30 lower paddy field is 20 retained much longer 10 after the end of the rainy season. 0 Water depth (cm) 50 T T T Hd Hd Hd Hv Hv Bottom Side slope Elevation levee Hv L Jul. E Aug. M Aug. L Aug. E Sep. M Sep. L Sep. E Oct. M Oct. L Oct. E Nov. M Nov. L Nov. E Dec. M Dec. T; Transplanting time, Hd; Heading time, Hv; Harvesting time Upper paddy field limits the heading time of rice to the end of October. Lower paddy field allow the longer growth duration.

11 11 Progress of transplanting and harvesting in Don Daeng (1983) Area(%) L. Jun. E.. Jul. M. Jul. L.. Jul. E. Aug. M. Aug. L. Aug. E. Sep. M. Sep (ca plots, 340ha) L. Sep. E. Oct. M. Oct. L. Oct. E. Nov. M. Nov. L. Nov. E. Dec. M. Dec. L. Dec Rainfall (mm) Water-logging zone Transplanting Heading Harvesting Accumulating zone Transplanting Heading Harvesting Intermediate zone Transplanting Heading Harvesting Draining zone Transplanting Heading Harvesting Rainfall(DD)

12 12 Planted area ratio of varieties in every water condition of paddy field in Don Daeng (1983) Draining zone Intermediate zone Accumulating zone Late-maturing varieties of glutinous rice Medium-maturing varieties of g.r. RD6 Early-maturing varieties of g.r. Nonglutinous varieties Waterlogging zone 0% 20% 40% 60% 80% 100% Area (%)

13 13 Transplanting and topo-sequence Lower middle upper paddy field From the lower paddy field with latematuring varieties. In the middle paddy field with mediummaturing varieties. The upper paddy field with medium and early-maturing varieties.

14 14 Harvesting Early medium late maturing variety Farmers harvested the rice in upper paddy field early, then in the middle paddy field and in the lower paddy field at the last.

15 15 Schematic relationship among rain, water and rice

16 16 Merit of varieties allocation according topo-sequence Early maturing varieties : avoidance of drought damage in upper paddy fields. Late maturing varieties: higher productivity depending on long growth duration.

17 17 RD6 expansion Improved glutinous variety, released in In Don Daeng Year Farmers planting RD6(%) Area planted by RD6 (%) Agricultural statistics shows that 83% of total glutinous rice area was planted by RD6 in the Northeast in 1995.

18 RD6 distribution (1997) 18

19 19 KDML (khao dawk mali) KDML105(released in1959), Chao Mali or Hom Mali by farmers dialect In 1995, KDML area reached 71% of the total nonglutinous rice planted area and 37% of the rice planted area of the Northeast. Core region; all districts of Buriram, Surin and Sisaket provinces (1997 by MAPNET). Expansion in Roiet,Yasothon, Amnat Charoen In Don Daeng, 7% in 1983, 15% in 1991, 4% in 1999.

20 Original KDML area distribution of non-glutinous (1997) rice 20

21 Adoption process 21 RD6 In the late 1980s, as investment in rice growing increased, RD6 spread rapidly in short. Two steps. In the first extension stage, the planted area of RD6 expanded with the introduction of modern growing technology to raise yields. a better yield response to fertilizer than other varieties. In the second stage, the RD6 explosion was aided by its cooking quality. once steamed in the morning, RD6 rice can maintain its soft quality until evening.

22 22 KDML expansion (Yasothon) To seek new cash income source. the price merit compared with glutinous rice. KDML planting could be possible after raising the yield of glutinous rice (as staple food) by introduction of RD6 and much manuring. Year-to-year variation of rice production was very small owing to favorable rainfall. Farmers can expect to get certain crop from rice.

23 23 Impact on agro-ecosystem In Don Daeng, All paddy fields on topo-sequence were occupied by RD6 and KDML belonging to medium-maturing varieties. The role of early -maturing varieties was replaced by irrigation. Yielding ability of long growth duration was replaced by fertilizer.

24 Planted area ratio of varieties in every water condition of paddy field in Don Daeng (1991) 24 Draining zone Intermediate zone Accumulating zone Late-maturing varieties of glutinous rice Medium-maturing varieties of g.r. RD6 Early-maturing varieties of g.r. Nonglutinous varieties Waterlogging zone 0% 20% 40% 60% 80% 100% Area (%)

25 25 Land consolidation For introduction of machinery Simultaneous events of variety change, input of chemicals.

26 26 Problems Submergence of grains in lower paddy fields. Active irrigation for upper paddy field leaded long time inundation in lower paddy fields after the rainy season. All paddy field had to be harvested at the same season.

27 Progress of transplanting and 27 harvesting in Don Daeng (1991) Area(%) < Transplanting > < Harvesting > 0 L E M L E M L E M L E M L E M L E M L Jun Jul Aug Sep Oct Nov Dec Draining zone Intermediate zone Accumulating zone Waterlogging zone Escape from labor competition Employment (transplanting, harvesting, threshing machine) Decrease area operated by one household

28 28 Results Yield are still very low and unstable in Don Daeng. There is a gradual increase in rice yield per harvested area. 2.5 per harvested area per operating area 2.0 Average yield (t/ha)

29 29 Sustainability of rice growing Rice growing 7000 contributes 6000 only to 2% of 5000 the total cash 4000 income The system is 2000 sustained by 1000 off-farm jobs of farmers. 0 Baht/household/year Expenditure Sales of rice In 1998/99 Non-glutinous rice Glutinous rice Threshing Harvesting Herbicide Pesticide Chemical fertilizer Organic manure Irrigation Transplanting Power tiller Seed